IPAC2013 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOODB103	Results of an Experiment on Hydrodynamic Tunnelling at the SPS HiRadMat High Intensity Proton Facility	target, proton, synchrotron, instrumentation	37
	R. Schmidt, J. Blanco, F. Burkart, D. Grenier, D. Wollmann CERN, Geneva, Switzerland E. Griesmayer CIVIDEC Instrumentation, Wien, Austria N.A. Tahir GSI, Darmstadt, Germany
	To predict the damage for a catastrophic failure of the protections systems for the LHC when operating with beams storing 362 MJ, simulation studies of the impact of an LHC beam on targets were performed. Firstly, the energy deposition of the first bunches in a target with FLUKA is calculated. The effect of the energy deposition on the target is then calculated with a hydrodynamic code, BIG2. The impact of only a few bunches leads to a change of target density. The calculations are done iteratively in several steps and show that such beam can tunnel up to 30-35 m into a target. Validation experiments for these calculations at LHC are not possible, therefore experiments were suggested for the CERN Super Proton Synchrotron (SPS), since simulation studies with the tools used for the LHC also predict hydrodynamic tunnelling for SPS beams. An experiment at the SPS-HiRadMat facility (High-Radiation to Materials) using the 440 GeV beam with 144 bunches was performed in July 2012. In this paper we compare the results of this experiment with our calculations of hydrodynamic tunnelling.
	Slides MOODB103 [40.426 MB]

MOODB202	Simulations and Measurements of Cleaning with 100 MJ Beams in the LHC	proton, collimation, beam-losses, betatron	52
	R. Bruce, R.W. Aßmann, V. Boccone, C. Bracco, M. Cauchi, F. Cerutti, D. Deboy, A. Ferrari, L. Lari, A. Marsili, A. Mereghetti, E. Quaranta, S. Redaelli, G. Robert-Demolaize, A. Rossi, B. Salvachua, E. Skordis, G. Valentino, V. Vlachoudis, Th. Weiler, D. Wollmann CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain E. Quaranta Politecnico/Milano, Milano, Italy G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The CERN Large Hadron Collider is routinely storing proton beam intensities of more than 100 MJ, which puts extraordinary demands on the control of beam losses to avoid quenches of the superconducting magnets. Therefore, a detailed understanding of the LHC beam cleaning is required. We present tracking and shower simulations of the LHC's multi-stage collimation system and compare with measured beam losses, which allow us to conclude on the predictive power of the simulations.
	Slides MOODB202 [6.343 MB]

MOPEA014	Temporal and Spectral Observation of Laser-induced THz Radiation at DELTA	electron, laser, radiation, storage-ring	94
	P. Ungelenk, H. Huck, M. Huck, M. Höner, S. Khan, R. Molo, A. Schick DELTA, Dortmund, Germany N. Hiller, V. Judin KIT, Karlsruhe, Germany
	Funding: Work supported by the DFG, the BMBF, the Federal State NRW, the Initiative and Networking Fund of the Helmholtz Association, and the German Federal Ministry of Education and Research. Coherent THz pulses caused by a laser-induced density modulation of the electron bunches are routinely produced and observed at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. New measurements performed with a fast hot-electron bolometer allow insight into the turn-by-turn evolution of these pulses. Furthermore, first results from a Fourier transform infrared spectrometer, which is currently under commissioning, are presented.

MOPEA016	The Main Stochastic Cooling System of the HESR	kicker, pick-up, accumulation, vacuum	100
	R. Stassen, R. Greven, R. Maier, G. Schug, H. Stockhorst FZJ, Jülich, Germany
	The main stochastic cooling system of the High-Energy Storage Ring HESR (1.5-15 GeV/c) for antiprotons at the FAIR complex (Facility for Antiprotons and Ion Research) in Darmstadt (GSI) will work in the frequency range of 2 - 4 GHz. The design work on pickup and kicker is now finished and the production of the first cooling tank has been started. The whole system layout will be presented taking into account new additional requirements concerning the accumulation and the cooling of heavy ions. All beam-coupling structures are nearly identical and contain several ring-slot blocks. These blocks consist of eight wall-current monitors coupled out by eight electrodes each. Most of the signal combining and splitting take place within the vacuum envelope to reduce the number of vacuum RF feed throughs. The long-distance transmission of the signals and the filters containing long signal delays work with near infrared optical elements.

MOPEA018	Feasibility Study of Heavy Ion Storage and Acceleration in the HESR with Stochastic Cooling and Internal Targets	target, cavity, ion, acceleration	106
	H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen FZJ, Jülich, Germany T. Katayama GSI, Darmstadt, Germany
	Stochastic cooling of heavy ions is investigated under the constraint of the present hardware design of the cooling system and RF cavities as well as the given magnet design as foreseen for anti-proton cooling in the HESR of the FAIR facility. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam to 2 GeV/u is studied under the basic condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The cooling simulations include the beam-target interaction due to a Hydrogen and Xenon target. Diffusion due to Schottky and thermal noise as well as intra beam scattering is accounted for. Due to the higher charge states of the ions Schottky particle noise power becomes an important issue. The analysis considers the electronic power limitation to 500 W in case of momentum cooling. Fast Filter cooling is only available if the revolution harmonics do not overlap in the cooling bandwidth. Since overlap occurs for lower energies the application of the Time-Of-Flight (TOF) momentum cooling method is discussed.

MOPEA021	Status of the HESR Electron Cooler Test Set-up	electron, cathode, controls, vacuum	115
	M.W. Bruker, K. Aulenbacher, J. Dietrich, S. Friederich, A. Hofmann, T. Weilbach HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany
	For the proposed High Energy Storage Ring (HESR) at FAIR, it is foreseen to install an electron cooling device with a beam current of 3 A and a beam energy of 8 MeV. A test set-up was built at Helmholtz-Insitut Mainz (HIM) to conduct a feasibility study. One of the main goals of the test set-up is to evaluate the gun design proposed by TSL (Uppsala) with respect to vacuum handling, EM fields and the resulting beam parameters. Another purpose of the set-up is to achieve an energy recuperation efficiency of 1 - 10^-5. To measure this quantity, a Wien filter has to be employed, which will also prove capable of mitigating collection losses. The current status of the project will be presented.

MOPEA032	Installation Status of Deuteron Injector of IFMIF Prototype Accelerator in Japan	neutron, rfq, emittance, alignment	148
	H. Shidara, J. Knaster IFMIF/EVEDA, Rokkasho, Japan D. Bogard, N. Chauvin, P. Girardot, R. Gobin, F. Harrault, D. Loiseau, P.A.P. Nghiem, A. Roger, F. Senée CEA/DSM/IRFU, France L. Semeraro F4E, Barcelona, Spain
	The International Fusion Materials Irradiation Facility (IFMIF) will generate a neutron irradiation field with the spectrum simulating the fusion D-T neutrons (14 MeV) to qualify suitable materials for fusion power plants. The IFMIF accelerator facility provides two CW / 40 MeV / 125 mA deuteron beams to the IFMIF Lithium target facility. In the Engineering Validation and Engineering Design Activities phase, the concept of IFMIF is validated with a single CW / 9 MeV / 125 mA deuteron accelerator prototype under construction in JAEA/Rokkasho. The injector part has been designed, constructed and successfully tested by CEA/Saclay. The ECR ion source produces a deuteron beam of 140 mA at 100 keV. In spring 2013, the injector will be delivered and re-installed on the Rokkasho site. This paper will focus on the detailed plan of the injector’s re-assembly as well as on the re-commissioning. Further possible improvements are discussed in order to achieve reliable operation.

MOPEA037	Theoretical Study on the Two-stage Collimation System Design	collimation, scattering, vacuum, space-charge	157
	N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	Two-stage collimation system is widely used in high intensity machines to localize the beam losses in a restricted area. In the well-known theory, the optical constrains are expressed by the betatronic phase advances between primary and secondary collimators, which minimize the size of the secondary halo. In this paper, the physical model is developed considering the characteristic of the space charge dominated beams. Numerical studied are performed to verify the theoretical model.

MOPEA040	Study of Geometry Dependent Multipacting of a Superconducting QWR	accelerating-gradient, electron, cavity, vacuum	166
	K. Zhou, X.Y. Lu, X. Luo, S.W. Quan, L. Yang, Z.Y. Yao PKU, Beijing, People's Republic of China
	Funding: The Major Research Plan of National Natural Science Foundation of China A superconducting quarter wave resonator (QWR) of frequency=162.5 MHz and β=0.085 has been designed at Peking University. This paper focus on the multipacting (MP) study for the QWR with CST Particle Studio. The simulation results for the initial designed model reveal that there is no sign of MP with its normal operating accelerating gradients in the range of 6-8 MV/m. The accelerating gradient range that may incur MP is from about 1.4 MV/m to 3.2 MV/m, and the places where MP may be encountered are mainly located at the top part of the QWR. So the effect of different top geometries on MP has also been studied in depth. Our results show that inward convex round roof is better than other round roofs, and plane roofs have an obvious advantage over round roofs on the suppression of MP in general. While considering the optimization of its electromagnetic (EM) design, our initial designed model is also acceptable.

MOPEA042	Research on the Design and Simulation of the CSRE Stochastic Cooling System	sextupole, pick-up, emittance, target	169
	X.J. Hu, H. Jia, Y.J. Yuan, X.H. Zhang IMP, Lanzhou, People's Republic of China
	Stochastic cooling by the use of a feedback system, aims at cooling of secondary particles or particles with large emittance or momentum spread. My research is mainly on the simulation of horizontal and longitudinal stochastic cooling process. The purpose of my work is to obtain the optimum parameters for stochastic cooling, according the actual accelerator lattice. Pickup and preamplifier are already installed on the CSRe, and preliminary results are get.

MOPEA043	Transverse Instabilities of Two Twisted Beams in a Storage Ring	ion, electron, storage-ring, kicker	172
	B.C. Jiang, M.Z. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China G.X. Xia UMAN, Manchester, United Kingdom
	Two twisted beams (two beams run on the different closed orbit) in a storage ring which is produced by fast kickers can potentially deliver two bunds of radiations through one insertion device or one bend magnet, in this way doubles the beam line stations. This operation mode needs higher beam current and more RF buckets to be filled to keep the brightness comparable to the single beam operation mode. The resistive wall instability and ion trapping effects is analysed to address the higher current operation possibility. The analyze results show that twisted beams can weaken those two instabilities.

MOPEA059	The Optimization of Transverse Stripline Kicker	kicker, vacuum, impedance, insertion	214
	H.P. Hsueh, C.-C. Chang, Y.P. Chang, J.-R. Chen, Y.T. Cheng, G.-Y. Hsiung, Y.C. Yang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. It is required to install stripline kickers to suppress instability generated by mismatch between injection kickers or imperfect installation of vacuum components all around. First, the design philosophy will be described for transverse stripline kickers. HFSS electromagnetic simulation software is used to optimize all structure parameters like electrode dimensions, electrode distance from vacuum chambers etc. to make transverse stripline kicker working more efficiently and effectively. All simulation results will be presented in this paper and all structure dimension choices will be discussed and the final prototype structure dimensions will be selected from the discussion.

MOPEA073	Current Status of the LBNE Neutrino Beam	target, proton, shielding, focusing	255
	C.D. Moore, K.R. Bourkland, C.F. Crowley, P. Hurh, J. Hylen, B.G. Lundberg, A. Marchionni, M.W. McGee, N.V. Mokhov, V. Papadimitriou, R.K. Plunkett, S.D. Reitzner, A.M. Stefanik, G. Velev, K.E. Williams, R.M. Zwaska Fermilab, Batavia, USA
	Funding: Work supported by the Fermilab Research Alliance, under contract DE-AC02-07CH11359 with the U.S. Dept of Energy. The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab. The facility is designed to aim a beam of neutrinos toward a detector placed in South Dakota. The neutrinos are produced in a three-step process. First, protons from the Main Injector hit a solid target and produce mesons. Then, the charged mesons are focused by a set of focusing horns into the decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined by an amalgam of the physics goals, the Monte Carlo modeling of the facility, and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ~700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW. The LBNE Neutrino Beam has made significant changes to the initial design through consideration of numerous Value Engineering proposals and the current design is described.

MOPEA083	Energy Modulation in Coherent Electron Cooling	electron, ion, plasma, FEL	276
	G. Wang, M. Blaskiewicz, V. Litvinenko BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Coherent electron cooling (CeC) relies on Debye shielding to imprint information of the ion beam to an electron beam [1]. Apart from the density modulation, Debye shielding also modulates the energy of electrons, which provides additional seeding for the free electron laser (FEL) amplifier. In this work, we show that the energy modulation of a longitudinal slice of the electrons, induced by dynamic Debye shielding of a moving ion in anisotropic electron plasma with κ-2 velocity distribution, can be expressed into a 1D integral. The results are then applied to the 1D FEL model to investigate the effects of energy modulation to the correcting force in the kicker. [1] V.N. Litvinenko, Y.S. Derbenev, Coherent Electron Cooling, Physical Review Letters, 102 (2009) 114801. http://link.aps.org/abstract/PRL/v102/e114801

MOPFI014	A Charge Lifetime Study of NEA GaAs Cathode by Ion Back-bombardment	electron, cathode, ion, vacuum	312
	M. Kuriki KEK, Ibaraki, Japan L. Guo, H. Iijima, K. Miyoshi HU/AdSM, Higashi-Hiroshima, Japan
	Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science and Technology; The title is High Brightness Photon Beam by Laser-Compton Scattering. NEA GaAs cathode is one of the most important techniques for advanced future projects based on linac. Up to 90% polarized beam can be generated with high quantum efficiency, 0.1 – 10%. The extremely low emittance beam can be generated driven by optimized wavelength laser. Although these remarkable features, the less robustness has been the biggest issue on the real operation of this cathode. According to past experiments, there are three sources of the cathode degradation; gas absorption, thermal desorption, and ion-back bombardment. First two processes could be controlled by less vacuum pressure in order of 10^-10Pa and keeping the cathode temperature low. The ion back-bombardment is the last issue which should be solved for high brightness operation in such as ERL. We observed the cathode quantum efficiency evolution in various laser power density and bias voltage. We found that the cathode degradation was due to the ion back-bombardment quantitatively and the deactivation coefficient of NEA surface by one ion collision did not depend on the bias voltage. We report the experimental results and its analysis based on the ion back-bombardment hypothesis.

MOPFI017	SuperKEKB Positron Source Target Protection Scheme	target, positron, electron, radiation	315
	L. Zang, T. Kamitani KEK, Ibaraki, Japan
	The SuperKEKB requires an intense beam with a large number of positrons, which is generated by a high energy electron beam strike on a solid tungsten target. The cascade shower in the target deposits large amount of energy in the material leading to target damage. The pulsed electron beam distributed the energy non-uniformly over the target. In that case, a mechanical stress appears due to the large thermal gradient during each pulse, which could potentially destroy the target. Based on the analysis of the SLAC damaged target, peak energy deposition density (PEDD) should not exceed 35 J/g to ensure a long term of safe operation. One way of reducing PEDD is increasing the beam spot size. Hence we proposed a target protection scheme, in which a protection target is placed upstream of generation target as a spoiler. The aim is to maintain the generation target’s PEDD below 35 J/g even with a point primary electron beam. In this paper, we will introduce graphite, aluminum and copper as the protection target material candidates. And also present the PEDD and positron yield evaluation as a function of various parameters such as protection target thickness and drift space.

MOPFI018	Design Study of a New Large Aperture Flux Concentrator	positron, target, solenoid, focusing	318
	L. Zang, M. Akemoto, S. Fukuda, K. Furukawa, T. Higo, K. Kakihara, T. Kamitani, Y. Ogawa, H. Someya, T. Takatomi KEK, Ibaraki, Japan
	For high luminosity electron-positron colliders, intense positron beam production is one of the key issues. Flux Concentrator (FC) is a pulsed solenoid that can generate high magnetic field of several Tesla and is often used for focusing positrons emerged from a production target. It works as an optical matching device in a positron capture section. With this device, high capture efficiency is achieved. In this paper, we will introduce a new design of a FC for the SuperKEKB positron source. The advantages of the new design are: 1. the aperture could be doubled of the previous design, 2. the transverse components are only 1/10 of the previous design, 3. maintain the same high peak longitudinal field. The new FC modeling has been done in CST Studio and we will report the results of new FC field evaluation. In order to calculate the positron yield and capture efficiency, a tracking simulation to the end of capture section has also been carried out, which is also included in this paper.

MOPFI026	Thermal Simulations of a New Target Configuration for Production of Radioactive Nuclide	target, neutron, radiation, ion	336
	L.H. Chen, B.Q. Cui, Q.H. Huang, W. Jiang, R. Ma, Y.J. Ma, B. Tang CIAE, Beijing, People's Republic of China
	China Advanced Rare Ion-beam Facility (CARIF) based on China Advanced Research Reactor (CARR) has been proposed in order exploring the frontier of nuclear physics. A target with 5 g 235U is proposed in the project. The thermal neutron fission of 235U will produce radioactive nuclei and the great thermal load (~50 kW). The target of CARIF needs endure high temperature and thermal energy deposit. A new multi-targets configuration is proposed. It consists of several discrete targets instead of traditional single-target structure used in accelerator driven facility. Because there is more thermal radiation area in this configuration, thermal radiation capacity is enhanced, so the target can withstand higher thermal power. The temperature distribution of multi-targets was simulated with finite element code. The results show that the configuration of multi targets can effectively reduce the target temperature. From the perspective of target temperature distribution, the configuration could endure 50kW thermal deposit. It's possible to use 5 g 235U in CARIF for production of radioactive nuclide.

MOPFI041	Study of Beam Longitudinal Motion for SSC	extraction, injection, cyclotron, acceleration	378
	X.N. Li, Y.J. Yuan IMP, Lanzhou, People's Republic of China
	The injection, acceleration and extraction of SSC（Separate Sector Cyclotron） is analyzed and simulated to get the longitudinal acceptance, using the typical ion 238U³⁶⁺ with energy 9.7MeV/u. In order to study the actual longitudinal acceptance of SSC, the isochronous magnetic field model in coincidence with the real one is established by Kr-Kb and Lagrange methods based on the actual measurement. Under the isochronous magnetic field, the longitudinal acceptance at the injection, acceleration and extraction is calculated. From the simulation results the transmission efficiency is very low in SSC because of the large phase width of the beam from the injector SFC (Sector Focus Cyclotron). In the machine commissioning, the phase width of the beam line from SFC to SSC is measured by the phase probe, the results show that the actual phase width is larger than the acceptance of SSC.

MOPFI045	Studying of Multipacting in Micro-pulse Electron Gun	electron, gun, resonance, cavity	383
	L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI046	Transverse RF Kicker Excitation and Longitudinal RF Noise Diffusion for Slow Extraction from SAPT	extraction, kicker, synchrotron, resonance	386
	L. Ouyang, M. Gu, D.M. Li, Q. Yuan, M.Z. Zhang SINAP, Shanghai, People's Republic of China
	Two key techniques used in the slow extraction from synchrotron accelerator: longitudinal RF stochastic noise acceleration, and transverse RF knock out excitation have been studied in this paper. Detailed comparison have revealed the potentials and limits of both methods. For the longitudinal RF stochastic acceleration excitation, the focus has been the phase space compression of particles, which makes the them to hasten around the RF bucket of the cavity, thus to lower the senstivity to ripple. For the transverse RF knock out excitation, the emphasis have been optimal schemes of amplitude modulation and frequency modulation of the RF singals. The optimizations are also used to lower the senstivity of the beam to the ripple and to enhance the uniformity of the extracted beam.

MOPFI050	Non-local Fast Extraction from the CERN SPS at 100 and 440 GeV	extraction, kicker, septum, injection	392
	F.M. Velotti, A. Alekou, W. Bartmann, E. Carlier, K. Cornelis, I. Efthymiopoulos, B. Goddard, L.K. Jensen, V. Kain, M. Kowalska, V. Mertens, R. Steerenberg CERN, Geneva, Switzerland
	The Long Straight Section 2 (LSS2) of the CERN SPS is connected with the North Area (NA), to which the beam to date has always been extracted using a resonant extraction technique. For new proposed short- and long-baseline neutrino experiments, a fast single turn extraction to this experimental area is required. As there are no kickers in LSS2, and the integration of any new kickers with the existing electrostatic septum would be problematic, a solution has been developed to fast extract the beam using non-local extraction with other SPS kickers. Two different kicker systems have been used, the injection kicker in LSS1 and the stronger extraction kicker in LSS6 to extract 100 and 440 GeV beam, respectively. For both solutions a large emittance beam was extracted after 5 or 9 full betatron periods. The concept and simulation details are presented with the analysis of the aperture and beam loss considerations and experimental results collected during a series of beam tests.

MOPFI059	Design and Performance of the Beam Transfer Lines for the HIE-ISOLDE Project	target, emittance, optics, dipole	416
	A.S. Parfenova, W. Andreazza, J. Bauche, E.D. Cantero, P. Farantatos, M.A. Fraser, B. Goddard, Y. Kadi, A.J. Kolehmainen, D. Lanaia, M. Martino, R. Mompo, E. Siesling, A.G. Sosa, M.A. Timmins, G. Vandoni, D. Voulot, E.S. Zografos CERN, Geneva, Switzerland
	Beam design and beam optics studies for the HIE-ISOLDE transfer lines have been carried out in MadX, and benchmarked against Trace3D results. Magnet field errors and alignment imperfections leading to deviations from design parameters have been treated explicitly, and the sensitivity of the machine's lattice to different individual error sources was studied. As a result, the tolerances for the various error-contributions have been specified for the different equipment systems. The design choices for the expected magnet field and power supply quality, alignment tolerances, instrument resolution and physical aperture were validated. The methodology and results of the studies are presented.

MOPFI065	VELA (formerly EBTF) Simulations and First Beam Commissioning	gun, diagnostics, laser, electron	431
	J.W. McKenzie, D. Angal-Kalinin, J.K. Jones, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	VELA (Versatile Electron Linear Accelerator), formerly known as EBTF (Electron Beam Test Facility), at STFC Daresbury Laboratory, is a photoinjector test facility which will provide beam into two user areas for scientific and industrial applications. It is based on a 2.5 cell S-band RF photoinjector driven by a Ti:Sapphire laser. The design is aimed to deliver short bunches at 10-250 pC charge with low transverse emittance. We present beam dynamics simulations of VELA as well as the results from first beam commissioning.

MOPFI070	Spallation is not the only Fruit: Low Energy Fusion as a Source of Neutrons	neutron, target, proton, radiation	443
	S.C.P. Albright, R. Seviour University of Huddersfield, Huddersfield, United Kingdom
	Commercially there is a growing interest in applications of neutrons. Currently the majority of neutron sources are based at research institutions from either reactors or spallation sources. Smaller portable sources contain either fissile isotope or sealed fusors are available, although they either use or produce tritium, or other long lived decay products. As an alternative to the large facilities and the radio-toxicology of current portable sources research is being performed with an aim to produce a fusion based neutron source with neither of these concerns. We show that MCNPX is able to accurately reproduce (p,n) reactions for a number of light elements. Simulations of low energy proton reactions with light nuclei simulated with MCNPX and Geant4 are compared with experiment.

MOPFI073	Optimisation Studies of a High Intensity Electron Antineutrino Source	target, neutron, proton, cyclotron	449
	A. Bungau, R.J. Barlow University of Huddersfield, Huddersfield, United Kingdom J.R. Alonso, J.M. Conrad, J. Spitz MIT, Cambridge, Massachusetts, USA M. Shaevitz Columbia University, New York, USA
	ISODAR (Isotopes-Decay-At-Rest) is a novel, high intensity source of electron antineutrinos produced by the decay of Li-8 isotopes, which aims for searches for physics beyond the standard model. The Li-8 isotopes are produced in the inelastic interactions of low energy protons or deuterons with a Beryllium target. In addition the Li-8 is produced in the surrounding materials by secondary neutrons. This paper focuses on the optimisation of the base design target, moderator and reflector.

MOPME003	Development of Diamond Sensors for Beam Halo and Compton Spectrum Diagnostics After The Interaction Point of ATF2	collimation, electron, photon, vacuum	470
	S. Liu, P. Bambade LAL, Orsay, France S. Bai IHEP, Beijing, People's Republic of China T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	ATF2 is a low energy (1.3GeV) prototype of the final focus system for ILC and CLIC linear collider projects. A major issue at ATF2 and in linear colliders is to control the beam halo, which consists of tails extending far beyond the Gaussian core of the beam. At present there is no dedicated collimation for the beam halo at ATF2, and the transverse distribution near the interaction point is not well known. The development of a sensor based on CVD diamond to scan the beam halo in the vacuum chamber a few meters after the interaction point is presented. This system also aims to detect the Compton recoil electrons generated by the laser interferometer (Shintake monitor) used to measure the beam size at the interaction point of ATF2.

MOPME012	Single-bunch Longitudinal Phase Space Diagnostics in Multi-bunch Mode at the European XFEL	septum, dipole, diagnostics, electron	494
	M. Yan, C. Gerth DESY, Hamburg, Germany
	Dedicated longitudinal electron beam diagnostics is highly demanded for the control and optimization of modern X-ray free-electron lasers (XFEL). At the European XFEL, 3 transverse deflecting structures (TDS) will be installed at different locations of the accelerator for measurements of slice emittance and longitudinal profile. Operation of a TDS in combined use with an energy spectrometer, e.g. a dispersive section after a single dipole magnet, allows additionally for longitudinal phase space (LPS) measurements. However, utilization of a dipole magnet is not compatible with single-bunch measurements in multi-bunch operation mode, which will be the standard operation mode of the European XFEL. In this paper, we propose a LPS diagnostic beamline consisting of a TDS, fast kicker and septum magnet for the European XFEL. The layout of the accelerator lattice with optimized optics for LPS measurements will be presented.

MOPME015	Numerical Wakefield Calculations for Electro-optical Measurements	wakefield, laser, storage-ring, impedance	503
	B. Kehrer, A. Borysenko, E. Hertle, N. Hiller, V. Judin, S. Marsching, A.-S. Müller, M.J. Nasse, M. Schuh KIT, Karlsruhe, Germany
	Funding: This project is funded by the Federal Ministry of Education and Research under the contract number 05K10VKC The technique of electro-optical measurements allows precise and single-shot measurements of the bunch length and shape. The installation of such a near-field setup changes the impedance of the storage ring and the corresponding effects have to be studied carefully. One possibility is to use numerical codes for simulating the wakefields induced by the setup. Such simulations has been done using the wakefield solver implemented in the CST Studio Suite. In this paper we present the simulation results together with first measurements.

MOPME020	Development of the New Measurement Method for the Incoherent Tune Spread and the Tune Shift Caused by the Space Charge Effect	dipole, emittance, injection, space-charge	512
	S. Kato Tohoku University, Graduate School of Science, Sendai, Japan H. Harada, H. Hotchi, M. Kinsho, K. Okabe JAEA/J-PARC, Tokai-mura, Japan
	For the high intensity accelerator, the incoherent tune which is the frequency of the individual particles is shifted and decreases due to the space charge effect. In addition, the incoherent tune is formed into spread shape commonly. When the incoherent tune satisfies a resonance condition, it might be occurred the beam emittance growth and the beam loss. So it is necessary to reduce the incoherent tune spread and the tune shift as much as possible. To achieve this condition, it is desired to measure the incoherent tune spread and the tune shift directly. Therefore we are developing the new measurement method of the incoherent tune spread and the shift due to the space charge effect. From the simulation results, it was cleared that the beam distribution can be modified in the case of using the mono frequency dipole exciter because a particle which has the tune corresponding to the exciter can be resonated temporary. In addition, it was cleared that it is possible to evaluate the incoherent tune spread and the tune shift by the measurement of the distribution transition. We present the outline of this method and the developing plane at the J-PARC RCS.

MOPME023	ORBIT Beam Simulation Progress in the 3-GeV Rapid Cycling Synchrotron of J-PARC	lattice, injection, impedance, synchrotron	521
	P.K. Saha, H. Harada, H. Hotchi, Y. Shobuda, M. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan J.A. Holmes ORNL, Oak Ridge, Tennessee, USA S. Kato Tohoku University, Graduate School of Science, Sendai, Japan
	We have made a numerous progress for beam simulation in the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) by using 3-D particle tracking code, ORBIT. Namely, the TEAPOT lattice file used for ORBIT tracking has been made to give exactly same results to that with SAD model used for the RCS beam commissioning. In addition, time dependent lattice functions of the injection chicane magnets and similar other time dependent lattice imperfections, which are already found to have significant influences on the beam losses in the real machine have also been successfully introduced. At present, time dependent transverse and longitudinal impedances are going to be introduced. That should prove the ORBIT code much more matured for beam simulations in synchrotrons. Latest beam simulation results illustrating these new realistic features are presented.

MOPME027	Bunch Length Measurement of 181 MeV Beam in J-PARC Linac	electron, linac, target, vacuum	532
	A. Miura, H. Oguri, N. Ouchi, J. Tamura JAEA/J-PARC, Tokai-mura, Japan A. Feschenko, A.N. Mirzojan RAS/INR, Moscow, Russia K. Futatsukawa, T. Miyao KEK, Ibaraki, Japan M. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan T. Maruta KEK/JAEA, Ibaraki-Ken, Japan
	In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. Because the longitudinal matching before ACS cavities is additionally required, we decided to employ the bunch shape monitors (BSMs) to measure the longitudinal beam profile. After three years from the start of BSM project, three BSMs were fabricated. All three BSMs were installed during the summer shutdown of 2012. We tried to measure the longitudinal beam profile exited from SDTL cavities. In this paper, we introduce the outline of BSM project, the first data acquisition and related small problems.

MOPME039	A New Method of Acquiring Fast Beam Transversal Profile in the Storage Ring	synchrotron, factory, electron, synchrotron-radiation	556
	C. Cheng, P. Lu, B.G. Sun, K. Tang, F.F. Wu, Y.Y. Xiao, Y.L. Yang, Z.R. Zhou, J.Y. Zou USTC/NSRL, Hefei, Anhui, People's Republic of China
	A new method of acquiring fast beam transverse profile has been developed and will be used in HLS II. This method is based on four signals from MAPMT (multi-anode photo-multiplier tube) and logarithm processing technique. First, the calculation formula of beam transversal size and position are deduced using above method. Then, the main performances (e.g. sensitivity and linearity range) are analyzed. According to stimulation result, regardless of cross-talk and inconsistency between channels, the size signal has a linear relation with size s when s=0.8-2mm and position d=±2mm, the position signal has a linear relation with position d and the linear range exceeds ±2mm when s=0.8-2mm. With channel cross-talk and channel inconsistency being considered, the stimulation results also are given. Finally, a fast beam transverse profile monitor is designed and provides turn-by-turn measurement of the beam transverse profile.

MOPME041	Design and Calculation of the Stripline Beam Position Monitor for HLS II Storage Ring	quadrupole, coupling, storage-ring, impedance	562
	F.F. Wu, C. Cheng, W.B. Li, P. Lu, T.J. Ma, B.G. Sun, H. Xu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by the National Science Foundation of China (10875117, 11005105, 11175173) According to the requirements of HLS II upgraded, in order to acquire the non-intercepting measurement of beam position and quadrupole component, a new stripline beam position monitor (BPM) was designed for storage ring. The BPM parameters were optimized to acquire impedence matching with characteristic impedance of the external transmission lines and the coupling coefficients between the electrodes were calculated. According to the difference/sum and log-ratio methods, the horizontal and vertical sensitivities, mapping figures and fitting polynomials wered acquired. The results showed that sensitivities using log-ratio method were bigger than those using difference/sum method. The sum signal was also simulated when beam displacement varied from (0 mm, 0 mm) to (5 mm, 5 mm), the result showed that the variation of normalized sum signal was no more than ±6%. The gaussian weighted method of a two-dimensional grid structure was used to simulate the gaussian bunch and simulate the beam transverse quadrupole component changing with position (x, y), the result showed that the beam transverse quadrupole component changed linearly with position combination (x2-y2).

MOPME042	A PRELIMINARY SIMULATION OF BPM SIGNAL DIODE DETECTOR FOR HLS II TUNE MEASUREMENT SYSTEM*	betatron, storage-ring, pick-up, synchrotron	565
	J.J. Zheng, P. Lu, T.J. Ma, B.G. Sun, Y.L. Yang, J.Y. Zou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11105141, 11175173) and the Fundamental Research Funds for the Central Universities (WK2310000015) A high sensitivity BPM signal detection front-end electronics has been designed for HLS II tune measurement system according to the HLS II upgrade requirements. Classical tune measurement systems filter out just one or a few of these betatron sidebands frequency. As a consequence, most of the betatron energy is dropped and only a very small energy remains for further processing. A new method, referred to as Direct Diode Detection (3D) by LHC[1], improves the situation. In this paper, the HLS II BPM signals have been calculated out in time domain and frequency domain. Basing on the characteristics of HLS II BPM signal, a preliminary simulation is performed to test and verify the feasibility of diode detector for HLS II tune measurement system. The simulation results clearly show that the technique of diode-based circuit can be applied to HLS II tune measurement.

MOPME044	A Novel Type of Forward Coupler Slotted Stripline Pickup Electrode for CSRe Stochastic Cooling	impedance, pick-up, vacuum, kicker	571
	J.X. Wu, X.J. Hu, M. Li, J.W. Xia, J.C. Yang, Y. Zhang, G. Zhu IMP, Lanzhou, People's Republic of China F. Caspers CERN, Geneva, Switzerland
	A novel type of slotted or perforated strip-line pick-up or kicker electrode structure for CSRe stochastic cooling for non relativistic particle beams with b=v/c values around 0.7 is presented. This slotted structure is to be used as a forward coupler with the output signal taken from the downstream end and has a rather large relative bandwidth of several octaves. The electrode structure and pickup tank, as well as the beam test result will be presented in this paper.

MOPME046	Preliminary Experimental Results of Axial B-dot Measuring Beam Tilt	high-voltage, coupling, dipole, impedance	577
	X. He, Q. Li, C. Ma, J. Pang, L. Zhao CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	Funding: This work is under the support of NSFC project No. 11175166 Beam monitors sensitive to the beam's azimuthal B-dot field (sometimes referred as B-dots) are widly used to measure the displacement of beam centroid, as the beam generates a dipole term of the azimuthal magnetic field. The authors have pointd out that the similar B-dots sensitive to axial magnetic field can be used to measure the beam tilt directly in earlier work. A monitor which consists of four azimuthal B-dots and four axial B-dos is designed and fabricated. The monitor was tested on a coaxial calibration stand, which has a character resistance of 50 Ohm. Two position tuners are installed on the calibration stand, to adjust the position and the tilt of the inner conductor. Experiments show that the axial B-dot monitor can be successfully used to measure the tilt of the inner conductor directly.

MOPME047	Simulation of a Beam Angel Monitor using the Axial B-dot Field	monitoring, coupling, induction, dipole	580
	J. Pang, X. He, Q. Li, C. Ma CAEP/IFP, Mainyang, Sichuan, People's Republic of China
	Funding: The National Natural Science Foundation of China A beam angel monitor using the axial B-dot field was presented recently while the one using azimuthal B-dot field had been widely employed to measure the beam positions for more than ten years. Basing on the principle of the proportionality between the deflection angel and the difference of axial B field with corresponding positions, the axial B-dot monitor has a potential use for beam deflection angle measurement directly. A test stand was built to test and improve the axial B-dot monitor, which is fabricated as a PCB structure. Meanwhile, simulations using the CST MWS code have been performed, demonstrating a good agreement to the test results and giving some advice to suppress the disturbance of position deviation of the beam.

MOPME051	Development of Cavity Beam Position Monitor System	cavity, FEL, coupling, electron	586
	B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou SINAP, Shanghai, People's Republic of China
	Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME058	DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2	cavity, dipole, electron, extraction	604
	S.W. Jang, E.-S. Kim KNU, Deagu, Republic of Korea Y. Honda, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described.

MOPME068	Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC	radiation, background, electron, vacuum	634
	N. Fuster Martinez, A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain H.L. Andrews LANL, Los Alamos, New Mexico, USA F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S.R. Stevenson JAI, Oxford, United Kingdom J. Barros, N. Delerue, M. Grosjean LAL, Orsay, France V. Bharadwaj, C.I. Clarke SLAC, Menlo Park, California, USA
	The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device.

MOPME070	Emittance and Beta Functions Measurements for the MAX IV Linac	quadrupole, emittance, linac, controls	640
	N. Čutić, E. Mansten MAX-lab, Lund, Sweden
	We plan to determine beam emittance and Twiss parameters for the MAX IV linac using multiple-quadrupoles scans. We investigate the possibility to perform such scans using matching sections' quadrupoles combined with beam profile measurements by fluorescent YAG screens. Beam pipe size, resolution and screen saturation limits and strengths of quadrupoles are taken into consideration. Our approach to this problem using Kalman filter is presented.

MOPWA009	Development of a Fast Compensation Kicker System for J-PARC Main-ring Injection	kicker, injection, impedance, power-supply	684
	S. Fukuoka University of Tsukuba, Graduate School of Pure and Applied Sciences,, Tsukuba, Ibaraki, Japan K. Fan, K. Ishii, H. Matsumoto, T. Sugimoto KEK, Ibaraki, Japan
	Injection system of J-PARC main ring employs four lumped kickers to deflect the incoming beam. The residual field caused by tail and reflection of excitation current increases the closed beam orbit leading to particle loss in high power operation. A correction method using a fast kicker system to compensate the remaining angle is being developed. Doe to the narrow bunch spacing, transmission line kicker is selected to satisfy requirements of fast rise and fall time. The kicker magnet uses ceramic capacitors instead of parallel metal plates to make the magnet compact and reduce the stray inductance. Capacitors are installed in vacuum chamber. A very thin core is used to reduce distributed inductance. A bandwidth is calculated as 160 MHz. A Marx generator using FET switches has been studied, which is able to produce fast rise and fall time as 50 ns. Any pulse shape is generated by choosing switches to fire. A prototype magnet and a power supply have been fabricated for parameters test. In this paper, we will report the details of the system design, analyze the measurement results and give future prospects.

MOPWA017	Design of the 500 kA Linear Transformer Driver Stage	pulsed-power, damping, high-voltage, induction	696
	T.X. Liang, X.F. Jiang, A.C. Qiu, F.J. Sun, Z.G. Wang, J.H. Yin, Z. Zhang NINT, Xi'an, People's Republic of China
	Funding: Supported by the funding of National Natural Science of China (Grant No. 51077111) and Stage Key Laboratory of Electrical Insulation and Power Equipment(Grant No.51077111) , Xi’an Jiaotong Univercity. Linear transformer driver (LTD) is a novel fast discharge high pulsed power source. It can realize many LTD stages in series or parallel conveniently, and can directly acquire 100~200ns high power pulse. The pulse maybe realizes to directly drive load without any pulse compressing and forming unit. This paper introduces the latest development of fast LTD technology in abroad. The 100kV/500kA LTD stage with the rise time of 150ns has been designed. The stage is consisting of 20 discharging bricks in parallel. The simplified circuit model of LTD stage is given and the output parameters are simulated with universal circuit simulation software program, and the matched load current of 500kA and the rise time of about 150ns is obtained at the charging voltage of the capacitors about ±80kV. Tianxue Liang is with the State Key Laboratory of Environment Simulation and Effect for Intense Pulsed Radiation, Northwest Institute of Nuclear Technology, P. O. Box 69-10, Xi’an 710024, China(phone:86-029-84767380; e-mail: liangtxlkk@163.com).

MOPWA021	Design of the Air Cooling System for the High Voltage Power Supply of a Electron Accelerator	power-supply, high-voltage, radiation, electron	705
	F. Zhong, X. Lei, J. Yang, L. Yang HUST, Wuhan, People's Republic of China
	High voltage electron accelerators are widely applied in many fields of radiation pro-cessing,and the high voltage power supply is the critical equipment for the accelerator. for the requirement of high voltage, the design of locate the power supply in a steel barrel filled with SF6 is commonly used. Considering the various losses of the power supply, an air-cooling system is needed. This paper presents the design of the air-cooling system for the high voltage power supply. The fluid simulation of SF6 based on Fluent and the optimal design of the air duct's structure and the thermal efficiency have been done. The comparison and analysis of the simulation and the empirical formula result is also carried out. It illustrates the design of the air-cooling system can satisfy the demand of the heat radiation This paper also provides an effective method for the optimal design of the air duct's structure and the maximize efficiency of heat exchange.

MOPWA022	A 500 kV Pulser with Fast Risetime for EMP Simulation	high-voltage, pulsed-power, impedance, laser	708
	W. Jia, W.Q. Chen, J.N. Li, J.P. Tang, L.S. Xie, Y.Z. Xie, G.W. Zhang NINT, Xi'an, People's Republic of China
	A fast risetime generator with 500kV rated output voltage for the electromagnetic pulse ( EMP ) effects experiment is fabricated. It mainly consists of a low inductance Marx ge nerator, a compact independent-sealed peaking capacitor, an output switch, and a small quantity of gas-sealed insulated containers. Compared with other similar pulsers mentioned in IEC 61000-4-32, the insulated containers of the generator are independent of each other in gas-sealed structure, and its number is les s than that of other pulsers. It can be used to drive a guided wave antenna directly to produce an electromagnetic environment, which conformed with the new standard for high-altitude nuclear explosion electromagnetic pulse (HEMP) developed by IEC. Output voltage produced by the generator in demo-load state can reach to 600kV. And, risetime of the waveform is 1.2ns, pulse width (FWHM) being 32ns. When the generator driving a 10m guided-wave antenna, an output voltage with a risetime of no more than 2.7ns and a FWHM of 30ns is achieved.

MOPWA023	A Low Jitter Pulse Generator Based on Two-stage Storage Module	pulsed-power, coupling, controls, high-voltage	711
	J.N. Li, W.Q. Chen, F. Guo, W. Jia NINT, Xi'an, People's Republic of China
	A scheme for a low jitter pulse generator based on two-stage storage module is described. The thyristor is used for the first stage of the generator, the UV-illumination gas switch is used for the second stage of the generator. Between them, the pulsed transformer is used for connecting. A capacitance-resistance coupling structure was designed to produce UV light which triggered the switch to decrease the breakdown jitter. The test result shows, the risetime of the current is 0.73μs, the peak value of the current is 1.8kA on 1.1Ω load. The delay of the generator is 35.1μs, and the jitter of the generator attaches to 0.22μs.

MOPWA031	Beam Induced Ferrite Heating of the LHC Injection Kickers and Proposals for Improved Cooling	vacuum, kicker, injection, impedance	732
	M.J. Barnes, S. Calatroni, F. Caspers, L. Ducimetière, M. Garlaschè, V. Gomes Namora, V. Mertens, Z.K. Sobiech, M. Taborelli, J.A. Uythoven, W.J.M. Weterings CERN, Geneva, Switzerland H.A. Day UMAN, Manchester, United Kingdom
	The two LHC injection kicker systems produce a kick of 1.3 T.m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. A beam screen is placed in the aperture of each magnet, which consists of a ceramic tube with conductors in the inner wall. The conductors provide a path for the beam image current and screen the ferrite yoke against wake fields. Recent LHC operation, with high intensity beam stable for many hours, resulted in significant heating of both the ferrite yoke and beam impedance reduction ferrites. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the ferrites can require several hours to cool enough to re-inject beam, thus limiting the availability of the LHC. Thermal measurement data has been analysed, a thermal model developed and emissivity measurements carried out. The effects of various measures to improve the ferrite cooling have been simulated, including an improved emissivity of the vacuum tank and active cooling on the outside of the tank.

MOPWA032	Reduction of Surface Flashover of the Beam Screen of the LHC Injection Kickers	kicker, injection, vacuum, impedance	735
	M.J. Barnes, P. Adraktas, S. Calatroni, F. Caspers, L. Ducimetière, V. Gomes Namora, V. Mertens, R. Noulibos, M. Taborelli, B. Teissandier, J.A. Uythoven, W.J.M. Weterings CERN, Geneva, Switzerland
	The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wake fields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. Operation with increasingly higher bunch intensity, and narrow bunches, now requires improved ferrite screening. This will be implemented by additional conductors; however the good high-voltage behaviour of the kicker magnets must not be compromised by the supplementary screening. Extensive studies and optimisations have been carried out, to better satisfy the often conflicting requirements for low beam coupling impedance, fast magnetic field rise-time, high vacuum and good high voltage behaviour. A new configuration is proposed which reduces significantly the electric field associated with the screen conductors and the secondary electron yield of the surface of the ceramic tube. Results of high voltage test results are also presented.

MOPWA034	Electron Tracking Simulations in the Presence of the Beam and External Fields	emittance, electron, proton, space-charge	741
	M. Patecki, B. Dehning, G. Iadarola, M. Sapinski CERN, Geneva, Switzerland
	The ionisation profile monitors installed in the CERN LHC and SPS, makes use of the ionisation of small quantities of injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. However, in the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 physics simulation package has been used to simulate the ionisation process, while the CERN-developed PyECLOUD code has been used for tracking the resulting ionised particles. In this paper the results of simulations are compared with observations, with conclusions presented on the accuracy of the reconstruction of high-intensity beam profiles.

MOPWA037	Commissioning of the CERN Linac4 BPM System with 50 MeV Proton Beams	linac, pick-up, proton, optics	750
	J. Tan, M. Ludwig, L. Søby, M. Sordet, M. Wendt CERN, Geneva, Switzerland
	The new Linac4 at CERN will provide a 160 MeV H⁻ ion beam for charge-exchange injection into the existing CERN accelerator complex. Shorted stripline pick-ups placed in the Linac intertank regions and the transfer lines will measure beam orbit, relative beam current, beam phase, and average beam energy via the time-of-flight between two beam pickups. A prototype Beam Position Monitor (BPM) system has been installed in the transfer line between the existing Linac2 and the Proton Synchrotron Booster (PSB) in order to study and review the complete acquisition chain. This paper presents measurements and performance of this BPM system operating with 50 MeV proton beams, and compares the results with laboratory measurements and electromagnetic simulations.

MOPWA051	ZEMAX Simulations for an Optical System for a Diffraction Radiation Monitor at CesrTA	target, radiation, electron, damping	789
	T. Aumeyr, V. Karataev JAI, Egham, Surrey, United Kingdom M.G. Billing CLASSE, Ithaca, New York, USA L.M. Bobb, B. Bolzon, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland
	Diffraction Radiation (DR) is produced when a relativistic charged particle moves in the vicinity of a medium. The target atoms are polarized by the electric field of the charged particle, which then oscillate thus emitting radiation with a very broad spectrum. The spatial-spectral properties of DR are sensitive to various electron beam parameters. Since the energy loss due to DR is so small that the electron beam parameters are unchanged, DR can be used to develop non-invasive diagnostic tools. The aim of this project is to measure the transverse (vertical) beam size using incoherent DR. To achieve the micron-scale resolution required by CLIC, DR in the UV and X-ray spectral-range must be studied. During the next few years, experimental validation of such a scheme will be conducted on the CesrTA at Cornell University, USA. This paper reports on simulations carried out with ZEMAX, studying the optical system used to image the emitted radiation.

MOPWA052	Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2	wakefield, cavity, quadrupole, extraction	792
	J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin JAI, Egham, Surrey, United Kingdom K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan G.R. White SLAC, Menlo Park, California, USA
	Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).

MOPWA056	Spectra of Coherent Smith-Purcell Radiation Observed from Short Electron Bunches: Numerical and Experimental Studies	electron, radiation, diagnostics, target	801
	F. Bakkali Taheri, G. Doucas, I.V. Konoplev, A. Reichold JAI, Oxford, United Kingdom H.L. Andrews LANL, Los Alamos, New Mexico, USA R. Bartolini Diamond, Oxfordshire, United Kingdom V. Bharadwaj, C.I. Clarke SLAC, Menlo Park, California, USA N. Delerue LAL, Orsay, France N. Fuster Martinez IFIC, Valencia, Spain J.D.A. Smith TXUK, Warrington, United Kingdom P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: This work performed [in part] under DOE Contract DE-AC02-7600515 There is a significant interest in the development of compact particle accelerators within research areas including X-ray and THz (T-ray) sources of radiation, particle physics and medical sciences. To support the progress in these areas, non-invasive, electron beam diagnostics that are capable of measuring a single femtosecond electron bunch are required. At the current stage such beam diagnostics for femtosecond-long electron bunches are still not available. The goal of the work presented is to understand the spectral characteristics of coherent Smith-Purcell radiation to enable its quick and reliable interpretation including the longitudinal profile reconstruction of electron bunches. The research presented comprises results from numerical modelling and experimental studies. Using the numerical data, we discuss the radiated spectra dependence on the electron bunch profile and analyse the results. We also discuss the experimental data and compare it with theoretical predictions.

MOPWA064	Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam	electron, cavity, proton, vacuum	825
	Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska Fermilab, Batavia, USA
	We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

MOPWA066	Components of Heating and Fueling of Fusion Plasmas	high-voltage, controls, cathode, synchrotron	831
	K. Schrock, M.P.J. Gaudreau, M.K. Kempkes Diversified Technologies, Inc., Bedford, Massachusetts, USA
	Funding: Funded by US DOE, Grant # DE-SC0004250 Next generation fusion facilities will require many megawatts of RF power from dozens of gyrotrons. Each gyrotron requires a power system that must deliver the high-voltage power, modulate cathode voltage, and protect these expensive gyrotrons from arcing damage. It must be highly efficient, to minimize both the power and cooling costs associated with operation and to ensure high facility availability. Diversified Technologies, Inc. (DTI) has bench-tested a table-top scale ‘Buck Matrix’ modulator which uses a single set of IGBT switches for voltage regulation, arc protection, and pulse modulation. Although pulse step modulators represent a one-step solution, their size, and the complexity of their driving transformer make them more expensive than DTI’s two-step approach. DTI’s Buck Matrix modulator, with an efficiency of ~96%, cuts the size of the system in half, using a single layer of solid state switches for both voltage regulation and arc protection/modulation. This cuts the total hardware costs by a~30% or more, and eliminates the need for a separate opening switch or crowbar. DTI will present the system components of the design as well as the performance results to date.

MOPWA071	A Comparison of Electron Cloud Density Measurements at CesrTA	electron, positron, resonance, pick-up	843
	J.P. Sikora, J.A. Crittenden, D.O. Duggins, Y. Li, X. Liu CLASSE, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time Resolved Retarding Field Analyzers (TR-RFA) and Shielded Pickups (SPU) that measure the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.

MOPWA085	Spin Dynamics Simulations and Horizontal Intrinsic Resonance Studies in the AGS using the Zgoubi Code	polarization, acceleration, resonance, extraction	870
	Y. Dutheil, L. A. Ahrens, H. Huang, F. Méot, V.H. Ranjbar, T. Roser, V. Schoefer, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A critical point for the polarized proton program of the RHIC is the polarization transmission through the AGS acceleration cycle. Recent developments in the Zgoubi model of the AGS allow multi-particle tracking with realistic beam and machine conditions on a large scale computing system. This gives the opportunity to simulate the influence of many beam and machine conditions on the polarization transmission and leads to a better understanding of the depolarization processes, for instance the horizontal intrinsic resonances, that cannot be accurately explored by the conventional simulation approaches or by the experiments with beam. This paper introduces the developments realized on the Zgoubi code to run these simulations and shows some of the latest results.

MOPWO001	Moment Method Beam Dynamics Code Development: Extended for Radio Frequency Quadrupole Simulations	rfq, multipole, quadrupole, radio-frequency	879
	T. Roggen, H. De Gersem, B. Masschaele KU Leuven, Kortrijk, Belgium W. Ackermann, S. Franke, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: This research is funded by grant “KUL 3E100118” “Electromagnetic Field Simulation for Future Particle Accelerators”, project FP7-Euratom No. 269565 and the Belgian Nuclear Research Centre (SCK•CEN). A Radio Frequency Quadrupole (RFQ) enables acceleration of a continuous low-velocity hadron beam, combining velocity independent electric focusing and adiabatic bunching, resulting in high-current compact bunches with nearly 100% capture and transmission efficiency. With virtually no post-construction tuning capabilities, an RFQ design phase requires all transient parameters (machining tolerances, thermo-mechanical deformation factors). This allows the determination of acceptable tolerances on input and output beam characteristics, of major importance in beam availability and beam trip prevention, and makes fast beam dynamics simulation codes incorporating RFQs indispensable. This article presents the implementation and validation of an RFQ beam line element into V-Code, a moment method beam dynamics simulation code. V-Code time integrates the Vlasov equation for an initial particle distribution represented by a discrete set of characteristic moments, accounting for all exerting internal and external forces. V-Code delivers highly accurate beam dynamics results with precision and efficiency advantages in terms of average or rms beam dimensions, projected emittances or total energy.

MOPWO002	PTCC: New Beam Dynamics Design Code for Linear Accelerators	linac, space-charge, plasma, cavity	882
	Y. N. Nour El-Din, T.M. Abuelfadl Cairo University, Giza, Egypt
	Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953. A fast and accurate beam dynamics design code, named PTCC (Particle Tracking Code in C) is developed to simulate particles dynamic in linear accelerators. PTCC solves the relativistic equations of motion for the macro-particles when subjected to electromagnetic fields excited in RF cavities. The self-fields of the particles are also part of the electromagnetic fields through which the particles are tracked. Self-fields are calculated using a modified 2D cylindrically symmetric mesh based method, making use of beam and field symmetry to provide fast simulation. The code has been benchmarked with the well known code ASTRA which is used mainly in simulations of next generation FEL linacs. PTCC provides a new tool for designing buncher section of linear accelerators that convert DC beam into bunches. New buncher design tool and benchmark results of PTCC with ASTRA are presented.

MOPWO004	Simulations and Studies of Electron Beam Dynamics under Compton Back-scattering for the Compact X-ray Source ThomX	electron, wakefield, collective-effects, photon	888
	I.V. Drebot, C. Bruni, N. Delerue, T. Demma, A. Variola, Z.F. Zomer LAL, Orsay, France A. Loulergue SOLEIL, Gif-sur-Yvette, France
	Funding: This work is supported by the French "Agence Nationale de la Recherche" under reference ANR-10-EQPX-51, and also by grants from Région Ile-de-France, Université Paris-Sud and IN2P3/CNRS. In this article are presented beam dynamics investiga- tions of a relativistic electron bunch in the compact storage ring ThomX (50 MeV), which is under construction at LAL to produce hard X-ray using Compton Back-Scattering (CBS). The effect of CBS has been implemented in a 6D tracking code. In addition to CBS, the influence of lattice non linearities and various collective effects on the flux of scattered Compton photons is investigated.

MOPWO005	Simulating Spin Dynamics and Depolarization using POLE	resonance, synchrotron, polarization, synchrotron-radiation	891
	J.F. Schmidt, O. Boldt, F. Frommberger, W. Hillert ELSA, Bonn, Germany
	Funding: BMBF The spin dynamics in circular accelerators with fast energy ramps, or short storage times of up to some seconds, can be investigated with spin tracking appropriately. Additionally, the spin motion of lepton beams is affected significantly by synchrotron radiation. Hence, spin dynamics simulations require spin tracking with a large number of particles to compute the beam polarization and thus take considerably long computing times. Therefore, high efficiency is crucial to perform systematic polarization studies. The new simulation tool POLE provides the ability to balance accuracy against computing time. To that end, adjustable approximations of magnetic fields and synchrotron radiation are implemented. POLE is accessible for a wide range of lepton storage rings because it uses the common MAD-X lattice files and the corresponding particle tracking results.

MOPWO008	Eigenmode Computation for Elliptical Cavities Subject to Geometric Variation using Perturbative Methods	cavity, factory, higher-order-mode, SRF	900
	K. Brackebusch, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by Federal Ministry for Research and Education BMBF under contracts 05H09HR5 and 05K10H. Parametric studies of geometric variations are an essential part of the performance optimization and error estimation in the design of accelerator cavities. Using common eigenmode solvers the analysis of intentional and undesired geometric perturbations tend to be very extensive since any geometric variation involves an entire eigenmode recomputation. Perturbative methods constitute an efficient alternative for the computation of a multitude of moderately varying geometries. They require a common eigenmode computation of solely one (so called unperturbed) geometry and allow for deriving the eigenmodes of similar but modified (so called perturbed) geometries from these unperturbed eigenmodes. In [],[] the practicability of perturbative methods was already proven by means of simple cavity geometries. In this paper we investigate the applicability and efficiency for practically relevant cavities. For this, basic geometric parameters of elliptical cavities are varied and the respective eigenmodes are computed by using perturbative as well as common methods. The accuracy of the results and the computational effort of the different methods are compared. K. Brackebusch, H.-W. Glock, U. van Rienen, WEPPC096, IPAC 2011 **K. Brackebusch, U. van Rienen, MOPPC062, IPAC 2012

MOPWO009	Numerical Studies on the Impact of Ionized Residual Gas on an Electron Beam in an ERL	ion, emittance, electron, linac	903
	G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Meseck HZB, Berlin, Germany
	Funding: Supported by BMBF under contract number 05K10HRC Energy Recovery Linacs (ERLs) are the most promising candidates for next-generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Typical measures to reduce the effect of ion clouds are clearing electrodes and clearing gaps in the bunch train. In this paper, we present numerical studies of the impact of ion clouds on the electron bunch train. The simulations are performed with the software package MOEVE PIC Tracking developed at Rostock University. ’The model for the bunch and the ion cloud takes into account a distribution of macro particles. The interaction of the bunch with the ion cloud is computed with a 3D space charge model. Hence, particle tracking allows for detailed studies of bunch characteristics such as the emittance. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPro.

MOPWO010	Machine Protection Studies for a Crab Cavity in the LHC	beam-losses, luminosity, cavity, collimation	906
	B. Yee-Rendon, R. Lopez-Fernandez CINVESTAV, Mexico City, Mexico T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland
	Funding: US-LARP and CONACYT Crab cavities (CCs) apply a transverse kick that rotate the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

MOPWO011	Surface Field Optimization of Accelerating Structures for CLIC using ACE3P on Remote Computing Facility	linac, GUI, target, damping	909
	K.N. Sjobak, E. Adli University of Oslo, Oslo, Norway A. Grudiev CERN, Geneva, Switzerland
	Funding: Research Council of Norway This paper presents a computer program for searching for the optimum shape of an accelerating structure cell by scanning a multidimensional geometry parameter space. For each geometry, RF parameters and peak surface fields are calculated using ACE3P on a remote high-performance computational system. Parameter point selection, mesh generation, result storage and post-analysis are handled by a GUI program running on the user’s workstation. This pa- per describes the program, AcdOptiGui. AcdOptiGui also includes some capability for automatically selecting scan points based on results from earlier simulations, which en- ables rapid optimization of a given parameterized geome- try. The software has previously been used as a part of the design process for accelerating structures for a 500 GeV CLIC.

MOPWO013	A New Scalable Software Package for Large Scale Beam Dynamic Simulations	space-charge, target, DTL, solenoid	912
	R. Zhao, J. Xu IS, Beijing, People's Republic of China Y. He, C. Li, X. Qi, L. Yang IMP, Lanzhou, People's Republic of China
	Large scale Beam Dynamics Simulations (BDS) are important in accelerator design and optimization. With the fast development of supercomputers, new software packages need to be developed in order to fully make use of hardware and software progresses. In this paper, we will introduce a new BDS software package, LOCUS3D, which is developed for efficient use of these new techniques. It is based on Particle-In-Cell (PIC) method, and includes space charge effect by solving the Poisson’s equation. Parallel Poisson solver has been developed with MPI. Standard accelerator devices can be simulated and new devices can be added. Benchmark results have been obtained on several different platforms, such as INSPUR cluster at RDCPS, BG/P at ANL. Large-scale simulation with 10⁹ particles can be simulated now in the simulations. LOCUS3D will be used for more realistic accelerator simulations in the near future.

MOPWO014	Numerical Methods to the Space Charge Compensation (SCC) Effect of the LEBT Beam	electron, ion, space-charge, ion-source	915
	S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, P.N. Lu, Y.T. Luo, H.T. Ren, Z.H. Wang, Y. Xu, T. Zhang, J. Zhao PKU, Beijing, People's Republic of China A.L. Zhang Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
	Numerical simulation as well as experimental researches on space charge compensation for high intensity, low energy ion beam has been done at Peking University (PKU). In this paper we will describe the simulation model proposed at PKU and use it on the PKU ECR single-charged ion source. It consists of a new concept of equivalent density and more consideration of physical process. A series of arithmetical equations is gained through theoretical derivation. Although no numerical solutions have been carried out from our computation, it is foreseeable that the final result will be achieved soon.

MOPWO018	Cellular Automaton Simulating the Motion of the Charged Particles Beam	acceleration, controls, lattice	918
	S.N. Andrianov, N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia V. Ryabusha Saint Petersburg State University, Saint Petersburg, Russia
	In this research we formulate and formalize the rules for the cellular automaton that emulates the motion of the charged particles beam under the effect of Coulomb force for one-, two- and three-dimensional cases. In this research we also describe the main principles of the realization of this approach in a paralleled cluster environment.

MOPWO019	An IDE for Spin-orbit Dynamics Simulation	lattice, controls, betatron, optics	921
	A.N. Ivanov, N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia
	In this paper a prototype of an IDE for simulation of spin-orbit motion is described. It is based on the component software development and provides a flexible graphic user interface. One of the main parts of it is numerical methods for ordinary differential equations integration. For numerical simulation it is possible use either the matrix map algorithm or traditional step-by-step methods. This workflow allows choosing one of numerical algorithms and to provide necessary computational experiments. It is also contains both a visual designer of an accelerator lattice and additional tools for control parameters of the model. There is also exists possibility for code generation in different programming languages and computation on high-performance systems.

MOPWO020	Space Charge Dominated Envelope Dynamics using GPUs	space-charge, controls, luminosity, focusing	924
	N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia
	High power accelerator facilities lead to necessity to consider space charge forces. It is therefore important to study the space charge dynamics in the corresponding channels. To represent the space charge forces of the beam we have developed special software based on some analytical models for space charge distributions. Because calculations for space charge dynamics become extremely time consuming, we use a special algorithm for predictor-corrector method for evaluation scheme for beam map evaluation including the space charge forces. This method allows us to evaluate the map along the references trajectory and to create the beam envelope dynamics. The corresponding computer codes are realized using CUDA implementation of maps for particle dynamics. Some numerical results for different types of the beam channels are discussed. The survey of advantages and disadvantages of using different methods of parallelization and some parallel approaches will be done.

MOPWO021	Data Management and Analysis for Beam Dynamics Simulation	lattice, EPICS, quadrupole, site	927
	D. Zyuzin FZJ, Jülich, Germany S.N. Andrianov, N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia
	Computer simulation of modern accelerator system is based on a number of specialized computer codes. Complexity of concerned processes and interpretation of simulation results requires comfortable and effective tools to design accelerator structure and beam characteristics, carry out computer experiments, process and visualize data. This paper proposes a prototype system with web-interface which allows the full research cycle: from lattice generation to data visualization. This approach represents a valuable tool for beam physicist providing methods to benchmark simulation engines as well as providing additional instruments for understanding physical processes in accelerator. The corresponding tools were used in application to the spin-orbit motion problems in electrostatic accelerators.

MOPWO026	Investigation of Numerical Precision Issues of Long Term Single Particle Tracking	dynamic-aperture, resonance, beam-beam-effects, HOM	942
	E. McIntosh, R. De Maria, M. Giovannozzi CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Long term single particle simplectic tracking is one of the most reliable tool to study the dynamic aperture of the circular accelerators. The present computational performance allows to explore the long term behaviour for an extended number of turns. It is well known that for instance single precision floating point arithmetic introduces too much numerical noise even after a moderate number of turns. In this paper we explore the artefacts of the double precision arithmetic that may be visible when the number of turns is in the order of 10⁶, 10⁷.

MOPWO028	Recent Developments and Future Plans for SixTrack	collimation, ion, HOM, multipole	948
	R. De Maria, R. Bruce, R. Calaga, L. Deniau, M. Fjellstrom, M. Giovannozzi, L. Lari, Y.I. Levinsen, E. McIntosh, A. Mereghetti, D. Pastor Sinuela, S. Redaelli, H. Renshall, A. Rossi, F. Schmidt, R. Tomás, V. Vlachoudis CERN, Geneva, Switzerland R. Appleby, D.R. Brett UMAN, Manchester, United Kingdom D. Banfi, J. Barranco EPFL, Lausanne, Switzerland B. Dalena CEA/IRFU, Gif-sur-Yvette, France L. Lari IFIC, Valencia, Spain V. Previtali Fermilab, Batavia, USA G. Robert-Demolaize BNL, Upton, Long Island, New York, USA
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. SixTrack is a symplectic 6D tracking code routinely used to simulate single particle trajectories in high energy circular machines like the LHC and RHIC. The paper presents the developments recently implemented and those foreseen for extending the physics models: exact Hamiltonian, different ions and charge states, RF multipoles, non-linear fringe fields, Taylor maps, e-lenses, ion scattering. Moreover new functionalities are also added like variable number of tracked particles, time dependent strengths, GPU computations with a refactoring of the core structure. The developments will benefit studies on the LHC and SPS, for collimation efficiency, ion operations, failure scenarios and HL-LHC design.

MOPWO029	Remote Estimate of Collimator Jaw Damages with Sound Measurements during Beam Impacts	proton, radiation, background, extraction	951
	D. Deboy, O. Aberle, R.W. Aßmann, F. Carra, M. Cauchi, J. Lendaro, A. Masi, S. Redaelli CERN, Geneva, Switzerland
	Irregular hits of high-intensity LHC beams on collimators can lead to severe damage of the collimator jaws. The identification of damaged collimator jaws by observation of beam measurements is challenging: online loss measurements at the moment of the impacts can be tricky and degradation of the overall performance from single collimator damage can be difficult to measure. Visual inspections are excluded because collimator jaws are enclosed in vacuum tanks without windows. However, the sound generated during the beam impact can be used to give an estimate of the damage level. In 2012, high-intensity beam comparable to a full nominal LHC bunch at 7 TeV was shot on a tertiary type LHC collimator at the HiRadMat test facility at CERN. The paper presents results from sound recordings of this experiment.

MOPWO031	High Energy Beam Impact Tests on a LHC Tertiary Collimator at CERN HiRadMat Facility	alignment, vacuum, collimation, proton	954
	M. Cauchi, O. Aberle, R.W. Aßmann, A. Bertarelli, F. Carra, A. Dallocchio, D. Deboy, L. Lari, S. Redaelli, A. Rossi CERN, Geneva, Switzerland M. Cauchi, P. Mollicone UoM, Msida, Malta L. Lari IFIC, Valencia, Spain N.J. Sammut University of Malta, Information and Communication Technology, Msida, Malta
	The correct functioning of the collimation system is crucial to safely operate the LHC. The requirements to handle high intensity beams can be demanding. In this respect, investigating the consequences of LHC particle beams hitting tertiary collimators (TCTs) in the experimental regions is a fundamental issue for machine protection. An experimental test was designed to investigate the robustness and effects of beam accidents on a fully assembled collimator, based on accident scenarios in the LHC. This experiment, carried out at the CERN HiRadMat (High Irradiation to Materials) facility, involved 440 GeV beam impacts of different intensities on the jaws of a horizontal TCT. This paper presents the experimental setup and the preliminary results obtained together with some first outcomes from visual inspection.

MOPWO033	Analysis of LHC Transfer Line Trajectory Drifts	injection, optics, extraction, dipole	960
	L.N. Drøsdal, W. Bartmann, H. Bartosik, C. Bracco, B. Goddard, V. Kain, Y. Papaphilippou, J.A. Uythoven, G. Vanbavinckhove, J. Wenninger CERN, Geneva, Switzerland E. Gianfelice-Wendt Fermilab, Batavia, USA
	The LHC is filled from the SPS via two 3km long transfer lines. In the first years of LHC operation large trajectory variations were discovered. The sources of bunch-by-bunch and shot-by-shot trajectory variations had been identified and improved by the 2012 LHC run. The origins of the longer term drifts were however still unclear and significant time was spent correcting the trajectories. In the last part of the 2012 run the optics in the SPS was changed to lower transition energy. Trajectory stability and correction frequency will be compared between before and after the optics change in the SPS. The sources of the variations have now been identified and will be discussed in this paper. Remedies for operation after the long shutdown will be proposed.

MOPWO035	Layouts for Crystal Collimation Tests at the LHC	collimation, optics, insertion, proton	966
	D. Mirarchi, S. Redaelli, W. Scandale CERN, Geneva, Switzerland D. Mirarchi The Imperial College of Science, Technology and Medicine, London, United Kingdom V. Previtali Fermilab, Batavia, USA
	Various studies have been carried out in the past years regarding crystal collimation for the LHC. A new extensive campaign of simulations was performed to determine optimum layouts for beam tests at the LHC. The layouts are determined based on semi-analytical models for the dynamics of channeled particles. Detailed SixTrack tracking with all collimators of the ring are then used to validate the different options. An overview of the ongoing studies is given. Comparative studies between the present collimation system, the crystal collimation system, and different crystal collimation layout are presented.

MOPWO037	SixTrack Simulation of Off-momentum Cleaning in LHC	radiation, synchrotron, betatron, synchrotron-radiation	972
	E. Quaranta, R. Bruce, S. Redaelli CERN, Geneva, Switzerland
	In the LHC, high-amplitude particles are cleaned by either betatron collimators or momentum collimators. Previously, betatron losses have been considered more important, but measurements during the first years of operation show high losses also in the off-momentum cleaning insertion. This causes a significant radiation dose to warm magnets downstream of the collimators. Our work in this paper aims at simulating with SixTrack the off-momentum particles, driven into the momentum collimators by radiation damping outside the RF system acceptance. The results are an important ingredient in assessing the effectiveness of new passive absorbers to protect the warm magnets.

MOPWO038	Cleaning Inefficiency of the LHC Collimation System during the Energy Ramp: Simulations and Measurements	collimation, proton, scattering, injection	975
	E. Quaranta, R. Bruce, L. Lari, D. Mirarchi, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain D. Mirarchi The Imperial College of Science, Technology and Medicine, London, United Kingdom G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The cleaning inefficiency of the LHC collimation system has already been studied in detail at injection and top energy (450 GeV and 4 TeV respectively). In this paper the results are presented for the cleaning inefficiency at intermediate energies, simulated using the SixTrack code. The first comparisons with measured provoked losses are discussed. This study helps in benchmarking the energy dependence of the simulated inefficiency and is thus important for the extrapolation to future operation at higher energies.

MOPWO041	Simulations and Measurements of Physics Debris Losses at the 4 TeV LHC	luminosity, proton, background, dipole	984
	A. Marsili, R. Bruce, F. Cerutti, S. Redaelli CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. Simulations of energy deposition from the physics debris are normally done with shower simulation tools like FLUKA. Tracking tools like SixTrack allow faster simulations that open the possibility to study parametrically and optimize different layouts. In this paper, the results of FLUKA and SixTrack simulations are compared to beam measurements done for different collimator settings at 4 TeV, with p-p luminosities up to 7·10³³ cm^-2s⁻¹.

MOPWO042	Simulations of Collimation Cleaning Performance with HL-LHC Optics	optics, collimation, luminosity, proton	987
	A. Marsili, R. Bruce, R. De Maria, S.D. Fartoukh, S. Redaelli CERN, Geneva, Switzerland
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges for the protection of the machine. The different optics considered might create new needs for collimation, and require new collimation locations. In order to evaluate the cleaning performances of the collimation system, different halo cleaning simulations were performed with the particle tracking code SixTrack. This paper presents the cleaning performance simulation results for the high luminosity Achromatic Telescopic Squeeze optics considered as baseline for the HL-LHC. The new limitations observed and possible solutions are discussed.

MOPWO043	Hollow Electron Lens Simulation for the SPS	electron, collimation, optics, proton	990
	V. Previtali, G. Stancari, A. Valishev Fermilab, Batavia, USA S. Redaelli CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No. DE-AC02-07CH11359 with the United States Dep. of Energy. This work was supported by the US LHC Accelerator Research Program (LARP). The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations.

MOPWO044	Numerical Simulations of a Hollow Electron Lens as a Scraping Device for the LHC	electron, collimation, resonance, proton	993
	V. Previtali, G. Stancari, A. Valishev Fermilab, Batavia, USA S. Redaelli CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No.DE-AC02-07CH11359 with the United States Dep. of Energy. This work was partially supported by US LHC Accelerator Research Program(LARP) The use of hollow electron beam lens for scraping high energy proton beams has been extensively tested at Fermilab's Tevatron collider. In order to evaluate a possible application of a similar a device in the LHC, a dedicated new routine has been implemented in the standard 6D tracking code used at CERN for the design of the LHC collimation system. The effects of a finite length cylinder of electrons encompassing the main proton beam and traveling in the opposite direction is described in the routine. Realistic electron distributions, including measured radial imperfections, have been included in the model. Various operating modes have been simulated for the 7 TeV machine operation with sextupoles and octupoles included. The loss rate caused by the electron lens has been studied through an extended simulation campaign; the obtained halo removal rates for the different electron lens operating modes are presented.

MOPWO046	Simulations and Measurements of Beam Losses on LHC Collimators during Beam Abort Failures	proton, collimation, emittance, kicker	996
	L. Lari, C. Bracco, R. Bruce, B. Goddard, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland A. Faus-Golfe, L. Lari IFIC, Valencia, Spain G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404. One of the main purposes of tracking simulations for collimation studies is to produce loss maps along the LHC ring, in order to identify the level of local beam losses during nominal and abnormal operation scenarios. The SixTrack program is the standard tracking tool used at CERN to perform these studies. Recently, it was expanded in order to evaluate the proton load on different collimators in case of fast beam failures. Simulations are compared with beam measurements at 4 TeV. Combined failures are assumed which provide worst-case scenarios of the load on tungsten tertiary collimators.

MOPWO053	Evolution of the Tracking Code PLACET	wakefield, linac, cavity, collider	1014
	A. Latina, Y.I. Levinsen, D. Schulte CERN, Geneva, Switzerland J. Snuverink JAI, Egham, Surrey, United Kingdom
	The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.

MOPWO057	A Precise Beam Dynamics Model of the PSI Injector 2	space-charge, cyclotron, injection, emittance	1020
	A.M. Kolano, R.J. Barlow University of Huddersfield, Huddersfield, United Kingdom A. Adelmann, C. Baumgarten PSI, Villigen PSI, Switzerland
	The Injector 2 at PSI (Paul Scherrer Institut), is a 72 MeV separate sector cyclotron producing a high intensity proton beam up to 3 mA CW, which is subsequently injected to the 590 MeV Ring Cyclotron. The injection energy of the pre-bunched beam is 870 keV at an intensity of 10 to 11 mA. In this paper we describe a full 3D model of the PSI injector 2, starting just before the two bunchers and including the multi stage collimation scheme in the cyclotron. The precise beam dynamics model is based on the OPAL (Object Oriented Parallel Accelerator Library) simulation code. OPAL is a tool for charged-particle optic calculations in large accelerator structures and beam lines including 3D space charge. The presented model will be validated with data from radial profile measurements and loss rates from the collimators and the electrostatic septum in the Injector 2. Based on this model we will estimate the intensity limit of this machine and comment of future operation modes.

MOPWO058	Injection Simulations for TPS Storage Ring	injection, storage-ring, kicker, lattice	1022
	C.C. Chiang, P.J. Chou NSRRC, Hsinchu, Taiwan
	We present injection simulations for the TPS (Taiwan Photon Source) storage ring. The baseline lattice of TPS storage ring is a 6-fold structure with 24 double bend cells. For the Step I commissioning, only baseline lattice with dummy chambers are installed. The three double mini-beta-y lattice with insertion devices will be applied during Step II commissioning. The Tracy-2 program is used to simulate the particle motion in 6-D phase space. We adopt lattice models which include errors of alignments and magnet fields. The particle loss due to scraping by chamber limit is recorded in Tracy-2 simulation. We can estimate the radiation distribution of a ring and provide a reference for the shielding design accordingly.

MOPWO061	Numerical Approaches for Simulation of Stochastic Cooling in 2D Phase Space	emittance, coupling, electromagnetic-fields, storage-ring	1028
	M. Dolinska NASU/INR, Kiev, Ukraine C. Dimopoulou, A. Dolinskyy, F. Nolden GSI, Darmstadt, Germany
	A consolidated fluid-dynamics algorithm for the analysis of beam dynamics under the influence of the electromagnetic field is presented. Aiming at simulating stochastic cooling of particle beams in 2D space, two numerical algorithms solving the 2D Fokker-Planck Equation are described. As an alternative approach, a numerical method based on the macro-particle tracking turn in turn in the ring (i.e. in the time domain) is introduced. Some results of the simulation of the stochastic cooling in the Collector Ring by both methods are discussed.

MOPWO066	GPU-accelerated Spin Dynamics and Analysis for RHIC	polarization, solenoid, quadrupole, proton	1037
	D.T. Abell, D. Meiser Tech-X, Boulder, Colorado, USA M. Bai, V.H. Ranjbar BNL, Upton, Long Island, New York, USA D.P. Barber DESY, Hamburg, Germany
	Funding: This work supported in part by the US DOE Office No. DE-SC0004432. Graphics processing units (GPUs) have now become powerful tools for scientific computation. Here we present our work on using GPUs (singly or in parallel) to speed the tracking of both orbital and spin degrees of freedom in particle accelerators. This work includes the development of new spin integrators that are both fast and accurate. We have also developed an integrated set of tools for analysing the results. To demonstrate the utility of these new tools, we use them to study the spin dynamics of protons in the Relativistic Heavy Ion Collider at Brookhaven National Lab.

MOPWO067	Beam Dynamics Simulations with a GPU-accelerated Version of Elegant	acceleration, collective-effects, storage-ring, controls	1040
	I.V. Pogorelov, K.M. Amyx, J. Balasalle, J.R. King Tech-X, Boulder, Colorado, USA M. Borland, R. Soliday ANL, Argonne, USA
	Funding: Work supported by the US DOE Office of Science, Office of Basic Energy Sciences under grant number DE-SC0004585, and by Tech-X Corporation Large scale particle tracking and tracking-based lattice optimization simulations can derive significant benefit from efficient implementation of general-purpose particle tracking on GPUs. We present the latest results of our work on accelerating Argonne National Lab's accelerator simulation code ELEGANT,* using CUDA-enabled GPUs. A sufficiently large number of Elegant beamline elements has been ported to GPUs to allow the GPU-accelerated simulation of realistic test lattices. We will identify some of performance-limiting factors, and briefly discuss optimization techniques for efficient utilization of the device memory space, with an emphasis on register usage. We also present a novel hardware-assisted technique for efficiently calculating a histogram from a large distribution of particle coordinates, and compare this to data-parallel implementations. * M. Borland, Elegant: A Flexible SDDS-compliant Code for Accelerator Simulation, APS LS-287, September 2000 ** Y. Wang, M. Borland, in Proc. of PAC07, THPAN095 (2007)

MOPWO068	Simulating Electron Cloud Evolution using Modulated Dielectric Models	plasma, electron, diagnostics, proton	1043
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499), and the SCiDAC-3 project (DE-SC0008920) Electron clouds can pose a serious threat to accelerator performance, and understanding cloud buildup and the effectiveness of different mitigation techniques can provide cost-saving improvements in accelerator design and fabrication. Microwave diagnostics of electron clouds are a non-destructive way to measure cloud buildup, but it is very difficult to measure the cloud density from spectral signals alone. Modeling travelling-wave rf diagnostics is very hard because of the large range of spatial and temporal scales that must be resolved to simulate spectra. New numerical models have been used to generate synthetic spectra for electron clouds when the cloud density is not changing, and results have been compared to theoretical results. Here we use dielectric models to generate spectra for clouds that evolve over many bunch crossings. We first perform detailed simulations of cloud buildup using kinetic particle models, and then use an equivalent plasma dielectric model corresponding to this density, at a finer time resolution, to compute spectra. The stability and accuracy of dielectric models that spectra can be accurately determined in these very long timescale simulations.

MOPWO070	Higher Order Symplectic Integration of Collective Effects	collective-effects, space-charge, wakefield, beam-transport	1046
	S.D. Webb, D.T. Abell Tech-X, Boulder, Colorado, USA
	Long time tracking simulations of intense beams requires a proper account for the collective effects. Many tracking codes allow the number of space charge kicks, for example, to be determined by the end user. This makes no guarantee that the integration is second order accurate in the step size. In this proceeding, we present results on the proper second- and fourth-order symplectic integration of the Hamiltonian dynamics of particles under collective interactions using a model Hamiltonian with collective space charge forces to illustrate the underlying principles.

MOPWO071	Coherent Electron Cooling: Status of Single-Pass Simulations	electron, FEL, ion, bunching	1049
	B.T. Schwartz, G.I. Bell, I.V. Pogorelov, S.D. Webb Tech-X, Boulder, Colorado, USA D.L. Bruhwiler CIPS, Boulder, Colorado, USA Y. Hao, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA S. Reiche PSI, Villigen PSI, Switzerland
	Funding: US DOE Office of Science. Contracts DE-FC02-07ER41499, DE-FG02-08ER85182, DE-AC02-05CH11231. Advances in nuclear physics depend on experiments that employ relativistic hadron accelerators with dramatically increased luminosity. Current methods of increasing hadron beam luminosity include stochastic cooling and electron cooling; however, these approaches face serious difficulties at the high intensities and high energies proposed for eRHIC . Coherent electron cooling promises to cool hadron beams at a much faster rate. A single pass of an ion through a coherent electron cooler involves the ion's modulating the charge density of a copropagating electron beam, amplification of the modulated electron beam in a free-electron laser, and energy correction of the ion in the kicker section. Numerical simulations of these three components are underway, using the parallel Vorpal framework and Genesis 1.3, with careful coupling between the two codes. Here we present validations of two components of the simulations: Adding bunching to an electron beam at the start of an FEL, and the time-dependent charge density modulation in the kicker. http://www.bnl.gov/cad/eRHIC/ ** V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).

MOPWO073	Design and Simulation of an Extraction Section for the University of Maryland Electron Ring	extraction, dipole, emittance, quadrupole	1052
	K.J. Ruisard, B.L. Beaudoin, S. Bernal, J.A. Butcher, I. Haber, R.A. Kishek, T.W. Koeth, D.F. Sutter UMD, College Park, Maryland, USA
	Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office. The University of Maryland Electron Ring (UMER) is a low-energy scaled facility for the study of intense beam dynamics, relevant to higher energy, high intensity accelerators. Many parameters crucial to understanding space charge dominated beam evolution, such as transverse emittance and longitudinal temperature, require the use of turn-by-turn interceptive diagnostics. To meet this need, we plan to implement an extraction section with a fast-pulsed electric-field kicker. This paper presents a suite of simulations used to guide the design process and predict extraction performance, using the WARP Particle-in-cell (PIC) code. Simulations in a transverse slice geometry predict beam trajectory and monitor beam evolution through extraction. After isolating a design based on centroid tracking, extraction acceptance is probed and an analysis proposed to estimate the error tolerances of the new ring elements.

MOPWO074	A Novel Differential Algebraic Adaptive Fast Multipole Method	target, multipole	1055
	S. Abeyratne, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA B. Erdelyi, S.L. Manikonda ANL, Argonne, USA
	The direct pairwise calculation of the potential/electric field created by a very large number of particles is computationally impracticable since it requires long run time and a large amount of memory. The Fast Multipole Method (FMM) is a fast algorithm which scales linearly with the number of particles and it enables highly accurate evaluation of the potentials and fields among the large number of particles using less memory compared to the direct evaluation. The FMM has two main forms, non-adaptive and adaptive. The former is suitable for uniform distributions while the latter is more efficient for non-uniform distributions typically encountered in beam physics. This paper presents an implementation of a novel 3D adaptive FMM algorithm and some results obtained from simulations performed with non-uniform particle distributions.

MOPWO080	GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders	luminosity, collider, electron, damping	1064
	Y. Roblin, V.S. Morozov, B. Terzić JLAB, Newport News, Virginia, USA M. Aturban, D. Ranjan, M. Zubair ODU CS, Norfolk, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.

MOPWO085	A Hybrid Technique for Computing Courant-Snyder Parameters from Beam Profile Data	space-charge, emittance, linac, DTL	1073
	C.K. Allen ORNL, Oak Ridge, Tennessee, USA E.N. Dai Washington University in St. Louis, St. Louis, USA
	Funding: Work supported by ORNL/SNS, which is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. We present a technique for computing the Courant-Snyder parameters of a charged-particle beam from profile measurement data. Such algorithms are not new, but this particular method has very robust convergence properties resulting from a novel approach that combines both deterministic and non-deterministic methods. The general idea is as follows: given a model of the beamline, in the zero-current case it is possible to compute the Courant-Snyder parameters directly from profile data using a deterministic, linear-algebraic approach. For the finite beam current case we can construct a smooth curve of these deterministic solutions starting from the zero-current solution and terminating at the finite-current case. We are guaranteed convergence, and convergence to the finite-current solution connected to the zero-current Courant-Snyder parameters. This approach avoids the convergence issues associated with a fully iterative, non-deterministic method. The details of the technique are outlined and examples are presented using profile data taken from the SNS accelerator.

MOPWO088	Semi-analytical Description of the Modulator Section of the Coherent Electron Cooling	electron, plasma, shielding, hadron	1082
	A. Elizarov, V. Litvinenko BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We discuss the theoretical description of the modulator section of the coherent electron cooling (CeC), the modern realization of the stochastic electron cooling, where the electron beam serves as a modulator and a kicker, i.e., it records the information about the hadron beam via electron density perturbations resulting from the shielding of the hadrons and then accelerates or decelerates hadrons by its electric field with respect to their velocities. To analyze the performance of the CeC shielding of a hadron in an electron beam should be computed with high precision. We propose a solution of this problem via Fourier and Laplace transforms for 1D, 2D and 3D plasmas. In some cases there are fully analytical solutions, which gave an opportunity to test semi-analytical ones involving numerical evaluations of the inverse integral transforms. Having its own practical value this solution will also serve as a testing ground for our general solution via numerical treatment of the integral equations applicable for the realistic case of the finite beam. V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009). ** A. Elizarov, V. Litvinenko, G. Wang, IPAC'12 Proceedings, weppr099 (2012).

TUODB103	Recent Results from CesrTA Intrabeam Scattering Investigations	emittance, coupling, damping, scattering	1126
	M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, D. Sagan, J.P. Shanks, S. Wang CLASSE, Ithaca, New York, USA
	Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505. Manifestation of intrabeam scattering (IBS) in an electron/positron storage ring depends on the radiation damping time in two ways. First, the beam size is the equilibrium of the IBS growth rate in each of the three degrees of freedom and corresponding damping rates. Second, scattering events that occur less frequently than order once per damping time contribute to non-Gaussian tails that are invisible to our beam size monitors. The tail cut procedure excludes these relatively rare events in the calculation of equilibrium beam size. In machines with short damping times, the tail cut significantly reduces the effective IBS growth rate. At CesrTA, we measure the dependence of beam size on bunch charge in IBS-dominated beams. We vary the vertical emittance using a closed optics bump that increases the vertical dispersion and transverse coupling in the wiggler regions. Measurements are taken at both 2.1 and 2.3 GeV. Here we report the results of these experiments and compare those results to theory.
	Slides TUODB103 [1.221 MB]

TUOCB202	Fast Orbit Feedback Scheme and Implementation for Taiwan Photon Source	feedback, power-supply, controls, EPICS	1146
	P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Kuo, C.Y. Wu NSRRC, Hsinchu, Taiwan
	TPS (Taiwan Photon Source) is a 3 GeV synchrotron light source which is being in construction at NSRRC. As most of 3rd generation light sources, the fast orbit feedback system would be adopted to eliminate various disturbances and improve orbit stability. Due to the vacuum chamber material made of aluminum with higher conductivity and lower bandwidth, both of slow and fast correctors will be used for FOFB correction. In general, there are two schemes to operate these hybrid correctors. One is to transfer correction from fast to slow correctors periodically and avoid fast corrector saturation. The other is the fast correctors operated only at higher frequency domain and slow ones take care of DC part. TPS would adopt the first scheme but the second one still as a substitute. Both schemes will be supported. This report summarizes the infrastructure of the FOFB and the simulation is also presented.
	Slides TUOCB202 [3.035 MB]

TUODB202	Experiment and Numerical Simulation Results of Plasma Window	plasma, vacuum, cathode, cavity	1155
	K. Zhu, S. Huang, Y.R. Lu, B.L. Shi PKU, Beijing, People's Republic of China
	Funding: Supported by NSFC 91026012 A windowless vacuum seal technique has been widely researched and designed, which can connect high pressure cavity to a vacuum condition with rather little thickness of material. As a result, it will reduce most interaction with the particle beam penetrating through comparing to that of foil window. It is desired extensively in experiments using high-intensity heavy ion beams which will break foil window in a short time or in experiments which require the injecting beams with mono-energy and high purity for example. In this work, we study the plasma window in argon which is used as a windowless vacuum sealing device. A numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the physical reasons of high pressure difference in plasma window. Further, preliminary experimental results are presented and discussed.
	Slides TUODB202 [2.180 MB]

TUPEA006	Towards Realistic Modelling of the FEL Radiation for the European XFEL	radiation, FEL, controls, undulator	1173
	I.V. Agapov, G. Geloni XFEL. EU, Hamburg, Germany
	For the operation phase of the European XFEL the possibility to characterize the FEL radiation taking realistic machine model into account is important. To achieve this, a software framework is being developed. It allows for interoperability of various simulation codes by means of a common graphical user interfaces, common input and output files, and common programming model for scripting; it includes the possibility of modeling beam jitters and machine imperfections to set errorbars on the simulation results, and has a connection to the control system for data acquisition. We report on the progress in the developing of this framework and give examples of FEL property calculations performed with it.

TUPEA017	Monoenergetic Electron Beams with Ultralow Normalized Emittance Generated from Laser-Gas Interaction	laser, electron, plasma, emittance	1196
	D.Z. Li, J. Gao, K. Huang, J. Jiarui, Y. Ma IHEP, Beijing, People's Republic of China L.M. Chen, W.C. Yan Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
	High quality electron bunches are generated by using 2 TW, 80 fs, high contrast laser pulses interacting with helium gas targets. In optimized condition, we get tens MeV monoenergetic electron beams with small energy spread and the normalized emittance 0.07π mm·mrad. Due to its ultra small emittance and high initial energy, such bunch is very suitable for high current linear accelerators.

TUPEA042	Linac Design for Dalian Coherent Light Source	linac, FEL, emittance, laser	1226
	M. Zhang, H.X. Deng, D. Gu, Q. Gu SINAP, Shanghai, People's Republic of China
	Dalian Coherent Light (DCL) Source is a FEL user facility in which HGHG scheme is adopted. Beam quality requirements for the linear accelerator (linac) are critical, including not only the beam brightness, but also the stability and the reliability. In this paper, optimization study is performed for the linac. Based on beam stability simulation in the longitudinal direction, the tolerant budget is formed for the short period jitter. For the transverse orbit error, beam based alignment (BBA) technique is implemented by beam dynamics simulations and the transverse jitter is also presented accordingly. Measurement method for the beam quality is also described in the paper.

TUPEA045	Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas	electron, plasma, positron, wakefield	1235
	J. Vieira, N.C. Lopes Instituto Superior Tecnico, Lisbon, Portugal E. Adli, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos SLAC, Menlo Park, California, USA Y. Fang USC, Los Angeles, California, USA C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi UCLA, Los Angeles, California, USA P. Muggli MPI, Muenchen, Germany O. Reimann MPI-P, München, Germany L.O. Silva IPFN, Lisbon, Portugal
	Funding: This work has been partially supported by Humboldt Foundation. The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored. G. Xia et al., J. Plasma Phys., 1-7 (2012). **J. Vieira et al., Phys. Plasmas 19, 063105 (2012).

TUPEA048	Simulation of Self-modulating Particle Beams in Plasma Wakefield Accelerators	plasma, wakefield, proton, electron	1238
	K.V. Lotov BINP SB RAS, Novosibirsk, Russia K.V. Lotov, A. Sosedkin NSU, Novosibirsk, Russia E. Mesyats ICM&MG SB RAS, Novosibirsk, Russia
	Funding: The Ministry of education and science of Russia, project 14.B37.21.0784. Controlled self-modulation of long proton or electron beams is a new trend in plasma wakefield acceleration which sets a new goal for simulation codes. Long interaction lengths (tens of meters), long beams (up to hundred of plasma wave periods), motion of plasma ions, and violation of fluid approximation are factors that makes the problem too heavy for general purpose codes. Only specialized codes can attack this problem in real geometry. We describe recent upgrades of the code LCODE which enabled simulations of long dense proton beams and report results of numerical studies of proton beam-plasma interaction in the context of AWAKE project.

TUPEA061	High-Brightness SASE Studies for the CLARA FEL	undulator, FEL, electron, radiation	1274
	R.N.C. Santer, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Compact Linear Accelerator for Research and Applications (CLARA) is a proposed 250 MeV FEL test facility to be constructed at STFC Daresbury Laboratory in the UK [1]. This paper presents study of a scheme for the temporal and spectral stabilisation of the SASE output. A feasibility study for the operation of the FEL in a novel High-Brightness SASE mode is presented. Electron beam delays are introduced between undulator sections to disrupt the localised collective FEL process, increase the radiation coherence length and reduce the rms bandwidth. This may extend the range of electron bunch lengths appropriate for the generation of temporally coherent single spike SASE FEL pulses.

TUPEA064	A Proposed Plasma Accelerator Research Station at CLARA Facility	plasma, electron, wakefield, acceleration	1280
	G.X. Xia, K. Hanahoe UMAN, Manchester, United Kingdom D. Angal-Kalinin, J.A. Clarke, J.K. Jones, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom J.D.A. Smith TXUK, Warrington, United Kingdom
	We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury lab. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in the electron beam driven plasma wakefield acceleration, e.g. the two bunch acceleration for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and the related beam instabilities. This paper discusses the feasibility studies of electron beam parameters to meet the requirements for beam driven wakefield acceleration and the possible experiments which can be conducted at PARS beam line.

TUPEA065	Design of a Photonic Crystal Accelerator for Basic Radiation Biology	laser, vacuum, acceleration, electron	1283
	A. Aimidula, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom A. Aimidula, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom K. Koyama, Y. Matsumura University of Tokyo, Tokyo, Japan T. Natsui, M.Y. Yoshida KEK, Ibaraki, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan G.X. Xia UMAN, Manchester, United Kingdom
	Funding: This work is supported by the EU under Grant Agreement 289485, the STFC Cockcroft Institute Core Grant No. ST/G008248/1 and KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120. The application of photonic crystals to realize an on-chip electron beam source for fundamental radiation biology is highly interesting for a number of applications. The unique combination of nanometer beam size and attosecond-short pulses has a very promising potential for use in microscopic and ultra-fast analyses of damage and repair of radiation-irradiated DNA and chromosomes. Simulations studies indicate an output electron beam energy, beam intensity and device size of the order of MeVs, fCs and a few cm, respectively. In this contribution, first results from numerical studies into the design of such compact accelerator structure are presented. The dimensions of a novel dual grating-based acceleration structure are shown together with the estimated laser parameters. Finally, a system consisting of an electron injector and multi-stage accelerating structures is proposed, which corresponds to a miniaturized optical linear accelerator.

TUPEA068	Wake-field Reduction in Hybrid Photonic Crystal Accelerator Cavities	wakefield, lattice, cavity, dipole	1289
	D. A. Rehn Colorado University at Boulder, Boulder, Colorado, USA C.A. Bauer, J.R. Cary, G.R. Werner CIPS, Boulder, Colorado, USA J.R. Cary, C.D. Zhou Tech-X, Boulder, Colorado, USA
	Funding: This work is supported by the U.S. Dept. of Energy, grant DE-FG02-04ER41317. Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping.

TUPEA071	THz Bench Tests of a Slab-symmetric Dielectric Waveguide	acceleration, laser, wakefield, emittance	1292
	F. Lemery, H. Panuganti, P. Piot Northern Illinois University, DeKalb, Illinois, USA D. Mihalcea, P. Piot Fermilab, Batavia, USA P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359. Dielectric-lined waveguides (DLW) are becoming more popular for beam driven acceleration applications. An experiment to demonstrate beam-driven acceleration using a slab-symmetric dielectric-lined waveguide driven by a flat beam is in preparation at the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In this paper we characterize the structure using a THz pulse obtained from optical rectification using an amplified laser pulse. After propagation through the DLW structure, the THz pulse is analyzed using a Michelson interferometer and single-shot electro-optical imaging. Data for various gap size will be presented.

TUPEA072	Toward a Dielectric-Wakefield Energy Doubler at the Fermilab's Advanced Superconducting Test Accelerator	emittance, acceleration, electron, wakefield	1295
	F. Lemery, D. Mihalcea, P. Piot, C.R. Prokop Northern Illinois University, DeKalb, Illinois, USA P. Piot, Y.-E. Sun Fermilab, Batavia, USA P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359. The Advanced Superconducting Test Accelerator (ASTA), presently under construction at Fermilab, will produce high-charge (~<3 nC) electron bunches with energies ranging from 50 to eventually 750 MeV. The facility is based on a superconducting linac capable of producing up to 3000 bunches in 1-ms macropulses repeated at 5 Hz. In this paper we explore the use of a short dielectric-lined-waveguide (DLW) linac to significantly increase the bunch energy. The method consists in (1) using advanced phase space manipulation techniques to shape the beam distribution and enhance the transformer ratio, and (2) optimize the generation and acceleration of a low-charge witness bunches. Start-to-end simulations of the proposed concept are presented. This DLW module could also be used to test some aspects of a recently proposed concept for a multiuser short-wavelength free-electron laser utilizing a series of DLW linacs. C. Jing et al., “A Compact Soft X-ray Free-Electron Laser Facility based on a Dielectric Wakefield Accelerator”, Advanced Photon Source LS Note LS-332, Argonne National Laboratory (2012).

TUPEA073	Performances of VORPAL-GPU Slab-symmetric DLW	wakefield, factory, electron, dumping	1298
	F. Lemery, K. Duffin, N. Karonis, D. Mihalcea, P. Piot, J. Winans Northern Illinois University, DeKalb, Illinois, USA P.J. Mullowney, P. Stoltz Tech-X, Boulder, Colorado, USA P. Piot Fermilab, Batavia, USA
	Funding: HDTRA1-10-1-0051, DOE(Grant No will be specified later) GPU-based computing has gained popularity in recent years due to its growing software support and greater processing capabilities than its CPU counterpart. GPU computing was recently added in the finite-difference time-domain program VORPAL. In this paper we carry electromagnetic simulations and optimization of a flat beam passing through a slab-symmetric dielectric-lined waveguide (DLW). We use this simulation model to explore the scaling of the GPU version of VORPAL on a new TOP1000-grade hybrid GPU/CPU computer cluster available at Northern Illinois University.

TUPEA087	Experiment on Multipactor Suppression in Dielectric-loaded Accelerating Structures with a Solenoid Field	multipactoring, solenoid, electron, plasma	1319
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA C. Chang, L. Ge, L. Xiao SLAC, Menlo Park, California, USA M.E. Conde, W. Gai, R. Konecny, J.G. Power ANL, Argonne, USA S.H. Gold NRL, Washington, DC, USA
	Funding: US DoE SBIR Phase I project under contract #DE-SC0007629 Efforts by numerous institutions have been ongoing over the past decade to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external rf source. Multipactor is the major issue limiting the gradient that was revealed in earlier experiments. A theoretical model predicts that the strength of solenoid field within an optimal range applied to DLA structures may completely block the multipactor. To demonstrate this approach, two DLA test structures have been built and the first high power test will be conducted in December 2012. The results will be reported.

TUPEA089	Modeling and Experimental Update on Quasi-phase Matched Direct Laser Electron Acceleration In Density-modulated Plasma Waveguides	plasma, laser, electron, target	1325
	M.W. Lin, D.R. Abercrombie, I. Jovanovic, A. Rakhman Penn State University, University Park, Pennsylvania, USA
	Funding: This work has been supported by the Defense Threat Reduction Agency through Contract HDTRA1-11-1-0009. Direct laser acceleration (DLA) of electrons using the axial electric field of a radially polarized, guided intense laser pulse has the potential to lead to compact laser-driven accelerators* for security and medical applications. A density-modulated plasma waveguide could be applied to extend the laser beam propagation distance and to achieve quasi-phase matching (QPM) between laser and electron pulses for efficient DLA. We conduct numerical simulations to design the appropriate plasma structure of the waveguides and investigate the properties of accelerated electron beams. An all-optical method, based on the igniter-heater scheme for plasma waveguide fabrication, is experimentally implemented to machine the density-modulated plasma waveguides with low-Z gas targets. A novel angle-multiplexed diagnostic technique has been developed to extract the polarization state and temporal characteristics of a radially polarized femtosecond laser pulse using spatial-spectral interferometry. The goal of our experiments is to characterize the propagation of femtosecond radially polarized pulses in plasma waveguides. P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000). M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012). *P. Bowlan, et al., Opt. Exp. 14, 11892 (2006)

TUPFI012	HL-LHC: Integrated Luminosity and Availability	luminosity, target, collider, hadron	1352
	A. Apollonio, M. Jonker, R. Schmidt, B. Todd, S. Wagner, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	The objective of LHC operation is to optimise the output for particle physics by maximising the integrated luminosity. An important constraint comes from the event pile–up for one bunch crossing that should not exceed 140 events per bunch crossing. With bunches every 25 ns the luminosity for data taking of the experiments should therefore not exceed 5*10³⁴ s⁻¹cm^-2. For the optimisation of the integrated luminosity it is planned to design HL-LHC for much higher luminosity than acceptable for the experiments and to limit the initial luminosity by operating with larger beam size at the collision points. During the fill, the beam size will be slowly reduced to keep the luminosity constant. The gain from luminosity levelling depends on the average length of the fills. Today, with the LHC operating at 4 TeV, most fills are terminated due to equipment failures, resulting in an average fill length of about 5 h. In this paper we discuss the expected integrated luminosity for HL-LHC as a function of fill length and time between fills, depending on the expected MTBF of the LHC systems with HL-LHC parameters. We derive an availability target for HL-LHC and discuss steps to achieve this.

TUPFI017	Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy	quadrupole, dipole, lattice, dynamic-aperture	1367
	Y. Nosochkov, Y. Cai, M.-H. Wang SLAC, Menlo Park, California, USA R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515. The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented. Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.

TUPFI019	Magnet Misalignment Studies for the Front-end of the Neutrino Factory	target, lattice, proton, factory	1373
	G. Prior, I. Efthymiopoulos CERN, Geneva, Switzerland D.V. Neuffer, P. Snopok Fermilab, Batavia, USA C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom D. Stratakis BNL, Upton, Long Island, New York, USA
	In the Neutrino Factory Front-End the muon beam coming from the interaction of a high-power (4 MW) proton beam on a mercury jet target, is transformed through a buncher, a phase rotator and an ionization cooling channel before entering the downstream acceleration system. The muon Front-End channel is densely packed with solenoid magnets, normal conducting radio-frequency cavities and absorber windows (for the cooling section). The tolerance to the misalignment of the different components has to be determined in order on one hand to set the limits beyond which the performance of the Front-End channel would be degraded; on the other hand to optimize the design and assembly of the Front-End cells such that the component alignment can be checked and corrected for where crucial for the performance of the channel. In this paper we will show the results of the simulations of the Front-End channel performance where different components such as magnets, cavities have been randomly shifted or rotated. Detailed simulations have been done in G4BeamLine. T. J. Roberts et al. G4BeamLine 2.06 (2010) http://g4beamline.muonsinc.com/

TUPFI020	Towards a Symmetric Momentum Distribution in the Muon Ionization Cooling Experiment	solenoid, quadrupole, collider, emittance	1376
	O.M. Hansen University of Oslo, Oslo, Norway A.P. Blondel DPNC, Genève, Switzerland I. Efthymiopoulos, O.M. Hansen CERN, Geneva, Switzerland
	The Muon Ionization Cooling Experiment (MICE) is under development at Rutherford Appleton Laboratory (UK). It's a proof-of-principle experiment for ionization cooling, which is a prerequisite for a future Neutrino Factory(NF) or a Muon Collider. The muon beam is designed to have a symmetrical momentum distribution in the cooling channel of the NF. In the MICE beamline pions are captured by a quadrupole triplet, then pion momentum is selected by dipole 1 (D1) after which the pions decay to muons in the decay solenoid. After the decay solenoid, the muon beam momentum is selected by dipole 2 (D2), the beam is focused in two quadrupole triplets and is finally characterized by a set of detectors. By doing a D1-scan of the currents, where the optics parameters are scaled according to the pion momentum, from 238-450 MeV/c the muon momentum distribution is changed. In this paper simulation results from G4Beamline and real data from MICE are presented and compared.

TUPFI024	Influence of the Ats Optics on Intra-Beam Scattering for HL-LHC	optics, luminosity, emittance, collider	1388
	M. Schaumann, R. Bruce, J.M. Jowett CERN, Geneva, Switzerland M. Schaumann RWTH, Aachen, Germany
	In the future High Luminosity (HL-)LHC the influence of intra-beam scattering (IBS) will be stronger than in the present LHC, because of higher bunch intensity, small emittance and new optics. The new ATS-optics scheme modifies the lattice in the arcs around the main interaction points (IP) to provide β* values as small as 0.15m in the IP, however those modifications affect the IBS growth rates. In this paper proton IBS emittance growth rates are calculated with MADX and the Collider Time Evolution (CTE) program for two ATS-optics versions, different settings of the crossing angles and required corrections and various beam conditions at injection (450 GeV) and collision (7 TeV) energy. CTE simulations of the expected luminosity, intensity, emittance and bunch length evolution during fills are also presented

TUPFI025	Bunch-by-Bunch Analysis of the LHC Heavy-Ion Luminosity	luminosity, injection, emittance, ion	1391
	M. Schaumann, J.M. Jowett CERN, Geneva, Switzerland
	After the first run in 2010, the LHC continued its heavy-ion operation with collisions of lead nuclei in late 2011. The beam dynamics of those high intensity lead beams are strongly influenced by intra-beam scattering (IBS), especially on the injection plateau. Each batch injected from the SPS spends a different time at injection, introducing significant changes from batch to batch. Within the batches there is an even larger spread imprinted by the SPS injection plateau. This results in a spread of the luminosity produced in each bunch crossing. The particle losses during collisions are dominated by nuclear electromagnetic processes, leading to a non-exponential intensity decay during the fill and short luminosity lifetime at 3.5 Z TeV. The luminosity, emittance, intensity and bunch length evolution of the 2011 run was analysed bunch-by-bunch and compared with simulations. Based on this analysis, estimates of the potential luminosity performance at 6.5 Z TeV, after the present shutdown, are given.

TUPFI045	Electron-cloud Maps for LHC Scrubbing Optimization	electron, injection, dipole, beam-losses	1451
	C.O. Domínguez, F. Zimmermann CERN, Geneva, Switzerland
	Electron-cloud maps as alternative to detailed build-up simulations have already been applied in the past for a few accelerators, e.g. RHIC and the LHC at 7 TeV. We here report a first application of maps to optimize the "beam scrubbing" of the LHC arcs at injection energy: Maps are used to efficiently determine the optimum bunch filling pattern which maximizes the electron flux on the chamber wall, while respecting constraints on the central cloud density to ensure beam stability. In addition, new features have been explored, e.g. by introducing thresholds which divide regions where either linear maps or cubic maps best describe the build-up and the decay of an electron cloud. In the near future we plan to extend the map formalism to individual slices in a dipole file in order to represent the vertical "stripes".

TUPFI046	The MICE Experiment	solenoid, target, emittance, quadrupole	1454
	A.P. Blondel DPNC, Genève, Switzerland
	Ionization Cooling is the only practical solution to preparing high brilliance muon beams for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (UK). It is characterized by exquisite emittance determination by 6D measurement of individual particles, a cooling section comprising 23 MV of acceleration at 200 MHz and 3 liquid hydrogen absorbers totaling 1m of liquid hydrogen on the path of 140-240 MeV/c muons. The beam has already been commissioned successfully and first measurements of beam emittance performed. We are setting up for the final high precision emittance determination and the measurements of cooling in Li Hydrogen. The design offers opportunities to observe cooling with various absorbers and several optics configurations. Results will be compared with detailed simulations of cooling channel performance to ensure full understanding of the cooling process. Progress towards the full cooling experiment with RF re-acceleration will also be reported. Submitted by the MICE speakers bureau hoping for a contributed oral to be give by the spokesperson, prof. A. Blondel

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MOODB103

Results of an Experiment on Hydrodynamic Tunnelling at the SPS HiRadMat High Intensity Proton Facility

target, proton, synchrotron, instrumentation

37

R. Schmidt, J. Blanco, F. Burkart, D. Grenier, D. Wollmann
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria
N.A. Tahir
GSI, Darmstadt, Germany

To predict the damage for a catastrophic failure of the protections systems for the LHC when operating with beams storing 362 MJ, simulation studies of the impact of an LHC beam on targets were performed. Firstly, the energy deposition of the first bunches in a target with FLUKA is calculated. The effect of the energy deposition on the target is then calculated with a hydrodynamic code, BIG2. The impact of only a few bunches leads to a change of target density. The calculations are done iteratively in several steps and show that such beam can tunnel up to 30-35 m into a target. Validation experiments for these calculations at LHC are not possible, therefore experiments were suggested for the CERN Super Proton Synchrotron (SPS), since simulation studies with the tools used for the LHC also predict hydrodynamic tunnelling for SPS beams. An experiment at the SPS-HiRadMat facility (High-Radiation to Materials) using the 440 GeV beam with 144 bunches was performed in July 2012. In this paper we compare the results of this experiment with our calculations of hydrodynamic tunnelling.

Slides MOODB103 [40.426 MB]

MOODB202

Simulations and Measurements of Cleaning with 100 MJ Beams in the LHC

proton, collimation, beam-losses, betatron

52

R. Bruce, R.W. Aßmann, V. Boccone, C. Bracco, M. Cauchi, F. Cerutti, D. Deboy, A. Ferrari, L. Lari, A. Marsili, A. Mereghetti, E. Quaranta, S. Redaelli, G. Robert-Demolaize, A. Rossi, B. Salvachua, E. Skordis, G. Valentino, V. Vlachoudis, Th. Weiler, D. Wollmann
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain
E. Quaranta
Politecnico/Milano, Milano, Italy
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The CERN Large Hadron Collider is routinely storing proton beam intensities of more than 100 MJ, which puts extraordinary demands on the control of beam losses to avoid quenches of the superconducting magnets. Therefore, a detailed understanding of the LHC beam cleaning is required. We present tracking and shower simulations of the LHC's multi-stage collimation system and compare with measured beam losses, which allow us to conclude on the predictive power of the simulations.

Slides MOODB202 [6.343 MB]

MOPEA014

Temporal and Spectral Observation of Laser-induced THz Radiation at DELTA

electron, laser, radiation, storage-ring

94

P. Ungelenk, H. Huck, M. Huck, M. Höner, S. Khan, R. Molo, A. Schick
DELTA, Dortmund, Germany
N. Hiller, V. Judin
KIT, Karlsruhe, Germany

Funding: Work supported by the DFG, the BMBF, the Federal State NRW, the Initiative and Networking Fund of the Helmholtz Association, and the German Federal Ministry of Education and Research.
Coherent THz pulses caused by a laser-induced density modulation of the electron bunches are routinely produced and observed at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. New measurements performed with a fast hot-electron bolometer allow insight into the turn-by-turn evolution of these pulses. Furthermore, first results from a Fourier transform infrared spectrometer, which is currently under commissioning, are presented.

MOPEA016

The Main Stochastic Cooling System of the HESR

kicker, pick-up, accumulation, vacuum

100

R. Stassen, R. Greven, R. Maier, G. Schug, H. Stockhorst
FZJ, Jülich, Germany

The main stochastic cooling system of the High-Energy Storage Ring HESR (1.5-15 GeV/c) for antiprotons at the FAIR complex (Facility for Antiprotons and Ion Research) in Darmstadt (GSI) will work in the frequency range of 2 - 4 GHz. The design work on pickup and kicker is now finished and the production of the first cooling tank has been started. The whole system layout will be presented taking into account new additional requirements concerning the accumulation and the cooling of heavy ions. All beam-coupling structures are nearly identical and contain several ring-slot blocks. These blocks consist of eight wall-current monitors coupled out by eight electrodes each. Most of the signal combining and splitting take place within the vacuum envelope to reduce the number of vacuum RF feed throughs. The long-distance transmission of the signals and the filters containing long signal delays work with near infrared optical elements.

MOPEA018

Feasibility Study of Heavy Ion Storage and Acceleration in the HESR with Stochastic Cooling and Internal Targets

target, cavity, ion, acceleration

106

H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen
FZJ, Jülich, Germany
T. Katayama
GSI, Darmstadt, Germany

Stochastic cooling of heavy ions is investigated under the constraint of the present hardware design of the cooling system and RF cavities as well as the given magnet design as foreseen for anti-proton cooling in the HESR of the FAIR facility. A bare uranium beam is injected from the collector ring CR into the HESR at 740 MeV/u. The beam preparation for an internal target experiment with cooling is outlined. The acceleration of the ion beam to 2 GeV/u is studied under the basic condition of the available cavity voltages and the maximum magnetic field ramp rate in the HESR. The cooling simulations include the beam-target interaction due to a Hydrogen and Xenon target. Diffusion due to Schottky and thermal noise as well as intra beam scattering is accounted for. Due to the higher charge states of the ions Schottky particle noise power becomes an important issue. The analysis considers the electronic power limitation to 500 W in case of momentum cooling. Fast Filter cooling is only available if the revolution harmonics do not overlap in the cooling bandwidth. Since overlap occurs for lower energies the application of the Time-Of-Flight (TOF) momentum cooling method is discussed.

MOPEA021

Status of the HESR Electron Cooler Test Set-up

electron, cathode, controls, vacuum

115

M.W. Bruker, K. Aulenbacher, J. Dietrich, S. Friederich, A. Hofmann, T. Weilbach
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

For the proposed High Energy Storage Ring (HESR) at FAIR, it is foreseen to install an electron cooling device with a beam current of 3 A and a beam energy of 8 MeV. A test set-up was built at Helmholtz-Insitut Mainz (HIM) to conduct a feasibility study. One of the main goals of the test set-up is to evaluate the gun design proposed by TSL (Uppsala) with respect to vacuum handling, EM fields and the resulting beam parameters. Another purpose of the set-up is to achieve an energy recuperation efficiency of 1 - 10^-5. To measure this quantity, a Wien filter has to be employed, which will also prove capable of mitigating collection losses. The current status of the project will be presented.

MOPEA032

Installation Status of Deuteron Injector of IFMIF Prototype Accelerator in Japan

neutron, rfq, emittance, alignment

148

H. Shidara, J. Knaster
IFMIF/EVEDA, Rokkasho, Japan
D. Bogard, N. Chauvin, P. Girardot, R. Gobin, F. Harrault, D. Loiseau, P.A.P. Nghiem, A. Roger, F. Senée
CEA/DSM/IRFU, France
L. Semeraro
F4E, Barcelona, Spain

The International Fusion Materials Irradiation Facility (IFMIF) will generate a neutron irradiation field with the spectrum simulating the fusion D-T neutrons (14 MeV) to qualify suitable materials for fusion power plants. The IFMIF accelerator facility provides two CW / 40 MeV / 125 mA deuteron beams to the IFMIF Lithium target facility. In the Engineering Validation and Engineering Design Activities phase, the concept of IFMIF is validated with a single CW / 9 MeV / 125 mA deuteron accelerator prototype under construction in JAEA/Rokkasho. The injector part has been designed, constructed and successfully tested by CEA/Saclay. The ECR ion source produces a deuteron beam of 140 mA at 100 keV. In spring 2013, the injector will be delivered and re-installed on the Rokkasho site. This paper will focus on the detailed plan of the injector’s re-assembly as well as on the re-commissioning. Further possible improvements are discussed in order to achieve reliable operation.

MOPEA037

Theoretical Study on the Two-stage Collimation System Design

collimation, scattering, vacuum, space-charge

157

N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

Two-stage collimation system is widely used in high intensity machines to localize the beam losses in a restricted area. In the well-known theory, the optical constrains are expressed by the betatronic phase advances between primary and secondary collimators, which minimize the size of the secondary halo. In this paper, the physical model is developed considering the characteristic of the space charge dominated beams. Numerical studied are performed to verify the theoretical model.

MOPEA040

Study of Geometry Dependent Multipacting of a Superconducting QWR

accelerating-gradient, electron, cavity, vacuum

166

K. Zhou, X.Y. Lu, X. Luo, S.W. Quan, L. Yang, Z.Y. Yao
PKU, Beijing, People's Republic of China

Funding: The Major Research Plan of National Natural Science Foundation of China
A superconducting quarter wave resonator (QWR) of frequency=162.5 MHz and β=0.085 has been designed at Peking University. This paper focus on the multipacting (MP) study for the QWR with CST Particle Studio. The simulation results for the initial designed model reveal that there is no sign of MP with its normal operating accelerating gradients in the range of 6-8 MV/m. The accelerating gradient range that may incur MP is from about 1.4 MV/m to 3.2 MV/m, and the places where MP may be encountered are mainly located at the top part of the QWR. So the effect of different top geometries on MP has also been studied in depth. Our results show that inward convex round roof is better than other round roofs, and plane roofs have an obvious advantage over round roofs on the suppression of MP in general. While considering the optimization of its electromagnetic (EM) design, our initial designed model is also acceptable.

MOPEA042

Research on the Design and Simulation of the CSRE Stochastic Cooling System

sextupole, pick-up, emittance, target

169

X.J. Hu, H. Jia, Y.J. Yuan, X.H. Zhang
IMP, Lanzhou, People's Republic of China

Stochastic cooling by the use of a feedback system, aims at cooling of secondary particles or particles with large emittance or momentum spread. My research is mainly on the simulation of horizontal and longitudinal stochastic cooling process. The purpose of my work is to obtain the optimum parameters for stochastic cooling, according the actual accelerator lattice. Pickup and preamplifier are already installed on the CSRe, and preliminary results are get.

MOPEA043

Transverse Instabilities of Two Twisted Beams in a Storage Ring

ion, electron, storage-ring, kicker

172

B.C. Jiang, M.Z. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
G.X. Xia
UMAN, Manchester, United Kingdom

Two twisted beams (two beams run on the different closed orbit) in a storage ring which is produced by fast kickers can potentially deliver two bunds of radiations through one insertion device or one bend magnet, in this way doubles the beam line stations. This operation mode needs higher beam current and more RF buckets to be filled to keep the brightness comparable to the single beam operation mode. The resistive wall instability and ion trapping effects is analysed to address the higher current operation possibility. The analyze results show that twisted beams can weaken those two instabilities.

MOPEA059

The Optimization of Transverse Stripline Kicker

kicker, vacuum, impedance, insertion

214

H.P. Hsueh, C.-C. Chang, Y.P. Chang, J.-R. Chen, Y.T. Cheng, G.-Y. Hsiung, Y.C. Yang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. It is required to install stripline kickers to suppress instability generated by mismatch between injection kickers or imperfect installation of vacuum components all around. First, the design philosophy will be described for transverse stripline kickers. HFSS electromagnetic simulation software is used to optimize all structure parameters like electrode dimensions, electrode distance from vacuum chambers etc. to make transverse stripline kicker working more efficiently and effectively. All simulation results will be presented in this paper and all structure dimension choices will be discussed and the final prototype structure dimensions will be selected from the discussion.

MOPEA073

Current Status of the LBNE Neutrino Beam

target, proton, shielding, focusing

255

C.D. Moore, K.R. Bourkland, C.F. Crowley, P. Hurh, J. Hylen, B.G. Lundberg, A. Marchionni, M.W. McGee, N.V. Mokhov, V. Papadimitriou, R.K. Plunkett, S.D. Reitzner, A.M. Stefanik, G. Velev, K.E. Williams, R.M. Zwaska
Fermilab, Batavia, USA

Funding: Work supported by the Fermilab Research Alliance, under contract DE-AC02-07CH11359 with the U.S. Dept of Energy.
The Long Baseline Neutrino Experiment (LBNE) will utilize a neutrino beamline facility located at Fermilab. The facility is designed to aim a beam of neutrinos toward a detector placed in South Dakota. The neutrinos are produced in a three-step process. First, protons from the Main Injector hit a solid target and produce mesons. Then, the charged mesons are focused by a set of focusing horns into the decay pipe, towards the far detector. Finally, the mesons that enter the decay pipe decay into neutrinos. The parameters of the facility were determined by an amalgam of the physics goals, the Monte Carlo modeling of the facility, and the experience gained by operating the NuMI facility at Fermilab. The initial beam power is expected to be ~700 kW, however some of the parameters were chosen to be able to deal with a beam power of 2.3 MW. The LBNE Neutrino Beam has made significant changes to the initial design through consideration of numerous Value Engineering proposals and the current design is described.

MOPEA083

Energy Modulation in Coherent Electron Cooling

electron, ion, plasma, FEL

276

G. Wang, M. Blaskiewicz, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling (CeC) relies on Debye shielding to imprint information of the ion beam to an electron beam [1]. Apart from the density modulation, Debye shielding also modulates the energy of electrons, which provides additional seeding for the free electron laser (FEL) amplifier. In this work, we show that the energy modulation of a longitudinal slice of the electrons, induced by dynamic Debye shielding of a moving ion in anisotropic electron plasma with κ-2 velocity distribution, can be expressed into a 1D integral. The results are then applied to the 1D FEL model to investigate the effects of energy modulation to the correcting force in the kicker.
[1] V.N. Litvinenko, Y.S. Derbenev, Coherent Electron Cooling, Physical Review Letters, 102 (2009) 114801. http://link.aps.org/abstract/PRL/v102/e114801

MOPFI014

A Charge Lifetime Study of NEA GaAs Cathode by Ion Back-bombardment

electron, cathode, ion, vacuum

312

M. Kuriki
KEK, Ibaraki, Japan
L. Guo, H. Iijima, K. Miyoshi
HU/AdSM, Higashi-Hiroshima, Japan

Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science and Technology; The title is High Brightness Photon Beam by Laser-Compton Scattering.
NEA GaAs cathode is one of the most important techniques for advanced future projects based on linac. Up to 90% polarized beam can be generated with high quantum efficiency, 0.1 – 10%. The extremely low emittance beam can be generated driven by optimized wavelength laser. Although these remarkable features, the less robustness has been the biggest issue on the real operation of this cathode. According to past experiments, there are three sources of the cathode degradation; gas absorption, thermal desorption, and ion-back bombardment. First two processes could be controlled by less vacuum pressure in order of 10^-10Pa and keeping the cathode temperature low. The ion back-bombardment is the last issue which should be solved for high brightness operation in such as ERL. We observed the cathode quantum efficiency evolution in various laser power density and bias voltage. We found that the cathode degradation was due to the ion back-bombardment quantitatively and the deactivation coefficient of NEA surface by one ion collision did not depend on the bias voltage. We report the experimental results and its analysis based on the ion back-bombardment hypothesis.

MOPFI017

SuperKEKB Positron Source Target Protection Scheme

target, positron, electron, radiation

315

L. Zang, T. Kamitani
KEK, Ibaraki, Japan

The SuperKEKB requires an intense beam with a large number of positrons, which is generated by a high energy electron beam strike on a solid tungsten target. The cascade shower in the target deposits large amount of energy in the material leading to target damage. The pulsed electron beam distributed the energy non-uniformly over the target. In that case, a mechanical stress appears due to the large thermal gradient during each pulse, which could potentially destroy the target. Based on the analysis of the SLAC damaged target, peak energy deposition density (PEDD) should not exceed 35 J/g to ensure a long term of safe operation. One way of reducing PEDD is increasing the beam spot size. Hence we proposed a target protection scheme, in which a protection target is placed upstream of generation target as a spoiler. The aim is to maintain the generation target’s PEDD below 35 J/g even with a point primary electron beam. In this paper, we will introduce graphite, aluminum and copper as the protection target material candidates. And also present the PEDD and positron yield evaluation as a function of various parameters such as protection target thickness and drift space.

MOPFI018

Design Study of a New Large Aperture Flux Concentrator

positron, target, solenoid, focusing

318

L. Zang, M. Akemoto, S. Fukuda, K. Furukawa, T. Higo, K. Kakihara, T. Kamitani, Y. Ogawa, H. Someya, T. Takatomi
KEK, Ibaraki, Japan

For high luminosity electron-positron colliders, intense positron beam production is one of the key issues. Flux Concentrator (FC) is a pulsed solenoid that can generate high magnetic field of several Tesla and is often used for focusing positrons emerged from a production target. It works as an optical matching device in a positron capture section. With this device, high capture efficiency is achieved. In this paper, we will introduce a new design of a FC for the SuperKEKB positron source. The advantages of the new design are: 1. the aperture could be doubled of the previous design, 2. the transverse components are only 1/10 of the previous design, 3. maintain the same high peak longitudinal field. The new FC modeling has been done in CST Studio and we will report the results of new FC field evaluation. In order to calculate the positron yield and capture efficiency, a tracking simulation to the end of capture section has also been carried out, which is also included in this paper.

MOPFI026

Thermal Simulations of a New Target Configuration for Production of Radioactive Nuclide

target, neutron, radiation, ion

336

L.H. Chen, B.Q. Cui, Q.H. Huang, W. Jiang, R. Ma, Y.J. Ma, B. Tang
CIAE, Beijing, People's Republic of China

China Advanced Rare Ion-beam Facility (CARIF) based on China Advanced Research Reactor (CARR) has been proposed in order exploring the frontier of nuclear physics. A target with 5 g 235U is proposed in the project. The thermal neutron fission of 235U will produce radioactive nuclei and the great thermal load (~50 kW). The target of CARIF needs endure high temperature and thermal energy deposit. A new multi-targets configuration is proposed. It consists of several discrete targets instead of traditional single-target structure used in accelerator driven facility. Because there is more thermal radiation area in this configuration, thermal radiation capacity is enhanced, so the target can withstand higher thermal power. The temperature distribution of multi-targets was simulated with finite element code. The results show that the configuration of multi targets can effectively reduce the target temperature. From the perspective of target temperature distribution, the configuration could endure 50kW thermal deposit. It's possible to use 5 g 235U in CARIF for production of radioactive nuclide.

MOPFI041

Study of Beam Longitudinal Motion for SSC

extraction, injection, cyclotron, acceleration

378

X.N. Li, Y.J. Yuan
IMP, Lanzhou, People's Republic of China

The injection, acceleration and extraction of SSC（Separate Sector Cyclotron） is analyzed and simulated to get the longitudinal acceptance, using the typical ion 238U³⁶⁺ with energy 9.7MeV/u. In order to study the actual longitudinal acceptance of SSC, the isochronous magnetic field model in coincidence with the real one is established by Kr-Kb and Lagrange methods based on the actual measurement. Under the isochronous magnetic field, the longitudinal acceptance at the injection, acceleration and extraction is calculated. From the simulation results the transmission efficiency is very low in SSC because of the large phase width of the beam from the injector SFC (Sector Focus Cyclotron). In the machine commissioning, the phase width of the beam line from SFC to SSC is measured by the phase probe, the results show that the actual phase width is larger than the acceptance of SSC.

MOPFI045

Studying of Multipacting in Micro-pulse Electron Gun

electron, gun, resonance, cavity

383

L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI046

Transverse RF Kicker Excitation and Longitudinal RF Noise Diffusion for Slow Extraction from SAPT

extraction, kicker, synchrotron, resonance

386

L. Ouyang, M. Gu, D.M. Li, Q. Yuan, M.Z. Zhang
SINAP, Shanghai, People's Republic of China

Two key techniques used in the slow extraction from synchrotron accelerator: longitudinal RF stochastic noise acceleration, and transverse RF knock out excitation have been studied in this paper. Detailed comparison have revealed the potentials and limits of both methods. For the longitudinal RF stochastic acceleration excitation, the focus has been the phase space compression of particles, which makes the them to hasten around the RF bucket of the cavity, thus to lower the senstivity to ripple. For the transverse RF knock out excitation, the emphasis have been optimal schemes of amplitude modulation and frequency modulation of the RF singals. The optimizations are also used to lower the senstivity of the beam to the ripple and to enhance the uniformity of the extracted beam.

MOPFI050

Non-local Fast Extraction from the CERN SPS at 100 and 440 GeV

extraction, kicker, septum, injection

392

F.M. Velotti, A. Alekou, W. Bartmann, E. Carlier, K. Cornelis, I. Efthymiopoulos, B. Goddard, L.K. Jensen, V. Kain, M. Kowalska, V. Mertens, R. Steerenberg
CERN, Geneva, Switzerland

The Long Straight Section 2 (LSS2) of the CERN SPS is connected with the North Area (NA), to which the beam to date has always been extracted using a resonant extraction technique. For new proposed short- and long-baseline neutrino experiments, a fast single turn extraction to this experimental area is required. As there are no kickers in LSS2, and the integration of any new kickers with the existing electrostatic septum would be problematic, a solution has been developed to fast extract the beam using non-local extraction with other SPS kickers. Two different kicker systems have been used, the injection kicker in LSS1 and the stronger extraction kicker in LSS6 to extract 100 and 440 GeV beam, respectively. For both solutions a large emittance beam was extracted after 5 or 9 full betatron periods. The concept and simulation details are presented with the analysis of the aperture and beam loss considerations and experimental results collected during a series of beam tests.

MOPFI059

Design and Performance of the Beam Transfer Lines for the HIE-ISOLDE Project

target, emittance, optics, dipole

416

A.S. Parfenova, W. Andreazza, J. Bauche, E.D. Cantero, P. Farantatos, M.A. Fraser, B. Goddard, Y. Kadi, A.J. Kolehmainen, D. Lanaia, M. Martino, R. Mompo, E. Siesling, A.G. Sosa, M.A. Timmins, G. Vandoni, D. Voulot, E.S. Zografos
CERN, Geneva, Switzerland

Beam design and beam optics studies for the HIE-ISOLDE transfer lines have been carried out in MadX, and benchmarked against Trace3D results. Magnet field errors and alignment imperfections leading to deviations from design parameters have been treated explicitly, and the sensitivity of the machine's lattice to different individual error sources was studied. As a result, the tolerances for the various error-contributions have been specified for the different equipment systems. The design choices for the expected magnet field and power supply quality, alignment tolerances, instrument resolution and physical aperture were validated. The methodology and results of the studies are presented.

MOPFI065

VELA (formerly EBTF) Simulations and First Beam Commissioning

gun, diagnostics, laser, electron

431

J.W. McKenzie, D. Angal-Kalinin, J.K. Jones, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

VELA (Versatile Electron Linear Accelerator), formerly known as EBTF (Electron Beam Test Facility), at STFC Daresbury Laboratory, is a photoinjector test facility which will provide beam into two user areas for scientific and industrial applications. It is based on a 2.5 cell S-band RF photoinjector driven by a Ti:Sapphire laser. The design is aimed to deliver short bunches at 10-250 pC charge with low transverse emittance. We present beam dynamics simulations of VELA as well as the results from first beam commissioning.

MOPFI070

Spallation is not the only Fruit: Low Energy Fusion as a Source of Neutrons

neutron, target, proton, radiation

443

S.C.P. Albright, R. Seviour
University of Huddersfield, Huddersfield, United Kingdom

Commercially there is a growing interest in applications of neutrons. Currently the majority of neutron sources are based at research institutions from either reactors or spallation sources. Smaller portable sources contain either fissile isotope or sealed fusors are available, although they either use or produce tritium, or other long lived decay products. As an alternative to the large facilities and the radio-toxicology of current portable sources research is being performed with an aim to produce a fusion based neutron source with neither of these concerns. We show that MCNPX is able to accurately reproduce (p,n) reactions for a number of light elements. Simulations of low energy proton reactions with light nuclei simulated with MCNPX and Geant4 are compared with experiment.

MOPFI073

Optimisation Studies of a High Intensity Electron Antineutrino Source

target, neutron, proton, cyclotron

449

A. Bungau, R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom
J.R. Alonso, J.M. Conrad, J. Spitz
MIT, Cambridge, Massachusetts, USA
M. Shaevitz
Columbia University, New York, USA

ISODAR (Isotopes-Decay-At-Rest) is a novel, high intensity source of electron antineutrinos produced by the decay of Li-8 isotopes, which aims for searches for physics beyond the standard model. The Li-8 isotopes are produced in the inelastic interactions of low energy protons or deuterons with a Beryllium target. In addition the Li-8 is produced in the surrounding materials by secondary neutrons. This paper focuses on the optimisation of the base design target, moderator and reflector.

MOPME003

Development of Diamond Sensors for Beam Halo and Compton Spectrum Diagnostics After The Interaction Point of ATF2

collimation, electron, photon, vacuum

470

S. Liu, P. Bambade
LAL, Orsay, France
S. Bai
IHEP, Beijing, People's Republic of China
T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

ATF2 is a low energy (1.3GeV) prototype of the final focus system for ILC and CLIC linear collider projects. A major issue at ATF2 and in linear colliders is to control the beam halo, which consists of tails extending far beyond the Gaussian core of the beam. At present there is no dedicated collimation for the beam halo at ATF2, and the transverse distribution near the interaction point is not well known. The development of a sensor based on CVD diamond to scan the beam halo in the vacuum chamber a few meters after the interaction point is presented. This system also aims to detect the Compton recoil electrons generated by the laser interferometer (Shintake monitor) used to measure the beam size at the interaction point of ATF2.

MOPME012

Single-bunch Longitudinal Phase Space Diagnostics in Multi-bunch Mode at the European XFEL

septum, dipole, diagnostics, electron

494

M. Yan, C. Gerth
DESY, Hamburg, Germany

Dedicated longitudinal electron beam diagnostics is highly demanded for the control and optimization of modern X-ray free-electron lasers (XFEL). At the European XFEL, 3 transverse deflecting structures (TDS) will be installed at different locations of the accelerator for measurements of slice emittance and longitudinal profile. Operation of a TDS in combined use with an energy spectrometer, e.g. a dispersive section after a single dipole magnet, allows additionally for longitudinal phase space (LPS) measurements. However, utilization of a dipole magnet is not compatible with single-bunch measurements in multi-bunch operation mode, which will be the standard operation mode of the European XFEL. In this paper, we propose a LPS diagnostic beamline consisting of a TDS, fast kicker and septum magnet for the European XFEL. The layout of the accelerator lattice with optimized optics for LPS measurements will be presented.

MOPME015

Numerical Wakefield Calculations for Electro-optical Measurements

wakefield, laser, storage-ring, impedance

503

B. Kehrer, A. Borysenko, E. Hertle, N. Hiller, V. Judin, S. Marsching, A.-S. Müller, M.J. Nasse, M. Schuh
KIT, Karlsruhe, Germany

Funding: This project is funded by the Federal Ministry of Education and Research under the contract number 05K10VKC
The technique of electro-optical measurements allows precise and single-shot measurements of the bunch length and shape. The installation of such a near-field setup changes the impedance of the storage ring and the corresponding effects have to be studied carefully. One possibility is to use numerical codes for simulating the wakefields induced by the setup. Such simulations has been done using the wakefield solver implemented in the CST Studio Suite. In this paper we present the simulation results together with first measurements.

MOPME020

Development of the New Measurement Method for the Incoherent Tune Spread and the Tune Shift Caused by the Space Charge Effect

dipole, emittance, injection, space-charge

512

S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan
H. Harada, H. Hotchi, M. Kinsho, K. Okabe
JAEA/J-PARC, Tokai-mura, Japan

For the high intensity accelerator, the incoherent tune which is the frequency of the individual particles is shifted and decreases due to the space charge effect. In addition, the incoherent tune is formed into spread shape commonly. When the incoherent tune satisfies a resonance condition, it might be occurred the beam emittance growth and the beam loss. So it is necessary to reduce the incoherent tune spread and the tune shift as much as possible. To achieve this condition, it is desired to measure the incoherent tune spread and the tune shift directly. Therefore we are developing the new measurement method of the incoherent tune spread and the shift due to the space charge effect. From the simulation results, it was cleared that the beam distribution can be modified in the case of using the mono frequency dipole exciter because a particle which has the tune corresponding to the exciter can be resonated temporary. In addition, it was cleared that it is possible to evaluate the incoherent tune spread and the tune shift by the measurement of the distribution transition. We present the outline of this method and the developing plane at the J-PARC RCS.

MOPME023

ORBIT Beam Simulation Progress in the 3-GeV Rapid Cycling Synchrotron of J-PARC

lattice, injection, impedance, synchrotron

521

P.K. Saha, H. Harada, H. Hotchi, Y. Shobuda, M. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
J.A. Holmes
ORNL, Oak Ridge, Tennessee, USA
S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan

We have made a numerous progress for beam simulation in the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) by using 3-D particle tracking code, ORBIT. Namely, the TEAPOT lattice file used for ORBIT tracking has been made to give exactly same results to that with SAD model used for the RCS beam commissioning. In addition, time dependent lattice functions of the injection chicane magnets and similar other time dependent lattice imperfections, which are already found to have significant influences on the beam losses in the real machine have also been successfully introduced. At present, time dependent transverse and longitudinal impedances are going to be introduced. That should prove the ORBIT code much more matured for beam simulations in synchrotrons. Latest beam simulation results illustrating these new realistic features are presented.

MOPME027

Bunch Length Measurement of 181 MeV Beam in J-PARC Linac

electron, linac, target, vacuum

532

A. Miura, H. Oguri, N. Ouchi, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
A. Feschenko, A.N. Mirzojan
RAS/INR, Moscow, Russia
K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan

In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. Because the longitudinal matching before ACS cavities is additionally required, we decided to employ the bunch shape monitors (BSMs) to measure the longitudinal beam profile. After three years from the start of BSM project, three BSMs were fabricated. All three BSMs were installed during the summer shutdown of 2012. We tried to measure the longitudinal beam profile exited from SDTL cavities. In this paper, we introduce the outline of BSM project, the first data acquisition and related small problems.

MOPME039

A New Method of Acquiring Fast Beam Transversal Profile in the Storage Ring

synchrotron, factory, electron, synchrotron-radiation

556

C. Cheng, P. Lu, B.G. Sun, K. Tang, F.F. Wu, Y.Y. Xiao, Y.L. Yang, Z.R. Zhou, J.Y. Zou
USTC/NSRL, Hefei, Anhui, People's Republic of China

A new method of acquiring fast beam transverse profile has been developed and will be used in HLS II. This method is based on four signals from MAPMT (multi-anode photo-multiplier tube) and logarithm processing technique. First, the calculation formula of beam transversal size and position are deduced using above method. Then, the main performances (e.g. sensitivity and linearity range) are analyzed. According to stimulation result, regardless of cross-talk and inconsistency between channels, the size signal has a linear relation with size s when s=0.8-2mm and position d=±2mm, the position signal has a linear relation with position d and the linear range exceeds ±2mm when s=0.8-2mm. With channel cross-talk and channel inconsistency being considered, the stimulation results also are given. Finally, a fast beam transverse profile monitor is designed and provides turn-by-turn measurement of the beam transverse profile.

MOPME041

Design and Calculation of the Stripline Beam Position Monitor for HLS II Storage Ring

quadrupole, coupling, storage-ring, impedance

562

F.F. Wu, C. Cheng, W.B. Li, P. Lu, T.J. Ma, B.G. Sun, H. Xu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China (10875117, 11005105, 11175173)
According to the requirements of HLS II upgraded, in order to acquire the non-intercepting measurement of beam position and quadrupole component, a new stripline beam position monitor (BPM) was designed for storage ring. The BPM parameters were optimized to acquire impedence matching with characteristic impedance of the external transmission lines and the coupling coefficients between the electrodes were calculated. According to the difference/sum and log-ratio methods, the horizontal and vertical sensitivities, mapping figures and fitting polynomials wered acquired. The results showed that sensitivities using log-ratio method were bigger than those using difference/sum method. The sum signal was also simulated when beam displacement varied from (0 mm, 0 mm) to (5 mm, 5 mm), the result showed that the variation of normalized sum signal was no more than ±6%. The gaussian weighted method of a two-dimensional grid structure was used to simulate the gaussian bunch and simulate the beam transverse quadrupole component changing with position (x, y), the result showed that the beam transverse quadrupole component changed linearly with position combination (x2-y2).

MOPME042

A PRELIMINARY SIMULATION OF BPM SIGNAL DIODE DETECTOR FOR HLS II TUNE MEASUREMENT SYSTEM*

betatron, storage-ring, pick-up, synchrotron

565

J.J. Zheng, P. Lu, T.J. Ma, B.G. Sun, Y.L. Yang, J.Y. Zou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11105141, 11175173) and the Fundamental Research Funds for the Central Universities (WK2310000015)
A high sensitivity BPM signal detection front-end electronics has been designed for HLS II tune measurement system according to the HLS II upgrade requirements. Classical tune measurement systems filter out just one or a few of these betatron sidebands frequency. As a consequence, most of the betatron energy is dropped and only a very small energy remains for further processing. A new method, referred to as Direct Diode Detection (3D) by LHC[1], improves the situation. In this paper, the HLS II BPM signals have been calculated out in time domain and frequency domain. Basing on the characteristics of HLS II BPM signal, a preliminary simulation is performed to test and verify the feasibility of diode detector for HLS II tune measurement system. The simulation results clearly show that the technique of diode-based circuit can be applied to HLS II tune measurement.

MOPME044

A Novel Type of Forward Coupler Slotted Stripline Pickup Electrode for CSRe Stochastic Cooling

impedance, pick-up, vacuum, kicker

571

J.X. Wu, X.J. Hu, M. Li, J.W. Xia, J.C. Yang, Y. Zhang, G. Zhu
IMP, Lanzhou, People's Republic of China
F. Caspers
CERN, Geneva, Switzerland

A novel type of slotted or perforated strip-line pick-up or kicker electrode structure for CSRe stochastic cooling for non relativistic particle beams with b=v/c values around 0.7 is presented. This slotted structure is to be used as a forward coupler with the output signal taken from the downstream end and has a rather large relative bandwidth of several octaves. The electrode structure and pickup tank, as well as the beam test result will be presented in this paper.

MOPME046

Preliminary Experimental Results of Axial B-dot Measuring Beam Tilt

high-voltage, coupling, dipole, impedance

577

X. He, Q. Li, C. Ma, J. Pang, L. Zhao
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

Funding: This work is under the support of NSFC project No. 11175166
Beam monitors sensitive to the beam's azimuthal B-dot field (sometimes referred as B-dots) are widly used to measure the displacement of beam centroid, as the beam generates a dipole term of the azimuthal magnetic field. The authors have pointd out that the similar B-dots sensitive to axial magnetic field can be used to measure the beam tilt directly in earlier work. A monitor which consists of four azimuthal B-dots and four axial B-dos is designed and fabricated. The monitor was tested on a coaxial calibration stand, which has a character resistance of 50 Ohm. Two position tuners are installed on the calibration stand, to adjust the position and the tilt of the inner conductor. Experiments show that the axial B-dot monitor can be successfully used to measure the tilt of the inner conductor directly.

MOPME047

Simulation of a Beam Angel Monitor using the Axial B-dot Field

monitoring, coupling, induction, dipole

580

J. Pang, X. He, Q. Li, C. Ma
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

Funding: The National Natural Science Foundation of China
A beam angel monitor using the axial B-dot field was presented recently while the one using azimuthal B-dot field had been widely employed to measure the beam positions for more than ten years. Basing on the principle of the proportionality between the deflection angel and the difference of axial B field with corresponding positions, the axial B-dot monitor has a potential use for beam deflection angle measurement directly. A test stand was built to test and improve the axial B-dot monitor, which is fabricated as a PCB structure. Meanwhile, simulations using the CST MWS code have been performed, demonstrating a good agreement to the test results and giving some advice to suppress the disturbance of position deviation of the beam.

MOPME051

Development of Cavity Beam Position Monitor System

cavity, FEL, coupling, electron

586

B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou
SINAP, Shanghai, People's Republic of China

Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME058

DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2

cavity, dipole, electron, extraction

604

S.W. Jang, E.-S. Kim
KNU, Deagu, Republic of Korea
Y. Honda, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described.

MOPME068

Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC

radiation, background, electron, vacuum

634

N. Fuster Martinez, A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain
H.L. Andrews
LANL, Los Alamos, New Mexico, USA
F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S.R. Stevenson
JAI, Oxford, United Kingdom
J. Barros, N. Delerue, M. Grosjean
LAL, Orsay, France
V. Bharadwaj, C.I. Clarke
SLAC, Menlo Park, California, USA

The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device.

MOPME070

Emittance and Beta Functions Measurements for the MAX IV Linac

quadrupole, emittance, linac, controls

640

N. Čutić, E. Mansten
MAX-lab, Lund, Sweden

We plan to determine beam emittance and Twiss parameters for the MAX IV linac using multiple-quadrupoles scans. We investigate the possibility to perform such scans using matching sections' quadrupoles combined with beam profile measurements by fluorescent YAG screens. Beam pipe size, resolution and screen saturation limits and strengths of quadrupoles are taken into consideration. Our approach to this problem using Kalman filter is presented.

MOPWA009

Development of a Fast Compensation Kicker System for J-PARC Main-ring Injection

kicker, injection, impedance, power-supply

684

S. Fukuoka
University of Tsukuba, Graduate School of Pure and Applied Sciences,, Tsukuba, Ibaraki, Japan
K. Fan, K. Ishii, H. Matsumoto, T. Sugimoto
KEK, Ibaraki, Japan

Injection system of J-PARC main ring employs four lumped kickers to deflect the incoming beam. The residual field caused by tail and reflection of excitation current increases the closed beam orbit leading to particle loss in high power operation. A correction method using a fast kicker system to compensate the remaining angle is being developed. Doe to the narrow bunch spacing, transmission line kicker is selected to satisfy requirements of fast rise and fall time. The kicker magnet uses ceramic capacitors instead of parallel metal plates to make the magnet compact and reduce the stray inductance. Capacitors are installed in vacuum chamber. A very thin core is used to reduce distributed inductance. A bandwidth is calculated as 160 MHz. A Marx generator using FET switches has been studied, which is able to produce fast rise and fall time as 50 ns. Any pulse shape is generated by choosing switches to fire. A prototype magnet and a power supply have been fabricated for parameters test. In this paper, we will report the details of the system design, analyze the measurement results and give future prospects.

MOPWA017

Design of the 500 kA Linear Transformer Driver Stage

pulsed-power, damping, high-voltage, induction

696

T.X. Liang, X.F. Jiang, A.C. Qiu, F.J. Sun, Z.G. Wang, J.H. Yin, Z. Zhang
NINT, Xi'an, People's Republic of China

Funding: Supported by the funding of National Natural Science of China (Grant No. 51077111) and Stage Key Laboratory of Electrical Insulation and Power Equipment(Grant No.51077111) , Xi’an Jiaotong Univercity.
Linear transformer driver (LTD) is a novel fast discharge high pulsed power source. It can realize many LTD stages in series or parallel conveniently, and can directly acquire 100~200ns high power pulse. The pulse maybe realizes to directly drive load without any pulse compressing and forming unit. This paper introduces the latest development of fast LTD technology in abroad. The 100kV/500kA LTD stage with the rise time of 150ns has been designed. The stage is consisting of 20 discharging bricks in parallel. The simplified circuit model of LTD stage is given and the output parameters are simulated with universal circuit simulation software program, and the matched load current of 500kA and the rise time of about 150ns is obtained at the charging voltage of the capacitors about ±80kV.
Tianxue Liang is with the State Key Laboratory of Environment Simulation and Effect for Intense Pulsed Radiation, Northwest Institute of Nuclear Technology, P. O. Box 69-10, Xi’an 710024, China(phone:86-029-84767380; e-mail: liangtxlkk@163.com).

MOPWA021

Design of the Air Cooling System for the High Voltage Power Supply of a Electron Accelerator

power-supply, high-voltage, radiation, electron

705

F. Zhong, X. Lei, J. Yang, L. Yang
HUST, Wuhan, People's Republic of China

High voltage electron accelerators are widely applied in many fields of radiation pro-cessing,and the high voltage power supply is the critical equipment for the accelerator. for the requirement of high voltage, the design of locate the power supply in a steel barrel filled with SF6 is commonly used. Considering the various losses of the power supply, an air-cooling system is needed. This paper presents the design of the air-cooling system for the high voltage power supply. The fluid simulation of SF6 based on Fluent and the optimal design of the air duct's structure and the thermal efficiency have been done. The comparison and analysis of the simulation and the empirical formula result is also carried out. It illustrates the design of the air-cooling system can satisfy the demand of the heat radiation This paper also provides an effective method for the optimal design of the air duct's structure and the maximize efficiency of heat exchange.

MOPWA022

A 500 kV Pulser with Fast Risetime for EMP Simulation

high-voltage, pulsed-power, impedance, laser

708

W. Jia, W.Q. Chen, J.N. Li, J.P. Tang, L.S. Xie, Y.Z. Xie, G.W. Zhang
NINT, Xi'an, People's Republic of China

A fast risetime generator with 500kV rated output voltage for the electromagnetic pulse ( EMP ) effects experiment is fabricated. It mainly consists of a low inductance Marx ge nerator, a compact independent-sealed peaking capacitor, an output switch, and a small quantity of gas-sealed insulated containers. Compared with other similar pulsers mentioned in IEC 61000-4-32, the insulated containers of the generator are independent of each other in gas-sealed structure, and its number is les s than that of other pulsers. It can be used to drive a guided wave antenna directly to produce an electromagnetic environment, which conformed with the new standard for high-altitude nuclear explosion electromagnetic pulse (HEMP) developed by IEC. Output voltage produced by the generator in demo-load state can reach to 600kV. And, risetime of the waveform is 1.2ns, pulse width (FWHM) being 32ns. When the generator driving a 10m guided-wave antenna, an output voltage with a risetime of no more than 2.7ns and a FWHM of 30ns is achieved.

MOPWA023

A Low Jitter Pulse Generator Based on Two-stage Storage Module

pulsed-power, coupling, controls, high-voltage

711

J.N. Li, W.Q. Chen, F. Guo, W. Jia
NINT, Xi'an, People's Republic of China

A scheme for a low jitter pulse generator based on two-stage storage module is described. The thyristor is used for the first stage of the generator, the UV-illumination gas switch is used for the second stage of the generator. Between them, the pulsed transformer is used for connecting. A capacitance-resistance coupling structure was designed to produce UV light which triggered the switch to decrease the breakdown jitter. The test result shows, the risetime of the current is 0.73μs, the peak value of the current is 1.8kA on 1.1Ω load. The delay of the generator is 35.1μs, and the jitter of the generator attaches to 0.22μs.

MOPWA031

Beam Induced Ferrite Heating of the LHC Injection Kickers and Proposals for Improved Cooling

vacuum, kicker, injection, impedance

732

M.J. Barnes, S. Calatroni, F. Caspers, L. Ducimetière, M. Garlaschè, V. Gomes Namora, V. Mertens, Z.K. Sobiech, M. Taborelli, J.A. Uythoven, W.J.M. Weterings
CERN, Geneva, Switzerland
H.A. Day
UMAN, Manchester, United Kingdom

The two LHC injection kicker systems produce a kick of 1.3 T.m with a flattop duration variable up to 7860 ns, and rise and fall times of less than 900 ns and 3000 ns, respectively. A beam screen is placed in the aperture of each magnet, which consists of a ceramic tube with conductors in the inner wall. The conductors provide a path for the beam image current and screen the ferrite yoke against wake fields. Recent LHC operation, with high intensity beam stable for many hours, resulted in significant heating of both the ferrite yoke and beam impedance reduction ferrites. For one kicker magnet the ferrite yoke approached its Curie temperature. As a result of a long thermal time-constant the ferrites can require several hours to cool enough to re-inject beam, thus limiting the availability of the LHC. Thermal measurement data has been analysed, a thermal model developed and emissivity measurements carried out. The effects of various measures to improve the ferrite cooling have been simulated, including an improved emissivity of the vacuum tank and active cooling on the outside of the tank.

MOPWA032

Reduction of Surface Flashover of the Beam Screen of the LHC Injection Kickers

kicker, injection, vacuum, impedance

735

M.J. Barnes, P. Adraktas, S. Calatroni, F. Caspers, L. Ducimetière, V. Gomes Namora, V. Mertens, R. Noulibos, M. Taborelli, B. Teissandier, J.A. Uythoven, W.J.M. Weterings
CERN, Geneva, Switzerland

The LHC injection kicker magnets include beam screens to shield the ferrite yokes against wake fields resulting from the high intensity beam. The screening is provided by conductors lodged in the inner wall of a ceramic support tube. Operation with increasingly higher bunch intensity, and narrow bunches, now requires improved ferrite screening. This will be implemented by additional conductors; however the good high-voltage behaviour of the kicker magnets must not be compromised by the supplementary screening. Extensive studies and optimisations have been carried out, to better satisfy the often conflicting requirements for low beam coupling impedance, fast magnetic field rise-time, high vacuum and good high voltage behaviour. A new configuration is proposed which reduces significantly the electric field associated with the screen conductors and the secondary electron yield of the surface of the ceramic tube. Results of high voltage test results are also presented.

MOPWA034

Electron Tracking Simulations in the Presence of the Beam and External Fields

emittance, electron, proton, space-charge

741

M. Patecki, B. Dehning, G. Iadarola, M. Sapinski
CERN, Geneva, Switzerland

The ionisation profile monitors installed in the CERN LHC and SPS, makes use of the ionisation of small quantities of injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. However, in the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 physics simulation package has been used to simulate the ionisation process, while the CERN-developed PyECLOUD code has been used for tracking the resulting ionised particles. In this paper the results of simulations are compared with observations, with conclusions presented on the accuracy of the reconstruction of high-intensity beam profiles.

MOPWA037

Commissioning of the CERN Linac4 BPM System with 50 MeV Proton Beams

linac, pick-up, proton, optics

750

J. Tan, M. Ludwig, L. Søby, M. Sordet, M. Wendt
CERN, Geneva, Switzerland

The new Linac4 at CERN will provide a 160 MeV H⁻ ion beam for charge-exchange injection into the existing CERN accelerator complex. Shorted stripline pick-ups placed in the Linac intertank regions and the transfer lines will measure beam orbit, relative beam current, beam phase, and average beam energy via the time-of-flight between two beam pickups. A prototype Beam Position Monitor (BPM) system has been installed in the transfer line between the existing Linac2 and the Proton Synchrotron Booster (PSB) in order to study and review the complete acquisition chain. This paper presents measurements and performance of this BPM system operating with 50 MeV proton beams, and compares the results with laboratory measurements and electromagnetic simulations.

MOPWA051

ZEMAX Simulations for an Optical System for a Diffraction Radiation Monitor at CesrTA

target, radiation, electron, damping

789

T. Aumeyr, V. Karataev
JAI, Egham, Surrey, United Kingdom
M.G. Billing
CLASSE, Ithaca, New York, USA
L.M. Bobb, B. Bolzon, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland

Diffraction Radiation (DR) is produced when a relativistic charged particle moves in the vicinity of a medium. The target atoms are polarized by the electric field of the charged particle, which then oscillate thus emitting radiation with a very broad spectrum. The spatial-spectral properties of DR are sensitive to various electron beam parameters. Since the energy loss due to DR is so small that the electron beam parameters are unchanged, DR can be used to develop non-invasive diagnostic tools. The aim of this project is to measure the transverse (vertical) beam size using incoherent DR. To achieve the micron-scale resolution required by CLIC, DR in the UV and X-ray spectral-range must be studied. During the next few years, experimental validation of such a scheme will be conducted on the CesrTA at Cornell University, USA. This paper reports on simulations carried out with ZEMAX, studying the optical system used to image the emitted radiation.

MOPWA052

Short Range Wakefield Measurements of High Resolution RF Cavity Beam Position Monitors at ATF2

wakefield, cavity, quadrupole, extraction

792

J. Snuverink, S.T. Boogert, F.J. Cullinan, Y.I. Kim, A. Lyapin
JAI, Egham, Surrey, United Kingdom
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
G.R. White
SLAC, Menlo Park, California, USA

Cavity beam position monitors (CBPM) have been used in several accelerator facilities and are planned to be used in future accelerators and light sources. High position resolution up to tens of nanometres has been achieved, but short range wakefields are a concern, especially for small beam emittances. This paper presents the wakefield calculations as well as the first measurements of the CBPM-generated short range wakefields performed at the Accelerator Test Facility (ATF2).

MOPWA056

Spectra of Coherent Smith-Purcell Radiation Observed from Short Electron Bunches: Numerical and Experimental Studies

electron, radiation, diagnostics, target

801

F. Bakkali Taheri, G. Doucas, I.V. Konoplev, A. Reichold
JAI, Oxford, United Kingdom
H.L. Andrews
LANL, Los Alamos, New Mexico, USA
R. Bartolini
Diamond, Oxfordshire, United Kingdom
V. Bharadwaj, C.I. Clarke
SLAC, Menlo Park, California, USA
N. Delerue
LAL, Orsay, France
N. Fuster Martinez
IFIC, Valencia, Spain
J.D.A. Smith
TXUK, Warrington, United Kingdom
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work performed [in part] under DOE Contract DE-AC02-7600515
There is a significant interest in the development of compact particle accelerators within research areas including X-ray and THz (T-ray) sources of radiation, particle physics and medical sciences. To support the progress in these areas, non-invasive, electron beam diagnostics that are capable of measuring a single femtosecond electron bunch are required. At the current stage such beam diagnostics for femtosecond-long electron bunches are still not available. The goal of the work presented is to understand the spectral characteristics of coherent Smith-Purcell radiation to enable its quick and reliable interpretation including the longitudinal profile reconstruction of electron bunches. The research presented comprises results from numerical modelling and experimental studies. Using the numerical data, we discuss the radiated spectra dependence on the electron bunch profile and analyse the results. We also discuss the experimental data and compare it with theoretical predictions.

MOPWA064

Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam

electron, cavity, proton, vacuum

825

Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska
Fermilab, Batavia, USA

We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

MOPWA066

Components of Heating and Fueling of Fusion Plasmas

high-voltage, controls, cathode, synchrotron

831

K. Schrock, M.P.J. Gaudreau, M.K. Kempkes
Diversified Technologies, Inc., Bedford, Massachusetts, USA

Funding: Funded by US DOE, Grant # DE-SC0004250
Next generation fusion facilities will require many megawatts of RF power from dozens of gyrotrons. Each gyrotron requires a power system that must deliver the high-voltage power, modulate cathode voltage, and protect these expensive gyrotrons from arcing damage. It must be highly efficient, to minimize both the power and cooling costs associated with operation and to ensure high facility availability. Diversified Technologies, Inc. (DTI) has bench-tested a table-top scale ‘Buck Matrix’ modulator which uses a single set of IGBT switches for voltage regulation, arc protection, and pulse modulation. Although pulse step modulators represent a one-step solution, their size, and the complexity of their driving transformer make them more expensive than DTI’s two-step approach. DTI’s Buck Matrix modulator, with an efficiency of ~96%, cuts the size of the system in half, using a single layer of solid state switches for both voltage regulation and arc protection/modulation. This cuts the total hardware costs by a~30% or more, and eliminates the need for a separate opening switch or crowbar. DTI will present the system components of the design as well as the performance results to date.

MOPWA071

A Comparison of Electron Cloud Density Measurements at CesrTA

electron, positron, resonance, pick-up

843

J.P. Sikora, J.A. Crittenden, D.O. Duggins, Y. Li, X. Liu
CLASSE, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time Resolved Retarding Field Analyzers (TR-RFA) and Shielded Pickups (SPU) that measure the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.

MOPWA085

Spin Dynamics Simulations and Horizontal Intrinsic Resonance Studies in the AGS using the Zgoubi Code

polarization, acceleration, resonance, extraction

870

Y. Dutheil, L. A. Ahrens, H. Huang, F. Méot, V.H. Ranjbar, T. Roser, V. Schoefer, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A critical point for the polarized proton program of the RHIC is the polarization transmission through the AGS acceleration cycle. Recent developments in the Zgoubi model of the AGS allow multi-particle tracking with realistic beam and machine conditions on a large scale computing system. This gives the opportunity to simulate the influence of many beam and machine conditions on the polarization transmission and leads to a better understanding of the depolarization processes, for instance the horizontal intrinsic resonances, that cannot be accurately explored by the conventional simulation approaches or by the experiments with beam. This paper introduces the developments realized on the Zgoubi code to run these simulations and shows some of the latest results.

MOPWO001

Moment Method Beam Dynamics Code Development: Extended for Radio Frequency Quadrupole Simulations

rfq, multipole, quadrupole, radio-frequency

879

T. Roggen, H. De Gersem, B. Masschaele
KU Leuven, Kortrijk, Belgium
W. Ackermann, S. Franke, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: This research is funded by grant “KUL 3E100118” “Electromagnetic Field Simulation for Future Particle Accelerators”, project FP7-Euratom No. 269565 and the Belgian Nuclear Research Centre (SCK•CEN).
A Radio Frequency Quadrupole (RFQ) enables acceleration of a continuous low-velocity hadron beam, combining velocity independent electric focusing and adiabatic bunching, resulting in high-current compact bunches with nearly 100% capture and transmission efficiency. With virtually no post-construction tuning capabilities, an RFQ design phase requires all transient parameters (machining tolerances, thermo-mechanical deformation factors). This allows the determination of acceptable tolerances on input and output beam characteristics, of major importance in beam availability and beam trip prevention, and makes fast beam dynamics simulation codes incorporating RFQs indispensable. This article presents the implementation and validation of an RFQ beam line element into V-Code, a moment method beam dynamics simulation code. V-Code time integrates the Vlasov equation for an initial particle distribution represented by a discrete set of characteristic moments, accounting for all exerting internal and external forces. V-Code delivers highly accurate beam dynamics results with precision and efficiency advantages in terms of average or rms beam dimensions, projected emittances or total energy.

MOPWO002

PTCC: New Beam Dynamics Design Code for Linear Accelerators

linac, space-charge, plasma, cavity

882

Y. N. Nour El-Din, T.M. Abuelfadl
Cairo University, Giza, Egypt

Funding: Work supported by the Egyptian Science and Technology Development Fund (STDF) No. 953.
A fast and accurate beam dynamics design code, named PTCC (Particle Tracking Code in C) is developed to simulate particles dynamic in linear accelerators. PTCC solves the relativistic equations of motion for the macro-particles when subjected to electromagnetic fields excited in RF cavities. The self-fields of the particles are also part of the electromagnetic fields through which the particles are tracked. Self-fields are calculated using a modified 2D cylindrically symmetric mesh based method, making use of beam and field symmetry to provide fast simulation. The code has been benchmarked with the well known code ASTRA which is used mainly in simulations of next generation FEL linacs. PTCC provides a new tool for designing buncher section of linear accelerators that convert DC beam into bunches. New buncher design tool and benchmark results of PTCC with ASTRA are presented.

MOPWO004

Simulations and Studies of Electron Beam Dynamics under Compton Back-scattering for the Compact X-ray Source ThomX

electron, wakefield, collective-effects, photon

888

I.V. Drebot, C. Bruni, N. Delerue, T. Demma, A. Variola, Z.F. Zomer
LAL, Orsay, France
A. Loulergue
SOLEIL, Gif-sur-Yvette, France

Funding: This work is supported by the French "Agence Nationale de la Recherche" under reference ANR-10-EQPX-51, and also by grants from Région Ile-de-France, Université Paris-Sud and IN2P3/CNRS.
In this article are presented beam dynamics investiga- tions of a relativistic electron bunch in the compact storage ring ThomX (50 MeV), which is under construction at LAL to produce hard X-ray using Compton Back-Scattering (CBS). The effect of CBS has been implemented in a 6D tracking code. In addition to CBS, the influence of lattice non linearities and various collective effects on the flux of scattered Compton photons is investigated.

MOPWO005

Simulating Spin Dynamics and Depolarization using POLE

resonance, synchrotron, polarization, synchrotron-radiation

891

J.F. Schmidt, O. Boldt, F. Frommberger, W. Hillert
ELSA, Bonn, Germany

Funding: BMBF
The spin dynamics in circular accelerators with fast energy ramps, or short storage times of up to some seconds, can be investigated with spin tracking appropriately. Additionally, the spin motion of lepton beams is affected significantly by synchrotron radiation. Hence, spin dynamics simulations require spin tracking with a large number of particles to compute the beam polarization and thus take considerably long computing times. Therefore, high efficiency is crucial to perform systematic polarization studies. The new simulation tool POLE provides the ability to balance accuracy against computing time. To that end, adjustable approximations of magnetic fields and synchrotron radiation are implemented. POLE is accessible for a wide range of lepton storage rings because it uses the common MAD-X lattice files and the corresponding particle tracking results.

MOPWO008

Eigenmode Computation for Elliptical Cavities Subject to Geometric Variation using Perturbative Methods

cavity, factory, higher-order-mode, SRF

900

K. Brackebusch, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by Federal Ministry for Research and Education BMBF under contracts 05H09HR5 and 05K10H.
Parametric studies of geometric variations are an essential part of the performance optimization and error estimation in the design of accelerator cavities. Using common eigenmode solvers the analysis of intentional and undesired geometric perturbations tend to be very extensive since any geometric variation involves an entire eigenmode recomputation. Perturbative methods constitute an efficient alternative for the computation of a multitude of moderately varying geometries. They require a common eigenmode computation of solely one (so called unperturbed) geometry and allow for deriving the eigenmodes of similar but modified (so called perturbed) geometries from these unperturbed eigenmodes. In [*],[**] the practicability of perturbative methods was already proven by means of simple cavity geometries. In this paper we investigate the applicability and efficiency for practically relevant cavities. For this, basic geometric parameters of elliptical cavities are varied and the respective eigenmodes are computed by using perturbative as well as common methods. The accuracy of the results and the computational effort of the different methods are compared.
*K. Brackebusch, H.-W. Glock, U. van Rienen, WEPPC096, IPAC 2011
**K. Brackebusch, U. van Rienen, MOPPC062, IPAC 2012

MOPWO009

Numerical Studies on the Impact of Ionized Residual Gas on an Electron Beam in an ERL

ion, emittance, electron, linac

903

G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Meseck
HZB, Berlin, Germany

Funding: Supported by BMBF under contract number 05K10HRC
Energy Recovery Linacs (ERLs) are the most promising candidates for next-generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Typical measures to reduce the effect of ion clouds are clearing electrodes and clearing gaps in the bunch train. In this paper, we present numerical studies of the impact of ion clouds on the electron bunch train. The simulations are performed with the software package MOEVE PIC Tracking developed at Rostock University. ’The model for the bunch and the ion cloud takes into account a distribution of macro particles. The interaction of the bunch with the ion cloud is computed with a 3D space charge model. Hence, particle tracking allows for detailed studies of bunch characteristics such as the emittance. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPro.

MOPWO010

Machine Protection Studies for a Crab Cavity in the LHC

beam-losses, luminosity, cavity, collimation

906

B. Yee-Rendon, R. Lopez-Fernandez
CINVESTAV, Mexico City, Mexico
T. Baer, J. Barranco, R. Calaga, A. Marsili, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland

Funding: US-LARP and CONACYT
Crab cavities (CCs) apply a transverse kick that rotate the bunches so as to have a head-on collision at the interaction point (IP). Such cavities were successfully used to improve the luminosity of KEKB. They are also a key ingredient of the HL-LHC project to increase the luminosity of the LHC. As CCs can rapidly change the particle trajectories, machine protection studies are required to assess the beam losses due to fast CC failures. In this paper, we discuss the effect of rapid voltage or phase changes in a CC for the HL-LHC layout using measured beam distributions from the present LHC.

MOPWO011

Surface Field Optimization of Accelerating Structures for CLIC using ACE3P on Remote Computing Facility

linac, GUI, target, damping

909

K.N. Sjobak, E. Adli
University of Oslo, Oslo, Norway
A. Grudiev
CERN, Geneva, Switzerland

Funding: Research Council of Norway
This paper presents a computer program for searching for the optimum shape of an accelerating structure cell by scanning a multidimensional geometry parameter space. For each geometry, RF parameters and peak surface fields are calculated using ACE3P on a remote high-performance computational system. Parameter point selection, mesh generation, result storage and post-analysis are handled by a GUI program running on the user’s workstation. This pa- per describes the program, AcdOptiGui. AcdOptiGui also includes some capability for automatically selecting scan points based on results from earlier simulations, which en- ables rapid optimization of a given parameterized geome- try. The software has previously been used as a part of the design process for accelerating structures for a 500 GeV CLIC.

MOPWO013

A New Scalable Software Package for Large Scale Beam Dynamic Simulations

space-charge, target, DTL, solenoid

912

R. Zhao, J. Xu
IS, Beijing, People's Republic of China
Y. He, C. Li, X. Qi, L. Yang
IMP, Lanzhou, People's Republic of China

Large scale Beam Dynamics Simulations (BDS) are important in accelerator design and optimization. With the fast development of supercomputers, new software packages need to be developed in order to fully make use of hardware and software progresses. In this paper, we will introduce a new BDS software package, LOCUS3D, which is developed for efficient use of these new techniques. It is based on Particle-In-Cell (PIC) method, and includes space charge effect by solving the Poisson’s equation. Parallel Poisson solver has been developed with MPI. Standard accelerator devices can be simulated and new devices can be added. Benchmark results have been obtained on several different platforms, such as INSPUR cluster at RDCPS, BG/P at ANL. Large-scale simulation with 10⁹ particles can be simulated now in the simulations. LOCUS3D will be used for more realistic accelerator simulations in the near future.

MOPWO014

Numerical Methods to the Space Charge Compensation (SCC) Effect of the LEBT Beam

electron, ion, space-charge, ion-source

915

S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, P.N. Lu, Y.T. Luo, H.T. Ren, Z.H. Wang, Y. Xu, T. Zhang, J. Zhao
PKU, Beijing, People's Republic of China
A.L. Zhang
Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China

Numerical simulation as well as experimental researches on space charge compensation for high intensity, low energy ion beam has been done at Peking University (PKU). In this paper we will describe the simulation model proposed at PKU and use it on the PKU ECR single-charged ion source. It consists of a new concept of equivalent density and more consideration of physical process. A series of arithmetical equations is gained through theoretical derivation. Although no numerical solutions have been carried out from our computation, it is foreseeable that the final result will be achieved soon.

MOPWO018

Cellular Automaton Simulating the Motion of the Charged Particles Beam

acceleration, controls, lattice

918

S.N. Andrianov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia
V. Ryabusha
Saint Petersburg State University, Saint Petersburg, Russia

In this research we formulate and formalize the rules for the cellular automaton that emulates the motion of the charged particles beam under the effect of Coulomb force for one-, two- and three-dimensional cases. In this research we also describe the main principles of the realization of this approach in a paralleled cluster environment.

MOPWO019

An IDE for Spin-orbit Dynamics Simulation

lattice, controls, betatron, optics

921

A.N. Ivanov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

In this paper a prototype of an IDE for simulation of spin-orbit motion is described. It is based on the component software development and provides a flexible graphic user interface. One of the main parts of it is numerical methods for ordinary differential equations integration. For numerical simulation it is possible use either the matrix map algorithm or traditional step-by-step methods. This workflow allows choosing one of numerical algorithms and to provide necessary computational experiments. It is also contains both a visual designer of an accelerator lattice and additional tools for control parameters of the model. There is also exists possibility for code generation in different programming languages and computation on high-performance systems.

MOPWO020

Space Charge Dominated Envelope Dynamics using GPUs

space-charge, controls, luminosity, focusing

924

N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

High power accelerator facilities lead to necessity to consider space charge forces. It is therefore important to study the space charge dynamics in the corresponding channels. To represent the space charge forces of the beam we have developed special software based on some analytical models for space charge distributions. Because calculations for space charge dynamics become extremely time consuming, we use a special algorithm for predictor-corrector method for evaluation scheme for beam map evaluation including the space charge forces. This method allows us to evaluate the map along the references trajectory and to create the beam envelope dynamics. The corresponding computer codes are realized using CUDA implementation of maps for particle dynamics. Some numerical results for different types of the beam channels are discussed. The survey of advantages and disadvantages of using different methods of parallelization and some parallel approaches will be done.

MOPWO021

Data Management and Analysis for Beam Dynamics Simulation

lattice, EPICS, quadrupole, site

927

D. Zyuzin
FZJ, Jülich, Germany
S.N. Andrianov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

Computer simulation of modern accelerator system is based on a number of specialized computer codes. Complexity of concerned processes and interpretation of simulation results requires comfortable and effective tools to design accelerator structure and beam characteristics, carry out computer experiments, process and visualize data. This paper proposes a prototype system with web-interface which allows the full research cycle: from lattice generation to data visualization. This approach represents a valuable tool for beam physicist providing methods to benchmark simulation engines as well as providing additional instruments for understanding physical processes in accelerator. The corresponding tools were used in application to the spin-orbit motion problems in electrostatic accelerators.

MOPWO026

Investigation of Numerical Precision Issues of Long Term Single Particle Tracking

dynamic-aperture, resonance, beam-beam-effects, HOM

942

E. McIntosh, R. De Maria, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Long term single particle simplectic tracking is one of the most reliable tool to study the dynamic aperture of the circular accelerators. The present computational performance allows to explore the long term behaviour for an extended number of turns. It is well known that for instance single precision floating point arithmetic introduces too much numerical noise even after a moderate number of turns. In this paper we explore the artefacts of the double precision arithmetic that may be visible when the number of turns is in the order of 10⁶, 10⁷.

MOPWO028

Recent Developments and Future Plans for SixTrack

collimation, ion, HOM, multipole

948

R. De Maria, R. Bruce, R. Calaga, L. Deniau, M. Fjellstrom, M. Giovannozzi, L. Lari, Y.I. Levinsen, E. McIntosh, A. Mereghetti, D. Pastor Sinuela, S. Redaelli, H. Renshall, A. Rossi, F. Schmidt, R. Tomás, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby, D.R. Brett
UMAN, Manchester, United Kingdom
D. Banfi, J. Barranco
EPFL, Lausanne, Switzerland
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
L. Lari
IFIC, Valencia, Spain
V. Previtali
Fermilab, Batavia, USA
G. Robert-Demolaize
BNL, Upton, Long Island, New York, USA

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
SixTrack is a symplectic 6D tracking code routinely used to simulate single particle trajectories in high energy circular machines like the LHC and RHIC. The paper presents the developments recently implemented and those foreseen for extending the physics models: exact Hamiltonian, different ions and charge states, RF multipoles, non-linear fringe fields, Taylor maps, e-lenses, ion scattering. Moreover new functionalities are also added like variable number of tracked particles, time dependent strengths, GPU computations with a refactoring of the core structure. The developments will benefit studies on the LHC and SPS, for collimation efficiency, ion operations, failure scenarios and HL-LHC design.

MOPWO029

Remote Estimate of Collimator Jaw Damages with Sound Measurements during Beam Impacts

proton, radiation, background, extraction

951

D. Deboy, O. Aberle, R.W. Aßmann, F. Carra, M. Cauchi, J. Lendaro, A. Masi, S. Redaelli
CERN, Geneva, Switzerland

Irregular hits of high-intensity LHC beams on collimators can lead to severe damage of the collimator jaws. The identification of damaged collimator jaws by observation of beam measurements is challenging: online loss measurements at the moment of the impacts can be tricky and degradation of the overall performance from single collimator damage can be difficult to measure. Visual inspections are excluded because collimator jaws are enclosed in vacuum tanks without windows. However, the sound generated during the beam impact can be used to give an estimate of the damage level. In 2012, high-intensity beam comparable to a full nominal LHC bunch at 7 TeV was shot on a tertiary type LHC collimator at the HiRadMat test facility at CERN. The paper presents results from sound recordings of this experiment.

MOPWO031

High Energy Beam Impact Tests on a LHC Tertiary Collimator at CERN HiRadMat Facility

alignment, vacuum, collimation, proton

954

M. Cauchi, O. Aberle, R.W. Aßmann, A. Bertarelli, F. Carra, A. Dallocchio, D. Deboy, L. Lari, S. Redaelli, A. Rossi
CERN, Geneva, Switzerland
M. Cauchi, P. Mollicone
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain
N.J. Sammut
University of Malta, Information and Communication Technology, Msida, Malta

The correct functioning of the collimation system is crucial to safely operate the LHC. The requirements to handle high intensity beams can be demanding. In this respect, investigating the consequences of LHC particle beams hitting tertiary collimators (TCTs) in the experimental regions is a fundamental issue for machine protection. An experimental test was designed to investigate the robustness and effects of beam accidents on a fully assembled collimator, based on accident scenarios in the LHC. This experiment, carried out at the CERN HiRadMat (High Irradiation to Materials) facility, involved 440 GeV beam impacts of different intensities on the jaws of a horizontal TCT. This paper presents the experimental setup and the preliminary results obtained together with some first outcomes from visual inspection.

MOPWO033

Analysis of LHC Transfer Line Trajectory Drifts

injection, optics, extraction, dipole

960

L.N. Drøsdal, W. Bartmann, H. Bartosik, C. Bracco, B. Goddard, V. Kain, Y. Papaphilippou, J.A. Uythoven, G. Vanbavinckhove, J. Wenninger
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, USA

The LHC is filled from the SPS via two 3km long transfer lines. In the first years of LHC operation large trajectory variations were discovered. The sources of bunch-by-bunch and shot-by-shot trajectory variations had been identified and improved by the 2012 LHC run. The origins of the longer term drifts were however still unclear and significant time was spent correcting the trajectories. In the last part of the 2012 run the optics in the SPS was changed to lower transition energy. Trajectory stability and correction frequency will be compared between before and after the optics change in the SPS. The sources of the variations have now been identified and will be discussed in this paper. Remedies for operation after the long shutdown will be proposed.

MOPWO035

Layouts for Crystal Collimation Tests at the LHC

collimation, optics, insertion, proton

966

D. Mirarchi, S. Redaelli, W. Scandale
CERN, Geneva, Switzerland
D. Mirarchi
The Imperial College of Science, Technology and Medicine, London, United Kingdom
V. Previtali
Fermilab, Batavia, USA

Various studies have been carried out in the past years regarding crystal collimation for the LHC. A new extensive campaign of simulations was performed to determine optimum layouts for beam tests at the LHC. The layouts are determined based on semi-analytical models for the dynamics of channeled particles. Detailed SixTrack tracking with all collimators of the ring are then used to validate the different options. An overview of the ongoing studies is given. Comparative studies between the present collimation system, the crystal collimation system, and different crystal collimation layout are presented.

MOPWO037

SixTrack Simulation of Off-momentum Cleaning in LHC

radiation, synchrotron, betatron, synchrotron-radiation

972

E. Quaranta, R. Bruce, S. Redaelli
CERN, Geneva, Switzerland

In the LHC, high-amplitude particles are cleaned by either betatron collimators or momentum collimators. Previously, betatron losses have been considered more important, but measurements during the first years of operation show high losses also in the off-momentum cleaning insertion. This causes a significant radiation dose to warm magnets downstream of the collimators. Our work in this paper aims at simulating with SixTrack the off-momentum particles, driven into the momentum collimators by radiation damping outside the RF system acceptance. The results are an important ingredient in assessing the effectiveness of new passive absorbers to protect the warm magnets.

MOPWO038

Cleaning Inefficiency of the LHC Collimation System during the Energy Ramp: Simulations and Measurements

collimation, proton, scattering, injection

975

E. Quaranta, R. Bruce, L. Lari, D. Mirarchi, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain
D. Mirarchi
The Imperial College of Science, Technology and Medicine, London, United Kingdom
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The cleaning inefficiency of the LHC collimation system has already been studied in detail at injection and top energy (450 GeV and 4 TeV respectively). In this paper the results are presented for the cleaning inefficiency at intermediate energies, simulated using the SixTrack code. The first comparisons with measured provoked losses are discussed. This study helps in benchmarking the energy dependence of the simulated inefficiency and is thus important for the extrapolation to future operation at higher energies.

MOPWO041

Simulations and Measurements of Physics Debris Losses at the 4 TeV LHC

luminosity, proton, background, dipole

984

A. Marsili, R. Bruce, F. Cerutti, S. Redaelli
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
Simulations of energy deposition from the physics debris are normally done with shower simulation tools like FLUKA. Tracking tools like SixTrack allow faster simulations that open the possibility to study parametrically and optimize different layouts. In this paper, the results of FLUKA and SixTrack simulations are compared to beam measurements done for different collimator settings at 4 TeV, with p-p luminosities up to 7·10³³ cm^-2s⁻¹.

MOPWO042

Simulations of Collimation Cleaning Performance with HL-LHC Optics

optics, collimation, luminosity, proton

987

A. Marsili, R. Bruce, R. De Maria, S.D. Fartoukh, S. Redaelli
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The upgrade of the LHC from the current set-up to high luminosity performances will provide new challenges for the protection of the machine. The different optics considered might create new needs for collimation, and require new collimation locations. In order to evaluate the cleaning performances of the collimation system, different halo cleaning simulations were performed with the particle tracking code SixTrack. This paper presents the cleaning performance simulation results for the high luminosity Achromatic Telescopic Squeeze optics considered as baseline for the HL-LHC. The new limitations observed and possible solutions are discussed.

MOPWO043

Hollow Electron Lens Simulation for the SPS

electron, collimation, optics, proton

990

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
S. Redaelli
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No. DE-AC02-07CH11359 with the United States Dep. of Energy. This work was supported by the US LHC Accelerator Research Program (LARP).
The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations.

MOPWO044

Numerical Simulations of a Hollow Electron Lens as a Scraping Device for the LHC

electron, collimation, resonance, proton

993

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
S. Redaelli
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No.DE-AC02-07CH11359 with the United States Dep. of Energy. This work was partially supported by US LHC Accelerator Research Program(LARP)
The use of hollow electron beam lens for scraping high energy proton beams has been extensively tested at Fermilab's Tevatron collider. In order to evaluate a possible application of a similar a device in the LHC, a dedicated new routine has been implemented in the standard 6D tracking code used at CERN for the design of the LHC collimation system. The effects of a finite length cylinder of electrons encompassing the main proton beam and traveling in the opposite direction is described in the routine. Realistic electron distributions, including measured radial imperfections, have been included in the model. Various operating modes have been simulated for the 7 TeV machine operation with sextupoles and octupoles included. The loss rate caused by the electron lens has been studied through an extended simulation campaign; the obtained halo removal rates for the different electron lens operating modes are presented.

MOPWO046

Simulations and Measurements of Beam Losses on LHC Collimators during Beam Abort Failures

proton, collimation, emittance, kicker

996

L. Lari, C. Bracco, R. Bruce, B. Goddard, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland
A. Faus-Golfe, L. Lari
IFIC, Valencia, Spain
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
One of the main purposes of tracking simulations for collimation studies is to produce loss maps along the LHC ring, in order to identify the level of local beam losses during nominal and abnormal operation scenarios. The SixTrack program is the standard tracking tool used at CERN to perform these studies. Recently, it was expanded in order to evaluate the proton load on different collimators in case of fast beam failures. Simulations are compared with beam measurements at 4 TeV. Combined failures are assumed which provide worst-case scenarios of the load on tungsten tertiary collimators.

MOPWO053

Evolution of the Tracking Code PLACET

wakefield, linac, cavity, collider

1014

A. Latina, Y.I. Levinsen, D. Schulte
CERN, Geneva, Switzerland
J. Snuverink
JAI, Egham, Surrey, United Kingdom

The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. A major restructuring of its core has resulted in an improvement in its modularity, with some immediate advantages: its tracking core, which is one of the fastest available for this kind of simulations, is now interfaced toward three different scripting languages to offer great simulation capabilities: Tcl/Tk, Octave and Python. These three languages provide access to a vast library of scientific tools, mechanisms for parallel computing, and access to Java interfaces for control systems (such as that of CTF3). Also, new functionalities have been added: parallel tracking to exploit modern multicore CPUs, the possibility to track through the interaction region in presence of external magnetic fields (detector solenoid) and higher order imperfections in magnets. PLACET is currently used to simulate the CLIC Drive Beam, the CLIC Main Beam, CTF3, FACET at SLAC, and ATF2 at KEK.

MOPWO057

A Precise Beam Dynamics Model of the PSI Injector 2

space-charge, cyclotron, injection, emittance

1020

A.M. Kolano, R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom
A. Adelmann, C. Baumgarten
PSI, Villigen PSI, Switzerland

The Injector 2 at PSI (Paul Scherrer Institut), is a 72 MeV separate sector cyclotron producing a high intensity proton beam up to 3 mA CW, which is subsequently injected to the 590 MeV Ring Cyclotron. The injection energy of the pre-bunched beam is 870 keV at an intensity of 10 to 11 mA. In this paper we describe a full 3D model of the PSI injector 2, starting just before the two bunchers and including the multi stage collimation scheme in the cyclotron. The precise beam dynamics model is based on the OPAL (Object Oriented Parallel Accelerator Library) simulation code. OPAL is a tool for charged-particle optic calculations in large accelerator structures and beam lines including 3D space charge. The presented model will be validated with data from radial profile measurements and loss rates from the collimators and the electrostatic septum in the Injector 2. Based on this model we will estimate the intensity limit of this machine and comment of future operation modes.

MOPWO058

Injection Simulations for TPS Storage Ring

injection, storage-ring, kicker, lattice

1022

C.C. Chiang, P.J. Chou
NSRRC, Hsinchu, Taiwan

We present injection simulations for the TPS (Taiwan Photon Source) storage ring. The baseline lattice of TPS storage ring is a 6-fold structure with 24 double bend cells. For the Step I commissioning, only baseline lattice with dummy chambers are installed. The three double mini-beta-y lattice with insertion devices will be applied during Step II commissioning. The Tracy-2 program is used to simulate the particle motion in 6-D phase space. We adopt lattice models which include errors of alignments and magnet fields. The particle loss due to scraping by chamber limit is recorded in Tracy-2 simulation. We can estimate the radiation distribution of a ring and provide a reference for the shielding design accordingly.

MOPWO061

Numerical Approaches for Simulation of Stochastic Cooling in 2D Phase Space

emittance, coupling, electromagnetic-fields, storage-ring

1028

M. Dolinska
NASU/INR, Kiev, Ukraine
C. Dimopoulou, A. Dolinskyy, F. Nolden
GSI, Darmstadt, Germany

A consolidated fluid-dynamics algorithm for the analysis of beam dynamics under the influence of the electromagnetic field is presented. Aiming at simulating stochastic cooling of particle beams in 2D space, two numerical algorithms solving the 2D Fokker-Planck Equation are described. As an alternative approach, a numerical method based on the macro-particle tracking turn in turn in the ring (i.e. in the time domain) is introduced. Some results of the simulation of the stochastic cooling in the Collector Ring by both methods are discussed.

MOPWO066

GPU-accelerated Spin Dynamics and Analysis for RHIC

polarization, solenoid, quadrupole, proton

1037

D.T. Abell, D. Meiser
Tech-X, Boulder, Colorado, USA
M. Bai, V.H. Ranjbar
BNL, Upton, Long Island, New York, USA
D.P. Barber
DESY, Hamburg, Germany

Funding: This work supported in part by the US DOE Office No. DE-SC0004432.
Graphics processing units (GPUs) have now become powerful tools for scientific computation. Here we present our work on using GPUs (singly or in parallel) to speed the tracking of both orbital and spin degrees of freedom in particle accelerators. This work includes the development of new spin integrators that are both fast and accurate. We have also developed an integrated set of tools for analysing the results. To demonstrate the utility of these new tools, we use them to study the spin dynamics of protons in the Relativistic Heavy Ion Collider at Brookhaven National Lab.

MOPWO067

Beam Dynamics Simulations with a GPU-accelerated Version of Elegant

acceleration, collective-effects, storage-ring, controls

1040

I.V. Pogorelov, K.M. Amyx, J. Balasalle, J.R. King
Tech-X, Boulder, Colorado, USA
M. Borland, R. Soliday
ANL, Argonne, USA

Funding: Work supported by the US DOE Office of Science, Office of Basic Energy Sciences under grant number DE-SC0004585, and by Tech-X Corporation
Large scale particle tracking and tracking-based lattice optimization simulations can derive significant benefit from efficient implementation of general-purpose particle tracking on GPUs. We present the latest results of our work on accelerating Argonne National Lab's accelerator simulation code ELEGANT*,** using CUDA-enabled GPUs. A sufficiently large number of Elegant beamline elements has been ported to GPUs to allow the GPU-accelerated simulation of realistic test lattices. We will identify some of performance-limiting factors, and briefly discuss optimization techniques for efficient utilization of the device memory space, with an emphasis on register usage. We also present a novel hardware-assisted technique for efficiently calculating a histogram from a large distribution of particle coordinates, and compare this to data-parallel implementations.
* M. Borland, Elegant: A Flexible SDDS-compliant Code for Accelerator Simulation, APS LS-287, September 2000
** Y. Wang, M. Borland, in Proc. of PAC07, THPAN095 (2007)

MOPWO068

Simulating Electron Cloud Evolution using Modulated Dielectric Models

plasma, electron, diagnostics, proton

1043

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499), and the SCiDAC-3 project (DE-SC0008920)
Electron clouds can pose a serious threat to accelerator performance, and understanding cloud buildup and the effectiveness of different mitigation techniques can provide cost-saving improvements in accelerator design and fabrication. Microwave diagnostics of electron clouds are a non-destructive way to measure cloud buildup, but it is very difficult to measure the cloud density from spectral signals alone. Modeling travelling-wave rf diagnostics is very hard because of the large range of spatial and temporal scales that must be resolved to simulate spectra. New numerical models have been used to generate synthetic spectra for electron clouds when the cloud density is not changing, and results have been compared to theoretical results. Here we use dielectric models to generate spectra for clouds that evolve over many bunch crossings. We first perform detailed simulations of cloud buildup using kinetic particle models, and then use an equivalent plasma dielectric model corresponding to this density, at a finer time resolution, to compute spectra. The stability and accuracy of dielectric models that spectra can be accurately determined in these very long timescale simulations.

MOPWO070

Higher Order Symplectic Integration of Collective Effects

collective-effects, space-charge, wakefield, beam-transport

1046

S.D. Webb, D.T. Abell
Tech-X, Boulder, Colorado, USA

Long time tracking simulations of intense beams requires a proper account for the collective effects. Many tracking codes allow the number of space charge kicks, for example, to be determined by the end user. This makes no guarantee that the integration is second order accurate in the step size. In this proceeding, we present results on the proper second- and fourth-order symplectic integration of the Hamiltonian dynamics of particles under collective interactions using a model Hamiltonian with collective space charge forces to illustrate the underlying principles.

MOPWO071

Coherent Electron Cooling: Status of Single-Pass Simulations

electron, FEL, ion, bunching

1049

B.T. Schwartz, G.I. Bell, I.V. Pogorelov, S.D. Webb
Tech-X, Boulder, Colorado, USA
D.L. Bruhwiler
CIPS, Boulder, Colorado, USA
Y. Hao, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA
S. Reiche
PSI, Villigen PSI, Switzerland

Funding: US DOE Office of Science. Contracts DE-FC02-07ER41499, DE-FG02-08ER85182, DE-AC02-05CH11231.
Advances in nuclear physics depend on experiments that employ relativistic hadron accelerators with dramatically increased luminosity. Current methods of increasing hadron beam luminosity include stochastic cooling and electron cooling; however, these approaches face serious difficulties at the high intensities and high energies proposed for eRHIC *. Coherent electron cooling promises to cool hadron beams at a much faster rate**. A single pass of an ion through a coherent electron cooler involves the ion's modulating the charge density of a copropagating electron beam, amplification of the modulated electron beam in a free-electron laser, and energy correction of the ion in the kicker section. Numerical simulations of these three components are underway, using the parallel Vorpal framework and Genesis 1.3, with careful coupling between the two codes. Here we present validations of two components of the simulations: Adding bunching to an electron beam at the start of an FEL, and the time-dependent charge density modulation in the kicker.
* http://www.bnl.gov/cad/eRHIC/
** V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).

MOPWO073

Design and Simulation of an Extraction Section for the University of Maryland Electron Ring

extraction, dipole, emittance, quadrupole

1052

K.J. Ruisard, B.L. Beaudoin, S. Bernal, J.A. Butcher, I. Haber, R.A. Kishek, T.W. Koeth, D.F. Sutter
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
The University of Maryland Electron Ring (UMER) is a low-energy scaled facility for the study of intense beam dynamics, relevant to higher energy, high intensity accelerators. Many parameters crucial to understanding space charge dominated beam evolution, such as transverse emittance and longitudinal temperature, require the use of turn-by-turn interceptive diagnostics. To meet this need, we plan to implement an extraction section with a fast-pulsed electric-field kicker. This paper presents a suite of simulations used to guide the design process and predict extraction performance, using the WARP Particle-in-cell (PIC) code. Simulations in a transverse slice geometry predict beam trajectory and monitor beam evolution through extraction. After isolating a design based on centroid tracking, extraction acceptance is probed and an analysis proposed to estimate the error tolerances of the new ring elements.

MOPWO074

A Novel Differential Algebraic Adaptive Fast Multipole Method

target, multipole

1055

S. Abeyratne, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
B. Erdelyi, S.L. Manikonda
ANL, Argonne, USA

The direct pairwise calculation of the potential/electric field created by a very large number of particles is computationally impracticable since it requires long run time and a large amount of memory. The Fast Multipole Method (FMM) is a fast algorithm which scales linearly with the number of particles and it enables highly accurate evaluation of the potentials and fields among the large number of particles using less memory compared to the direct evaluation. The FMM has two main forms, non-adaptive and adaptive. The former is suitable for uniform distributions while the latter is more efficient for non-uniform distributions typically encountered in beam physics. This paper presents an implementation of a novel 3D adaptive FMM algorithm and some results obtained from simulations performed with non-uniform particle distributions.

MOPWO080

GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders

luminosity, collider, electron, damping

1064

Y. Roblin, V.S. Morozov, B. Terzić
JLAB, Newport News, Virginia, USA
M. Aturban, D. Ranjan, M. Zubair
ODU CS, Norfolk, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.

MOPWO085

A Hybrid Technique for Computing Courant-Snyder Parameters from Beam Profile Data

space-charge, emittance, linac, DTL

1073

C.K. Allen
ORNL, Oak Ridge, Tennessee, USA
E.N. Dai
Washington University in St. Louis, St. Louis, USA

Funding: Work supported by ORNL/SNS, which is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
We present a technique for computing the Courant-Snyder parameters of a charged-particle beam from profile measurement data. Such algorithms are not new, but this particular method has very robust convergence properties resulting from a novel approach that combines both deterministic and non-deterministic methods. The general idea is as follows: given a model of the beamline, in the zero-current case it is possible to compute the Courant-Snyder parameters directly from profile data using a deterministic, linear-algebraic approach. For the finite beam current case we can construct a smooth curve of these deterministic solutions starting from the zero-current solution and terminating at the finite-current case. We are guaranteed convergence, and convergence to the finite-current solution connected to the zero-current Courant-Snyder parameters. This approach avoids the convergence issues associated with a fully iterative, non-deterministic method. The details of the technique are outlined and examples are presented using profile data taken from the SNS accelerator.

MOPWO088

Semi-analytical Description of the Modulator Section of the Coherent Electron Cooling

electron, plasma, shielding, hadron

1082

A. Elizarov, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We discuss the theoretical description of the modulator section of the coherent electron cooling (CeC)*, the modern realization of the stochastic electron cooling, where the electron beam serves as a modulator and a kicker, i.e., it records the information about the hadron beam via electron density perturbations resulting from the shielding of the hadrons and then accelerates or decelerates hadrons by its electric field with respect to their velocities. To analyze the performance of the CeC shielding of a hadron in an electron beam should be computed with high precision. We propose a solution of this problem via Fourier and Laplace transforms for 1D, 2D and 3D plasmas. In some cases there are fully analytical solutions, which gave an opportunity to test semi-analytical ones involving numerical evaluations of the inverse integral transforms. Having its own practical value this solution will also serve as a testing ground for our general solution via numerical treatment of the integral equations applicable for the realistic case of the finite beam**.
* V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** A. Elizarov, V. Litvinenko, G. Wang, IPAC'12 Proceedings, weppr099 (2012).

TUODB103

Recent Results from CesrTA Intrabeam Scattering Investigations

emittance, coupling, damping, scattering

1126

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, D. Sagan, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
Manifestation of intrabeam scattering (IBS) in an electron/positron storage ring depends on the radiation damping time in two ways. First, the beam size is the equilibrium of the IBS growth rate in each of the three degrees of freedom and corresponding damping rates. Second, scattering events that occur less frequently than order once per damping time contribute to non-Gaussian tails that are invisible to our beam size monitors. The tail cut procedure excludes these relatively rare events in the calculation of equilibrium beam size. In machines with short damping times, the tail cut significantly reduces the effective IBS growth rate. At CesrTA, we measure the dependence of beam size on bunch charge in IBS-dominated beams. We vary the vertical emittance using a closed optics bump that increases the vertical dispersion and transverse coupling in the wiggler regions. Measurements are taken at both 2.1 and 2.3 GeV. Here we report the results of these experiments and compare those results to theory.

Slides TUODB103 [1.221 MB]

TUOCB202

Fast Orbit Feedback Scheme and Implementation for Taiwan Photon Source

feedback, power-supply, controls, EPICS

1146

P.C. Chiu, K.T. Hsu, K.H. Hu, C.H. Kuo, C.Y. Wu
NSRRC, Hsinchu, Taiwan

TPS (Taiwan Photon Source) is a 3 GeV synchrotron light source which is being in construction at NSRRC. As most of 3rd generation light sources, the fast orbit feedback system would be adopted to eliminate various disturbances and improve orbit stability. Due to the vacuum chamber material made of aluminum with higher conductivity and lower bandwidth, both of slow and fast correctors will be used for FOFB correction. In general, there are two schemes to operate these hybrid correctors. One is to transfer correction from fast to slow correctors periodically and avoid fast corrector saturation. The other is the fast correctors operated only at higher frequency domain and slow ones take care of DC part. TPS would adopt the first scheme but the second one still as a substitute. Both schemes will be supported. This report summarizes the infrastructure of the FOFB and the simulation is also presented.

Slides TUOCB202 [3.035 MB]

TUODB202

Experiment and Numerical Simulation Results of Plasma Window

plasma, vacuum, cathode, cavity

1155

K. Zhu, S. Huang, Y.R. Lu, B.L. Shi
PKU, Beijing, People's Republic of China

Funding: Supported by NSFC 91026012
A windowless vacuum seal technique has been widely researched and designed, which can connect high pressure cavity to a vacuum condition with rather little thickness of material. As a result, it will reduce most interaction with the particle beam penetrating through comparing to that of foil window. It is desired extensively in experiments using high-intensity heavy ion beams which will break foil window in a short time or in experiments which require the injecting beams with mono-energy and high purity for example. In this work, we study the plasma window in argon which is used as a windowless vacuum sealing device. A numerical 2D FLUENT-based magneto-hydrodynamic model has been developed to investigate the physical reasons of high pressure difference in plasma window. Further, preliminary experimental results are presented and discussed.

Slides TUODB202 [2.180 MB]

TUPEA006

Towards Realistic Modelling of the FEL Radiation for the European XFEL

radiation, FEL, controls, undulator

1173

I.V. Agapov, G. Geloni
XFEL. EU, Hamburg, Germany

For the operation phase of the European XFEL the possibility to characterize the FEL radiation taking realistic machine model into account is important. To achieve this, a software framework is being developed. It allows for interoperability of various simulation codes by means of a common graphical user interfaces, common input and output files, and common programming model for scripting; it includes the possibility of modeling beam jitters and machine imperfections to set errorbars on the simulation results, and has a connection to the control system for data acquisition. We report on the progress in the developing of this framework and give examples of FEL property calculations performed with it.

TUPEA017

Monoenergetic Electron Beams with Ultralow Normalized Emittance Generated from Laser-Gas Interaction

laser, electron, plasma, emittance

1196

D.Z. Li, J. Gao, K. Huang, J. Jiarui, Y. Ma
IHEP, Beijing, People's Republic of China
L.M. Chen, W.C. Yan
Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China

High quality electron bunches are generated by using 2 TW, 80 fs, high contrast laser pulses interacting with helium gas targets. In optimized condition, we get tens MeV monoenergetic electron beams with small energy spread and the normalized emittance 0.07π mm·mrad. Due to its ultra small emittance and high initial energy, such bunch is very suitable for high current linear accelerators.

TUPEA042

Linac Design for Dalian Coherent Light Source

linac, FEL, emittance, laser

1226

M. Zhang, H.X. Deng, D. Gu, Q. Gu
SINAP, Shanghai, People's Republic of China

Dalian Coherent Light (DCL) Source is a FEL user facility in which HGHG scheme is adopted. Beam quality requirements for the linear accelerator (linac) are critical, including not only the beam brightness, but also the stability and the reliability. In this paper, optimization study is performed for the linac. Based on beam stability simulation in the longitudinal direction, the tolerant budget is formed for the short period jitter. For the transverse orbit error, beam based alignment (BBA) technique is implemented by beam dynamics simulations and the transverse jitter is also presented accordingly. Measurement method for the beam quality is also described in the paper.

TUPEA045

Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas

electron, plasma, positron, wakefield

1235

J. Vieira, N.C. Lopes
Instituto Superior Tecnico, Lisbon, Portugal
E. Adli, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos
SLAC, Menlo Park, California, USA
Y. Fang
USC, Los Angeles, California, USA
C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
UCLA, Los Angeles, California, USA
P. Muggli
MPI, Muenchen, Germany
O. Reimann
MPI-P, München, Germany
L.O. Silva
IPFN, Lisbon, Portugal

Funding: This work has been partially supported by Humboldt Foundation.
The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN*. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times**. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored.
*G. Xia et al., J. Plasma Phys., 1-7 (2012).
**J. Vieira et al., Phys. Plasmas 19, 063105 (2012).

TUPEA048

Simulation of Self-modulating Particle Beams in Plasma Wakefield Accelerators

plasma, wakefield, proton, electron

1238

K.V. Lotov
BINP SB RAS, Novosibirsk, Russia
K.V. Lotov, A. Sosedkin
NSU, Novosibirsk, Russia
E. Mesyats
ICM&MG SB RAS, Novosibirsk, Russia

Funding: The Ministry of education and science of Russia, project 14.B37.21.0784.
Controlled self-modulation of long proton or electron beams is a new trend in plasma wakefield acceleration which sets a new goal for simulation codes. Long interaction lengths (tens of meters), long beams (up to hundred of plasma wave periods), motion of plasma ions, and violation of fluid approximation are factors that makes the problem too heavy for general purpose codes. Only specialized codes can attack this problem in real geometry. We describe recent upgrades of the code LCODE which enabled simulations of long dense proton beams and report results of numerical studies of proton beam-plasma interaction in the context of AWAKE project.

TUPEA061

High-Brightness SASE Studies for the CLARA FEL

undulator, FEL, electron, radiation

1274

R.N.C. Santer, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Compact Linear Accelerator for Research and Applications (CLARA) is a proposed 250 MeV FEL test facility to be constructed at STFC Daresbury Laboratory in the UK [1]. This paper presents study of a scheme for the temporal and spectral stabilisation of the SASE output. A feasibility study for the operation of the FEL in a novel High-Brightness SASE mode is presented. Electron beam delays are introduced between undulator sections to disrupt the localised collective FEL process, increase the radiation coherence length and reduce the rms bandwidth. This may extend the range of electron bunch lengths appropriate for the generation of temporally coherent single spike SASE FEL pulses.

TUPEA064

A Proposed Plasma Accelerator Research Station at CLARA Facility

plasma, electron, wakefield, acceleration

1280

G.X. Xia, K. Hanahoe
UMAN, Manchester, United Kingdom
D. Angal-Kalinin, J.A. Clarke, J.K. Jones, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom

We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury lab. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in the electron beam driven plasma wakefield acceleration, e.g. the two bunch acceleration for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and the related beam instabilities. This paper discusses the feasibility studies of electron beam parameters to meet the requirements for beam driven wakefield acceleration and the possible experiments which can be conducted at PARS beam line.

TUPEA065

Design of a Photonic Crystal Accelerator for Basic Radiation Biology

laser, vacuum, acceleration, electron

1283

A. Aimidula, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Aimidula, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
K. Koyama, Y. Matsumura
University of Tokyo, Tokyo, Japan
T. Natsui, M.Y. Yoshida
KEK, Ibaraki, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
G.X. Xia
UMAN, Manchester, United Kingdom

Funding: This work is supported by the EU under Grant Agreement 289485, the STFC Cockcroft Institute Core Grant No. ST/G008248/1 and KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120.
The application of photonic crystals to realize an on-chip electron beam source for fundamental radiation biology is highly interesting for a number of applications. The unique combination of nanometer beam size and attosecond-short pulses has a very promising potential for use in microscopic and ultra-fast analyses of damage and repair of radiation-irradiated DNA and chromosomes. Simulations studies indicate an output electron beam energy, beam intensity and device size of the order of MeVs, fCs and a few cm, respectively. In this contribution, first results from numerical studies into the design of such compact accelerator structure are presented. The dimensions of a novel dual grating-based acceleration structure are shown together with the estimated laser parameters. Finally, a system consisting of an electron injector and multi-stage accelerating structures is proposed, which corresponds to a miniaturized optical linear accelerator.

TUPEA068

Wake-field Reduction in Hybrid Photonic Crystal Accelerator Cavities

wakefield, lattice, cavity, dipole

1289

D. A. Rehn
Colorado University at Boulder, Boulder, Colorado, USA
C.A. Bauer, J.R. Cary, G.R. Werner
CIPS, Boulder, Colorado, USA
J.R. Cary, C.D. Zhou
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by the U.S. Dept. of Energy, grant DE-FG02-04ER41317.
Photonic crystals (PhCs) have attractive properties for manipulating electromagnetic radiation. In one application, PhCs are composed of a number of dielectric rods that can be arranged to make an accelerator cavity. These structures trap an accelerating mode and allow higher order modes to propagate out. Previous work showed that PhC structures allow excitation of unwanted transverse wake-fields that can disrupt the beam and limit luminosity levels. This work focuses on optimizing PhC cavities to reduce transverse wake-fields by minimizing the Q-factor of unwanted modes, while keeping the Q-factor of the accelerating mode high. The transverse wake-fields in the new optimized structures are compared with previously optimized structures and the CLIC cavity with HOM damping.

TUPEA071

THz Bench Tests of a Slab-symmetric Dielectric Waveguide

acceleration, laser, wakefield, emittance

1292

F. Lemery, H. Panuganti, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
D. Mihalcea, P. Piot
Fermilab, Batavia, USA
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
Dielectric-lined waveguides (DLW) are becoming more popular for beam driven acceleration applications. An experiment to demonstrate beam-driven acceleration using a slab-symmetric dielectric-lined waveguide driven by a flat beam is in preparation at the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In this paper we characterize the structure using a THz pulse obtained from optical rectification using an amplified laser pulse. After propagation through the DLW structure, the THz pulse is analyzed using a Michelson interferometer and single-shot electro-optical imaging. Data for various gap size will be presented.

TUPEA072

Toward a Dielectric-Wakefield Energy Doubler at the Fermilab's Advanced Superconducting Test Accelerator

emittance, acceleration, electron, wakefield

1295

F. Lemery, D. Mihalcea, P. Piot, C.R. Prokop
Northern Illinois University, DeKalb, Illinois, USA
P. Piot, Y.-E. Sun
Fermilab, Batavia, USA
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Advanced Superconducting Test Accelerator (ASTA), presently under construction at Fermilab, will produce high-charge (~<3 nC) electron bunches with energies ranging from 50 to eventually 750 MeV. The facility is based on a superconducting linac capable of producing up to 3000 bunches in 1-ms macropulses repeated at 5 Hz. In this paper we explore the use of a short dielectric-lined-waveguide (DLW) linac to significantly increase the bunch energy. The method consists in (1) using advanced phase space manipulation techniques to shape the beam distribution and enhance the transformer ratio, and (2) optimize the generation and acceleration of a low-charge witness bunches. Start-to-end simulations of the proposed concept are presented. This DLW module could also be used to test some aspects of a recently proposed concept for a multiuser short-wavelength free-electron laser utilizing a series of DLW linacs*.
* C. Jing et al., “A Compact Soft X-ray Free-Electron Laser Facility based on a Dielectric Wakefield Accelerator”, Advanced Photon Source LS Note LS-332, Argonne National Laboratory (2012).

TUPEA073

Performances of VORPAL-GPU Slab-symmetric DLW

wakefield, factory, electron, dumping

1298

F. Lemery, K. Duffin, N. Karonis, D. Mihalcea, P. Piot, J. Winans
Northern Illinois University, DeKalb, Illinois, USA
P.J. Mullowney, P. Stoltz
Tech-X, Boulder, Colorado, USA
P. Piot
Fermilab, Batavia, USA

Funding: HDTRA1-10-1-0051, DOE(Grant No will be specified later)
GPU-based computing has gained popularity in recent years due to its growing software support and greater processing capabilities than its CPU counterpart. GPU computing was recently added in the finite-difference time-domain program VORPAL. In this paper we carry electromagnetic simulations and optimization of a flat beam passing through a slab-symmetric dielectric-lined waveguide (DLW). We use this simulation model to explore the scaling of the GPU version of VORPAL on a new TOP1000-grade hybrid GPU/CPU computer cluster available at Northern Illinois University.

TUPEA087

Experiment on Multipactor Suppression in Dielectric-loaded Accelerating Structures with a Solenoid Field

multipactoring, solenoid, electron, plasma

1319

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
C. Chang, L. Ge, L. Xiao
SLAC, Menlo Park, California, USA
M.E. Conde, W. Gai, R. Konecny, J.G. Power
ANL, Argonne, USA
S.H. Gold
NRL, Washington, DC, USA

Funding: US DoE SBIR Phase I project under contract #DE-SC0007629
Efforts by numerous institutions have been ongoing over the past decade to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external rf source. Multipactor is the major issue limiting the gradient that was revealed in earlier experiments. A theoretical model predicts that the strength of solenoid field within an optimal range applied to DLA structures may completely block the multipactor. To demonstrate this approach, two DLA test structures have been built and the first high power test will be conducted in December 2012. The results will be reported.

TUPEA089

Modeling and Experimental Update on Quasi-phase Matched Direct Laser Electron Acceleration In Density-modulated Plasma Waveguides

plasma, laser, electron, target

1325

M.W. Lin, D.R. Abercrombie, I. Jovanovic, A. Rakhman
Penn State University, University Park, Pennsylvania, USA

Funding: This work has been supported by the Defense Threat Reduction Agency through Contract HDTRA1-11-1-0009.
Direct laser acceleration (DLA) of electrons using the axial electric field of a radially polarized, guided intense laser pulse has the potential to lead to compact laser-driven accelerators* for security and medical applications. A density-modulated plasma waveguide could be applied to extend the laser beam propagation distance and to achieve quasi-phase matching (QPM) between laser and electron pulses for efficient DLA**. We conduct numerical simulations to design the appropriate plasma structure of the waveguides and investigate the properties of accelerated electron beams. An all-optical method, based on the igniter-heater scheme for plasma waveguide fabrication, is experimentally implemented to machine the density-modulated plasma waveguides with low-Z gas targets. A novel angle-multiplexed diagnostic technique has been developed to extract the polarization state and temporal characteristics of a radially polarized femtosecond laser pulse using spatial-spectral interferometry***. The goal of our experiments is to characterize the propagation of femtosecond radially polarized pulses in plasma waveguides.
* P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000).
** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012).
***P. Bowlan, et al., Opt. Exp. 14, 11892 (2006)

TUPFI012

HL-LHC: Integrated Luminosity and Availability

luminosity, target, collider, hadron

1352

A. Apollonio, M. Jonker, R. Schmidt, B. Todd, S. Wagner, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

The objective of LHC operation is to optimise the output for particle physics by maximising the integrated luminosity. An important constraint comes from the event pile–up for one bunch crossing that should not exceed 140 events per bunch crossing. With bunches every 25 ns the luminosity for data taking of the experiments should therefore not exceed 5*10³⁴ s⁻¹cm^-2. For the optimisation of the integrated luminosity it is planned to design HL-LHC for much higher luminosity than acceptable for the experiments and to limit the initial luminosity by operating with larger beam size at the collision points. During the fill, the beam size will be slowly reduced to keep the luminosity constant. The gain from luminosity levelling depends on the average length of the fills. Today, with the LHC operating at 4 TeV, most fills are terminated due to equipment failures, resulting in an average fill length of about 5 h. In this paper we discuss the expected integrated luminosity for HL-LHC as a function of fill length and time between fills, depending on the expected MTBF of the LHC systems with HL-LHC parameters. We derive an availability target for HL-LHC and discuss steps to achieve this.

TUPFI017

Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy

quadrupole, dipole, lattice, dynamic-aperture

1367

Y. Nosochkov, Y. Cai, M.-H. Wang
SLAC, Menlo Park, California, USA
R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first*. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented.
* Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.

TUPFI019

Magnet Misalignment Studies for the Front-end of the Neutrino Factory

target, lattice, proton, factory

1373

G. Prior, I. Efthymiopoulos
CERN, Geneva, Switzerland
D.V. Neuffer, P. Snopok
Fermilab, Batavia, USA
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
D. Stratakis
BNL, Upton, Long Island, New York, USA

In the Neutrino Factory Front-End the muon beam coming from the interaction of a high-power (4 MW) proton beam on a mercury jet target, is transformed through a buncher, a phase rotator and an ionization cooling channel before entering the downstream acceleration system. The muon Front-End channel is densely packed with solenoid magnets, normal conducting radio-frequency cavities and absorber windows (for the cooling section). The tolerance to the misalignment of the different components has to be determined in order on one hand to set the limits beyond which the performance of the Front-End channel would be degraded; on the other hand to optimize the design and assembly of the Front-End cells such that the component alignment can be checked and corrected for where crucial for the performance of the channel. In this paper we will show the results of the simulations of the Front-End channel performance where different components such as magnets, cavities have been randomly shifted or rotated. Detailed simulations have been done in G4BeamLine*. * T. J. Roberts et al. G4BeamLine 2.06 (2010) http://g4beamline.muonsinc.com/

TUPFI020

Towards a Symmetric Momentum Distribution in the Muon Ionization Cooling Experiment

solenoid, quadrupole, collider, emittance

1376

O.M. Hansen
University of Oslo, Oslo, Norway
A.P. Blondel
DPNC, Genève, Switzerland
I. Efthymiopoulos, O.M. Hansen
CERN, Geneva, Switzerland

The Muon Ionization Cooling Experiment (MICE) is under development at Rutherford Appleton Laboratory (UK). It's a proof-of-principle experiment for ionization cooling, which is a prerequisite for a future Neutrino Factory(NF) or a Muon Collider. The muon beam is designed to have a symmetrical momentum distribution in the cooling channel of the NF. In the MICE beamline pions are captured by a quadrupole triplet, then pion momentum is selected by dipole 1 (D1) after which the pions decay to muons in the decay solenoid. After the decay solenoid, the muon beam momentum is selected by dipole 2 (D2), the beam is focused in two quadrupole triplets and is finally characterized by a set of detectors. By doing a D1-scan of the currents, where the optics parameters are scaled according to the pion momentum, from 238-450 MeV/c the muon momentum distribution is changed. In this paper simulation results from G4Beamline and real data from MICE are presented and compared.

TUPFI024

Influence of the Ats Optics on Intra-Beam Scattering for HL-LHC

optics, luminosity, emittance, collider

1388

M. Schaumann, R. Bruce, J.M. Jowett
CERN, Geneva, Switzerland
M. Schaumann
RWTH, Aachen, Germany

In the future High Luminosity (HL-)LHC the influence of intra-beam scattering (IBS) will be stronger than in the present LHC, because of higher bunch intensity, small emittance and new optics. The new ATS-optics scheme modifies the lattice in the arcs around the main interaction points (IP) to provide β* values as small as 0.15m in the IP, however those modifications affect the IBS growth rates. In this paper proton IBS emittance growth rates are calculated with MADX and the Collider Time Evolution (CTE) program for two ATS-optics versions, different settings of the crossing angles and required corrections and various beam conditions at injection (450 GeV) and collision (7 TeV) energy. CTE simulations of the expected luminosity, intensity, emittance and bunch length evolution during fills are also presented

TUPFI025

Bunch-by-Bunch Analysis of the LHC Heavy-Ion Luminosity

luminosity, injection, emittance, ion

1391

M. Schaumann, J.M. Jowett
CERN, Geneva, Switzerland

After the first run in 2010, the LHC continued its heavy-ion operation with collisions of lead nuclei in late 2011. The beam dynamics of those high intensity lead beams are strongly influenced by intra-beam scattering (IBS), especially on the injection plateau. Each batch injected from the SPS spends a different time at injection, introducing significant changes from batch to batch. Within the batches there is an even larger spread imprinted by the SPS injection plateau. This results in a spread of the luminosity produced in each bunch crossing. The particle losses during collisions are dominated by nuclear electromagnetic processes, leading to a non-exponential intensity decay during the fill and short luminosity lifetime at 3.5 Z TeV. The luminosity, emittance, intensity and bunch length evolution of the 2011 run was analysed bunch-by-bunch and compared with simulations. Based on this analysis, estimates of the potential luminosity performance at 6.5 Z TeV, after the present shutdown, are given.

TUPFI045

Electron-cloud Maps for LHC Scrubbing Optimization

electron, injection, dipole, beam-losses

1451

C.O. Domínguez, F. Zimmermann
CERN, Geneva, Switzerland

Electron-cloud maps as alternative to detailed build-up simulations have already been applied in the past for a few accelerators, e.g. RHIC and the LHC at 7 TeV. We here report a first application of maps to optimize the "beam scrubbing" of the LHC arcs at injection energy: Maps are used to efficiently determine the optimum bunch filling pattern which maximizes the electron flux on the chamber wall, while respecting constraints on the central cloud density to ensure beam stability. In addition, new features have been explored, e.g. by introducing thresholds which divide regions where either linear maps or cubic maps best describe the build-up and the decay of an electron cloud. In the near future we plan to extend the map formalism to individual slices in a dipole file in order to represent the vertical "stripes".

TUPFI046

The MICE Experiment

solenoid, target, emittance, quadrupole

1454

A.P. Blondel
DPNC, Genève, Switzerland

Ionization Cooling is the only practical solution to preparing high brilliance muon beams for a neutrino factory or muon collider. MICE is under development at the Rutherford Appleton Laboratory (UK). It is characterized by exquisite emittance determination by 6D measurement of individual particles, a cooling section comprising 23 MV of acceleration at 200 MHz and 3 liquid hydrogen absorbers totaling 1m of liquid hydrogen on the path of 140-240 MeV/c muons. The beam has already been commissioned successfully and first measurements of beam emittance performed. We are setting up for the final high precision emittance determination and the measurements of cooling in Li Hydrogen. The design offers opportunities to observe cooling with various absorbers and several optics configurations. Results will be compared with detailed simulations of cooling channel performance to ensure full understanding of the cooling process. Progress towards the full cooling experiment with RF re-acceleration will also be reported.
Submitted by the MICE speakers bureau
hoping for a contributed oral
to be give by the spokesperson, prof. A. Blondel

TUPFI054

MICE Spectrometer Solenoid Magnetic Field Measurements

solenoid, emittance, shielding, factory

1466

M.A. Leonova
Fermilab, Batavia, USA

The Muon Ionisation Cooling Experiment (MICE) is designed to demonstrate ionization cooling in a muon beam. Its goal is to measure a 10% change in transverse emittance of a muon beam going through a prototype Neutrino Factory cooling channel section with a 1% accuracy, corresponding to an absolute measurement accuracy of 0.1%. To measure the emittance, MICE uses two solenoidal spectrometers. The Spectrometer Solenoids are designed to have 4 T solenoidal fields, uniform at 3 per mil level in the tracking volumes. Analysis of magnetic field measurements of the Spectrometer Solenoids will be discussed, and results of extracting precise coil positions, angles, and coil radius measurements for input into magnet models will be presented.

TUPFI055

Stochastic Injection Scenarios and Performance for NuSTORM

injection, storage-ring, target, proton

1469

D.V. Neuffer
Fermilab, Batavia, USA
A. Liu
Indiana University, Bloomington, Indiana, USA

At Fermilab, we are developing NuSTORM (Neutrinos from STORed Muons), a neutrino beam from muon decay in a long straight section of a storage ring. The baseline design for NuSTORM uses what was called “stochastic injection”. In that method, high-energy protons on a nuclear target produce pions that are directed by a chicane into a straight section of the storage ring. Pions that decay within that straight section can provide lower-energy muons that are within the circulating acceptance of the storage ring. This decay acceptance enables injection for multiple storage ring turns without kickers, and muon accumulation can be reasonably high. The design of a muon storage ring with pion injection is described and simulations of acceptance are discussed. Alternative injection approaches are also discussed.

TUPFI058

Simulation of Beam-induced Gas Plasma in High Gradient RF Field for Muon Colliders

electron, ion, plasma, electromagnetic-fields

1478

K. Yonehara, M. Chung, A.V. Tollestrup
Fermilab, Batavia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
R.P. Johnson, T.J. Roberts
Muons. Inc., USA
R.D. Ryne
LBNL, Berkeley, California, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA
K. Yu
SBU, Stony Brook, USA

There is a strong limit of available RF gradient in a vacuum RF cavity under magnetic fields because the magnetic field enhances a dark current density due to electron focusing and increases probability of an electric breakdown. This limits the cooling performance. A dense hydrogen gas filled RF cavity can break this limit because the gas acts as a buffer of dark current. However, RF power loading due to a beam-induced plasma in a dense gas filled RF cavity (plasma loading effect) is crucial to design the practical cavity. Experiment shows that the plasma loading can be mitigated in denser hydrogen gas and by doping a small amount of electronegative gas in the cavity. A complicate plasma chemical reaction should be dominated in such a dense hydrogen gas condition. A beam-induced plasma is simulated by taking into account the plasma chemistry to reproduce the condition by using the supercomputer at LBNL. We will also investigate the space charge effect in a dense gas in this effort.

TUPFI060

Complete Muon Cooling Channel Design and Simulations

emittance, beam-cooling, dipole, factory

1484

C. Y. Yoshikawa, C.M. Ankenbrandt, R.P. Johnson
Muons. Inc., USA
Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
D.V. Neuffer, K. Yonehara
Fermilab, Batavia, USA

Considerable progress has been made in developing promising subsystems for muon beam cooling channels to provide the extraordinary reduction of emittance required for an Energy-Frontier Muon Collider, but lacks an end-to-end design. Meanwhile, the recent discovery of a Higgs-like boson has created interest in the High Energy physics community for a Higgs Factory to investigate its properties and verify whether it is Standard Model or beyond. We present principles and tools to match emittances between and within muon beam cooling subsystems that may have different characteristics. The Helical Cooling Channel (HCC), which combines helical dipoles and a solenoid field, allows a general analytic approach to guide designs of transitions from one set of cooling channel parameters to another. These principles and tools will be applied to design a complete cooling channel that would be applicable to a Higgs Factory and an Energy Frontier Muon Collider.

TUPFI062

Operational Results of the LHC Luminosity Monitors until LS1

luminosity, proton, monitoring, radiation

1490

A. Ratti, S.C. Hedges, J. Jones, H.S. Matis, M. Placidi, W.C. Turner, V.K. Vytla
LBNL, Berkeley, California, USA
E. Bravin, F. Roncarolo
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: Work funded by the US Department of Energy through the US- LARP program.
The monitors for the high luminosity regions in the LHC have been operating since 2009 to optimize the LHC's luminosity. The devices are gas ionization chambers inside the neutral particle absorber 140 m from the interaction point and monitor showers produced by high energy neutral particles from the collisions. They have the ability to resolve the bunch-by-bunch luminosity as well as to survive the extreme level of radiation in the nominal LHC operation. The devices have operated on a broad range of luminosity, from the initial 10²⁸ until the levels well beyond 10³³ reached in 2012. We present operational results of the device during proton and lead ion operations until LS1, which include runs at 40 MHz bunch rate and with p-Pb collisions.

TUPFI063

Electromagnetic Coupling between High Intensity LHC Beams and the Synchrotron Radiation Monitor Light Extraction System

resonance, impedance, extraction, synchrotron

1493

F. Roncarolo, W. Andreazza, A. Bertarelli, E. Bravin, F. Caspers, M. Garlaschè, A. Goldblatt, J-J. Gras, O.R. Jones, T. Lefèvre, E. Métral, A.A. Nosych, B. Salvant, G. Trad, R. Veness, C. Vollinger, M. Wendt
CERN, Geneva, Switzerland

The CERN LHC is equipped with two Synchrotron Radiation Monitor systems used to characterise transverse and longitudinal beam distributions. Since the end of the 2011 LHC run the light extraction system, based on a retractable mirror, has suffered deformation and mechanical failure that is correlated to the increase in beam intensity. Temperature probes have associated these observations to a strong heating of the mirror support with a dependence on the longitudinal bunch length and shape, indicating the origin as electromagnetic coupling between the beam and the structure. This paper combines all this information with the aim of characterising and improving the system in view of its upgrade during the current LHC shutdown. Beam-based observations are presented along with electromagnetic and thermomechanical simulations and complemented by laboratory measurements, including the study of the RF properties of different mirror bulk and coating materials.

TUPFI066

Muon Ionization Cooling Experiment Step VI

solenoid, emittance, site, target

1502

D. Rajaram
Illinois Institute of Technology, Chicago, Illinois, USA
P. Snopok
IIT, Chicago, Illinois, USA

In the Muon Ionization Cooling Experiment (MICE) the transverse emittance of the muon beam is reduced (muon cooling) by passing it through low-Z material, then through RF cavities to compensate for the energy loss. Transverse emittance reduction of the muon beam will be demonstrated for the first time in MICE Step IV configuration using liquid Hydrogen absorbers as well as a variety of solid absorbers. Current status and efforts towards Step IV are summarized, including hardware fabrication and testing, Monte Carlo simulations, track reconstruction algorithms.

TUPFI083

Simulation Study of Head-on Beam-beam Compensation with Realistic RHIC Lattices

lattice, dynamic-aperture, proton, resonance

1541

Y. Luo, M. Bai, W. Fischer, C. Montag, V.H. Ranjbar, S. Tepikian
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We performed numerical simulations to study the effects of head-on beam-beam compensation with the realistic RHIC lattices. To better cancel the beam-beam resonance driving terms during half beam-beam compensation operation, the betatron phase advances between the interaction point IP8 and the center of the electron lens should be multiples of pi. for this purpose two shunt power supplies were added to the main quadrupole circuit buses in the arc between them. For the realistic beam-beam compensation lattices, the integer tunes are (27, 29) for the Blue ring and (29, 30) for the Yellow ring. The betatron phase advances between IP8 and the e-lens are (8pi,11pi) in the Blue ring and (11pi, 9pi) in the Yellow ring. Recent simulation results will be presented.

TUPFI086

A Tapered Six Dimensional Cooling Lattice for a Muon Collider

emittance, collider, lattice, focusing

1547

D. Stratakis, R.C. Fernow, R.B. Palmer
BNL, Upton, Long Island, New York, USA

Designs for Neutrino Factories and Muon Colliders use ionization cooling to reduce the emittance of the muon beam prior to acceleration. Two lattices based on the original RFOFO ring design representing different configurations of the magnetic field are considered. One is with a flip magnetic field and one with a non-flip magnetic field configuration that is used to eliminate for possible space-charge effects. The details of the G4Beamline tracking studies of both channels are presented and compared to the independent ICOOL code.

TUPFI088

Space-charge Studies for Ionization Cooling Lattices

emittance, lattice, space-charge, collider

1553

D. Stratakis, R.B. Palmer
BNL, Upton, Long Island, New York, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: This work is funded by US Dept. of Energy grant numbers DE AC02-98CH10886
Intense muon beams provide a promising solution to a variety of applications ranging from nanotechnology to nuclear detections systems and from medical sciences to high energy physics. Production of such intense beam requires the beam to be cooled and ionization cooling via particle matter interaction is considered one of the most practical methods. Here a theoretical and numerical study on space-charge effects on such ionization cooling channels is presented. We show that space-charge can strongly affect the design of muon cooling systems by limiting their minimum cooling rate. Space-charge compensation solutions are discussed and the minimum cooling emittance as a function of the beam charge and pulse width is identified.

TUPME001

Effect of Self-consistency on Space Charge Induced Beam Loss

resonance, space-charge, emittance, controls

1556

G. Franchetti
GSI, Darmstadt, Germany

In long term storage space charge driven incoherent effect may lead to a slow beam diffusion that causes emittance growth and beam loss. However, when beam loss are relevant the full mechanism cannot be understood only driven by an incoherent effect. In this proceeding the issue of the self-consistency is discussed, and its impact presented for simplified examples and for the SIS100.

TUPME007

Beam Lifetime in Low Emittance Rings

scattering, lattice, background, factory

1574

M. Boscolo
INFN/LNF, Frascati (Roma), Italy

In this paper I will review the main effects in low emittance rings that determine the beam lifetime by causing beam losses along the ring. As an example, the case for a B-factory based on the crab-waist collision scheme has been studied. During the machine design all the effects that determine the beam lifetime and induce backgrounds in the detector have been analyzed in details. The crab-waist scheme provides an higher luminosity, but at the same time it induces higher beam losses at the final focus. For this reason single beam effects such as Touschek and beam-gas scattering have been studied in details, by means of a macroparticle tracking code developed for this purpose*. Also Radiative Bhabha scattering, that is the dominant effect to lifetime and backgrounds has been studied with the same technique to check possible multiturn losses at IR. An efficient collimation system has been designed to intercept scattered particles that would be lost in the IR in both the horizontal and the vertical plane. Recently, the Touschek tracking simulation code has been implemented to study the lifetime behavior for extremely low-emittance rings.
* M. Boscolo and P. Raimondi, “Monte Carlo simulation for the Touschek effect with the crab-waist scheme”, Phys. Rev. ST-AB 15 104201 (2012)

TUPME011

Simulated Beam-beam Limit for Circular Higgs Factories

luminosity, synchrotron, beam-beam-effects, radiation

1586

K. Ohmi
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

We report simulation studies of the beam-beam limit for two proposed circular e⁺e⁻ Higgs factories with circumference of 27 and 80 km, respectively, called LEP3 and TLEP. In particular we investigate the dependence of the steady-state luminosity and transverse beam sizes on the synchrotron tune (or momentum compaction factor) and on the betatron tunes, as well as the consequences of the strong radiation damping and the implications of the large hourglass effect.

TUPME014

Coherent Synchrotron Radiation Predicted at the SuperKEKB Damping Ring

damping, linac, vacuum, emittance

1595

H. Ikeda, M. Kikuchi, K. Ohmi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

The damping ring of SuperKEKB is under construction in order to inject low emittance positron beam into the main ring. We calculated the bunch lengthening and the energy spread caused by the longitudinal wake, which is dominated by the CSR wake field. The result was within the tolerance level.

TUPME016

Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB

luminosity, lattice, resonance, betatron

1601

D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto
KEK, Ibaraki, Japan

Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME017

Validation of the Microwave Instability in the Damping Ring of SuperKEKB using VFP Solver

impedance, damping, wakefield, synchrotron

1604

L. Wang
SLAC, Menlo Park, California, USA
H. Ikeda, K. Ohmi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

Microwave instability driven by CSR impedance in the damping ring of Super-KEKB is a concern due to its high bunch current. To understand the beam dynamics, we simulate the microwave instability using Vlasov-Fokker-Planck (VFP) solver. The longitudinal wake potential is calculated as a sum of the contributions due to vacuum chamber components distributed around the ring, including geometry wake field and CSR wake. To improve the accuracy of the simulation of microwave instability, the coherent synchrotron radiation impedance is calculated to very high frequency to get more accurate wake field with a short bunch. The CSR wake is much larger than the geometry wake. The threshold is just above the design current and saw-tooth type of instability is found above the threshold.

TUPME019

Simulation for Control of Longitudinal Beam Emittance in J-PARC MR

emittance, injection, bunching, acceleration

1610

M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-mura, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
KEK, Ibaraki, Japan

The J-PARC MR receives a high intensity beam from the RCS. The designed longitudinal emittance of the RCS is 5 eVs, whereas the MR rf bucket has enough margin to accept up to 10 eVs. Although the RCS emittance can be increased by using PM method and a large emittance is desirable to increase the bunching factor and to avoid instability, it is difficult to receive such large emittance beam in the MR because of the MR kicker performance. We have performed the particle tracking simulation of longitudinal emittance control for enlarging the beam emittance by PM method and for keeping the bunching factor high using 2nd harmonic rf during the MR injection period.

TUPME026

Optimization on RF parameters of a Choke-Mode Structure for the Clic Main LINAC

wakefield, linac, accelerating-gradient, cavity

1628

H. Zha, H.B. Chen, J. Shi
TUB, Beijing, People's Republic of China

Funding: This work was support by the National Natural Science Foundation of China (Grant No. 11135004).
A tapered choke-mode structure for the main linac of Compact Linear Collider (CLIC) had been designed. Wakefield suppression of this structure fits the beam dynamic requirements. But it has a lower RF performance compared to the baseline design of CLIC main linac. A genetic algorithm is used in the procedure to find the optimum solution. A new choke-mode structure with 24 regular cells working on 100MV/m has been design, which fits beam dynamic constraints and has higher RF efficiency and lower surface field.

TUPME030

Emittance Reconstruction from Measured Beam Sizes

emittance, coupling, optics, FEL

1640

J. Giner Navarro, A. Faus-Golfe, J. Fuentes, J. Navarro, J. Resta
IFIC, Valencia, Spain

In this paper we analyze the projected emittance (2D) and the intrinsic emittance (4D) reconstruction method by using the beam size measurements at different locations. We have studied analytically the conditions of solvability of the systems of equations involved in this process and we have obtained some rules about the locations of the measurement stations to avoid unphysical results. Presently, simulations are being made to test the robustness of the algorithm in realistic scenarios with high coupling and measurement errors. The special case of a multi-OTR system in ATF2 is being studied in much detail. The results of these studies will be very useful to better determine the location of the emittance measurement stations in the diagnostic sections of Future Linear Colliders.

TUPME032

Update on Beam Induced RF Heating in the LHC

impedance, injection, kicker, proton

1646

B. Salvant, O. Aberle, G. Arduini, R.W. Aßmann, V. Baglin, M.J. Barnes, W. Bartmann, P. Baudrenghien, O.E. Berrig, A. Bertarelli, C. Bracco, E. Bravin, G. Bregliozzi, R. Bruce, F. Carra, F. Caspers, G. Cattenoz, S.D. Claudet, H.A. Day, M. Deile, J. Esteban Müller, P. Fassnacht, M. Garlaschè, L. Gentini, B. Goddard, A. Grudiev, B. Henrist, S. Jakobsen, O.R. Jones, O. Kononenko, G. Lanza, L. Lari, T. Mastoridis, V. Mertens, N. Mounet, E. Métral, A.A. Nosych, J.L. Nougaret, S. Persichelli, A.M. Piguiet, S. Redaelli, F. Roncarolo, G. Rumolo, B. Salvachua, M. Sapinski, R. Schmidt, E.N. Shaposhnikova, L.J. Tavian, M.A. Timmins, J.A. Uythoven, A. Vidal, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
H.A. Day
UMAN, Manchester, United Kingdom
L. Lari
IFIC, Valencia, Spain

Since June 2011, the rapid increase of the luminosity performance of the LHC has come at the expense of increased temperature and pressure readings on specific near-beam LHC equipment. In some cases, this beam induced heating has caused delays whilie equipment cools down, beam dumps and even degradation of these devices. This contribution gathers the observations of beam induced heating attributable to beam coupling impedance, their current level of understanding and possible actions that are planned to be implemented during the long shutdown in 2013-2014.

TUPME048

Imperfection Tolerances for On-line Dispersion Free Steering in the Main Linac of CLIC

linac, wakefield, emittance, quadrupole

1673

J. Pfingstner, A. Latina, D. Schulte
CERN, Geneva, Switzerland

Long-term ground motion misaligns the elements of the main linac of CLIC over time. Especially the misaligned quadrupoles create dispersion and hence the beam quality is decreased gradually due to an effect called chromatic dilution. Over longer time periods, orbit feedback systems are not capable to fully recover the beam quality and have to be supplemented by dispersion correction algorithms. In this paper, such and dispersion correction algorithm is presented, which is an extended version of the well-known dispersion free steering algorithm. This extended algorithm can recover the beam quality over long time scaled without stopping the accelerator operation (on-line). Tolerances for different imperfections of the system have been identified and a strong sensitivity to the resolution of the wake field monitors of the main linac accelerating structures has been identified. This problem can be mitigated by using a local excitation scheme as will be shown in this work.

TUPME050

Performance Comparison of Different System Identification Algorithms for FACET and ATF2

kicker, emittance, linac, alignment

1679

J. Pfingstner, A. Latina, D. Schulte
CERN, Geneva, Switzerland

Good system knowledge is an essential ingredient for the operation of modern accelerator facilities. For example, beam-based alignment algorithms and orbit feedbacks rely strongly on a precise measurement of the orbit response matrix. The quality of the measurement of this matrix can be improved over time by statistically combining the effects of small system excitations with the help of system identification algorithms. These small excitations can be applied in a parasitic mode without stopping the accelerator operation (on-line). In this work, different system identification algorithms are used in simulation studies for the response matrix measurement at ATF2. The results for ATF2 are finally compared with the results for FACET, latter originating from an earlier work.

TUPME059

Collisional Effects in Particle-in-Cell Beam-Beam Simulations

emittance, collider, luminosity, proton

1700

S. Paret, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
Self-consistent particle tracking simulations (strong-strong) can be used to investigate the deterioration of colliding beams in a storage ring. However, the use of a small number of macroparticles copmared to the real number of particles magnifies the collisional effects and causes numerical noise. In particular, predictions of the emittance lifetime suffer from this numerical noise. In order to produce usable emittance predictions, the contribution of numerical noise to the simulated emittance growth has to be known. In this paper, we apply a diffusion model to strong-strong beam-beam simulations to study the numerical noise driven emittance growth. The scaling of emittance growth with numerical and physical parameters is discussed.

TUPME060

Tune Studies with Beam-Beam Effects in LHC

emittance, resonance, luminosity, collider

1703

S. Paret, J. Qiang
LBNL, Berkeley, California, USA
R. Alemany-Fernandez, X. Buffat, R. Calaga, K. Cornelis, M. Fitterer, R. Giachino, W. Herr, A. Macpherson, G. Papotti, T. Pieloni, S. Redaelli, F. Roncarolo, M. Schaumann, R. Suykerbuyk, G. Trad
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
In high brightness colliders, the tune spread due to the collisions has a significant impact on the quality of the beams. The impact of the working point on emittance growth and beam lifetime has been observed in beam experiments in LHC. Strong-strong beam-beam simulations that were accomplished to better understand such observations are shown. Compared to experiments, wide ranged parameter scans can be done easily. Tune footprints and scans of the emittance growth obtained from simulations are discussed. Three cases are considered: Very high intensity, moderate intensity and collisions with separated beams.

TUPME061

Emittance Growth with Crab Cavity and Damper Noise in LHC

emittance, pick-up, resonance, damping

1706

S. Paret, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work was partially supported by the U.S. LARP and the NERSC of the U.S. Department of Energy under contract No. DE-AC02-05CH11231.
Strong-strong beam-beam simulations are employed to investigate the noise sensitivity of the emittance in the future High Luminosity (HL)-LHC. Noise in the accelerator causes fluctuations of the bunch centroids at the interaction points (IPs) which cause emittance growth for large beam-beam parameters. Two noise sources are examined: Crab cavities and the transverse damper. The damper noise is adjusted to bring simulations in agreement with an emittance measurement in a past LHC run. Results from simulations with HL-LHC beam parameters using different noise levels, damper gains and working points are discussed.

TUPME062

Simulation and Analysis of Microbunching Instability in a High Repetition rate FEL Beam Delivery System

electron, laser, linac, FEL

1709

J. Qiang, J.N. Corlett, P. Emma, C.E. Mitchell, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
Microbunching instability in the accelerator beam delivery system of an FEL can significantly degrade the electron beam quality and limit performance of the X-ray radiation. In this paper, we present detailed numerical simulation and analytical analysis of the microbunching instability in a high repetition rate X-ray FEL beam delivery system that is being studied at Lawrence Berkeley National Laboratory. Our results suggest that by using a flexible accelerator design and a laser heater, the effects of microbunching instability can be suppressed without significantly sacrificing the final electron beam quality.

TUPME064

Envelope Perturbations in a Space-Charge-Dominated Electron Beam

resonance, space-charge, quadrupole, lattice

1712

W.D. Stem, B.L. Beaudoin, I. Haber, R.A. Kishek, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Linear perturbation analysis of the RMS envelope equations predicts a frequency splitting of the transverse envelope resonances with the onset of space charge. These resonances are a potential source of beam degradation for space-charge-dominated particle accelerators and storage rings. We use WARP for both envelope code integration and particle-in-cell (PIC) simulations to predict the behavior of these resonances for an existing alternating gradient lattice storage ring. The focus of these simulations is tailored toward examining physics that is scalable to future high-intensity accelerators. This paper provides detailed simulation results and a design for an experimental demonstration at the University of Maryland Electron Ring (UMER), a high intensity 10 keV electron storage ring.

TUPME065

Experimental Study of Horizontal-Longitudinal Coupling at CesrTA

coupling, lattice, cavity, scattering

1715

M. P. Ehrlichman, A. Chatterjee, W. Hartung, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, S. Wang
CLASSE, Ithaca, New York, USA

Funding: This research was supported by NSF and DOE contracts PHY-0734867, PHY-1002467, PHYS-1068662, DE-FC02-08ER41538, DE-SC0006505.
In storage rings, the presence of horizontal dispersion in the RF cavities introduces x-z coupling. The result is that the beam is skewed in the horizontal-longitudinal plane. The skew angle is proportional to the V15 term of the 6X6 coupling matrix which is proportional to the RF cavity voltage and the horizontal dispersion in the cavity. Here we report experiments at CesrTA where x-z coupling was explored using three distinct lattice configurations with different V15 coupling terms. We explore x-z coupling for each of these lattices by measuring the horizontal projection of the beam with a beam size monitor, as the RF voltage is varied. The first lattice has about 1 m dispersion in the RF cavities, resulting in a V15 term at the beam size monitor source point corresponding to 16 mrad x-z tilt. In the second, the V15 generated in one pair of cavities is compensated at the second pair by adjusting the horizontal betatron phase advance between the cavity pairs. In the third, the optics are adjusted so that the RF cavity region is dispersion-free, eliminating the coupling entirely. Additionally, intra-beam scattering is evident in our measurements of beam size vs. RF voltage.

TUPWA005

Study of Collective Beam Instabilities for the MAX IV 3 GeV Ring

impedance, vacuum, damping, wakefield

1730

M. Klein, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France
G. Skripka, P.F. Tavares, E.J. Wallén
MAX-lab, Lund, Sweden

The present paper reports on a systematic simulation study made on the collective beam instability in the MAX IV 3 GeV ring. We study both single and multibunch instabilities in the longitudinal plane. Specifically, we focus on the microwave instabilities which are considered to be particularly dangerous for MAX IV, in view of its small effective radius of aperture (b_eff < 11 mm), the high intensity (500 mA) and the low emittance (0.24 nm.rad) nature of the circulating beam. Single and multibunch tracking are performed using wake fields that were numerically obtained using GdfidL for the ensemble of the vacuum components. A special effort was made to include dynamically the effect of harmonic cavities that lengthen the bunch and introduce Landau damping, whose details are described in the companion paper *. The study aims to confirm the effectiveness of storing long bunches in the 100 MHz RF system, where tune spreads are further increased by the harmonic cavities, in order to fight against collective instabilities.
* M. Klein and R. Nagaoka "Multibunch Tracking Code Development to Account for Passive Landau Cavities", these proceedings

TUPWA008

Computation of Wakefields for an In-vacuum Undulator at PETRA III

vacuum, undulator, wakefield, impedance

1736

E. Gjonaj, L. Lünzer, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
R. Wanzenberg
DESY, Hamburg, Germany

Funding: Work supported by DESY, Hamburg, Germany
At DESY the installation of an in-vacuum undulator at the synchrotron radiation facility PETRA III is under consideration. The moveable magnet array of the undulator is installed inside the vacuum chamber to achieve shorter wavelength synchrotron radiation. A thin metal foil covers the magnet structure to mitigate resistive wall wakefields. Moveable tapered transitions connect the magnet structure and the adjacent vacuum duct to reduce the geometric wakefields. Nevertheless these moveable tapered transitions contribute significantly to the impedance budget of PETRA III. The computer codes MAFIA, CST-Studio and PBCI have been used to calculate the longitudinal and transverse wakefields. The results for the loss and kick parameters are presented and compared to the corresponding parameters for a standard undulator section.

TUPWA011

Investigation of Emittance Growth in a Small PET Cyclotron CYCIAE-14

resonance, cyclotron, emittance, extraction

1745

M. Li, Shizhong. An, T.J. Zhang
CIAE, Beijing, People's Republic of China

In order to satisfy the rapidly increased domestic needs for PET in China, a small medical cyclotron named CYCIAE-14 is designed and constructed in CIAE ( China Institute of Atomic Energy ) . As the beam intensity in CYCIAE-14 is high, the beam emittance should be controlled strictly in order to reduce the beam loss in the cyclotron. Precessional mixing and resonance crossing are the two main factors leading to emittance growth in the cyclotron with stripping extraction. In this paper, the physical mechanism of precessional mixing in a stripping extraction cyclotron is investigated. After that, the maximum allowable field errors in CYCIAE-14 are derived using the Hamiltonian formalism and numerical simulation, which provides a reference for the cyclotron design and field shimming.

TUPWA012

The Influence of the Magnetic Field Errors in CYCIAE-100 Cyclotron

emittance, resonance, cyclotron, TRIUMF

1748

H.J. Yao, M. Li, T.J. Zhang, J.Q. Zhong
CIAE, Beijing, People's Republic of China

The main magnet size of CYCIAE-100 is 2.31 m in height and 6.16 m in diameter and the outer radius of the sector is 2.0 m, and the total iron weight is about 415t. The magnetic filed can not be absolutely ideal because of imperfections during manufacturing and installation of this big magnet. Therefore the influence of the magnetic field errors on the beam behavior should be studied to provide the reference for magnet mapping and shimming. Magnetic field errors in a cyclotron will excite coherent oscillations through displacing the center of orbit or distorting the transverse phase space. This effect is especially important in the CYCIAE-100 cyclotron because there are a number of different turns in the extracted beam. The tolerances for the magnetic field errors are given in this paper based on analytic calculations and numerical simulations. The resonances vr=1, 2vr=2 driven by the 1st, 2nd harmonic magnetic field are considered, which will result in the radial emittance growth .Besides that, the resonances cause the vertical emittance growth are considered. The maximum allowable field errors for CYCIAE-100 are presented in this paper.

TUPWA013

Study of the C-ADS Longitudinal Beam Instabilities Caused by HOMS

HOM, linac, emittance, damping

1751

P. Cheng, Z. Li, J.Y. Tang, J.Q. Wang
IHEP, Beijing, People's Republic of China

The C-ADS accelerator is a CW proton linac which accelerates the beam to 1.5GeV. It has the characteristics of being very high beam power and very high reliability that are not posed by any of the existing proton linacs. The accelerator uses two families (β=0.63 and β=0.82 ) of elliptical five cell superconducting cavities. High Order Modes can severely limit the operation of these cavities. Monopole modes are found by Microwave Studio CST. Then the longitudinal instability caused by these monopole modes are primarily investigated with code bbusim, taking into account of effects like High Order Modes frequency spread, beam input jitters and other beam and RF parameters of the beams and cavities. Preliminary simulation results show that monopole modes induced instability is not a problem if High Order Modes frequency spread is not less than 1MHz. However, further investigations are necessary in order to make a critical decision such as whether HOM damper will be adopted. Study on the transverse case is under way.

TUPWA014

The Status of Coupling Impedance Measurement for the CSNS/RCS Extraction Kicker Prototype*

impedance, kicker, coupling, extraction

1754

L. Huang, Y. Li, R.H. Liu, Y.D. Liu, S. Wang, O. Xiao
IHEP, Beijing, People's Republic of China

Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is a high intensity proton accelerator, with average beam power of 100kW. In order to high intensity beam operation, the beam coupling impedance of the extracted kickers must be controlled. Longitudinal and transverse impedance of extracted kicker prototype with power supply had been roughly measured by coaxial-wire and dual-wire methods respectively. At the same time, impedance of window has been analyzed theoretically and simulated based on CST PARTICLE STUDIO.

TUPWA019

Comparison of Tracking Simulation with Experiment on the GSI UNILAC

DTL, emittance, linac, space-charge

1763

X. Yin
IHEP, Beijing, People's Republic of China
W.A. Barth, W.B. Bayer, L. Groening, I. Hofmann, S.G. Richter, S.G. Yaramyshev
GSI, Darmstadt, Germany
A. Franchi
CERN, Geneva, Switzerland
A.C. Sauer
IAP, Frankfurt am Main, Germany

In the European framework “High Intensity Pulsed Proton Injector” (HIPPI), the 3D linac code comparison and benchmarking program with experiment have been initialed. PARMILA and HALODYN are involved in this work. Both of these codes have been developed and used for linac design and beam dynamics studies. In this paper, we compare the simulation results with experiment results which was carried out on the UNILAC Alvarez DTL. And discuss physics aspects of the different linac design and beam dynamics simulation codes.

TUPWA021

Multi-Pass, Multi-Bunch Beam Breakup of ERLs with 9-cell Tesla Cavities

HOM, cavity, betatron, dipole

1769

S. Chen, J.E. Chen, L.W. Feng, S. Huang, Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu
PKU, Beijing, People's Republic of China

Funding: Supported by the Major State Basic Research Development Program of China under Grant No. 2011CB808303 and No. 2011CB808304
In this paper, multi-pass, multi-bunch beam break-up of some small-scale Energy Recovery Linac(ERL) configuration using 9-cell Tesla cavity is discussed. The threshold currents of different cases are investigated and some factors that influence the threshold currents are discussed.

TUPWA022

Beam Dynamics Design of a 325 MHz RFQ

rfq, cavity, emittance, proton

1772

F.J. Jia, J.E. Chen, G. Liu, Y.R. Lu, X.Q. Yan
PKU, Beijing, People's Republic of China
B.Q. Cui, J.H. Li, G.H. Wei
CIAE, Beijing, People's Republic of China

The beam dynamic design of a 325 MHz Radio Frequency Quadrupole (RFQ) is presented in this paper. This 4-vane RFQ will accelerate pulsed proton beam from 30 keV to 3 MeV with repetition frequency of 1 MHz. A 1 MHz chopper and a 5 MHz buncher are arranged in the Low-Energy-Beam-Transport (LEBT) to produce the injected beam. The beam length at the RFQ entrance is about 3 ns, and the energy-spread is about 10%. The code of PARMTEQM is used to simulate RFQ structure. The design should realize high transmission for very high intensity beam meanwhile low emittance growth and relatively short length should be kept.

TUPWA023

Design of the Tuning System for the He⁺ Coupled RFQ-SFRFQ Cavity

cavity, rfq, linac, impedance

1775

W.L. Xia, J.E. Chen, S.L. Gao, Z.Y. Guo, Y.R. Lu, S.X. Peng, Z. Wang, X.Q. Yan, J. Zhao, K. Zhu
PKU, Beijing, People's Republic of China

Funding: Supported by NSFC 10905003, 11079001, 91026012 Corresponding author: wangzhi@pku.edu.cn
The CRS (coupled RFQ-SFRFQ) cavity is a new type linac that couples traditional RFQ (radio frequency quadrupole) and SFRFQ (separated function RFQ) electrodes into a single cavity. The overall design of the CRS cavity has been completed and the linac is being manufactured currently. In this paper, we aimed to design a frequency tuning system for the CRS cavity, which will be used to explore the electromagnetic field distribution between RFQ and SFRFQ sections in the cavity. The frequency range, variation of Q value, power consumption and electric field distribution were investigated. Based on the beam dynamic program SFRFQDYNv1.0, we analysed the beam transmission properties of the cavity under the unbalanced electric field distribution. The optimized parameters of the tuning system were obtained.

TUPWA024

The Beam Gass Coulomb Scattering in Electron Storage Ring

scattering, electron, radiation, synchrotron

1778

X.L. Yu, Z. Bai, W.W. Gao, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Among the various factors which determine the beam life time of the HLSII electron storage ring, the beam loss due to the scattering on residual gas is simulated using MC method. The paper will give the process of elastic and inelastic scattering, and the probability of each scattering is calculated, then using MC sampling to decide which particles will participate in the collision. Tracking the beam with scattering of beam-gas included, the spatial distribution of beam will be obtained. Finally we will give the influence analysis of beam-gas scattering.

TUPWA025

DESIGN STUDIES OF THE C-ADS MAIN LINAC WITH ONLY SPOKE CAVITIES

linac, emittance, proton, space-charge

1781

S.H. Liu, Y. He, Z.J. Wang
IMP, Lanzhou, People's Republic of China

The China ADS(C-ADS) project undertaken by the Chinese Academy of Science is based on superconducting proton linac. The design goal is to accelerate 10mA CW proton beam up to 1.5GeV. The accelerator includes an injector section and a main superconducting linac. Two injectors are under studying by IHEP and IMP respectively. In this paper, an alternative design of the main linac with full spoke cavity base on the beam characteristics from IMP injectorⅡis described. In addition, multi-particle beam dynamics simulations have been performed using TraceWin code to estimate the space charge effect.

TUPWA039

Identification of the SPS Impedance at 1.4 GHz

impedance, optics, resonance, bunching

1793

T. Argyropoulos, T. Bohl, H. Damerau, J. Esteban Müller, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland

In the SPS spectrum measurements of very long single bunches were used in the past to identify sources of longitudinal microwave instability. Shielding of the identified objects significantly improved the beam stability. However, longitudinal instabilities are still one of the limitations for high intensity LHC beams in the SPS. Recently the same measurement technique was used again, revealing a strong high frequency resonance. During the slow de-bunching with the RF switched off, the presence of different resonant impedances leads to a line density modulation at the resonant frequencies. Longitudinal profiles of bunches of various intensities were acquired. For sufficiently high intensities their spectra show a fast growing and strong modulation at 1.4 GHz. Measurements using two transverse optics with different transition energy are compared. Reproducing the measurements with numerical simulations, including the known SPS longitudinal impedances, allowed the parameter range of this unknown source to be determined. Possible candidates as impedance sources in the SPS ring are investigated.

TUPWA040

Loss of Landau Damping for Inductive Impedance in a Double RF System

damping, emittance, synchrotron, impedance

1796

T. Argyropoulos, E.N. Shaposhnikova
CERN, Geneva, Switzerland
A.V. Burov
Fermilab, Batavia, USA

In this paper the thresholds of the loss of Landau damping due to the presence of inductive impedance in a single and double harmonic RF systems are determined, both from calculations and particle simulations. High harmonic RF system, operating in bunch lengthening mode is used in many accelerators with space charge or inductive impedance to reduce the peak line density or stabilize the beam. An analytical approach, based on emerging of the discrete Van Kampen modes, shows that improved stability in a double RF system can be achieved only below some critical value of longitudinal emittance. Above this threshold, a phase shift of more than 15 degrees between the two RF components is proven to stabilize the bunch. These results, confirmed also by particle simulations, are able to explain now observations during the ppbar operation of the SPS. The thresholds in bunch shortening mode as well as in a single RF case are compared with this regime.

TUPWA042

Lessons Learned and Mitigation Measures for the CERN LHC Equipment with RF Fingers

impedance, resonance, vacuum, damping

1802

E. Métral, O. Aberle, R.W. Aßmann, V. Baglin, M.J. Barnes, O.E. Berrig, A. Bertarelli, G. Bregliozzi, S. Calatroni, F. Carra, F. Caspers, H.A. Day, M. Ferro-Luzzi, M.A. Gallilee, C. Garion, M. Garlaschè, A. Grudiev, J.M. Jimenez, O.R. Jones, O. Kononenko, R. Losito, J.L. Nougaret, V. Parma, S. Redaelli, B. Salvant, P.M. Strubin, R. Veness, C. Vollinger, W.J.M. Weterings
CERN, Geneva, Switzerland

Beam-induced RF heating has been observed in several LHC components when the bunch/beam intensity was increased and/or the bunch length reduced. In particular eight bellows, out of the ten double-bellows modules present in the machine in 2011, were found with the spring, which should keep the RF fingers in good electrical contact with the central insert, broken. Following these observations, the designs of all the components of the LHC equipped with RF fingers have been reviewed. The lessons learnt and mitigation measures are presented in this paper.

TUPWA043

Impedance Studies for VMTSA Module of LHC Equipped with RF Fingers

impedance, resonance, factory

1805

O. Kononenko, F. Caspers, A. Grudiev, E. Métral, B. Salvant
CERN, Geneva, Switzerland

During 2011 run of LHC it was found that beam-induced heating causes many issues for accelerator components. Particularly some of the double-bellow modules, called VMTSA modules, were found to have deformed RF fingers and a broken spring which ensured good contact between them and a central insert. Impedance studies have been performed for different types of nonconformities and benchmarked against measurements. It was found that even a small gap between the fingers and a central insert could be fatal for the VMTSA operation. Results of this study were an input for the further thermal analysis.

TUPWA045

Longitudinal Space Charge Effects in the CLIC Drive Beam

space-charge, quadrupole, lattice, luminosity

1811

R.L. Lillestøl, S. Döbert, A. Latina, D. Schulte
CERN, Geneva, Switzerland
E. Adli, K.N. Sjobak
University of Oslo, Oslo, Norway

The CLIC main beam is accelerated by rf power generated from a high-intensity, low-energy electron drive beam. The accelerating fields are produced in Power Extraction and Transfer Structures, and are strongly dependent on the drive beam bunch distribution, as well as other parameters. We investigate how longitudinal space charge affects the bunch distribution and the corresponding power production, and discuss how the bunch length evolution can affect the main beam. We also describe the development of a Particle-in-Cell space charge solver which was used for the study.

TUPWA046

Experimental Results from the Test Beam Line in the CLIC Test Facility 3

emittance, quadrupole, lattice, extraction

1814

R.L. Lillestøl, S. Döbert, M. Olvegård
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway

In the CLIC two-beam scheme, the main beam is accelerated by rf power provided by energy extraction from a secondary drive beam. This energy is extracted in decelerators, and the first prototype decelerator is the Test Beam Line in the CLIC Test Facility 3. The line is currently equipped with 12 Power Extraction and Transfer Structures (PETS), which allows for extracting up to 40% of the beam energy. We correlate the measured deceleration with predictions from the beam current and the rf power produced in the PETS. We also discuss recent bunch length measurements and how it influences the deceleration. Finally we look at the evolution of the transverse emittance.

TUPWA047

Collimator Impedance Measurements in the LHC

impedance, optics, proton, collimation

1817

N. Mounet, R. Bruce, E. Métral, S. Redaelli, B. Salvachua, B. Salvant, G. Valentino
CERN, Geneva, Switzerland

The collimation system of the LHC is one of the largest impedance contributors of the machine, in particular for its imaginary part. To evaluate the collimator impedance and its evolution with integrated luminosity, several measurement campaigns were performed along the year 2012, in which collimator jaws were moved back-and-forth leading to significant tune shifts for a nominal intensity bunch in the machine. These observations are compared to the results from HEADTAIL simulations with the impedance model in its current state of development.

TUPWA052

Loss Factor and Impedance Analysis for the Diamond Storage Ring

impedance, storage-ring, vacuum, wiggler

1826

R. Bartolini, R.T. Fielder, C.A. Thomas
Diamond, Oxfordshire, United Kingdom

Diamond Light Source is investigating the possibility of increasing the storage ring operating current above the nominal 300 mA. A campaign of measurements and simulations has been carried out in order to understand the extent of the parasitic energy loss and characterise the most important items which build up the machine impedance. In this paper we report on the most recent measurements of the longitudinal loss factor and the present status of the impedance database with an initial comparison between the two.

TUPWA054

PXIE End-to-end Simulations

rfq, cryomodule, solenoid, emittance

1829

J.-F. Ostiguy, J.-P. Carneiro, V.A. Lebedev, A. Saini, N. Solyak
Fermilab, Batavia, USA

Funding: US DOE contract DE-AC02-76CH03000.
Construction of PXIE, (Project-X Injector Experiment) has recently begun. The goal is to validate the design of the injector and low energy acceleration front-end for a future Project-X. PXIE operates in CW mode and consists in an ion source, a magnetically focused LEBT, a 162.5 MHz RFQ, a MEBT equipped with high bandwidth traveling wave kickers, a cryomodule equipped with 162.5 MHz half-wave resonators and a single cryomodule based on 325 MHz spoke resonators. The arrangement is meant to be closely representative of a future Project-X front end, and will include a variety of diagnostics. In this contribution we present detailed end-to-end tracking simulations. In particular, we examine possible impact of the RFQ longitudinal distribution, neutralization effects in the LEBT as well as of various imperfections in the MEBT on losses in the first superconducting cavities.

TUPWA058

Experimental Study of Soliton Wave Trains in Intense Electron Beams

electron, space-charge, laser, induction

1835

Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Longitudinal perturbations in intense beams can lead to instabilities or degradation of beam quality, ultimately affecting the performance of accelerators, especially near the source where space charge is important. In this experimental study, conducted on the University of Maryland Electron Ring (UMER), large-amplitude perturbations are purposefully generated and their propagation observed over a long transport length. It is found that narrow, large-amplitude perturbations on a long-pulse beam develop into Korteweg-deVries (KdV) type soliton wave trains. Each peak in the wave train has a constant width and amplitude over a long propagation distance, with the amplitude inversely proportional to the square of the width. Furthermore, two such pulses are seen to interact with each other and emerge from the collision unchanged. The experimental data is compared with the KdV model and particle-in-cell simulations with good agreement. We induce perturbations using two methods: using photoemission to perturb the density at the cathode, or using an induction cell to directly perturb particle velocities.

TUPWA059

End-to-end Beam Simulations for the C-ADS Injector II

proton, linac, rfq, diagnostics

1838

X. Wu, E. Tanke, Q. Zhao
FRIB, East Lansing, Michigan, USA
Y. He, H. Jia, Z.J. Wang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

The Injector II for the proposed Chinese Accelerator Driven System (C-ADS) is designed to accelerate proton beam to ~ 10 MeV with beam current up to ~ 10 mA. The accelerator system will include a proton ECR ion source, a Low Energy Beam Transport System (LEBT), a room-temperature radio frequency quadrupole (RFQ), a Medium Energy Beam Transport System (MEBT), a Superconducting (SC) linac and a High Energy Beam Transport System (HEBT). Both RFQ and the SC linac will have a base frequency of 162.5 MHz. The accelerating cryomodules in the SC linac uses SC half-wave cavities for acceleration and SC solenoids with dipole correctors for transverse focusing and central orbit correction. End-to-end beam simulations starting with a realistic initial input beam from the ECR ion source were performed using DYNAC and IMPACT codes to evaluate the C-ADS Injector II accelerator system performance, code benchmarking with TRACK and explore system design options for future optimizations. The results of these beam dynamics studies will be presented in the paper.

TUPWA061

Observation at CesrTA of the Reduction of the Vertical Beam Size of the Lead Bunch in a Train Due to the Presence of a Precursor Bunch

electron, positron, dipole, feedback

1841

M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, R.E. Meller, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams
CLASSE, Ithaca, New York, USA
J.W. Flanagan
KEK, Ibaraki, Japan
R. Holtzapple, M. Randazzo
CalPoly, San Luis Obispo, California, USA
M.A. Palmer
Fermilab, Batavia, USA

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467.
Electron cloud-induced beam dynamics is being studied at CesrTA under various conditions. These measurements make use of instrumentation for the detection of the coherent self-excited spectrum for each bunch within the train and bunch-by-bunch vertical beam size. In the position spectrum coherent betatron dipole and head-tail motion is detectable for each individual bunch within the train. These techniques are utilized to study the electron cloud-related interactions, which cause the growth of coherent motion and beam size along the train. We report on the observations of the vertical enlargement of the first bunch(es) in 30 bunch-long trains. We also report that the addition of a precursor bunch following the train of bunches and before the start of the next train can counteract the vertical enlargement of the first bunch(es) in the train. Results from these observations will be presented.

TUPWA066

Space Charge Neutralization of Low Energy H⁻ Beam

emittance, space-charge, ion, ion-source

1856

Y.K. Batygin, I.N. Draganić, C.M. Fortgang, G. Rouleau
LANL, Los Alamos, New Mexico, USA

LANSCE Ion Source Test Stand is used for systematic study of H⁻ source performance and details of low energy beam transport. It includes cesiated, multicusp-field, surface production H⁻ ion source, focusing solenoids, slit-collector emittance stations, 4.5o bending magnet, and electrostatic deflector. Series of experiments were performed to measure space charge neutralization of low energy H⁻ beam. Measurements were done for 80 keV and 35 keV H⁻ beams at various pressure of residual gas. Results of measurements are compared with results of beam dynamics simulations to determine level of space charge neutralization. Applicability of theoretical models of beam neutralization is discussed.

TUPWA068

Model Independent Beam Tuning

quadrupole, linac, beam-transport, drift-tube-linac

1862

A. Scheinker
LANL, Los Alamos, New Mexico, USA

This work presents a new model independent feedback control scheme for optimization and tuning of particle accelerator components, with a simulation demonstrating the method on a low energy, space-charge dominated beam. The scheme presented here does not depend on an accurate model of the system it is stabilizing, and may even be unaware of its control input direction (such as having rotated quadrupole magnets and alignment errors) and this direction may change with time (thermal cycling and hysteresis). Stability properties are demonstrated both analytically and through a simulation in which the current settings of twenty two quadrupole magnets are simultaneously tuned through the transport section of the Los Alamos Linear Proton Accelerator. The controller is unaware of the complex nonlinear beam dynamics, with its only input being the surviving beam current readings along the transport region. Starting with all magnet settings at zero, in which case all of the beam is lost by the end of the transport, the feedback control tunes the magnets resulting in successful transport to the first drift tube linac section.

TUPWA074

Studies of Ion Beam Instabilities for Low Energy RHIC Operations with Electron Cooling

ion, electron, impedance, emittance

1871

G. Wang, M. Blaskiewicz, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron cooling has the potential to compensate the emittance growth of the circulating ion beam due to intra-beam scattering at low energy. A test of electron cooling for RHIC low energy operations has been planned at IP2. Apart from the wakefield from the environment, the coherent interaction between the electron beam and ion beam could also play a role for the instability threshold. This work presents studies of ion beam stabilities in presence of coherent electron-ion interactions for the planned low energy RHIC electron-cooling test using the simulation code TRANFT.

TUPWO007

Investigation of the Magnetic Chicane of the New Short-Pulse Facility at the DELTA Storage Ring

undulator, laser, electron, klystron

1889

R. Molo, J.A. Grewe, H. Huck, M. Huck, M. Höner, S. Khan, A. Schick, P. Ungelenk
DELTA, Dortmund, Germany

Funding: Supported by DFG, BMBF, and the Federal State NRW.
The new short-pulse facility at DELTA (a 1.5-GeV synchrotron light source) based on coherent harmonic generation (CHG) utilizes an electromagnetic undulator which can be configured as optical klystron (undulator – chicane – undulator). To optimize the CHG signal, the energy modulation of the electrons in the first undulator and the dispersion of the magnetic chicane (i.e. the R56 matrix element) have to be optimized. Since the R56 value of the present chicane is not sufficient, it is planned to rewire the magnetic coils to create a more efficient chicane. Simulations of the present chicane will be compared to measurements of the R56 matrix element and a new chicane configuration will be presented which increases the R56 value by a factor of ten.

TUPWO008

High-Current Beam Transport Simulations Including Gabor Lenses in Varying Non-Neutral Plasma States

electron, focusing, plasma, space-charge

1892

M. Droba, H. Dinter, O. Meusel, D. Noll, U. Ratzinger, K. Schulte
IAP, Frankfurt am Main, Germany

The Gabor space charge lens has theoretically and experimentally been investigated at IAP for many years. Especially the application in high current, Low Energy Beam Transport (LEBT) sections seems efficient and attractive. The focusing properties and imaging quality of this lens type depend on the transverse and longitudinal confinement of the electron column. Different non-neutral plasma states have been observed and calculated. In general, they can be disturbed by the interaction with ion beams. This results in a shift and in a modification of the work function with a rise of aberrations and beam emittance growth. It is necessary to understand such processes for transport channels using intense ion beams to preserve the high beam brilliance. The beam transport simulations including Gabor lenses in various non-neutral plasma states will be presented and compared with experimental results.

TUPWO010

Optimal Twiss Parameters for Emittance Measurement in Periodic Transport Channels

emittance, betatron, beam-transport, focusing

1898

N. Golubeva, V. Balandin, W. Decking
DESY, Hamburg, Germany

From the point of view of the optimality criteria introduced in *, we study in this paper the procedure of emittance measurement in periodic beam transport channels.
* V.Balandin, W.Decking, N.Golubeva. “Invariant Criteria for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections”, These Proceedings.

TUPWO011

Invariant Criterion for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections

emittance, betatron, coupling, optics

1901

V. Balandin, W. Decking, N. Golubeva
DESY, Hamburg, Germany

By studying errors in the reconstructed beam parameters as functions of the errors in the beam size measurements, we introduce an optimality criteria which can be used for the design and comparison of multiple beam profile emittance and Twiss parameters measurement sections and which is independent from the position of the reconstruction point.

TUPWO016

Beam Dynamics Design of 3 MeV Medium Energy Beam Transport for Beam Intensity Upgrade of J-PARC Linac

emittance, DTL, cavity, linac

1916

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The J-PARC linac has a plan to upgrade its beam power in the summer 2013. This plan includes the replacement of the front-end components (ion source and 3 MeV RFQ) to increase the peak current from present 30 mA to 50 mA. Since it results in the different injection beam profile to medium energy beam transport (MEBT), which locates the RFQ downstream, we designed the beam dynamics of MEBT. In this presentation, we disscuss the new design of beam dynamics in MEBT.

TUPWO017

Simulation on the Breaking of αx Multiknob Orthogonality in the Presence of Gradient and Coupling Errors and Experimental Investigation

coupling, quadrupole, sextupole, linear-collider

1919

S. Bai, J. Gao
IHEP, Beijing, People's Republic of China
P. Bambade
LAL, Orsay, France
G.R. White
SLAC, Menlo Park, California, USA

The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam can break the orthogonality in the main σ34 and σ32 waist corrections required to reduce the vertical beam size at IP. Concerning the method of doing αx scan and measuring the vertical beam size to diagnose the IPBSM fringe tilt or residual σ13, one thing should be studied is to check what could break the orthogonality of the αx knob other than σ13 and the IPBSM fringe tilt. In this paper, we report on the simulation study that check for the breaking of orthogonality of the αx knob in the presence of gradient and coupling errors; to what extent this breaking of orthogonality can go; and also calculate the IPBSM fringe tilt angle from experiment results.

TUPWO023

Parasitic Slow Exraction of Extremely Weak Beam From a High-intensity Proton Rapid Cycling Synchroton

scattering, extraction, proton, synchrotron

1931

Y. Zou, H.T. Jing, C. Meng, J.Y. Tang, Z. Yang
IHEP, Beijing, People's Republic of China

This paper proposes a new method to extract extremely weak beam from a high-intensity proton rapid cycling synchrotron in the parasitic mode, while maintaining the normal fast extraction. The usual slow extraction from a synchrotron by third-order resonance method cannot be applied in a RCS due to very short flat-top at the extraction energy. This is even more difficult when it is high-intensity synchrotron due to the strict control on beam loss. The parasitic slow extraction method to extract extremely weak beam from the RCS of CSNS has been studied in details. By moving only beam halo to a scatting foil in the arc region by a local orbit bump in about 2 ms before the fast extraction, one can extract a very small part of the scattered particles with very limited beam loss in the process. At 1.6 GeV and 62.5 A in beam power, halo particles of about 10^-4 total particles are involved in the parasitic slow extraction can result in a beam intensity of 2105 protons per cycle or lower. Detailed studies including scattering effect in the foil, orbit bumps by bump magnets and energy displacement by adjusting RF, and multi-particle simulations by ORBIT and TURTLE codes are presented.

TUPWO030

Beam-based Alignment Simulation on Flash-I Undulator

undulator, quadrupole, alignment, electron

1940

D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China
M. Vogt, N.J. Walker
DESY, Hamburg, Germany

In order to ensure the SASE process can take place in the whole FLASH-I undulator section, a straight beam trajectory is mandatory which can only be achieved through beam-based alignment (BBA) method based on electron energy variations. In this paper, a detailed result of simulation is presented which demonstrate that the alignment can be achieved within accuracy of a few 10 μm after several iterations. The influence of Quadrupole and BPM offsets, magnet-mover calibration errors, quadrupole gradient errors are also discussed.

TUPWO038

Start-to-end Simulations for Heavy-ion Accelerator of RISP

linac, rfq, emittance, proton

1958

E.-S. Kim, S.W. Jang
KNU, Deagu, Republic of Korea
J. Bahng, J.G. Hwang
Kyungpook National University, Daegu, Republic of Korea
B. Choi, D. Jeon, H.J. Kim, H.J. Kim
IBS, Daejeon, Republic of Korea

RAON has been designed as a facility for rare isotope accelerator at Korea. The aceelerator consists of 28 GHz superconducting ion source, LEBT, RFQ, MEBT, superconducting linac and HEBT. The linac accelerates ion beams to 200 MeV/u with a beam power of 400 kW. Start-to-End simulations are performed from ECR-IS to HEBT and the detailed beam simulation results are presented. The beam dynamics issues are also discussed.

TUPWO046

The ESS Linac Simulator: A First Benchmark with TraceWin

space-charge, linac, cavity, multipole

1970

E. Laface, M. Eshraqi, R. Miyamoto
ESS, Lund, Sweden

The ESS Linac Simulator, ELS, will be the core of the online model used in the normal operations of the ESS linac. ESS Linac Simulator will operate through the eXtensible Accelerator Language, XAL, in order to provide an effective interface capable to simulate and predict the beam dynamics of the accelerator. The ELS is capable of simulating the dynamics of the beam envelope in both transverse and longitudinal planes in real time. In order to validate the effectiveness of the physics implemented, the ELS calculations are here benchmarked with TraceWin: the simulation code used for the design of the accelerator.

TUPWO048

Understanding the Tune, Coupling, and Chromaticity Dependence of the LHC on Landau Octupole Powering

closed-orbit, octupole, coupling, alignment

1976

E.H. Maclean, M. Giovannozzi, W. Herr, Y.I. Levinsen, G. Papotti, T. Persson, P.K. Skowroński, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland

During the 2012 LHC run there were several observations of unexpectedly large shifts to the tune, chromaticity, and coupling which were correlated with changes in the powering of Landau octupoles (MO). Understanding the chromaticity dependence is of particular importance given it's influence on instabilities. This paper summarizes the observations and our attempts to-date to understand the relationship between Q, Q', c- and the MO powering.

TUPWO054

Recent Results from the EMMA Experiment

acceleration, betatron, synchrotron, closed-orbit

1988

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Appleby, J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
J.S. Berg, F. Méot
BNL, Upton, Long Island, New York, USA
C.S. Edmonds, J.K. Jones, I.W. Kirkman, B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.S. Edmonds, I.W. Kirkman, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After a recent demonstration of acceleration in the serpentine channel, the injected EMMA beam was further studied. This entails the continuation of the exploration of the large transverse and longitudinal acceptance and the effects of slower integer tune crossing on the betatron amplitude. A single closed orbit correction that is effective at multiple momenta (and hence over a significant range in tune space) was implemented. A comparison with a detailed model based on measured field maps, and the experimental mapping of the machine by relating the initial and final phase space coordinates was also done. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.

TUPWO056

Modelling of the EMMA ns-FFAG Ring using GPT

space-charge, electron, injection, closed-orbit

1994

R.T.P. D'Arcy
UCL, London, United Kingdom
J.K. Jones, B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE serves as an injector for the EMMA ring, within an effective energy range of 10 to 20 MeV. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Acceleration over many turns of the EMMA machine has recently been confirmed. In some cases the bunch will traverse upwards of 100 turns, at which point the effects of space-charge may be significant. It is therefore necessary to model the electron beam transport in the ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modelled for comparison with experimental results and those of other codes. The simulated effects of space-charge on the tune shift of the machine are also compared with those expected from theory.

TUPWO059

Reducing Emittance of a H⁻ Beam in a Solenoid-based Low-energy Beam Transport through Numerical Modeling

solenoid, emittance, rfq, electron

2000

J. von Stecher, D.L. Bruhwiler, B.T. Schwartz, S.A. Veitzer
Tech-X, Boulder, Colorado, USA
B. Han, M.P. Stockli
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844
A solenoid-based low-energy beam transport (LEBT) subsystem is under development for the H⁻ linac front end of the Spallation Neutron Source. The LEBT design includes MHz frequency chopping of the partially neutralized H⁻ beam that can potentially lead to beam instabilities. We report results of numerical modeling using the parallel Vorpal framework for 3D electrostatic particle-in-cell (PIC) to simulate H⁻ beam dynamics in the LEBT, over multiple chopping events. We detail how the addition of a positively biased potential barrier near the entrance of the chopper can improve LEBT performance by eliminating chopper-induced emittance increases over many chopping events.
DLB is now at University of Colorado, Boulder

TUPWO060

Flat Electron Bunch Compression at the Advanced Superconducting Test Accelerator

emittance, quadrupole, cathode, solenoid

2003

C.R. Prokop, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
B.E. Carlsten
LANL, Los Alamos, New Mexico, USA
P. Piot, Y.-E. Sun
Fermilab, Batavia, USA

Funding: This work is supported by LANL LDRD #20110067DR and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
The generation of flat beam using round-to-flat beam conversion of an incoming canonical-angular-momentum dominated electron beam could have important application in the field of advanced acceleration techniques and accelerator-based light source. In this paper we explore the temporal compression of flat beams and especially compare the resulting phase space dilutions with the case of round beam. Finally, we propose and detail a possible experiment to investigate the flat-beam bunch compression at the Advanced Superconducting Test Accelerator currently in construction at Fermilab.

TUPWO064

Online Optimization Algorithms for Accelerators and Experimental Results

injection, coupling, optics, quadrupole

2012

X. Huang, W.J. Corbett, J.A. Safranek, J. Wu
SLAC, Menlo Park, California, USA

Online optimization of accelerators is becoming increasingly more important as accelerator systems become more and more complex. Online accelerator optimization is generally a multi-variant nonlinear problem with considerable noise. Efficiency and robustness are critical for online applications. Therefore optimization algorithms require special considerations. In this study we evaluate the viability of several online optimization algorithms for both ring and linac machines. Numerical simulations and experimental tests are presented to investigate performance of the algorithms.

TUPWO065

Anomalously Long Bunches from the SLAC North Damping Ring

electron, linac, klystron, damping

2015

G. Yocky, F.-J. Decker, N. Lipkowitz, U. Wienands, M. Woodley
SLAC, Menlo Park, California, USA

The SLC damping ring provides emittance reduced beam to the beginning of the FACET accelerator. In measurements conducted during the 2012 FACET run, we find the bunch-length to be ~20% longer than canonical. A study is performed with longitudinal simulation code to determine the impact on the various stages of compression for FACET experimental running.

TUPWO067

Start-to-end Particle Tracking of the FACET Accelerator

emittance, linac, klystron, wakefield

2018

N. Lipkowitz, F.-J. Decker, G.R. White, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE-AC02-76SF00515.
The Facility for Advanced aCcelerator Experimental Tests (FACET) consists of the first two-thirds of the SLAC two-mile linac followed by a final focus and experimental end station. To date, wakefield-dominated emittance growth and dispersion in the linac, as well as dispersive and chromatic effects in the final focus have precluded regular reliable operation that meets the design parameters for final spot size. In this work, a 6-D particle tracking code (Lucretia) is used to simulate the complete machine, with input parameters taken directly from saved machine configurations. Sensitivities of various tuning parameters to the final spot sizes are compared with measurements taken from the real machine, and a set of tuning protocols is determined to improve regular machine operation.

TUPWO069

Optimization of FACET Optics

sextupole, optics, lattice, chromatic-effects

2024

M.-H. Wang, F.-J. Decker, N. Lipkowitz, Y. Nosochkov, G.R. White, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: supported by the US Department of Energy contract DE-AC02-76SF00515.
The FACET accelerator facility is designed to provide short and intense e^- or e⁺ bunches with small spot size for plasma wakefield accelerator research and other experiments. It is based on the SLAC linac with a compressor chicane in sector-10, and a second compressor chicane and final focus in sector-20 (S20). Originally, the S20 chicane was designed to be compatible with an upgrade to include a second S20 chicane for simultaneous transport of e^- and e⁺ bunches. This placed additional optics constraints which lead to strong focusing in the S20 chicane. The latter increases the effects of errors causing emittance growth. Lately, it has been decided not to proceed with the upgrade option. Therefore, there is a potential for improving the optics by relaxing the constraints. In this study, we explore alternative optics designs where beta functions in the S20 chicane and final focus are reduced in order to minimize the error effects. The optics and non-linear aberrations are evaluated, and the chromatic correction is optimized for each design. Beam tracking simulations are performed using Elegant and Lucretia. The most optimal designs are identified based on these simulations.

TUPWO074

Reducing Spin Tune Spread by Matching DX Prime at Snakes in RHIC

quadrupole, proton, power-supply, polarization

2030

C. Liu, M. Bai, E.D. Courant, A. Marusic, M.G. Minty, V.H. Ranjbar, S. Tepikian, R.A. Thomas, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
At the Relativistic Heavy Ion Collider (RHIC) at BNL the physics program includes collisions between beams of polarized protons at high beam energies. Maintaining the proton's polarization is vital and preserved primarily by application of a pair of Siberian snakes. Measurements from recent high-energy physics runs indicate polarization loss during acceleration between 100 and 250 GeV. Based on analytic estimations for off-momentum particles and/or beams, a nonzero difference in DX prime - the dispersion function angle - between the snakes can result in a shift in the spin tune, or equivalently, of the conditions of snake resonances in close proximity to the beam during acceleration. Requiring that DX prime at the two Siberian snakes in RHIC being equal would reduce the spin tune shift for off-energy particles so helping to maintain polarization during the energy ramp. Preservation of half-integer spin tune is also important for future operation of the spin flipper at store. In this report, the matching scheme and simulations using MAD-X will be presented together with a newly applied method based on response matrices.

WEOAB101

Single Particle Tracking for Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring

cavity, HOM, synchrotron, optics

2038

M. Ruprecht, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
T. Weis
DELTA, Dortmund, Germany

A scheme where 1.5 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed (BESSY^VSR*). This paper presents simulations of single particle beam dynamics influenced by superconducting cavities used for the strong longitudinal beam focusing. The effect of RF jitter on (very short) bunches is investigated and results are discussed. Furthermore, possible effects on beam dynamics during ramp up and ramp down of the high gradient fields in the cavities are studied. The primary goal is to reveal preliminary design specifications for RF jitter on the basis of single particle dynamics.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain

Slides WEOAB101 [3.955 MB]

WEOAB103

Experimental Observations of a Multi-stream Instability in a Long Intense Beam

electron, space-charge, factory, background

2044

B.L. Beaudoin, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
We have observed evidence of a multi-stream instability in a long non-relativistic space-charge dominated beam evolving with an initial non-linear distribution and zero external longitudinal containment. This type of instability can be detrimental to intense accelerators that propagate rectangular distributions, such as in a ring with single or multi-bunch injection. The longitudinal forces in these intense bunches causes the beam to expand axially; in the case of the University of Maryland Electron Ring (UMER), the initial long bunch is injected to fill a fraction of the ring, coasting beyond the point where the head and tail overlap. Adjacent filaments at that point are separated in velocity space by 2cs and approach a separation of cs. The onset of the instability has been observed to depend on the injected beam current, bunch length, and other experimental factors. Comparisons with simple analytical calculations and PIC simulations have shown good agreement in the time to onset.

Slides WEOAB103 [1.681 MB]

WEPWA008

Simulating the Bunch Structure in the THz Source FLUTE

space-charge, laser, linac, dipole

2141

S. Naknaimueang, E. Huttel, S. Marsching, A.-S. Müller, M.J. Nasse, R. Rossmanith, M. Schreck, M. Schuh, M. Schwarz, M. Weber, P. Wesolowski
KIT, Karlsruhe, Germany
M.T. Schmelling
MPI-K, Heidelberg, Germany

FLUTE is a planned THz source at KIT operating at a beam energy of 40 to 50 MeV in a wide bunch charge range. It consists of a laser driven rf-gun, a linac and a magnetic bunch compressor. The high current density combined with relatively low energy of FLUTE leads to complex strong self-field and beam-radiation field interactions, which are the limiting factors for the bunch compression efficiency. The results of numerical studies are presented in this paper.

WEPWA009

RF Bunch Compression Studies for FLUTE

linac, cavity, gun, space-charge

2144

M. Schuh, E. Huttel, S. Marsching, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schwarz, M. Weber, P. Wesolowski
KIT, Karlsruhe, Germany
R.W. Aßmann, K. Flöttmann, H. Schlarb
DESY, Hamburg, Germany

FLUTE is a planned 40 to 50 MeV accelerator test facility consisting, in the first phase, of an electron gun with an output energy of about 7 MeV, a traveling wave linac and a magnet chicane bunch compressor. The machine will serve as a source of intense THz radiation using coherent synchrotron radiation (CSR), coherent transition radiation (CTR), and coherent edge radiation (CER) as generation mechanisms. It is planned to operate the machine in the charge regime from a few pC up to several nC in order to study bunch compression schemes as well as the THz radiation generation. In this contribution the effect of velocity bunching by using a dedicated buncher cavity at low energy and operating the linac off-crest is studied in order to deliver RMS bunch lengths in the femtosecond range at low charge.

WEPWA021

X-ray Spectra Reconstruction with HOPG Crystal on TTX

photon, scattering, electron, laser

2174

Z. Zhang, Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, D. Wang, L.X. Yan
TUB, Beijing, People's Republic of China

Thomson Scattering sources, as the new generation of bright X-ray sources, have great application potential in many respects. Traditional spectra measurement methods, applied to measured the spectra of Thomson Scattering source, are troublesome as the X-ray beam is too intense to cause pile up problems. In this article, we use the HOPG crystal to reconstruct the X-ray spectra of Tsinghua Thomson X-ray source (TTX) through Braggs law. This method can get reasonable results with single or several shots, with high energy resolution. We also compare the experiment results of this method with the reconstructed spectra by analyzing the attenuation data of the X-ray beam in silicon , and these two results agree well with each other.

WEPWA026

Mechanical Design of Shift Driving System for DEPU at SSRF

polarization, controls, undulator

2187

R.B. Deng, W.L. Chen, H.W. Du, Z.B. Yan, M. Zhang
SINAP, Shanghai, People's Republic of China

Double elliptically polarized undulator (DEPU) for a soft X-ray beamline for ARPES and PEEM is being built at SSRF. In DEPU, two EPUs with different period lengths have the roughly same magnet array lengths and share a common H style frame. The shift driving systems for polarization adjustment, which are set on top of the backing beams for the constraint of space, are sophisticated designed to assure position stability under longitudinal magnet force change. Finite-element analyses are also performed to guarantee the rigidity of the systems. The system performance is tested under full operation range and the results are described in this paper.

WEPWA030

Using the Power Spectral Density Method to Characterize and Evaluate the X-ray Mirrors Surfaces

synchrotron, focusing, optics, brilliance

2196

W.Q. Hua, F.G. Bian, Y.M. He, W.H. Lin, L. Song, J. Wang, N. Zhao
SINAP, Shanghai, People's Republic of China

Rapid progress in synchrotron X-ray beams’ coherence and X-ray optics performance places a high demand on characterization and evaluation of optical surface figure and slope errors and roughness on meter-long optics over spatial frequencies as short as 0.1mm. In this paper, the propagation model of hard X-ray beams through reflecting mirror surface is proposed based on wave-front propagation, and numerical simulations are performed for predicting the hard X-ray focusing performance of different imperfect mirrors using a Fresnel diffraction calculation. The imperfect mirror surface height maps synthesized from power spectral functions are used to analyze and evaluate the influences of different mirror surface errors on the reflected hard X-ray beam properties.

WEPWA037

Effect of Ground Vibration on the Out-coupled Power in a Terahertz FEL Oscillator

FEL, cavity, alignment, laser

2211

Q. Fu, L.Z. Deng, B. Qin, P. Tan, Y.Q. Xiong, Y.B. Yibin, H. Zeng
HUST, Wuhan, People's Republic of China

To acquire high power out-coupled, we must ensure the co-axis of electron orbit, optical beam and magnetic field. The propagation of ground vibration through the optical platform will lead to misalignment of the optical axis in the FEL optical cavity. Based on measurement results of the ground vibration, simulations of misalignment are studied with GENESIS+OPC. The tolerance of mirror tilt and offset is also discussed.

WEPWA038

Influence of Magnet Errors and Waveguide Permeability on Magnetic Field Performance in Pure Permanent Undulators

undulator, FEL, permanent-magnet, radiation

2214

X. Liu, K.F. Liu, B. Qin, P. Tan, B. Wu, Y.Q. Xiong, J. Yang, L. Yang
HUST, Wuhan, People's Republic of China

Abstract For pure permanent magnet (PM) undulator, unavoidable divergences of remanence field and magnetization vector in PM blocks and installation error will cause magnetic field error at the central line of the undulator. This paper presents the simulation results of the magnetic field in non-ideal undulator containing these errors, with specified tolerances in Normal distribution. As well as the peak field error, increases of the harmonic components and impact on field integrals are calculated. The influence on magnetic field caused by waveguide permeability is also discussed.

WEPWA044

Electron Trajectories in a Three-dimensional Undulator Magnetic Field

undulator, electron, focusing, radiation

2223

N.V. Smolyakov, S.I. Tomin
NRC, Moscow, Russia
G. Geloni
XFEL. EU, Hamburg, Germany

In this contribution we present an analysis of electron trajectories in the three dimensional magnetic field from a planar undulator. The electron trajectory is influenced by the focusing properties of the undulator field. In the European XFEL case, long segmented undulators (21 segments for the SASE3 beamline to 35 for SASE1 and SASE2) are planned to be installed, with quadrupole lenses between different segments. These focusing properties should be taken into account in simulations of spontaneous radiation, which constitutes the background signal of the FEL. The ideal magnetic field of an undulator can be described by a sinusoidal vertical magnetic field on the undulator axis, and by horizontal and longitudinal field components that appear out of axis. Exploiting this description for the ideal case, an experimentally measured magnetic field is accounted for by solving the differential equations of motion. The electrons' trajectories for the experimentally measured magnetic field were also simulated numerically. To that aim, a computer code was written, which relies on the Runge-Kutta algorithm. The analytical and numerical methods show a good agreement.

WEPWA047

Longitudinal Stability of Multiturn ERL with Split Accelerating Structure

linac, electron, cavity, resonance

2226

Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
T. Atkinson
HZB, Berlin, Germany
N. Vinokurov
KAERI, Daejon, Republic of Korea

Some modern projects of the new generation light sources use the conception of multipass energy recovery linac with split (CEBAF-like) accelerating structures. One of the advantages of these light sources is the possibility to obtain a small longitudinal beam size. To help reduce it, the longitudinal dispersion should be non-zero in some arcs of the accelerator. However small deviations in voltages of the accelerating structures can be enhanced by induced fields from circulating bunches due to the dependence of the flight time on the energy spread and the high quality factor of the superconducting radio-frequency cavities. Therefore, instabilities related with interactions of the electron bunches and longitudinal modes of the cavities can develop in the installation. Stability conditions for the interactions with fundamental accelerating mode of the split accelerating system are discussed. Numerical simulations are made for two projects - MARS and FSF.

WEPWA049

Top-up Safety Simulations for the ALBA Storage Ring

dipole, quadrupole, sextupole, storage-ring

2229

G. Benedetti
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

The potential hazards introduced by injecting into the ALBA storage ring with front end shutters open are determined through particle tracking simulations. The method is based on the possible overlap between phase space of forwards and backwards tracking between the straight section downstream the front end and the beamline. Realistic magnetic field, trajectory, aperture and energy errors are taken into account. Scenarios that could bring an injected beam of electrons passing through an open beamline front end are identified. The interlocks required to prevent such situations from arising are stated.

WEPWA064

Simulations of the ALICE ERL

FEL, linac, electron, space-charge

2265

J.K. Jones, D.J. Dunning, F. Jackson, J.W. McKenzie, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

ALICE is a low-energy Energy Recovery Linac operated at Daresbury Laboratory in Cheshire, UK. The ALICE injector is based around a 350 kV DC photo-cathode electron gun. With an operating voltage of 325 keV, electron dynamics in the ALICE injector are space-charge dominated and highly non-linear, and this complicates simulations of the beam dynamics in this region. With an intermediate energy of 6.5 MeV, and a final ring energy of 27.5 MeV, the space-charge effects in the rest of the machine can also not be ignored. In this paper we summarise some of the work that has been performed to understand and optimise the simulations of the ALICE ERL, in several different operating modes, and using several different modelling codes.

WEPWA081

Status of the Praseodymium Undulator with Textured Dysprosium Poles for Compact X-Ray FEL Applications

undulator, cryogenics, vacuum, radiation

2298

F.H. O'Shea, R.B. Agustsson, Y.C. Chen, T.J. Grandsaert, A.Y. Murokh, K.E. Woods
RadiaBeam, Santa Monica, USA
J. Park, R.L. Stillwell
NHMFL, Tallahassee, Florida, USA
V. Solovyov
BNL, Upton, Long Island, New York, USA

The demand for high-brightness hard x-ray fluxes from next generation light sources has spurred the development of insertion devices with shorter periods and higher fields than is feasible with conventional materials and designs. RadiaBeam Technologies is currently developing a novel high peak field, ultrashort period undulator with praseodymium-iron-boron (PrFeB) permanent magnets and textured dysprosium (Tx Dy) ferromagnetic field concentrators. This device will offer an unparalleled solution for compact x-ray light sources, as well as for demanding applications at conventional synchrotron radiation sources. A 1.4T on-axis field has already been achieved in a 9mm period undulator, demonstrating the feasibility of using Tx Dy poles in a hybrid undulator configuration with PrFeB magnets. Facets of the undulator design, optimization of the Tx Dy production and characterization process, and magnetic measurements of Tx Dy will be presented.

WEPWO004

Studies of Systematic Flux Expulsion in Superconducting Niobium

niobium, cavity, lattice, controls

2316

J.M. Vogt, J. Knobloch, O. Kugeler
HZB, Berlin, Germany

The quality factor Q0 that can be obtained in a superconducting cavity is known to depend on various factors like niobium material properties, treatment history and magnetic shielding. We believe that cooling conditions have an additional impact, as they appear to influence the amount of trapped flux and hence the residual resistance. We have constructed a test stand using niobium rods to study flux trapping. Here we can precisely control the temperature and approach Tc from below in the superconducting state. Although the sample remains in the superconducting state, a change in the amount of trapped flux is visible. The procedure can be applied repeatedly resulting in a significantly lowered level of trapped flux in the sample. Furthermore, simulations using the Radia software package for Mathematica developed by the ESR were used to better unterstand the measured changes in magnetic flux around the Sample. Applying a similar procedure for minimization of trapped magnetic flux to a superconducting cavity could allow for reduction of the magnetic contribution to the surface resistance and result in a significant improvement of Q0.

WEPWO005

Microphonics Analysis of the SC 325 MHz CH-Cavity

cavity, resonance, vacuum, status

2319

M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

Since the walls of superconducting (sc) cavities are kept very thin to support the cooling process, even small mechanical disturbances can detune the cavity. One of the main sources of detuning a cavity is microphonics. These low-frequent vibrations caused by vacuum pumps or underground noise are transferred to the cryostat and excite mechanical resonances of the cavity which may lead to frequency shifts larger than the bandwidth. To determine the mechanical resonance frequencies of the sc 325 MHz CH-cavity (Crossbar-H-Mode) simulations with ANSYS Workbench have been performed in a first step. Additionally, microphonics measurements were taken at room temperature as well as in a vertical cryostat at 4K in the cryo-lab of the IAP, Frankfurt University. Furthermore, the contraction of the cavity walls and the resulting frequency shift due to the cavity cool-down has been measured. A comparison between simulation results and the measured values is presented in this paper.

WEPWO008

SRF Conical Half-wave Resonator Tuning Developments

cavity, target, resonance, cryomodule

2325

E.N. Zaplatin
FZJ, Jülich, Germany
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This Work is supported by the DOE SBIR Program, contract # DE-SC0006302.
A conical Half-Wave Resonator is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz for a high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X). We present results of different options of the cavity mechanical tuning. The "standard" tuning method of beam port deformations is an effective tuning method still requiring a relatively high tuning pressure. The side tuning is considered as a novel option for the resonance frequency adjustment featuring lower tuning force and an option of the structure design for the resonator frequency shift self compensation.

WEPWO009

Numerical Coupling Analyses of BERLinPro SRF Gun

cavity, gun, SRF, cathode

2328

E.N. Zaplatin
FZJ, Jülich, Germany
W. Anders, A. Burrill, T. Kamps, J. Knobloch, O. Kugeler, A. Neumann
HZB, Berlin, Germany

BERLinPro is an approved ERL project to demonstrate energy recovery at 100 mA beam current by pertaining a high quality beam. These goals place stringent requirements on the SRF cavity (1300 MHz, β=1) for the photoinjector which has to deliver a small emittance 100 mA beam with at least 1.8 MeV kinetic energy while limited by fundamental power coupler performance to about 230 kW forward power. The RF and beam dynamics gun cavity features 1.4 λ/2 cell resonator. We present results of mechanical structure developments of SRF gun. The main purpose of the whole structure optimization was the design of the gun helium vessel together with the tuner and stiffening rings to provide the simple construction for structure tuning with minimization of the cavity frequency dependence on external pressure. During the resonator tuning and external load structure deformations the cavity field profile variation along the beam path should stay within 5%.

WEPWO010

BERLinPro Seven-cell SRF Cavity Optimization and HOMs External Quality Factors Estimation

cavity, HOM, factory, SRF

2331

T. Galek, K. Brackebusch, T. Flisgen, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
J. Knobloch, A. Neumann
HZB, Berlin, Germany
B. Riemann, T. Weis
DELTA, Dortmund, Germany

Funding: Work funded by EU FP7 Research Infrastructure Grant No. 227579 and by German Federal Ministry of Research and Education, Project: 05K10HRC.
The main scope of this work is the optimization of the superconducting radio frequency (SRF) accelerating cavity design for the Berlin Energy Recovery Linac Project (BERLinPro)*. BERLinPro shall serve as a demonstrator for 100-mA-class ERLs with CW LINAC technology. High-current operation requires an effective damping of higher-order modes (HOMs) of the 1.3 GHz main-linac cavities. Consequently it is important, at the SRF cavity design optimization stage, to calculate the external quality factors of HOMs to avoid beam break up (BBU) instabilities. The optimization of the SRF cavity design consists of two steps. In the first step the cavities' end half-cells are tuned with respect to field flatness, effective shunt impedance and geometrical factor of the fundamental accelerating mode using robust eigenmode simulations. The second step involves frequency domain simulations and the extraction of external quality factors of HOMs from transmission S-parameter spectra using vector fitting procedure and an automated scheme to remove non-static poles **. The eigenmode,as well as the frequency domain simulations are performed using CST Microwave Studio ***.
* A. Neumann et al., Proc. of ICAP2012, pp. 278–280.
** T. Galek et al., Proc. of ICAP2012, pp. 152–154.
*** CST AG, http://www.cst.com

WEPWO019

Development of Frequency Measurement Setup for ADS 650MHz and 1.3GHz Superconducting RF Cavities at IHEP

cavity, SRF, linac, controls

2358

S. Jin, J. Gao, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China

The Accelerator Driven Sub-critical System (ADS) is under development in China, and the 650MHz β=0.82 superconducting RF cavity (SRF) has been chosen as a possible candidate to accelerate the proton bunches in the medium energy section from 360MeV to 1.5GeV [1]. In order to obtain quality management and quality assurance during fabrication, radio frequency measurements on parts and subassemblies of SRF cavities become a proper method [2]. In this paper, study on developing a new frequency measurement setup mainly for half cells, dumb-bells and end groups of ADS650MHz cavities at IHEP was reported. A digital pressure sense was assembled in the setup. Together with the simulation on the structural and frequency by ANSYS Workbench, a quantitative standard for the frequency measurement was built for the cavity fabrication. Since a 9-cell TESLA-Like cavity is also under study in the meantime, via a slight modification, the setup can be also used for it.

WEPWO025

Preliminary Design of 325 MHz Half-Wave Resonator

cavity, proton, controls, heavy-ion

2369

X.Y. Zhang, X. Chen, Z.Q. Li, Q. Ma, W.M. Pan, Y. Sun, G.W. Wang, Q.Y. Wang, B. Xu, G.Y. Zhao
IHEP, Beijing, People's Republic of China

Funding: This work is supported by the "Strategic Priority Research Program" of CAS.
The Half-Wave Resonator (HWR) has been widely used in proton and heavy ion accelerators, for it has particular advantages of accelerating low energy charged particles. Preliminary design of a 325 MHz β=0.12 superconducting HWR cavity has been proposed at Institute of High Energy Physics (IHEP). The basic geometric parameters choices of the cavity are based upon theoretical model and numerical calculation, and then the RF performances are optimized by extensive electromagnetic simulations. In this paper, the detailed mechanical analysis, frequency control, and the considerations for fabrication of the 325 MHz HWR cavity are also presented.

WEPWO029

Design of a SRF Quarter Wave Electron Gun at Peking University

cavity, electron, gun, SRF

2378

P.L. Fan, K.X. Liu, S.W. Quan, F. Zhu
PKU, Beijing, People's Republic of China

Funding: Work supported by National Basic Research Project (No. 2011CB808302) and National Natural Science Funds (No. 11075007)
Superconducting RF electron guns hold out the promise of very bright beams for use in electron injectors, particularly in future high average power free-electron lasers (FELs) and energy recovery linacs (ERLs). Peking University is designing a new SRF gun which is composed of a quarter wave resonator (QWR) and an elliptical cavity. Comparing to the elliptical cavity, the QWR is sufficiently compact at the same frequency and its electric field is quasi-DC. We have finished the preliminary design of the QWR cavity. The simulation shows that multipacting is not a critical issue for our cavity structure. Beam dynamic simulation of the QWR cavity is also presented.
contact author : zhufeng7726@pku.edu.cn

WEPWO039

Prototyping of TEM-like Mode Resonators in the RAON

cavity, multipactoring, niobium, electron

2384

H.C. Jung, M.O. Hyun, D. Jeon, H.J. Kim
IBS, Daejeon, Republic of Korea

Preliminary electric-magnetic designs of TEM-like mode resonators(a quarter wave resonator, a half wave resonator, two single spoke resonators) are accomplished for the superconducting linear accelerator in the RAON. Resonant cavities are numerically optimized using a CST MWS code to obtain higher E-field gradient along the beam line in conditions of the peak E-field and B-field is less than 30MV/m, 60mT respectively. Prototyping test of a quater wave resonator of optimum beta 0.047 using OFC(Oxygen Free Cupper)is in progress to analyze resonant frequency shifting by tolerances in fabrication process and external perturbations. It is compared with expected one using compuational codes.

WEPWO040

Design of HWR at RISP

cavity, quadrupole, electromagnetic-fields, niobium

2387

G.-T. Park, H.J. Cha, H.C. Jung
IBS, Daejeon, Republic of Korea

At RISP, superconducting cavity resonators to accelerate the various ions in high current are being developed. In particular, hal-wave resonator (HWR) will be used for β=0.12, f=162.5 MHz. Here we present the structural analysis of HWR, which includes the prediction of resonant frequency shift during the manufacturing and testing process, stiffening measures to minimize the shift, and the tuning mechanism. The processes of welding, polishing, vacuuming, cooling (to crygenic temperature)as well as Lorentz force, helium pressure fluctuation, microphonics, and interaction with the helium vessel and tuning system will be simulated optimizing the frequency shift.

WEPWO047

A Double Quarter-Wave Deflecting Cavity for the LHC

cavity, HOM, multipole, higher-order-mode

2408

R. Calaga
CERN, Geneva, Switzerland
S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu, B. P. Xiao
BNL, Upton, Long Island, New York, USA

Funding: The HiLumi LHC Design Study (a sub-system of HL-LHC) is cofunded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404
An asymmetric quarter wave deflecting cavity at 400 MHz for crab crossing in the LHC was already proposed in 2011. Due to improved cancellation of on-axis longitudinal field and the higher order components of the deflecting field, a symmetric version is now considered as the baseline for the quarter wave geometry. Relevant RF properties of the symmetric cavity are compared to the original asymmetric cavity. Some aspects of input coupler design, higher order modes, multipacting and frequency tuning are also addressed.

WEPWO050

Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade

cavity, luminosity, vacuum, electron

2417

B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu
BNL, Upton, Long Island, New York, USA
L. Alberty Vieira, R. Calaga
CERN, Geneva, Switzerland
T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA

A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.

WEPWO054

Multistep Mechanical Analyses of Centrifugal Barrel Polishing Barrel and Cavity

cavity, SRF, acceleration, niobium

2426

M. Chen, C.A. Cooper, L. Ristori
Fermilab, Batavia, USA

Funding: US Department of Energy
Fermilab has successfully demonstrated the ability to improve the performance of damaged 1.3 GHz single cell and 9-cell Tesla–type cavities by using a modified centrifugal barrel polishing (CBP) process that leaves a mirror finish on the inside of the cavity. Fermilab now is developing and constructing a new CBP machine which can handle both 650 MHz and 1.3 GHz cavities. The new machine will have a larger moment arm and therefore impart more force on the cavity and machine. Because of these increased forces the effects on cavity supports and machine design were examined. This paper will document the multistep mechanical analyses for the CBP barrel and cavity, calculations of the fatigue life and the requirements for the structural welds.

WEPWO056

Update of the Mechanical Design of the 650 MHZ β=0.9 Cavities for Project X

cavity, resonance, niobium, linac

2432

I.V. Gonin, M.H. Awida, M.H. Foley, C.J. Grimm, T.N. Khabiboulline, Y.M. Pischalnikov, V.P. Yakovlev
Fermilab, Batavia, USA

Five-cell elliptical 650 MHz β=0.9 cavities to accelerate 1 mA of average H⁻ beam current in the range 520-3000 MeV of the Project X Linac are currently planned. We will present the results of optimization of mechanical design of cavities with their Helium Vessel. We discuss the efforts to optimize the mechanical stability of the cavity versus the Helium bath pressure fluctuations, cavity tunability. We present also modal and thermal analysis; discuss tuner options and other issues.

WEPWO057

Update of SSR2 Cavities Design for Project X and RISP

cavity, linac, cryomodule, heavy-ion

2435

M. Merio, M.H. Awida, P. Berrutti, I.V. Gonin, T.N. Khabiboulline, D. Passarelli, Y.M. Pischalnikov, L. Ristori, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Single spoke resonators SSR2 (f=325 MHz) are under development at Fermilab. These cavities can meet requirements of Project X (FNAL) and RISP (Korea). The initial design of SSR2 cavities has been modified and optimized in order to satisfy the necessities of both projects. This paper will discuss the RF optimization for a single spoke resonator with a 50 mm beam pipe aperture and an optimal beta of 0.51. Further, the approach to the mechanical design of the cavity will be presented together with the proposed helium vessel. The latter is intended to guarantee a low He pressure sensitivity df/dp of the entire jacketed SSR2 and actively control the microphonics.

WEPWO065

Optimization of Elliptical SRF Cavities for β <1

cavity, SRF, HOM, niobium

2450

V.D. Shemelin
CLASSE, Ithaca, New York, USA
J. Newbolt
Rochester University, Rochester, New York, USA

Funding: NSF award DMR-0807731
A systematic approach to optimization of SRF cavities which was done earlier for β=1 is extended to β<1 Some improvements for earlier developed designs are proposed.

WEPWO067

Conditions for the Existence of 1- and 2-point Multipactor in SRF Cavities

cavity, electron, multipactoring, superconductivity

2456

V.D. Shemelin
CLASSE, Ithaca, New York, USA

Funding: NSF award DMR-0807731
One- and two-point multipactor (MP) in RF cavities are well-known phenomena. However, conditions when this or the other type of discharge develops were not clearly defined up to now. Here, an explicit description of these two types of the MP is presented, geometrical parameters, or figures of merit, responsible for initiation of the MP defined, and areas of their existence delineated. Small sizes of trajectories in the MP require a very precise calculation of fields for simulations. On the other hand, due to these small sizes, fields can be presented as the Taylor expansions and trajectories can be found solving ordinary differential equations of motion. Conditions of motion stability and influence of the Miller force are also accounted.

WEPWO082

Ferroelectric Based High Power Tuner for L-band Accelerator Applications

controls, linac, cavity, vacuum

2486

A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Kazakov, V.P. Yakovlev
Fermilab, Batavia, USA
A.B. Kozyrev
LETI, Saint-Petersburg, Russia
E. Nenasheva
Ceramics Ltd., St. Petersburg, Russia

Funding: US Department of Energy
With this paper, we present our recent breakthrough with a new fast ferroelectric tuner development. The tuner is based on BST(M) ferroelectric elements (ε~150), which are designed to be used as the basis for L-band accelerator components intended for ERL, ILC, Project X and other applications. These new ferroelectric elements are to be fabricated for the new fast active tuner for SC cavities that can operate in air at low biasing DC fields. Note there were no reliable results on the long-term piezo actuators operations in CW regime. Specific features of ERL, ILC and Project X accelerator technology and challenges of the designs are high magnitude and phase stability of its operations. Mechanical vibrations, or microphonics affect the SRF resonator, while the ferroelectric tuners have shown extremely high tuning speed. We have demonstrated successful mitigation of the residual effects on the ferroelectric-metal interface along with the acceptable level of the overall loss factor of the tuner element. A new concepts of a tuning element based on low dielectric constant ferroelectrics along with fabrication technology of these new BST(M) ferroelectric elements will be presented.

WEPWO085

Commissioning SRF Gun for the R&D ERL at BNL

gun, SRF, cavity, HOM

2492

W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, H. Hahn, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, K.S. Smith, A.N. Steszyn, T.N. Tallerico, R. Than, R.J. Todd, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, I. Ben-Zvi, J. Dai
Stony Brook University, Stony Brook, USA

Funding: This work is supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S.
The R&D ERL project at BNL aims to demonstrate a high charge, high current energy recovery linac. One of the key SRF system is the 704 MHz half-cell SRF gun. The SRF gun is designed to deliver up to 0.5 A beam at 2 MeV with 1 MW of CW RF power. The gun commissioning started in November 2012. The first photoemission beam from the SRF gun is expected in early 2013. This presentation will discuss the results of the SRF gun commissioning, and the performance of the high-power RF system.

WEPEA001

Simulation Studies of Longitudinal RF-noise and Phase Displacement Acceleration as Driving Mechanism for the MedAustron Synchrotron Slow Extraction

extraction, acceleration, resonance, synchrotron

2501

U. Dorda
EBG MedAustron, Wr. Neustadt, Austria
M. Benedikt, H.O. Schönauer, A. Wastl
CERN, Geneva, Switzerland

MedAustron is a synchrotron based hadron therapy and research facility located in Austria currently entering the installation stage. It is an implementation of the CERN-PIMMS design which proposed induction acceleration by a betatron core as the driving mechanism for the third-order slow resonant extraction. Primarily in order to increase the accelerators flexibility towards future irradiation schemes but also as back-up options, two alternative extraction driving mechanism have been studied: Longitudinal RF-noise and phase displacement acceleration. The advantages as well as the corresponding limitations are explained, analytical estimates and particle tracking results performed with the 2D tracking codes LONG1D and a specifically developed Python based simulation code are presented.

WEPEA008

Influence of Higher Order Phase Slip Factor Contributions on Beam Loss during SIS-100 Proton Operation

quadrupole, sextupole, lattice, dynamic-aperture

2507

S. Sorge, O. Boine-Frankenheim, G. Franchetti
GSI, Darmstadt, Germany

The projected FAIR synchrotron SIS-100 is envisaged to accelerate intense proton and heavy-ion beams. The maximum proton energy will be E=29 GeV. In order to stay below transition energy a special powering scheme of the quadrupoles has been introduced which provides a maximum transition gamma of 45.5. The resulting settings of the quadrupole focusing strengths generate large maxima of the horizontal beta and dispersion functions. In particle tracking simulation we observed beam loss caused by a large momentum spread in the deformed rf bucket close to transition. Application of the chromaticity correction sextupoles led to a reduction of the first-order phase slip factor term and of the beam losses. In this contribution we will analyze the effect of the sextupoles on the higher-order components of the phase slip factor. The rf bucket shape will be discussed as well as the transverse beam loss and possible longitudinal instabilities.

WEPEA009

Effects of Field Imperfections in the Isochronous Mode of the CR Storage Ring at FAIR

dipole, quadrupole, octupole, sextupole

2510

S.A. Litvinov, A. Dolinskyy, O.E. Gorda, M. Steck, H. Weick
GSI, Darmstadt, Germany
D. Toprek
VINCA, Belgrade, Serbia

Today the challenge is to measure masses of exotic nuclei up to the limits of nuclear existence which are characterized by low production cross-sections and short half-lives. The large acceptance Collector Ring (CR) at FAIR tuned in the isochronous ion-optical mode offers unique possibilities for such measurements. Nonlinear field errors as well as fringe fields of the wide aperture quadrupoles and dipoles strongly excite the high-order aberrations which negatively affect the time resolution of the isochronous ring. Their influence is investigated here and a possible correction scheme is shown.

WEPEA010

Modeling Longitudinal Bunched Beam Dynamics in Hadron Synchrotrons using Scaled Fourier-Hermite Expansions

synchrotron, hadron, controls, feedback

2513

K. Gross, D.E.M. Lens
TU Darmstadt, RTR, Darmstadt, Germany

To devise control strategies and to analyze the stability of systems with feedback, a set of few ODEs describing the underlying dynamics is required. Numerical Fourier-Hermite solutions of the Vlasov equation have been studied for over fifty years. The idea to expand the distribution function in Fourier series in space and Hermite functions in velocity is transferred to the dynamics of bunched beams in hadron synchrotrons in this contribution. The Hermite basis is a natural choice for plasmas with Maxwellian velocity profile as well as for particle beams with Gaussian momentum spread. The Fourier basis used for spatially nearly uniform plasmas has to be adapted to bunched beams where the beam profile is not uniform in phase. This is achieved analogously to the deduction of the three term recursion relations to construct orthogonal polynomials, but applied to Fourier series with the weight function taken from the Hamiltonian. The resulting system of ODEs for the expansion coefficients of desired order - dependent on the number of functions retained - is checked against macro particle tracking simulations.

WEPEA011

Bursting Patterns of Coherent Synchrotron Radiation in the ANKA Storage Ring

impedance, radiation, electron, synchrotron

2516

M. Schwarz, V. Judin, A.-S. Müller
KIT, Karlsruhe, Germany
M. Klein
SOLEIL, Gif-sur-Yvette, France

We report measurements of bursting patterns of coherent synchrotron radiation (CSR) for a wide range of single bunch currents at the ANKA storage ring. The radiation was detected with a fast THz detector, a Hot Electron Bolometer, and its signal acquired with both a spectrum analyzer and an external sampling oscilloscope. Both analysis methods consistently show the onset of bursting at a threshold current with the appearance of strong high frequency bands with higher harmonics in the several 10th of kHz range. For currents higher than twice the threshold value an abrupt change in the bursting pattern occurs. These results are compared with different numerical models solving the one-dimensional Vlasov-Fokker-Planck equation.

WEPEA012

Study of Laser Wakefield Accelerators as Injectors for Synchrotron Light Sources

laser, synchrotron, lattice, storage-ring

2519

S. Hillenbrand, V. Judin, A.-S. Müller
KIT, Karlsruhe, Germany
R.W. Aßmann, S. Hillenbrand
CERN, Geneva, Switzerland
O. Jansen, A.M. Pukhov
HHUD, Dusseldorf, Germany

Short bunch lengths, high beam energies, and small facility footprint make Laser Wakefield Accelerators (LWFA) very interesting as injectors for Synchrotron Light Sources. In this paper, we describe exemplary investigations for the ANKA storage ring.

WEPEA013

Electron Cloud Studies for the Upgrade of the CERN PS

electron, extraction, synchrotron, proton

2522

G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy
H. Damerau, S.S. Gilardoni, G. Iadarola, S. Rioja Fuentelsaz, G. Rumolo, G. Sterbini, C. Yin Vallgren
CERN, Geneva, Switzerland
M.T.F. Pivi
SLAC, Menlo Park, California, USA

The observation of a significant dynamic pressure rise as well as measurements with dedicated detectors indicate that an electron cloud develops in the CERN PS during the last stages of the RF manipulations for the production of LHC type beams, especially with 25ns bunch spacing. Although presently these beams are not degraded by the interaction with the electron cloud, which develops only during few milliseconds before extraction, the question if this effect could degrade the future high intensity and high brightness beams foreseen by the LHC Injectors Upgrade (LIU) project is still open. Therefore several studies are being carried out employing both simulations and measurements with the electron cloud detectors in the machine. The aim is to develop a reliable electron cloud model of the PS vacuum chambers in order to identify possible future limitations and find suitable countermeasures.

WEPEA014

Recent Electron Cloud Studies in the SPS

electron, injection, emittance, vacuum

2525

G. Iadarola, H. Bartosik, M. Driss Mensi, H. Neupert, G. Rumolo, M. Taborelli
CERN, Geneva, Switzerland
G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy

It is important to qualify the present status of the SPS with respect to the electron cloud before the Long Shutdown of the CERN accelerator complex, which will take place in 2013-2014. Therefore several electron cloud studies were performed during the 2012 run in order to get a full characterization of the behavior of the SPS with the LHC-type beams with 25 ns bunch spacing, which can be very sensitive to electron cloud effects. The collected information should allow to understand up to which extent this long period without beam operation - and the related interventions on the machine - will degrade the present conditioning state of the SPS, which has been achieved by “scrubbing” over several years. Several measurements with different beam conditions have been collected also on the electron cloud detectors installed in the machine. These results, in combination with detailed simulation studies, will provide the basis for defining strategies of electron cloud mitigation as required for the production of future high intensity and high brightness beams within the LHC Injectors Upgrade (LIU) project.

WEPEA022

Analytical Estimations of the Dynamic Apertures of Beams with Momentum Deviation and Application in FFAG

dynamic-aperture, sextupole, positron, lattice

2546

M. Xiao, J. Gao
IHEP, Beijing, People's Republic of China

Analytical formulae for estimating the dynamic apertures of synchrotron particles has been well established. Based on the standard mapping, we extend the analytical formulae of dynamic aperture for off-momentum particles in circular accelerator. And we compare the analytical results with the simulation ones in the BEPC-II positron ring lattice under some conditions. What's more, we give the analytical formulae of dynamic aperture for FFAG in the similar way.

WEPEA023

Space Charge Effects for Different CSNS/RCS Working Points

resonance, lattice, space-charge, emittance

2549

S.Y. Xu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) operates at 25 Hz repetition rate with the design beam power of 100 KW. CSNS consists of an 80-MeV linac and a 1.6-GeV Rapid Cycling Synchrotron (RCS). Due to the high beam density and high repetition rate for CSNS/RCS, the rate of beam loss must be controlled to a very low level. The major source of beam loss is associated with resonances. Thus, choosing he best suitable working points on the tune diagram is important to reach low beam loss. Different tune areas are explored and compared by considering resonances and the effects of space charge, which can drive particles into the excited resonances. Different working points are simulated and compared by using the codes ORBIT and SIMPSONS.

WEPEA024

Combine Effects of Space Charge and Chromaticity Sextupoles at CSNS/RCS

sextupole, emittance, space-charge, acceleration

2552

S.Y. Xu, S. Wang
IHEP, Beijing, People's Republic of China

Most high current proton synchrotrons, such as The Rapid Cycling Synchrotron (RCS) of The China Spallation Neutron Source (CSNS), are operated under the transition energy, and the natural chromaticity is small. These proton synchrotrons can work without chromatic correction. To reduce the tune spread produced by the chromaticity, chromatic correction is considered by using chromaticity sextupoles for this type of proton synchrotrons, such as J-PARC and SNS. Many chromatic correction schemes are compared for the CSNS/RCS, and the harmonic sextupoles are considered to correct nonlinear effect of chromaticity sextupoles. The dynamic aperture is obtained by particle tracking, and the combine effects of sextupole field and space charge effects are investigated by using the code ORBIT and SIMPSONS.

WEPEA030

Simulation of Beam Capture Process in HIRFL-CSRm

acceleration, extraction, cavity, injection

2564

P. Li, P. Jiang, J.W. Xia, J.C. Yang, Y.J. Yuan
IMP, Lanzhou, People's Republic of China

In this paper, the beam capture processes are simulated in CSRm with the real RF cavity curves. By now, CSRm can accelerate all ions from protons up to the heaviest element, uranium, with variable energies and different efficiency. During the beam capture processes, the capture voltage and capture time must be cheese properly to avoid the beam loss. Moreover, the mismatch between the actual and the setting beam energy and space charge effect are investigated for high beam capture efficiency. The evolution of longitudinal phase space during the capture processes is presented in this simulation too.

WEPEA037

Testing of Symplectic Integrator of Spin-orbit Motion Based on Matrix Formalism

storage-ring, lattice, electromagnetic-fields

2582

A.N. Ivanov, S.N. Andrianov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia
R. Maier, Y. Senichev, D. Zyuzin
FZJ, Jülich, Germany

Investigation of spin-orbital motion in electromagnetic fields requires different numerical methods. Approaches for long-term evolution modelling need both performance and symplecticity. In this paper we discuss matrix maps method for numerical simulation. We examine symplectification and accuracy in terms of electostatic storage ring. The results are compared with traditional symplectic step-by-step methods.

WEPEA038

Two and three Dimensional Models for Analytical and Numerical Space Charge Simulation

space-charge, controls, linac, ion

2585

S.N. Andrianov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

In this article there is described an analytical approach to describe the self-field of two- and three dimensional ellipsoidal presentation of space charge distribution. The corresponding results can be evaluated in both numerical and the analytic presentation for some model distributions of charge. The corresponding results can be embedded in the Lie formalism used to describe the map for the beam dynamics. The corresponding linear and nonlinear maps are evaluated in terms of the matrix representation of the evolution operator of the beam. Appropriate solutions for nonlinear differential equations are based on a prediction-correction method (the converging recursive procedure). These solutions are compared with the Vlasov equation solutions. A special software package for the described approach is presented.

WEPEA040

Space Charge and Cavity Modeling for the ESS Linac Simulator

space-charge, linac, cavity, proton

2588

E. Laface, M. Eshraqi, R. Miyamoto
ESS, Lund, Sweden

The proton linac of the European Spallation Source will operate at unprecedented beam power of 5 MW. Such power requires a precise modeling of the beam dynamics in order to protect its components from losses. The high peak current of 62.5 mA produces a space charge force that dominates the dynamics at low energy, while the high gradient required to accelerate up to 2 GeV in the 500 m of linac length is challenging for the dynamics in the RF cavities. This paper presents modelings of the space charge force and RF cavities used in the ESS Linac Simulator. The simulator is under development as part of the XAL on-line model, and it will be adopted for the ESS linac operations.

WEPEA045

Specifications of the Field Quality at Injection Energy of the New Magnets for the HL-LHC Upgrade Project

injection, dynamic-aperture, multipole, optics

2603

R. De Maria, S.D. Fartoukh, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The HL-LHC project relies on new magnet designs and technologies to achieve very small β^* values. In particular, Nb3Sn magnets show large allowed multipole imperfections at low current. These field errors may have a non-negligible impact on the dynamic aperture and beam life time in the HL-LHC, also because of the smaller-than-nominal β^* values foreseen IR1 and IR5 at injection energy, which aims at decreasing the dynamic range of the squeeze and therefore contributing to optimize the turn around time. The paper describes an analysis of the machine performance based on analytical estimates and tracking simulations with the goal of providing field quality specifications for the new magnets.

WEPEA048

Specification of a System of Correctors for the Triplets and Separation Dipoles of the LHC Upgrade

multipole, dipole, optics, insertion

2612

M. Giovannozzi, R. De Maria, S.D. Fartoukh
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The luminosity upgrade of the LHC aims at reducing β^* from 55 cm to 15 cm or beyond. This can be achieved by the ATS* scheme and means of new large aperture superconducting triplet (IT) quadrupoles (150 mm), preferably using the Nb3Sn technology in order to keep the gradient reasonably high (140 T/m). The field quality requires careful specification in order to ensure a large enough dynamic aperture. In this context, dedicated corrector magnets are foreseen to provide semi-local corrections of specific multipole components and find the best possible compromise between the demand and what can be realistically achieved by the magnet manufacturer. In this paper the layout and main parameters of the IT corrector package are presented together with the correction strategy. Moreover, the foreseen performance is discussed in detail.
* S. Fartoukh, ‘’An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

WEPEA049

Analysis of the Non-linear Fringe Effects of Large Aperture Triplets for the HL LHC Project

quadrupole, dipole, optics, luminosity

2615

A.V. Bogomyagkov, E.B. Levichev, P.A. Piminov
BINP SB RAS, Novosibirsk, Russia
A. Chancé, B. Dalena, J. Payet
CEA/IRFU, Gif-sur-Yvette, France
R. De Maria, S.D. Fartoukh, M. Giovannozzi
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
The HL-LHC project relies on large aperture quadrupoles which are compatible with the very large beam sizes in the inner triplets resulting from the strong reduction of β^*. As a result the beam is much more sensitive to non-linear perturbations in this region, such as those induced by the fringe fields of the low-beta quadrupoles. The spatial extension of these fringe fields increases as well more or less linearly with the coil aperture, which is an additional motivation to analyse this aspect in detail in the framework of the High Luminosity LHC design study. This paper will quantify this effect both by direct analytical estimates using first order Hamiltonian perturbation theory, and via numerical studies thanks to the dedicated implementation of a fringe field symplectic integrator in SixTrack.

WEPEA050

Analysis of Possible Functional Forms of the Scaling Law for Dynamic Aperture as a Function of Time

dynamic-aperture, luminosity, beam-losses, lattice

2618

M. Giovannozzi, R. De Maria, F. Lang
CERN, Geneva, Switzerland

Funding: The HiLumi LHC Design Study is included in the HL-LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404.
In recent studies, the evolution of the dynamic aperture with time has been fitted with a simple scaling law based on a limited number of free parameters. In this paper, different approaches to improve the numerical stability of the fit are presented, together with a new functional form. The results are discussed in details and applied to a set of numerical simulations for the LHC.

WEPEA052

Investigations on CERN PSB Beam Dynamics with Strong Direct Space Charge Effects Using the PTC-ORBIT Code

emittance, space-charge, resonance, injection

2621

V. Forte, E. Benedetto, C. Carli, M. Martini, B. Mikulec, E. Métral, F. Schmidt
CERN, Geneva, Switzerland
A.Y. Molodozhentsev
KEK, Ibaraki, Japan

The CERN PS Booster (PSB) is the first synchrotron of the LHC injector chain consisting out of four superposed rings and providing beam for many users. As part of the LIU project, the machine will be upgraded. Space charge and resonances are serious issues for the good quality of the beam at injection energy. Consequently simulations are needed to track the beam in the machine taking into account space charge effects: PTC-ORBIT has been used as tracking code. This paper presents simulations results compared with the measurements for machine performances evaluation and code-benchmarking purposes.

WEPEA053

Progress with the Upgrade of the SPS for the HL-LHC Era

electron, kicker, extraction, emittance

2624

B. Goddard, T. Argyropoulos, W. Bartmann, H. Bartosik, T. Bohl, F. Caspers, K. Cornelis, H. Damerau, L.N. Drøsdal, L. Ducimetière, J. Esteban Müller, R. Garoby, M. Gourber-Pace, W. Höfle, G. Iadarola, L.K. Jensen, V. Kain, R. Losito, M. Meddahi, A. Mereghetti, V. Mertens, O. Mete, E. Montesinos, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, M. Taborelli, H. Timko, F.M. Velotti
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, USA

The demanding beam performance requirements of the HL-LHC project translate into a set of requirements and upgrade paths for the LHC injector complex. In this paper the performance requirements for the SPS and the known limitations are reviewed in the light of the 2012 operational experience. The various SPS upgrades in progress and still under consideration are described, in addition to the machine studies and simulations performed in 2012. The expected machine performance reach is estimated on the basis of the present knowledge, and the remaining decisions that still need to be made concerning upgrade options are detailed.

WEPEA054

CERN PS Optical Properties Measured with Turn-by-turn Orbit Data

resonance, optics, extraction, kicker

2627

C. Hernalsteens, T. Bach, S.S. Gilardoni, M. Giovannozzi, A. Lachaize, G. Sterbini, R. Tomás, R. Wasef
CERN, Geneva, Switzerland

The performance of the PS has been constantly increasing over the years both in terms of beam parameters (intensity and brightness) and beam manipulations (transverse and longitudinal splitting). This implies a very good knowledge of the linear and non-linear model of the ring. In this paper we report on a detailed campaign of beam measurements based on turn-by-turn orbit data aimed at measuring the optics in several conditions as well as the resonance driving terms. The goal of this study is to assess whether any specific correction system should be envisaged to achieve the required future performance.

WEPEA055

Quantitative Evaluation of Trapping and Overall Efficiency for Simple Models in One-degree of Freedom

resonance, controls, synchrotron, extraction

2630

C. Hernalsteens, C. Frye, M. Giovannozzi
CERN, Geneva, Switzerland
A. Bazzani
Bologna University, Bologna, Italy

A key ingredient for the Multi-Turn Extraction at the CERN Proton Synchrotron is the beam trapping in stable islands of transverse phase space. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, a method allowing an analytical estimation of the fraction of beam trapped into stable islands as a function of the Hamiltonian parameters is presented for a very simple model of the dynamics (pendulum) and is extended to the case of the interpolating Hamiltonian of the Hénon model, the latter being a good 2D model of the MTE dynamics. The analytical results are compared with numerical simulations. Additional numerical simulations are presented for the minimum trapping amplitude and a fitted model is proposed. Results are discussed in detail.

WEPEA064

SixTrack-Fluka Active Coupling for the Upgrade of the SPS Scrapers

coupling, injection, luminosity, synchrotron

2657

A. Mereghetti, F. Cerutti, R. De Maria, B. Goddard, V. Kain, M. Meddahi, O. Mete, Y. Papaphilippou, D. Pastor Sinuela, V. Vlachoudis
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

The LHC Injectors Upgrade (LIU) Project aims at upgrading the systems in the LHC injection chain, to reliably deliver the beams required by the High-Luminosity LHC (HL-LHC). Essential for the clean injection into the LHC, the SPS scrapers are one of the important systems under revision. In order to take into account of the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. Knob-like, time-dependent strengths have been implemented in SixTrack, since the designed scraper system foresees the use of a magnetic bump. The study is intended to assess the robustness of the proposed scraper as well as its effectiveness with respect to the desired performance.

WEPEA073

A 180 MeV Injection Upgrade Design for the ISIS Synchrotron

injection, space-charge, synchrotron, acceleration

2678

J.W.G. Thomason, D.J. Adams, B.S. Drumm, D.J.S. Findlay, I.S.K. Gardner, M.C. Hughes, S.J.S. Jago, B. Jones, R.J. Mathieson, S.J. Payne, B.G. Pine, A. Seville, H. V. Smith, C.M. Warsop, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
D.C. Plostinar, C.R. Prior, G.H. Rees
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Obsolescence and reliability issues are motivating plans to replace the present 70 MeV H minus linac, and this paper presents an overview of a design to allow injection of beam into the present ISIS ring at 180 MeV, which would increase intensity as a result of reduced space charge and optimised injection. The key topics addressed are design of the injection straight, injection painting and dynamics, foil specifications, acceleration dynamics, transverse space charge, instabilities, RF beam loading and activation.

WEPEA075

Large Emittance Beam Measurements for COMET Phase-I

solenoid, electron, proton, background

2684

A. Kurup, I. Puri, Y. Uchida, Y. Yap
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing
UCL, London, United Kingdom

The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. Understanding the pion production yield and transport properties of the beam line is an important part of the experiment. The beam line is a continuous solenoid channel, so it is only possible to place a beam diagnostic device at the end of the beam line. Building COMET in two phases provides the opportunity to investigate the pion production yield and to measure the transport properties of the beam line in Phase-I. This paper will demonstrate how this will be done using the experimental set up for COMET Phase-I.

WEPEA082

AGS Model in Zgoubi. RHIC Run 13 Polarization Modeling. Status.

optics, polarization, extraction, injection

2699

F. Méot, L. A. Ahrens, K.A. Brown, Y. Dutheil, J.W. Glenn, C.E. Harper, H. Huang, V.H. Ranjbar, T. Roser, V. Schoefer, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
This paper gives a status of the AGS model in the ray-tracing code Zgoubi and its operation via the ‘‘AgsZgoubiModel'' and the ‘‘AgsModelViewer'' applications available from the controls system application launcher, ‘‘StartUp''. Examples of typical uses and studies performed using these are included, as optics controls, spin matching to RHIC, etc. A companion paper (MOPWA085) gives additional details, regarding especially spin dynamics and polarization studies aimed at determining optimal AGS settings for polarization during RHIC Run 13. This work is an additional step towards further combination with the already existing RHIC spin tracking model in Zgoubi, and AGS's Booster model in Zgoubi, a promising suite for detailed beam and spin dynamics studies and optimizations.

WEPFI003

A New Timing System and Electron Gun Modulator

gun, electron, linac, synchrotron

2705

A.S. Setty, A.S. Chauchat, D. Fasse, D. Jousse
Thales Communications & Security (TCS), Gennevilliers Cedex, France

In the last decade, Thales Communications & Security has manufactured turnkey linacs for the SOLEIL, ALBA and BESSY II synchrotrons. In the meanwhile, a new timing system and electron gun modulator was designed and a gun pulse length of 600 ps was measured. This paper will describe the system and will present the beam dynamics simulations results, comparing them with those obtained with the previous gun modulator *.
* A. Setty, "Beam dynamics of the 100 MeV preinjector for the Spanish synchrotron ALBA", PAC07, Albuquerque, USA, June 2007.

WEPFI009

RF Measurement during CW Operation of an RFQ Prototype

rfq, cavity, proton, linac

2720

M. Vossberg, H.C. Lenz, H. Podlech, A. Schempp
IAP, Frankfurt am Main, Germany
A. Bechtold
NTG Neue Technologien GmbH & Co KG, Gelnhausen, Germany

A 17 MeV MHz proton linac is being developed as a front end of the driver accelerator for the MYRRHA facility in Mol. As a part of the MAX (MYRRHA Accelerator Experiment and Development) project a 4-rod Test-RFQ with a resonance frequency of 176 MHz has been designed and built for the MAX-Project. The RFQ has been modified to solve the cooling problem at cw-operation, the geometrical precision had to be improved as well as the rf-contacts. The developments led to a new layout and a sophisticated production procedure of the stems and the electrodes. Calculations show an improved Rp-value leading to power losses less than 30 kW/m, which is about 60 % of the power losses which could be achieved safely at cw-operation of the similar Saraf-RFQ. Thermal measurements and simulations with the single components has been completed. During cw-operation the temperature distribution will be measured and the rf-performance checked.

WEPFI015

Design and Field Measurements of a Linear Accelerator Endowed with Single Feed with Movable Short Coupler

emittance, linac, dipole, electron

2732

M. Dal Forno, R. Vescovo
University of Trieste, Trieste, Italy
P. Craievich, M. Dal Forno, G. Penco
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
P. Craievich
PSI, Villigen PSI, Switzerland

The free electron laser performances strongly depend on the beam quality. The dipolar field present in the linac coupler causes the beam emittance degradation. This paper studies an alternative solution for reducing the dipolar field, by using a symmetrical coupler with single feed input and a movable short circuit placed on the opposite waveguide. The structure has been simulated and optimized with the Ansys HFSS simulation code. An aluminum prototype has been machined in the workshop of “Elettra - Sincrotrone Trieste S.C.p.A.”. After matching and tuning the accelerating structure, the phase advance and the coupler field asymmetries have been measured by means of the bead-pull method and have been compared with the simulation results.

WEPFI016

Upgrade of Power Supply System for RF-Chopper At J-PARC Linac

pick-up, linac, cavity, LLRF

2735

K. Futatsukawa, Z. Fang, Y. Fukui, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan
E. Chishiro, K. Hirano, Y. Ito, N. Kikuzawa, A. Miura, F. Sato, S. Shinozaki
JAEA/J-PARC, Tokai-mura, Japan
T. Hori
JAEA, Ibaraki-ken, Japan
Y. Liu, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
T. Suzuki
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

In the J-PARC Linac, the radio frequency deflector was adopted as a chopper to capture the particles into the RF-bucket in the next synchrotron. The chopper, consists of two deflectors, was installed on the medium-energy beam-transport line. In the operation of the RF-chopper, the fast rise/fall time of the pulse is a fundamental requirement to minimize the beam loss due to insufficient deflection to some beam bunches. In the previous system, the two series-connected chopper deflectors were driven by one solid- state amplifier. However, the fall time indicated a poor result to effect the ringing into each cavity. Therefore, the additional solid-state amplifier and low level RF system were installed in the summer 2012 and the connection changed to the parallel system from the series using two amplifiers. The rise/fall time of the chopped beam, is defined as the step height of 10% and 90%, was about 20 nsec in the beam current of 15 mA and the effect of the ringing was decreased. We would like to introduce the performance of the new chopper system.

WEPFI023

Study on Two-cell RF-deflector Cavity for Ultra-short Electron Bunch Measurement

cavity, electron, gun, target

2753

Y. Nishimura, K. Sakaue, T. Takahashi, M. Washio
Waseda University, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT.
We have been developing an S-band Cs-Te photocathode rf electron gun system for pulse radiolysis and laser Compton scattering experiment at Waseda University. These researches demand for high quality and well controlled electron beam. In order to measure the ultra-short electron bunch, we decided to use rf-deflector cavity, which can convert the longitudinal distribution to that of transverse. With this technique, the longitudinal bunch profile can be obtained as the transverse profile. We used the 3D electromagnetic simulation codes HFSS for designing rf deflector cavity and GPT for beam tracking. The cavity has 2 cell structures operating on π mode, standing wave, dipole (TM120) mode at 2856MHz. We have confirmed on HFSS that 2 cell rf-deflector cavity can produce 660G magnetic field per cell on beam line with 750kW input rf power. This field strength is enough for our target, which is 100fs bunch length measurement at 4.3MeV. In this conference, we will present the cavity structure design, the present progresses and future plan.

WEPFI024

Anisotropic Ferrite Magnet Focusing System for Klystrons

klystron, focusing, cathode, permanent-magnet

2756

Y. Fuwa, H. Ikeda, Y. Iwashita, R. Kitahara, Y. Nasu, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, T. Matsumoto, S. Michizono
KEK, Ibaraki, Japan

The permanent magnet beam focusing for klystrons can eliminate the solenoid coil with the water cooling system and the power supply that consumes electricity. Hence the failure rate and the operating cost of RF systems should decrease. This feature is suitable for a large facility that requires a lot of klystrons such as ILC. Since the required magnetic field for klystron beam is moderate, inexpensive anisotropic ferrite magnets can be applied. The test model is fabricated for a 1.3 GHz klystron whose output power is 800 kW. Each magnet block in the model is movable for magnetic field adjustment and the iron yoke in the oil tank improves magnetic field distribution around cathode area. The result of a klystron power test will be presented.

WEPFI031

Development of an X-Band Metallic Power Extractor for the Argonne Wakefield Accelerator

damping, impedance, extraction, cavity

2771

J. Shi, H.B. Chen, Q. Gao, X.W. Wu, Y. Yang, H. Zha
TUB, Beijing, People's Republic of China
W. Gai, C.-J. Jing
ANL, Argonne, USA

An X-band (11.7GHz) power extractor has been developed for RF power generation at Argonne Wakefield Accelerator (AWA). The structure is a 2pi/3-mode disk-loaded structure with group velocity of 22% of the speed of light and a total length of about 300mm. It is build with copper disks brazed together. This note presents the design and the fabrication of this structure, as well as the RF measurement results.

WEPFI036

R&D on a Main Accelerating Section of a Compact THz-FEL

electron, laser, FEL, radiation

2780

W. Bai, M. Li, X. Shen, H. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

In order to develop a tera-hertz(THz) radiation source and to make scientific researches on application of THz technology, a study on tera-hertz source is performed. The radiation source is based on technology of free electron laser(FEL). The energy booster section of the injector uses a 9 Cell standing wave accelerator as the main accelerator for the FEL. The accelerator works at S band.(2856 MHz), excited by a microwave power of about 3.5 MW. At the end of the accelerator, the high quality beam energy is of 6.5MeV ~ 7 MeV, and the current about 300 mA. This paper presents the newly prgress of the , as well as the working condition of the main accelerator.

WEPFI039

New X-band Deflecting Cavity Design for Ultra-short Bunch Length Measure of FEL at SINAP

cavity, electron, impedance, FEL

2788

J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

For the development of Free Electron Lasers (FEL) at SINAP, ultra-short bunch is the crucial requirement for excellent lasing performance. It’s big challenge for deflecting cavity to measure the length of ultra-short bunch, and higher deflecting gradient is required for higher measurement resolution. X-band travelling wave deflecting structure has features of higher deflecting voltage and compact structure, which is good performance at ultra-short bunch length measuring. In this paper, a new X-band deflecting structure was designed, operated at HEM11- 2π/3 mode. For suppressing the polarization of deflection plane of the HEM11 mode, two symmetrical caves are added on the cavity wall to separate two polarized modes. More details of design and simulation results are presented in this paper.

WEPFI040

R&D of C-band Pulse Compression for Soft X-ray FEL at SINAP

cavity, coupling, FEL, klystron

2791

C.P. Wang, W. Fang, Q. Gu, W.C. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact Soft X-ray Free Electron Lasers facility is presently being constructed at SINAP, and 8 C-band accelerating structure unit are required for third-stage including 4 pulse compressors. The field mode of C-band SLED is TE0.1.15 with high quality factor Q, and the coupling coefficient is 8.5. Based on the design, the power pulse of klystron is compressed from 2.5μs to 0.5μs, and finally the power gain is about 3.1. In this paper, the details and simulation of 3-dB coupler, mode convertors and the resonant cavities are presented, meanwhile some cold test results of cavity are also analyzed at the end of this paper.

WEPFI044

High Power Test of New SLED System with Biplanar 3-dB Power Divider and Dual Side-wall Coupling Irises for PAL XFEL

coupling, klystron, cavity, free-electron-laser

2803

Y.D. Joo, H. Heo, W.H. Hwang, H.-S. Lee, K.M. Oh, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

The new type of the Stanford Linear Accelerator Energy Doubler (SLED) system for the PAL (Pohang Accelerator Laboratory) XFEL (X-ray Free Electron Laser) is developed to be operated with an RF input power of 80 MW and a pulse width of 4 μs. To prevent the RF breakdown such a high power operation, a biplanar 3-dB power divider and dual side-wall coupling irises structure are used in the new SELD system. It is shown that the field gradient and surface current is reduced from that of the original SLED system using the the finite-difference time-domain (FDTD) simulation. The high power test result of the new SLED system in the PAL XFEL test facility will be presented.

WEPFI049

CoStub: A 6 1/8” Coaxial Short Circuit using Stubs

cavity, background, synchrotron, high-voltage

2809

B. Bravo, F. Mares, F. Pérez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3Gev synchrotron light source located in Barcelona and operating with users since May 2012. The ALBA storage ring uses six room temperature cavities; each one fed by two 80kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. The two possible operation modes of CaCo at high power have been tested. The symmetrical mode (two IOTs feed the CaCo symmetrically) works properly and without presenting any problem. But in the asymmetrical mode (one IOT feeds the CaCo and the other is keeping passive) a standing wave is created between the passive IOT and Caco, provoking a large voltage in the gap of the passive IOT that broke the ceramic. A new device, CoStub (coaxial stub), to short circuit the coaxial waveguide of the passive arm and protects the passive IOT has been built and successfully tested. This paper presents the design details and the low level and high power test of this device.

WEPFI064

Prototype Refinement of the VELA Transverse Deflecting Cavity Design

cavity, target, vacuum, emittance

2842

P. Goudket, S.R. Buckley, L.S. Cowie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The Versatile Linear Accelerator (VELA) at Daresbury Laboratory will deliver low energy (5/6 MeV) short bunches (~40 fs) to a number of industrial experimental stations and for scientific research. In order to measure the longitudinal profile of the bunch an S-band transverse deflecting cavity will be inserted into the beamline. A transverse kick of around 5 MV is required therefore a 9 cell design has been chosen. As part of the design iteration a three-cell prototype has been built. Frequency measurements have been performed on the prototype cavity as well as Coordinate Measuring Machine to confirm that the dimensions are to the required design tolerances. Subsequently, further modelling has been performed to improve and refine the design of the 9-cell cavity, to ensure that the frequency of the final design is within the tuning range of the water thermal control system and that the field flatness requirement can be obtained.

WEPFI070

Design of RFQ Coupler for PXIE Project

rfq, cavity, coupling, ion

2854

S. Kazakov, T.N. Khabiboulline, V. Poloubotko, O. Pronitchev, V.P. Yakovlev
Fermilab, Batavia, USA

Design of new coupler for PXIE RFQ is reported. Two couplers are supposed to deliver ~ 100 kW total CW RF power to RFQ at 162.5 MHz. Coupler has a magnetic loop coupling with the RFQ. Nevertheless it allows to apply a HV bias to suppress a multipactor due to original design of the coupling loop. Results of RF, multipactor and thermal simulations are presented.

WEPFI073

A Modular Cavity for Muon Ionization Cooling R&D

cavity, coupling, vacuum, solenoid

2860

D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA
C. Adolphsen, L. Ge, A.A. Haase, K.H. Lee, Z. Li, D.W. Martin
SLAC, Menlo Park, California, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A. Moretti, M.A. Palmer, R.J. Pasquinelli, Y. Torun
Fermilab, Batavia, USA
R.B. Palmer
BNL, Upton, Long Island, New York, USA

The Muon Accelerator Program (MAP) collaboration is developing an ionization cooling channel for muon beams. Ionization cooling channel designs call for the operation of high-gradient, normal-conducting RF cavities in multi-Tesla solenoidal magnetic fields. However, strong magnetic fields have been shown to limit the maximum achievable gradient in RF cavities. This gradient limit is characterized by RF breakdown and damage to the cavity surface. To study this issue, we have developed an experimental program based on a modular pillbox cavity operating at 805 MHz. The modular cavity design allows for the evaluation of different cavity materials - such as beryllium - which may ameliorate or circumvent RF breakdown triggers. Modular cavity components may furthermore be prepared with different surface treatments, such as high-temperature baking or chemical polishing. This poster presents the design and experimental status of the modular cavity, as well as future plans for the experimental program.

WEPFI079

Electromagnetic Modeling of RF Drive in the LANSCE DTL

cavity, coupling, DTL, HOM

2878

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

A 3D electromagnetic model of the RF drive module in the LANSCE DTL tank 4 has been developed with the CST MicroWave Studio. The model is explored both with eigensolver and in time domain to evaluate maximal fields in the drive module and RF coupling. Here we describe the model and present simulation results.

WEPFI081

High Power Tests of Overmoded Waveguide for the ILC Klystron Cluster Scheme

resonance, klystron, linac, coupling

2884

F.Y. Wang, C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA

A Klystron Cluster Scheme has been proposed for the ILC Main Linacs in which the output power of up to thirty, 10 MW, 1.3 GHz klystrons are combined in a single, 0.5 m diameter circular waveguide in a surface building and transported down to and along the accelerator tunnel where it is periodically tapped-off to power strings of cavities. This schemes eliminates the need for a separate linac service tunnel and simplifies the linac electric and cooling distribution systems. Recently, a 40 meter long circular waveguide with a coaxial input coupler and a 90 degree rf bend were assembled and run in a resonant configuration to test the concept. With the pipe pressurized with up to 30 psig of N2 to raise the rf breakdown threshold, it was demonstrated that field levels equal to those for the 300 MW transmission required for ILC could be sustained reliably. We report on these and other test results from this program.

WEPFI082

Double-tip Magnetic Field Enhancement

cavity, vacuum, electron, cathode

2887

F.Y. Wang, L. Xiao
SLAC, Menlo Park, California, USA

The local electric field enhancement factor β in an rf accelerator cavity has been studied experimentally for decades and found to be in the range from few tens up to few hundreds for various rf frequencies and materials. A large field enhancement factor is usually thought to come from sharp tips whose β is roughly the ratio of their height to their tip radius. For a β of few hundred, the corresponding tip height would need to be more than 10 microns, which should be visible in a scanning electron microscope (SEM). However, the estimated β from SEM images of cavity surfaces is around 10. Therefore, the physics of such large β values is still not clear. In this paper, we have studied differentμstructures and found that the magnetic field could be enhanced many times in the presence of two nearby tips with β of 10. The large local magnetic field enhancement could lead to large enhanced pulsed heating and thus could melt surface in a very short time and form a liquid Taylor cone.

WEPFI084

High Power S-band RF Window Optimized to Minimize Electric and Magnetic Field on the Surface

klystron, linac, vacuum, positron

2893

A.D. Yeremian, V.A. Dolgashev, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515
RF windows are used to separate vacuum from atmosphere in high power microwave systems, such as klystrons. RF breakdowns in these megawatt power environments are frequent and problematic. And S-band RF window was designed to have reduced electric and magnetic field in the ceramic and waveguide joints. Specifically the normal component of the electric field on the ceramic is minimized and a traveling wave is created inside the ceramic by optimizing the shape of the window and the geometry of the joint between the circular waveguide to the rectangular waveguide. A prototype of this window in the process of being made at SLAC for high power tests.

WEPFI090

An X-band Dielectric-based Wakefield Power Extractor

wakefield, damping, vacuum, impedance

2908

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA
V.A. Dolgashev, J.R. Lewandowski, S.G. Tantawi, S.P. Weathersby
SLAC, Menlo Park, California, USA
I. Syratchev
CERN, Geneva, Switzerland

Funding: US DoE SBIR Phase II project under Contract#DE-SC0004322
An X-band dielectric-based wakefield power extractor is under development to function as a high power rf source primarily for Two Beam Accelerator applications. A low surface electric field to gradient ratio and low fabrication cost are two main advantages of the dielectric-loaded accelerating/decelerating structure. We have designed a 12 GHz dielectric-based power extractor that has similar performance parameters to the CLIC PETS (23 mm beam channel, 240 ns pulse duration, 135 MW output per structure) using the CLIC drive beam. In order to study potential rf breakdown issues, as a first step we built a 11.424 GHz dielectric-based power extractor scaled from the 12 GHz design. A high power rf test will be conducted using the SLAC 11.424 GHz high power rf source in Dec. 2012. Results of the high power testing will be reported. Meanwhile, the 12 GHz fully featured dielectric power extractor is also under construction; construction progress and bench tests will be discussed.

WEPFI091

Design of a Normal-conducting RF-dipole Deflecting Cavity

cavity, dipole, luminosity, extraction

2911

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D. Li
LBNL, Berkeley, California, USA

In this paper we present a novel design of a CW normal conducting RF deflecting cavity. The cavity is designed into a dipole-like structure, resulting a high (R/Q)_transverse. The geometry at high H field is optimized to lower the surface peak power. We will show the design of a 325 MHz and 163 MHz cavity based on this structure and compare their performances with their superconducting counterparts.

WEPFI092

Multipacting Simulation of the MICE 201 MHz RF Cavity

cavity, solenoid, electron, coupling

2914

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D.L. Bowring, A.J. DeMello, D. Li, P. Pan, S.P. Virostek
LBNL, Berkeley, California, USA
L. Ge
SLAC, Menlo Park, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse cooling of muon beams by ionization. The MICE ionization cooling channel requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. Multipacting is a resonant electron discharge produced by the synchronization of emitted electrons with the RF fields, which can cause breakdown at high power RF operation. In this paper, we present the study of the multipacting effect in the MICE 201 MHz cavities with the SLAC ACE3P code. The simulation is carried out in the cavity body, the RF coupler region, and the coaxial waveguide, with the external magnetic field from the Coupling Coil. We will identify potential RF breakdowns due to multipacting and propose a solution to suppress them.

WEPME044

Generation of Controlled Losses in Milisecond Timescale with Transverse Damper in LHC

beam-losses, proton, emittance, injection

3025

M. Sapinski, T. Baer, V. Chetvertkova, B. Dehning, W. Höfle, A. Priebe, R. Schmidt, D. Valuch
CERN, Geneva, Switzerland

A controlled way of generating of beam losses is required in order to investigate the quench limits of the superconducting magnets in the LHC. This is especially difficult to achieve for losses with millisecond duration. A series of experiments using the transverse damper system has proven that such a fast loss can be obtained even in the case of rigid 4 TeV beams. This paper describes the optimisation of beam parameters and transverse damper waveform required to mimic fast loss scenarios and reports on extensive tracking simulations undertaken to fully understand the time and spatial structure of these losses. The application of this method to the final quench tests is also presented.

WEPME058

Integrated System Modeling Analysis of a Multi-cell Deflecting-mode Cavity in Cryogenic Operation

cavity, cryomodule, vacuum, coupling

3064

Y.-M. Shin, M.D. Church, J. Ruan
Fermilab, Batavia, USA

Over the past decade, multi-cell deflecting (TM110) mode cavities have been employed for experiments on six-dimensional phase-space beam manipulation *,**,***,****,****** at the A0 Photo-Injector Lab (16 MeV) in Fermilab and their extended applications with vacuum cryomodules are currently scheduled at the Advanced Superconducting Test Accelerator (ASTA) user facility (> 50 MeV). Despite the successful test results, the cavity, however, demonstrated limited RF performance during liquid nitrogen (LN2) ambient operation that was inferior to theoretic prediction. We thus fully inspected the cavity design with theoretical calculation (based on Panofsky-Wenzel theorem) combined with RF simulations. Also, we are extensively developing an integrated computational tool with comprehensive system analysis capacity to solve complex thermodynamics and mechanical stresses of a high-Q deflecting-mode cryomodule. We will benchmark simulation analysis result with experimental data from high power RF tests in Fermilab. Successfully developed modeling tool will be potentially used for prompt assessment on RF performance of vacuum-cryomodules.
* D. A. Edwards, LINAC 2002
** Y.-E Sun, PRTAB 2004
*** P. Piot, PRSTAB2006
**** J. Ruand et al., PRL 2011
***** Y.-E. Sun, et al., PRL 2010

WEPME061

A Wideband Slotted Kicker Design for SPS Transverse Intra-bunch Feedback

kicker, impedance, feedback, coupling

3073

J.M. Cesaratto, J.D. Fox, C.H. Rivetta
SLAC, Menlo Park, California, USA
D. Alesini, A. Drago, A. Gallo, F. Marcellini, M. Zobov
INFN/LNF, Frascati (Roma), Italy
S. De Santis
LBNL, Berkeley, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP) and by the EU FP7 HiLumi LHC - Grant Agreement 284404.
Control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential for the SPS to meet the beam intensity demands for the HL-LHC upgrade. A wideband intra-bunch feedback method is in development, based on a 4 GS/s data acquisition and processing, and with a back end frequency structure extending to 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, has been considered as the terminal element of the feedback chain. It offers the most promising deflecting structure characteristics to meet the system requirements in terms of bandwidth, shunt impedance, and beam coupling impedance. Different types of slotted structures have been explored and simulated, including a ridged waveguide and coaxial type waveguide. In this paper we present our findings and the conceptual design of a vertical SPS wideband kicker consistent with the stay clear, vacuum, frequency band coverage, and peak shunt impedance requirements.

THOAB103

Phase Space Tomography Research at Daresbury

quadrupole, space-charge, electron, FEL

3096

K.M. Hock, D.J. Holder, M.G. Ibison, B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

We report on the progress of phase space tomography research at Daresbury. The efforts over the past three years have been focussed on measuring the electron beam at the ALICE tomography section. Based on this result, we have developed techniques for improving resolution using normalised phase space, removing streaking artefacts by thresholding, demonstrating reliability of reconstructed phase space. We have developed in-house reconstruction codes using both the Filtered Back Projection and the Maximum Entropy Techniques. We are currently using a combination of simulation and measurements to investigate the onset of space charge effects at low bunch charges over short distances.

Slides THOAB103 [0.878 MB]

THOBB101

Transverse-to-longitudinal Emittance Exchange at the Fermilab Advanced Superconducting Test Accelerator

emittance, quadrupole, cavity, controls

3103

C.R. Prokop, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
B.E. Carlsten
LANL, Los Alamos, New Mexico, USA
M.D. Church, P. Piot
Fermilab, Batavia, USA

Funding: LANL LDRD program, project 20110067DR U.S. DoE under Contract No. DE-FG02-08ER41532 with Northern Illinois University and under Contract No. DE-AC02-07CH11359 the Fermi Research Alliance, LLC.
Earlier experiments at Fermilab’s A0 Photoinjector Laboratory demonstrated successful transverse-to-longitudinal emittance exchange (EEX) using a transverse-deflecting cavity (TDC) located between two identical doglegs. Such a design has the disadvantage of transversely displacing the beam. An interesting alternative is an EEX beamline designed out of a variable R56 bunch compressor chicane. In this paper, we present design and simulation testing for a chicane-based EEX for eventual implementation at Fermilab’s Advanced Superconducting Test Accelerator. We explore several advanced EEX concepts, including bunch current profile shaping, bunch compression, and dispersion-boosting to relax the requirements on TDC power and cooling.

Slides THOBB101 [2.582 MB]

THOAB201

Development of the Dielectric Wall Accelerator

proton, dipole, radiation, shielding

3115

A. Zografos, T. Brown, C. Cohen-Jonathan, C. Hettler, F. Huang, V. Joshkin, K. Leung, M. Moyers, Y.K. Parker, D. Pearson, M. Rougieri
CPAC, Livermore, CA, USA
R.W. Hamm
R&M Technical Enterprises, Pleasanton, California, USA

The Compact Particle Accelerator Corporation has developed an architecture to produce pulsed proton bunches that will be suitable for proton beam therapy. The Dielectric Wall Accelerator engineering prototype includes a RFQ injection system with a pulsed kicker to select the desired proton bunches and a linear accelerator incorporating a High Gradient Insulator with stacked transmission to produce the required voltage. The transmission lines are switched with solid state laser driven optical switches. A computational model has been developed that is in very good agreement with the experimental results. The system is presently achieving accelerating gradients of approximately 15 MeV/m. The computational model has been used to design the next generation system that will achieve 25 MeV/m by early 2013. This paper will discuss the status of the apparatus, the basic elements of the computational model, experimental results and comparison to the model predictions. In addition, the paper will present concepts for proton therapy systems that incorporate the Dielectric Wall Accelerator and fully leverage its features to achieve clinical requirements.

Slides THOAB201 [1.650 MB]

THPPA02

Features and Applications of the Program ELEGANT

electron, linac, FEL, lattice

3139

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
ELEGANT is an open-source accelerator design and simulation code that has been in use and development for nearly two decades. In that time, it has evolved into a fairly general code for the design and modeling of linacs and storage rings, due in no small measure to suggestions and feedback from users world-wide. The code is best known for modeling of linacs for free electron lasers and particularly its relatively fast and straightforward modeling of coherent synchrotron radiation in magnetic bunch compression systems. This capability led to the discovery of a microbunching instability in such systems, thus helping to seed a new field of research. ELEGANT's capabilities are enhanced by the use of self-describing data files and the Self-Describing Data Sets (SDDS) toolkit. In this paper, we briefly review the features and capabilities of the code, then give a series of application examples from simulation of linear accelerators and storage rings.

Slides THPPA02 [0.477 MB]

THPEA006

!CHAOS Historical Engine

controls, insertion

3158

M. Mara, A. Paoletti
Istituto Nazionale di Fisica Nucleare, Amministrazione Centrale, Frascati, Italy
C. Bisegni, G. Di Pirro, L.G. Foggetta, G. Mazzitelli, A. Stecchi
INFN/LNF, Frascati (Roma), Italy
L. Catani, F. Zani
INFN-Roma II, Roma, Italy

!CHAOS is an INFN project aimed at creating the communication framework and the services needed for the definition of a new control system standard, mainly addressed to large experimental apparatus and particle accelerators. !CHAOS is under test at DAΦNE accelerator and has been developed to overcome the strong requirements throughput of new accelerators, like superB. One of the main components of the framework is the historical engine (HST Engine), a cloud-like environment optimized for the fast storage of large amount of data produced by the control system’s devices and services (I/O channels, alerts, commands, events, etc.), each with its own storage and aging rule. The HST subsystem is designed to be highly customizable, such to adapt to any desirable data storage technologies, database architecture, indexing strategy and fully scalable in each part. The architecture of HST Engine and the results of preliminary tests for the evaluation of performance are presented.

THPEA008

Study on the Energy Response of a Multi-layer Planar High Pressure Ionization Chamber using MCNP Program

photon, radiation, ion, electron

3164

Y.D. Ding, P.F. Wang, Q.B. Wang, Q.J. Zhang
IHEP, Beijing, People's Republic of China

High pressure ionization chamber is widely used to detect various radiation fields due to its good energy response. A new Multi-layer planar high pressure ionization chamber is designed suitable for measuring directional radiation field of high dose rate, because of its high electric field strength. In this paper, MCNP program is used to simulate and calculate the energy response of this ionization chamber to obtain the energy response of high energy photons, which could not be obtained by experimental methods. The results show that this ionization chamber can measure photon radiation energy up to 10MeV.

THPEA010

Design and Implementation of the Remote Control System of the Digital Magnet Power Supply of China Spallation Neutron Source

controls, power-supply, EPICS, status

3167

X. Wu, Y.C. He, J. Liu, C.H. Wang, J.C. Wang
IHEP, Beijing, People's Republic of China

The magnet power supplies of the China Spallation Neutron Source (CSNS) can be classified into three types: rapid cycling synchrotron (RCS) resonant power supplies, fast response power supplies and DC power supplies. All of the magnet power supplies are controlled by the intelligent controller called Digital Power Supply Control Module (DPSCM), which can regulate the current and voltage circuit. The DPSCM is developed by the power supply group. It has two RS232 communication interfaces. All the command setting and reading power parameters are transmitted by Modbus protocol. Therefore, we made the communication protocol based on Modbus RTU between the remote control system and the DPSCM. This paper introduces the design of the remote control interface to the DPSCM. We developed EPICS IOC applications and real-time database on MOXA embedded serial device DA710 and OPIs using Control System Studio (CSS) according to different kinds of the power supplies. We have tested the remote control system with these kinds of power supplies. The test result shows that the remote control system is stable and reliable and it can basically meet the requirements of power supply system and physicists.

THPEA027

Radiation Calculations for Advanced Proton Therapy Facility

shielding, proton, radiation, target

3201

J.Q. Xu, J.J. Lu, G. Wang, X. Xia
SINAP, Shanghai, People's Republic of China

The shielding calculations for Advanced Proton Therapy Facility (APTRON), which is under design in Shanghai, were carried out. The thickness of radiation shielding walls for the accelerator and treatment rooms of APTRON were determined by Monte Carlo simulation and empirical formula. Beam loss scenarios and workloads of different energy at LINAC, synchrotron, beam transport line and treatment are given for the calculations. The calculations were carried out for the proton energy of 150MeV, 220MeV and 250MeV, and the targets of iron and equivalent tissue material. Source terms and attenuation length were calculated with different angles by the simulation using FLUKA code. Based on the source terms and the attenuation length, the thickness of the bulk walls were determined. Local shielding and maze design were also concerned.

THPEA039

Radiation Protection Study for the Shielding Design of the LINAC 4 Beam Dump at CERN

linac, shielding, radiation, neutron

3225

J. Blaha, J. Vollaire
CERN, Geneva, Switzerland

Linac4, a new 160 MeV H⁻ accelerator, is currently being constructed at CERN. The accelerator is terminated by a dump collecting beam which is not intended for further utilization. The aim of this study is to determine an optimal shielding of the beam dump fulfilling the radio-protection requirements. The proposed shielding must take into account different accelerator operational phases, the space constraints inside the accelerator vault as well as the decommissioning of the installation at the end of its lifetime. Therefore a detailed Monte-Carlo calculation using FLUKA particle transport and interaction code has been performed and the relevant physics quantities have been evaluated for different irradiation profiles and shielding material. Moreover, the residual dose rate and induced activation have been calculated for several cooling times in order to optimize the choice of the shielding material following the ALARA principle. Finally the airborne radioactivity induced by particles escaping the shielding as well as the activation of the beam dump cooling water have been also calculated using FLUKA and simplified laminar flow models.

THPEA045

Beam Induced Quenches of LHC Magnets

injection, quadrupole, beam-losses, kicker

3243

M. Sapinski, T. Baer, M. Bednarek, G. Bellodi, C. Bracco, R. Bruce, B. Dehning, W. Höfle, A. Lechner, E. Nebot Del Busto, A. Priebe, S. Redaelli, B. Salvachua, R. Schmidt, D. Valuch, A.P. Verweij, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

In the years 2009-2013 LHC was operating with the beam energy of 3.5 and 4 TeV instead of the nominal 7 TeV, with the corresponding currents in the superconducting magnets also half nominal. To date only a small number of beam-induced quenches have occurred, with most being due to specially designed quench tests. During normal collider operation with stored beam there has not been a single beam induced quench. This excellent result is mainly explained by the fact that the cleaning of the beam halo worked very well and, in case of beam losses, the beam was dumped before any significant energy was deposited in the magnets. However, conditions are expected to become much tougher after the long LHC shutdown, when the magnets will be working at near nominal currents in the presence of high energy and intensity beams. This paper summarizes the experience to date with beam-induced quenches. It describes the techniques used to generate controlled quench conditions which were used to study the limitations. Results are discussed along with their implication for LHC operation after the first Long Shutdown.

THPEA047

Diamond Particle Detector Properties during High Fluence Material Damage Tests and their Future Applications for Machine Protection in the LHC

target, proton, beam-losses, radiation

3249

F. Burkart, J. Blanco, J. Borburgh, B. Dehning, M. Di Castro, E. Griesmayer, A. Lechner, J. Lendaro, F. Loprete, R. Losito, S. Montesano, R. Schmidt, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

Experience with LHC machine protection (MP) during the last three years of operation shows that the MP systems sufficiently protect the LHC against damage in case of failures leading to beam losses with a time constant exceeding 1ms. An unexpected fast beam loss mechanism, called UFOs, was observed, which could potentially quench superconducting magnets. For such fast losses, but also for better understanding of slower losses, an improved understanding of the loss distribution within a bunch train is required. Diamond particle detectors with bunch-by-bunch resolution and high dynamic range have been developed and successfully tested in the LHC and in experiments to quantify the damage limits of LHC components. This paper will focus on experience gained in use of diamond detectors. The properties of these detectors were measured during high-fluence material damage tests in CERN's HiRadMat facility. The results will be discussed and compared to the cross-calibration with FLUKA simulations. Future applications of these detectors in the LHC to understand beam losses and to improve the protection against fast particle losses will be discussed.

THPEA059

Database for Accelerator Modeling

lattice, controls, monitoring, extraction

3273

C.P. Chu, J. Wu
SLAC, Menlo Park, California, USA
D. Dohan, G. Shen
BNL, Upton, Long Island, New York, USA
H.H. Lv
IHEP, Beijing, People's Republic of China
Y. Zhang
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
A database for model data is design for the Facility for Rare Isotope Beams (FRIB) Project. The database schema design takes most general approach and is not limited to FRIB models. Programmatically access to the database can be done through a set of Application Programming Interfaces (APIs). Initial data population demonstrates that the database is suitable for XAL application framework. The model database is also part of a collaboration for complete database needs among various domains across an accelerator.

THPFI005

Simulations for Mechanical Design of Nozzle for Extrude of Windowless Solid Hydrogen Cryogenic Target

target, extraction, cryogenics

3297

H. Gassot, C. Commeaux
IPN, Orsay, France

The hydrogen (H2 and D2) target is the determining element of unstable nucleus spectroscopy. This target is proposed for heavy ions beam of several MeV/nucleon in SPIRAL and SPIRAL 2 projects. Without window, the carbone contamination of the hydrogen target could be avoided. Within the project of CHyMENE (Cible d’Hydrogène Mince pour l’Etude des Noyaux Exotiques), the development of hydrogen target is supported by ANR (Agence National de la Recherche) which federates differents French research institutes such as CNRS and CEA. The IPN Orsay is involved on the conception and simulations of a nozzle which can deliver a solid ribbon of 50 micron thickness; it is a very challenging program since the knowledge about hydrogen solid at 12 K is rare, especially in terms of experimental characterizations. The important work consists at first to propose models of simulations in order to study mechanical behaviours of solid hydrogen at cryogenic temperature under pressure and optimize the geometry parameters as well as rheology properties of nozzle. The mechanical non linear modelling including contact behaviours are presented. The first simulations results are summarized.

THPFI006

A New External Beamline for Detector Tests

quadrupole, dipole, electron, extraction

3300

N. Heurich, F. Frommberger, P. Hänisch, W. Hillert, S. Patzelt
ELSA, Bonn, Germany

At the electron accelerator ELSA, a new external beamline is under construction, whose task is to provide a primary electron beam for detector tests. In the future, the accelerator facility will not only be offering an electron beam to the currently installed double polarization experiments for baryon spectroscopy, but to the new "Research and Technology Center Detector Physics" as well. This institution will be established near the accelerator in Bonn and is charged with the development of detectors for particle and astroparticle physics. The requirement for the new beamline is to be able to vary the beam parameters such as beam current and width over a wide range. With the resonance extraction method, it is possible to extract electrons with a maximum energy of 3.2 GeV slowly to the test area. A quasi-continuous external beam current of 1 fA to 100 pA can be offered. A further reduction of the beam current can be realized by utilizing the single-pulse operation mode at ELSA. The beam width can be changed in both transverse directions from 1 mm to 8 mm.

THPFI011

Thermal Simulations of Charge-exchange Stripper Foils for High-melting-point Materials

stripper, injection, radiation, proton

3312

Y. Takeda
KEK, Ibaraki, Japan
M.A. Plum
ORNL, Oak Ridge, Tennessee, USA

Charge-exchange stripper foils can be very quickly broken by high-current beams. Hence, a long-lived foil that can withstand prolonged beam irradiation is eagerly awaited. It is well known that the maximum temperature of the foil plays an important role in the foil lifetime. Therefore, the temperature distribution map and the maximum temperature of the foils were investigated in detail by using simulation software of the finite element method and applications with ANSYS. Moreover, the heating properties of several kinds of high-melting-point materials were researched. According to the results, stripper foils of the same effective thickness showed drastically different maximum temperatures, differing by up to about 200 K. From these results, we show that the emissivity and specific heat of the foil considerably influences its maximum temperature.

THPFI019

Main Magnet Installation for CYCIAE-100

target, cyclotron, tandem-accelerator, vacuum

3336

Y.L. Lu, W. Jing, Z.H. Wang, T.J. Zhang
CIAE, Beijing, People's Republic of China

The CYCIAE-100 proton cyclotron being constructed in CIAE is designed to extract the proton beam of 100MeV and 200uA. The main magnet is the importantest part of the cyclotron. The diameter of the CYCIAE-100 main magnet is 6160mm. Its height is 3860mm. Its total weight is about 416 tons, and the largest part is about 170 tons. The beamline of CYCIAE-100 will be connected to the HI-13 tandem accelerator at CIAE. So, the CYCIAE-100 main magnet should be installed accurately. The vertical tolerance of the CYCIAE-100 main magnet is 0.20mm, and the horizontal tolerance is 0.50mm. The CYCIAE-100 main magnet is located in an underground building which level is -4m. There is a horizontal hole on the west wall of the accelerator building. All parts of the main magnet had been transported through this horizontal hole. The CYCIAE-100 main magnet had been installed in November 2012 at CIAE. In fact the error of installation is: the vertical 0.10mm, the horizontal 0.20mm. The installation process will be shown in this paper.

THPFI023

A Newly Developed High Directivity X-band Waveguide Directional Coupler

coupling, insertion, pick-up, vacuum

3345

X. He, X. Wang, F. Zhao
IHEP, Beijing, People's Republic of China

A new X-band waveguide directional coupler working at 11.9924 GHZ is designed. Four holes symmetrical to the structure is drilled along the central line of the narrow-wall, which is used to couple the electromagnetic power from the main-waveguide to the sub-waveguide. The final prototype has got a measurement result of 32.2 dB Directivity (-47.0 dB Coupling Degree) together with a very low VSWR (1.067) and Insertion Loss (-0.11 dB) at 11.9924 GHz. The vacuum performance is also qualified.

THPFI025

Design and Experimental Results of an Electro-static Pre-chopper for CSNS LEBT

rfq, power-supply, radiation, cavity

3351

H.C. Liu, S. Fu, K.Y. Gong, H.F. Ouyang, J. Peng
IHEP, Beijing, People's Republic of China

The China Spallation Neutron Source (CSNS) front end incorporates a pre-chopper in the Low Energy Beam Transport line (LEBT) that will remove a 530ns section of beam at approximately 1MHz rate, which is the RF frequency of the ring at injection. It’s one of the most critical devices for properly controlling the injecting beam loss. Physical designing of the pre-chopper is carried out, and the RFQ itself was used as the beam dump of the chopper system. In order to examine the reliability of the pre-chopper design, the beam study of a similar chopper system was successfully performed. Results of physical design and experiments will be presented.

THPFI031

Development of Beam Collimators for the 1.6 GeV Rapid Cycling Synchrotron of CSNS

collimation, vacuum, synchrotron, shielding

3364

J.B. Yu, pf.He. He, L. Kang, H. Qu, Y.Q. Zou
IHEP, Beijing, People's Republic of China

In order to reduce the uncontrolled losses in the localized station, the beam collimation system has been performed for the 1.6GeV synchrotron of CSNS. The CSNS/RCS transverse collimation system is designed to be a two-stage system which consists of one primary collimator and four secondary collimators. Much work about machinery design and manufacture of the collimation system has been done till now. This paper will show the exterior frame of collimation system by considering the physical demands and spatial position. Then the progress which contains design and machining of collimators will also be introduced. Finally some problems which are mainly about the design of secondary collimators will be mentioned.

THPFI035

Design of A 4-cavities Collinear Load Coated with FeSiAl Alloy for 14 MeV LINAC

cavity, linac, target, instrumentation

3370

F. Zhang, L.G. Shen
USTC/PMPI, Hefei, Anhui, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

Collinear load is a substitute for waveguide load to miniaturize linear accelerator and make the beam quality better. Coating with a kind of high efficient microwave-absorbing material FeSiAl alloy, a collinear load section composed of 4 cavities (at 2 /3 mode) with different coating dimensions is designed to absorb 4kW remnant power. Cavity dimensions are adjusted to compensate the frequency shift from 2856 MHz respectively. Simulation shows the loss material FeSiAl only need to be coated on the inner surface of the ring. This makes the design and construction of the cooling system for the load segment easier. Coming with a specific water cooling system can makes the working frequency of the accelerator and the collinear load more close to the supposed. Eventually, based on optimized uniform power absorption principle concluded from the simulation of temperature field, a four-cavity collinear load is designed with one-way attenuation of 76.1 dB, while the largest shift from operation frequency is 35 kHz.

THPFI046

First Results of an Experiment on Advanced Collimator Materials at CERN HiRadMat Facility

proton, vacuum, instrumentation, laser

3391

A. Bertarelli, O. Aberle, R.W. Aßmann, E. Berthomé, V. Boccone, M. Calderón Cueva, F. Carra, F. Cerutti, N. Charitonidis, C. Charrondière, A. Dallocchio, M. Donzé, P. Francon, M. Garlaschè, L. Gentini, M. Guinchard, N. Mariani, A. Masi, P. Moyret, S. Redaelli, A. Rossi, S.D.M. dos Santos
CERN, Geneva, Switzerland
M. Calderón Cueva
Universidad San Francisco de Quito, Cumbayá, Colombia
N. Charitonidis
EPFL, Lausanne, Switzerland
L. Peroni, M. Scapin
Politecnico di Torino, Torino, Italy

Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project EuCARD, grant agreement no. 227579
A comprehensive, first-of-its-kind experiment (HRMT-14) has been recently carried out at CERN HiRadMat facility on six different materials of interest for Beam Intercepting Devices (collimators, targets, dumps). Both traditional materials (Mo, W and Cu alloys) as well as advanced metal/diamond and metal/graphite composites were tested under extreme conditions as to pressure, density and temperature, leading to the development of highly dynamic phenomena as shock-waves, spallation, explosions. Experimental data were acquired, mostly in real time, relying on extensive embarked instrumentation (strain gauges, temperature and vacuum sensors) and on remote acquisition devices (laser Doppler vibrometer and high speed camera). The experiment was a success under all points of view in spite of the technological challenges and harsh environment. First measurements are in good agreement with results of complex simulations, confirming the effectiveness of the acquisition system and the reliability of advanced numerical methods when material constitutive models are completely available. Interesting information has been collected as to thermal shock robustness of tested materials.

THPFI062

Design of Air-cooled Beam Dump for Extraction Line of PS Booster

shielding, booster, cavity, proton

3436

A. Perillo-Marcone, T. Antonakakis, M. Battistin, M.A. Czapski, G.W. Mason, E.M. Nowak, A. Sarrió Martínez, S. Sgobba, V. Venturi, V. Vlachoudis
CERN, Geneva, Switzerland

A new beam dump has been designed, which withstands the future proton beam extracted from the PS Booster at CERN, consisting of up to 10¹⁴ protons per pulse at 2 GeV after its upgrade in 2018/2019. In order to be able to efficiently release the deposited heat, the new dump will be made out of a single cylindrical block of a copper alloy and be cooled by forced ventilation. In order to determine the energy density distribution deposited by the beam in the dump, Monte Carlo simulations were performed using FLUKA, and thermo-mechanical analyses carried out by importing the energy density into Ansys. In addition, CFD simulations of the airflow were carried out in order to accurately estimate the heat transfer convection coefficient on the surface of the dump. In this paper we describe the design process and highlight the constraints of integrating a new dump for increased beam power into the existing facility.

THPFI064

Crystal-assisted Collimation Experiment from the SPS to the LHC

collimation, extraction, background, alignment

3442

W. Scandale, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

UA9 was operated in the CERN-SPS for more than six years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 μrad, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency, showing a steady reduction of almost one order of magnitude of the loss rate at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency also in LHC. After a concise description of the results collected in the SPS we propose a scenario to integrate bent crystals in the LHC collimation system for machine experiment.

THPFI065

Thermo-mechanical Investigations of the SINQ "Cannelloni" Target

target, factory, neutron, scattering

3445

R. Sobbia, S. Dementjevs, S. Joray, M. Wohlmuther
PSI, Villigen PSI, Switzerland

Numerical results of three-dimensional ANSYS thermo-mechanical simulations of single components of the SINQ target system are presented. Thermal stresses are generated by energy deposition in so-called ‘‘cannelloni'' consisting of a Zircaloy-2 rod filled with Lead to 90% of its inner volume. The molten region of the inner Lead filling is calculated by thermal analysis using the energy deposition profile imported from MCNPX calculations. Induced mechanical stresses are studied for a set of predefined parameters, the heat transfer coefficient and the bulk temperature of the heavy water cooling system. Critical stress regions are investigated to provide possible failure scenarios and overall system performance.

THPFI072

Heat Transfer Analysis of a Water-cooled Channel for the TPS Front End Components

synchrotron, synchrotron-radiation, radiation, insertion

3466

C.K. Kuan, J.-R. Chen, Y.T. Cheng, J.Y. Chuang, H.Y. Lin, P.A. Lin, Y.K. Liu, I.C. Sheng, T.C. Tseng
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The masks, absorbers and slits must withstand the extremely high power and power density in the TPS front end. The material always used is OFHC or Glidcop. One solution is to increase the cooling efficiency of the water-cooled channel in these components. With the restrictions of water pressure < 7 kg/cm² and water flow velocity < 3 m/s, the wire coil is chosen to enhance the average heat- transfer coefficient and increase not too much the loss of water pressure. With a water channel of diameter 7.5 mm and wire coil inserts of pitch 7.5 mm and wire diameter 1 mm, the cooling efficiency becomes enhanced 1.4 to 2 times in the components of the TPS front end. The wire coils of varied pitches are simulated and calculated in this work. We also compare our investigated data with other experimental data of other authors.

THPFI082

Targetry Challenges at Megawatt Proton Accelerator Facilities

target, proton, radiation, kaon

3484

P. Hurh, K. Ammigan, B.D. Hartsell, R.S. Tschirhart
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02- 07CH11359 with the U.S. Department of Energy.
High intensity, multi-megawatt proton accelerator facilities, such as the proposed Project X at Fermilab, offer the opportunity to explore science in multiple experiments and programs simultaneously. The reliable operation of the associated target facilities is as critical to the success of the experimental program as the high intensity proton accelerator itself. The targetry requirements for the Project X experimental program range from 1 GeV, 1 MW, CW proton beam on a high-Z target (possibly liquid metal) to 120 GeV, 2.3 MW, pulsed proton beam on a low-Z target and include stringent, experiment-specific operating environments such as high magnetic fields from super-conducting magnets and/or moderator arrays for optimal neutronic production. Meeting the challenges presented by such wide-ranging and intertwined requirements calls for coordinated and cross-cutting R&D activities. Areas of interest applicable to many of the experimental facilities includes radiation damage, thermal shock, radiological protection, and target instrumentation. Descriptions of these challenges and Fermilab R&D activities to overcome these difficult challenges are presented.

THPFI085

Status of PXIE MEBT Absorber Development

electron, vacuum, radiation, gun

3490

A.V. Shemyakin, C.M. Baffes, K. Carlson, A.Z. Chen, Y.I. Eidelman, B.M. Hanna, L.R. Prost, J.T. Walton
Fermilab, Batavia, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
One of the goals of the Project X Injector Experiment (PXIE) at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will be taking place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. A ¼ - size prototype of the absorber is manufactured, and its thermal properties are tested with an electron beam generating a peak power density similar to the one expected during normal operation of the PXIE beam line. The paper describes the absorber concept, the prototype, the testing procedure with the electron beam, and the latest results.

THPFI090

Accuracy of Measurements of ε and μ of Lossy Materials

HOM, higher-order-mode, insertion, damping

3499

V.D. Shemelin, J.J. Kaufman
CLASSE, Ithaca, New York, USA

Funding: NSF award DMR-0807731
Measurements of samples of lossy ceramic and ferrites for Higher Order Mode Loads are performed routinely in our Lab. Some difference of results for different batches of materials can be explained not only by technological deviations in the material production but also by errors in the dimensions of the measured samples. Simulations with MicroWave Studio for samples in the form of coaxial washers in the frequency range from 1 to 12.4 GHz helped to define the main sources of errors and to improve accuracy of measurements.

THPME007

HTS Magnet to Polarize Ultra Cold Neutrons

neutron, dipole

3522

K. Hatanaka, M. Fukuda, N. Hamatani, K. Kamakura, T. Saito, H. Ueda, Y. Yasuda, T. Yorita
RCNP, Osaka, Japan
T. Kawaguchi
KT Science Ltd., Akashi, Japan

We have developed magnets using High Temperature Superconductor (HTS) wires for this decade. A HTS magnet was designed and fabricated to polarize ultra cold neutrons (UCN). It consists of 10 double pancakes and the number of the total winding is 2,800 turns. The inner diameter of the coil is 131.5 mm and the coil is 10⁵ mm long. The coil is conduction cooled by a pulse tube cryocooler and the operating temperature is expected to be 20 K. The maximum rated current is 200 A and the magnetic field is higher than 3.5 T at the center. Results of cooling tests and field measurements are presented.

THPME010

Magnetic Shielding for the 1.3 GHz Cryomodule at IHEP

shielding, cavity, SRF, cryomodule

3528

S. Jin, Y. Chen, J. Gao, R. Ge, Y. Liu, Z.C. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
F. Yang
China Iron and Steel Research Institute Group, Beijing, People's Republic of China

An ILC-type Superconducting RF (SRF) accelerating unit is being studied at IHEP. In order to achieve the design performance including both accelerating gradient and quality factor, the SRF cavity must be cooled with ambient magnetic field well shielded to the level of several mG[1,2]. In this paper, permeability of several kinds of materials for magnetic shielding made in China is systematically studied in cooperation with China Iron & Steel Research Institute Group (CISRI) and reported for the first time. By using proper material, numerical calculation for the magnetic shielding design was done via the program of Opera-3D, and then magnetic shield was fabricated by CISRI. This paper will show those studies above and the final magnetic shielding effect at room temperature. Comparisons between simulation result and real effect will also be discussed in the paper, as well as the preliminary analysis for the magnetic field leaking of this design.

THPME036

Design and Measurement of the Transfer Line Magnets for the Taiwan Photon Source

quadrupole, dipole, booster, linac

3591

C.Y. Kuo, C.-H. Chang, H.-H. Chen, Y.L. Chu, J.C. Huang, M.-H. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin
NSRRC, Hsinchu, Taiwan

The Taiwan photon source (TPS) transfer line from the linac to the booster (LTB) is made of 1 bending magnet, 11 quadrupoles and the booster to the storage ring (BTS) is include of 2 bending magnets, 7 quadrupoles. LTB bending magnet is provided for 11 degrees defection from the linac to the booster and 31 degrees from the linac to the beam dumper with two operating currents. The BTS quadrupoles are included four 0.3m and three 0.4m magnets which cross sections are the same with booster quadrupole give different integral quadrupole field strengths and cooling systems are redesign from 2 circuits to 4. The magnetic fields were simulated with Opera 2D and 3D; optimum processes are discussed. All of the magnets have been constructed by Danfysik, scanditronix and Gongin. This paper discusses the features, the design concept and the results of field measurements of these transfer line magnets.

THPME047

Progress of the RFQ Accelerator for PXIE

rfq, emittance, beam-transport, ion

3618

D. Li, M.D. Hoff, A.R. Lambert, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
T.H. Luo
UMiss, University, Mississippi, USA
S. Nagaitsev, G.V. Romanov, A.V. Shemyakin, R.P. Stanek, J. Steimel
Fermilab, Batavia, USA

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
The proposed Project X Injector Experiment (PXIE) is currently under development at Fermilab. PXIE is an R&D test accelerator that will replicate the front-end portion of Project X. The PXIE accelerator complex consists of a H⁻ ion source(s), low-energy beam transport (LEBT), 162.5 MHz normal conducting CW Radio-Frequency-Quadrupole (RFQ) accelerator, medium-energy beam transport (MEBT), broad-band beam chopper(s) and two superconducting cryomodules. In this paper, we will review and present recent progress of the PXIE RFQ, which will include an overview of the RFQ beam dynamics design, RF structure design, detailed thermal and mechanical analyses, fabrication test results and fabrication plan and schedule.

THPWA002

Optimization of the Photoneutron Flux Emitted by an Electron Accelerator for Neutron Interrogation Applications using MCNPX and TRIPOLI-4 Monte Carlo Codes

target, electron, neutron, photon

3630

A. Sari, F. Carrel
CEA/DRT/LIST, Gif-sur-Yvette Cedex, France
C. Jouanne, A. Lyoussi, O. Petit
CEA, Gif-sur-Yvette, France

Various applications require neutron interrogation to detect special nuclear material. In a previous study*, we demonstrated the feasibility of this technique using the photoneutron flux emitted by a 16 MeV linear electron accelerator. This approach enables to reach average emission intensity on the order of one decade beyond the one produced by deuterium-tritium neutron generators traditionally used for such applications. Higher average emission intensities of the photoneutron flux would enable to expand boundaries of neutron interrogation. This new study aims at optimizing the photoneutron flux emitted by an electron accelerator. In order to ensure accuracy and reliability of our results, two Monte Carlo particle transport codes were used in parallel in this study: MCNPX developed by Los Alamos National Laboratory, and TRIPOLI-4 developed by the French Alternative Energies and Atomic Energy Commission. Potential discrepancies between results obtained with the two codes were investigated. Furthermore, careful attention was given to minimize the high-energy photon beam contained in the photoneutron flux in order to reduce spurious photofission reactions during measurements.
*A. Sari et al., IEEE Trans. Nucl. Sci., vol. 59, no.3, pp. 605-611, 2012.

THPWA008

Design of a Fast-cycling High-gradient Rotating Linac for Protontherapy

linac, cyclotron, proton, klystron

3642

A. Degiovanni, U. Amaldi, D. Bergesio, C. Cuccagna, A. Lo Moro, P. Magagnin, P. Riboni, V. Rizzoglio
TERA, Novara, Italy

General interest has been shown over the last years for the development of single room facilities serving a population of about 2 million people for proton cancer therapy. Compact machines are needed to accelerate proton beams of few nanoamperes up to 230 MeV. In this framework the project TULIP (Turning LInac for Protontherapy), patented by TERA Foundation, foresees a linac mounted on a rotating gantry used as a booster for protons previously accelerated by a cyclotron. The linac is composed of modular units powered by independently controlled klystrons. The RF power transmission is made possible by high power rotating joints developed in collaboration with CLIC group. The final beam energy can be varied in steps of few MeV from pulse to pulse by amplitude and/or phase modulation of the klystron signals, making possible the implementation of active spot scanning technique with tumor multi-painting. The present paper provides the main characteristics of TULIP, describing the different choices for the linac design parameters together with the structural design of the supporting gantry and of the final beam line.

THPWA011

Concepts of 220 MeV Racetrack Microtron for Non-destructive Nuclear Material Detection System

electron, microtron, acceleration, gun

3651

T. Hori, T. Kii, R. Kinjo, H. Ohgaki, M. Omer, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
I. Daito, R. Hajima, T. Hayakawa, M. Kando, H. Kotaki
JAEA, Kyoto, Japan
F. Sakai
SHI, Tokyo, Japan

Funding: Japan Science and Technology Agency Special Coordination Funds for Promoting Science and Technology (Grant No. 066)
A nuclear material detection system (NMDS) using the quasi-monochromatic gamma-ray beam from a laser Compton scattering (LCS) source is proposed for the container inspection, where nuclear resonance fluorescence method is to be employed for the specific isotope identification such as U-235. In the system an electron beam of good quality at about 220-MeV must be provided for LCS. One of the most promising electron source is a compact electron accelerator named racetrack microtron (RTM). Some concepts of RTM suitable for NMDS and expected beam qualities will be presented.

THPWA016

Design and Optimization of the Target in Electron Linear Accelerator

target, electron, radiation, photon

3663

Q. Gao, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

The target in electron linear accelerator plays an important role in the production of photon. Different materials and thickness of target have influence on dose rate. For 6MeV electron beam, this study gives the thickness of target for several materials in which the dose rate can be higher and drain electron can be lower. Then a X-ray target had been designed for 6MeV electron linac by FLUKA simulations. It can deliver 1000 cGy/min at 1 meter in front of the target if providing 6 MeV electron beam with 100uA current, which can achieve high-dose rate radiotherapy.

THPWA021

Studies of Density Distribution and Emittance Measurement for High Current Electronic Beam

emittance, electron, gun, ion

3672

Q.C. Li, Z.-F. He, J.M. Huang, D.M. Li, Y.-T. Zhang, X.K. Zhu
SINAP, Shanghai, People's Republic of China

Beam density distribution and emittance are the important parameters of an accelerator. The accurate emittance measurement has an important reference significance for the design of accelerating tube, and provides a design basis for the aperture size of accelerating tube. This paper introduces a beam measurement method which uses multiwire, can rotate in the horizontal plane and adjust in the Z coordinate. The results of simulation show that this method can accurately measure the beam density distribution and emittance, and the accuracy can meet the requirements of applied accelerator.

THPWA023

Research on Modeling of the High-density Current Electron Gun System Based on T-S Fuzzy Model

electron, gun, controls, cathode

3678

B. Lv, D.M. Li, H.J. Su
SINAP, Shanghai, People's Republic of China

Abstract: The stability of the electron beam is considered as an important performance of industrial electron accelerators. For the beam control system of the accelerator, it is significant to obtain the accurate model of the electron gun system. The paper presents a fuzzy modeling method based on the Takagi-Sugeno (T-S) fuzzy model. A T-S model can be obtained using the system identification algorithms from input-output data. In our approach, fuzzy c-means (FCM) clustering algorithm is applied to identify the model structure. And a hybrid method based on quantum-inspired differential evolution algorithm (QDE) and genetic algorithm (GA) is proposed to learn the parameters of T-S fuzzy model. Experiments on the Box-Jenkins gas furnace data have verified the validity of the modeling approach. The simulation results show that the T-S fuzzy model is very well to describe the electron gun system and reveal its performance.

THPWA027

Evaluation of Zero-failure Data in Transient Ionizing Radiation Based on Ordering Method in the Sample Space

radiation, laser, target, electron

3681

X.Y. Bai, X.M. Jin, R.B. Li, Y. Liu, Q. Ma, Ch. Qi
NINT, Xi'an, People's Republic of China

The conventional method for the evaluation of data in lot acceptance testing (LAT) of transient ionizing radiation is non-parametric method. But the evaluation results are very conservative. After the discovery of data in transient ionizing radiation belonging to one universal data model “case 1 interval censored data”, ordering method in the sample space was introduced and applied to evaluate zero-failure data and was compared with non-parametric method both theoretically and via a practical LAT on QG-Ⅰ. Through the comparisons, it is concluded that ordering method can expand the scope of dose rate corresponding to the same lower confidence limit. It improves data utilization and this improvement could have practical significance in LAT. It can reduce requirements for the radiation source and can also reduce the number of trials.

THPWA030

Design and Prototype Test of C-band Standing-wave Accelerating Structure to Enhance RF Phase Focusing

electron, focusing, coupling, bunching

3690

H. Yang, M.-H. Cho, W. Namkung, S.-G. Shin
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Kim
ANL, Argonne, USA
J.-S. Oh
NFRI, Daejon, Republic of Korea

Funding: This research was financially supported by the MOTIV, KIAT and Dongnam Institute for Regional Program Evaluation through the Leading Industry Development for Economic Region
A C-band standing-wave accelerator for X-ray and electron beam sources of medical radiotherapy is designed and being fabricated. The accelerator system is to be operated in two modes, using the X-ray and electron beams. Because of the energy loss in electron mode, the accelerator is capable of producing 6-MeV, 100-mA electron beams with peak 2-MW RF power, and 7.5-MeV, 20 mA electron beams with peak 2.5-MW RF power. The beam radius at the end of column was < 0.5 mm without focusing magnets in PARMELA simulations, because the bunching cells are designed to enhance the RF phase focusing. Each cavity in the bunching and normal cells was designed by the MWS code to maximize the effective shunt impedance with 3.8% inter-cell coupling in normal cells. The dimensions of normal cells were determined by the low power RF test of prototype cells with 5711.06-MHz resonant frequency and 3.5% inter-cell coupling. In this paper, we present details of the accelerator design and prototype test.

THPWA039

GEANT4 Target Simulations for Low Energy Medical Applications

target, proton, neutron, cyclotron

3717

N. Ratcliffe, R.J. Barlow, A. Bungau, C. Bungau, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom

The GEANT4 code offers an extensive set of hadronic models for various projectiles and energy ranges. These models include theoretical, parameterized and, for low energy neutrons, data driven models. Theoretical or semi-empirical models sometimes cannot reproduce experimental data at low energies(<100MeV), especially for low Z elements, and therefore recent GEANT4 developments included a new particle\_hp package which uses evaluated nuclear databases for proton interactions below 200 MeV. These recent developments have been used to study target designs for low energy proton accelerators, as replacements of research reactors, for medical applications. Presented in this paper are results of benchmarking of these new models for a range of targets, from lithium neutron production targets to molybdenum isotope production targets, with experimental data. Also included is a discussion of the most promising target designs that have currently been studied.

THPWA041

Acceptance and Transmission Simulations of the FETS RFQ

emittance, rfq, space-charge, solenoid

3720

S. Jolly, R.T.P. D'Arcy
UCL, London, United Kingdom
A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
J.K. Pozimski
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

A 4m-long, 324MHz four-vane RFQ, consisting of four coupled sections, has been designed for the Front End Test Stand (FETS) at RAL in the UK. A novel design method, integrating the CAD and electromagnetic design of the RFQ with beam dynamics simulations, was used to optimise the design of the RFQ. With the design of the RFQ fixed, the focus has been on optimising the transmission of the RFQ at 3 MeV and matching the output of the FETS Low Energy Beam Transport (LEBT) to the RFQ acceptance. Extensive simulations have been carried out using General Particle Tracer (GPT) to map out the acceptance of the FETS RFQ for a 65 keV H⁻ input beam. Particular attention has focussed on optimising the simulations to match the optimised output of the FETS Penning-type H⁻ ion source. Results are presented of the transverse phase space limits on the RFQ input acceptance in both the zero current and full space charge regimes.

THPWA043

Production of the FETS RFQ

rfq, vacuum, pick-up, alignment

3726

P. Savage, M. Aslaninejad, J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
M. Dudman, D.S. Wilsher
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
A. Garbayo
AVS, Eibar, Gipuzkoa, Spain
A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The Front End Test Stand (FETS) project at RAL will use a 324 MHz 4-vane Radio Frequency Quadrupole (RFQ) to accelerate H⁻ ions from 65keV to 3 MeV. This paper will report on the current status of the production of the FETS RFQ and will detail the manufacturing strategy used to produce the major and minor vanes. In addition the inspection results will be shown and the experiences from the assembly and alignment operations will be shared. Finally, the design of the bead-pull apparatus, end flanges, tuners and pick-ups required to measure the frequency and field-flatness of the assembled RFQ will be discussed.

THPWA046

Accelerator Optimization within the oPAC Project

linac, cryogenics, radiation, electron

3735

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by the EU under Grant Agreement 289485.
Many of the today’s most advanced research infrastructures rely on the use of particle accelerators. This includes for example synchrotron light sources and FELs, high intensity hadron accelerators for the generation of exotic beams and spallation sources, as well as much smaller accelerator facilities for precision experiments and fundamental studies. Moreover, accelerators are very important for many commercial applications, such as for example medical applications, material studies and treatment, lithography, or security applications, such as scanners at airports or cargo stations. The full potential of any accelerator can only be exploited if the performance of all its parts are continuously optimized, if numerical tools are made available that allow for developing and improving advanced machine designs, if methods are developed in partnership between the academic and industry sectors to monitor beams with ever higher intensities and brightness, shorter pulse lengths or smaller dimensions. This contribution presents the R&D program of the oPAC project that optimizes existing and future accelerators.

THPWA051

Compact, Inexpensive X-band Linacs as Radioactive Isotope Source Replacements

linac, gun, electron, radiation

3746

S. Boucher, R.B. Agustsson, L. Faillace, J.J. Hartzell, A.Y. Murokh, A.V. Smirnov, S. Storms, K.E. Woods
RadiaBeam, Santa Monica, USA

Funding: Work supported by DNDO Phase II SBIR HSHQDC-10-C-00148 and DOE Phase II SBIR DE- SC0000865.
Radioisotope sources are commonly used in a variety of industrial and medical applications. The US National Research Council has identified as a priority the replacement of high-activity sources with alternative technologies, due to the risk of accidents and diversion by terrorists for use in Radiological Dispersal Devices (“dirty bombs”). RadiaBeam Technologies is developing novel, compact, inexpensive linear accelerators for use in a variety of such applications as cost-effective replacements. The technology is based on the MicroLinac (originally developed at SLAC), an X-band linear accelerator powered by an inexpensive and commonly available magnetron. Prototypes are currently under construction. This paper will describe the design, engineering, fabrication and testing of these linacs at RadiaBeam. Future development plans will also be discussed.

THPWO003

Final Design of the IFMIF Injector at CEA/Saclay

extraction, rfq, diagnostics, solenoid

3758

R. Gobin, D. Bogard, N. Chauvin, O. Delferrière, P. Girardot, F. Harrault, J.L. Jannin, D. Loiseau, C. Marolles, P. Mattei, A. Roger, F. Senée, O. Tuske
CEA/DSM/IRFU, France
H. Shidara
IFMIF/EVEDA, Rokkasho, Japan

The IFMIF accelerator dedicated to high neutron flux production for material studies is now entering in a new phase. For this irradiation tool, IRFU institute from CEA/Saclay is in charge of the design, construction and characterization of the Injector. The high intensity deuteron beam is produced by an ECR source located on a 100 kV platform. The 2 m long LEBT, based on 2 solenoids, is ended by a cone installed at the entrance of the RFQ. Specific diagnostics (cameras, Allison type emittance scanner, fiberscope) have been installed for the beam characterization. During the last weeks, after Injector conditioning, more than 100 mA of deuteron beams have been characterized after the RFQ entrance cone in pulsed and continuous mode*. The shipment of the Injector towards the Rokkasho site in Japan (where it will be reinstalled) is foreseen at the beginning of 2013. This paper will focus on the final design used during the beam characterization experiments at Saclay.
* N. Chauvin et al. this conference

THPWO006

Beam Commissioning of the Linear IFMIF Prototype Accelerator Injector: Measurements and Simulations

solenoid, emittance, ion-source, ion

3767

N. Chauvin, S. Chel, O. Delferrière, R. Gobin, P.A.P. Nghiem, F. Senée, M. Valette
CEA/IRFU, Gif-sur-Yvette, France
A. Mosnier
Fusion for Energy, Garching, Germany
Y. Okumura
JAEA, Rokkasho, Japan
H. Shidara
IFMIF/EVEDA, Rokkasho, Japan
D. Uriot
CEA/DSM/IRFU, France

The EVEDA (Engineering Validation and Engineering Design Activities) phase of the IFMIF (International Fusion Materials Irradiation Facility) project consists in building, testing and operating, in Japan, a 125 mA/9 MeV deuteron accelerator, called LIPAc, which has been developed in Europe. The 140 mA cw D⁺ beam that has to be delivered by the LIPAc injector is produced by a 2.45 GHz ECR ion source based on the SILHI design. The low energy beam transfer line (LEBT) relies on a dual solenoid focusing system to transport the beam and to match it into the RFQ*. The beam line is equipped by several diagnostics: intensity measurement, emittance measurement unit, profilers and beam proportion analysis. During the LIPAc injector beam commissioning performed in CEA-Saclay, the deuteron beam intensity transported at the end of the LEBT reached an unprecedented value of 140 mA at 100 keV. In this paper, the results obtained during the commissioning are presented. In particular, beam emittance measurements as a function of duty cycle, extracted current from the ion source and solenoid tunings are exposed. The experimental results are discussed and compared to beam dynamics simulations.
* R. Gobin et al., this conference

THPWO017

A Coupled RFQ-IH Cavity for the Neutron Source FRANZ

rfq, DTL, linac, cavity

3797

M. Heilmann, C. Claessens, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz
IAP, Frankfurt am Main, Germany

The Frankfurt neutron Source at the Stern-Gerlach-Zentrum (FRANZ) delivers neutrons in the energy range from 1 to 300 keV at high intensities. The neutrons are produced using the the 7Li(p,n)7Be reaction with 2 MeV protons. The linac accelerator cavities consists of a 4-rod-RFQ coupled with an 8 gap interdigital H-type drift tube section with a total cavity length of 2.3 m. It accelerates the 120 keV beam to 2.03 MeV at a frequency of 175 MHz. The combined cavity will be powered by one RF amplifier to reduce investment and operation costs. The inductive power coupler will be located at the RFQ part. The coupling into the IH – section is provided by direct inductive coupling within the cavity. The coupled RFQ-IH combination is investigated with CST-MWS-simulations and by an RF model. The linac combination has to match the resonance frequency, flatness along the RFQ and the voltage ratio between both cavity sections. Beam operation will be cw (a few mA) and pulsed 250 kHz, 50 ns (up to 50 mA and beyond). The thermal cavity losses are about 200 kW and the cooling is the challenging topic.

THPWO018

Power Tests of the 325 MHz 4-ROD RFQ Prototype

rfq, cavity, impedance, pick-up

3800

B. Koubek, H. Podlech, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

For the FAIR project of GSI as part of the proton linac a 325 MHz RFQ with an output energy of 3 MeV is planned. Simulations that have lead to a prototype of a 4-Rod Radio Frequency Quadrupole (RFQ) have been done. The RF parameters have been verified with the prototype. Power tests of this 6 stem copper RFQ should now verify parameters like shunt impedance, electrode voltage and give answers of how much power the structure can sustain.

THPWO020

Simulations on the Boundary Fields of 4-rod RFQ Electrodes

rfq, cavity, quadrupole, shielding

3803

J.S. Schmidt, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

If the RF design of a 4-rod Radio Frequency Quadrupole (RFQ) is not performed carefully with respect to the boundary fields of its electrodes, it can produce errors compared to beam dynamic simulations. An additional field component can be induced on the beam axis, which influences the properties of the particle beam, like energy per nucleon for example, dramatically. Therefore, the influences of different geometric parameters of 4-rod RFQs on these fields have been studied in detail. The results of these simulations will be presented in this paper.

THPWO022

Beam Dynamics Design, Simulation and Benchmarking for the C-ADS Injector-II RFQ

rfq, emittance, linac, quadrupole

3809

C. Zhang
GSI, Darmstadt, Germany
C. Xiao
IAP, Frankfurt am Main, Germany

The planned Chinese Accelerator Driven System (C-ADS) will use two 10 MeV, up to 10 mA, and CW (Continuous Wave) proton linacs in parallel as injectors. Two versions of the injectors with different resonant frequencies as well as different cavity configurations are under development. This paper will focus on the beam dynamics design, simulation and benchmarking performed for the 162.5 MHz, 2.1 MeV Injector-II RFQ (Radio-Frequency Quadrupole).

THPWO024

PROGRESS ON DTL DESIGN FOR ESS

DTL, linac, multipole, emittance

3815

M. Comunian, F. Grespan, A. Pisent, C. Roncolato
INFN/LNL, Legnaro (PD), Italy
R. De Prisco
ESS, Lund, Sweden
P. Mereu
INFN-Torino, Torino, Italy

In the European Spallation Source (ESS) accelerator, the Drift Tube Linac (DTL) will accelerate a proton beam of 50 mA pulse peak current from 3 to ~80 MeV. In this paper the engineering design of DTL tanks with the beam dynamics errors studies and the RF design are shown.

THPWO027

Lattice and Error Studies for J-PARC Linac Upgrade to 50mA/400MeV

emittance, linac, lattice, focusing

3818

Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Equi-partitioning (EP) setting is applied as base-line design for the J-PARC linac upgrade from present 15mA/181MeVto 50mA/400MeV H⁻ beam. We also studied the possibility of mitigating the intra-beam stripping (IBSt) with constant-envelop setting for the frequency jump from 324MHz to the 972MHz ACS section. Since the constant-envelop setting here for the frequency jump is away from equi-partitioning and close to the resonances kz=3kx, kz=2kx and so on, considerable emittance exchange and mismatch were found in the simulation. It is natural to continue the work to explore the parameter space around the above two typical settings. Three key points are to be checked. The first is the tradeoff between the envelopes big enough to suppress the IBSt and tunes not to be too depressed to the space charge region. The second point is the sensitivity of these lattices vs. errors. The third is about the criterion of mismatch in the presence of emittance exchange. When emittance exchange is serious the mismatch can be unavoidable. So it is crucial to ensure the settings are in the safe region free from un-controlled mismatch.

THPWO030

Recent Progress in Beam Commissioning of J-PARC Linac

linac, DTL, resonance, radiation

3827

M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
T. Maruta
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
A. Miura, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan

The beam operation of J-PARC linac has been restored from the earthquake, and started to pursue higher beam power operation. We have also started to prepare for coming energy and intensity upgrade. In this paper, we review recent progress in beam commissioning of J-PARC linac with emphasis on the beam loss mitigation and preparation for the upgrade.

THPWO033

High Intensity Beam Trial of up to 540 kW in J-PARC RCS

injection, resonance, proton, linac

3836

H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie
KEK, Ibaraki, Japan
S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan

Recently we have performed a high intensity beam trial of up to 540 kW. In this paper, beam intensity dependece and injection painting parameter dependence of beam loss, observed in this beam experiment, will be discussed with the corresponding numerical simulation results.

THPWO035

Numerical Study on the Effect of Magnetic Shield of a Bunch Shape Monitor in J-PARC Linac

electron, linac, beam-transport, quadrupole

3842

J. Tamura, H. Ao, A. Miura, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
T. Miyao, K. Takata
KEK, Ibaraki, Japan

In the annual shutdown period of 2012, three bunch shape monitors (BSMs) have been installed to the J-PARC linac beam transport line at the downstream of the 181-MeV separated DTL. To measure the longitudinal micro-bunch shape, the BSM detects the electrons produced by the accelerated protons hitting the negatively energized wire. Due to the space limitation, the each BSM is installed at the center of the quadrupole doublet, where the fringe field from the quadrupole magnets exists. It has been observed that the fringe field significantly affects the orbit of the emitted electrons. To shield the magnetic field, iron plates have been inserted to the spaces between the quadrupole magnets and BSM. This causes changes of the total magnetic flux density (GL) and the amount of quadrupole component of the fringe field. In this paper, numerical estimation of the shield effect is presented.

THPWO042

Macroparticle Simulation Studies of a Beam-core Matching Experiment

quadrupole, rfq, proton, emittance

3860

H. Jiang, P. Chen, S. Fu, T. Huang, F. Li, P. Li, H.C. Liu, C. Meng, M. Meng, Z.C. Mu, H.F. Ouyang, J. Peng, L.Y. Rong, B. Sun, J.M. Tian, B. Wang, S.C. Wang, W.Q. Xin, T.G. Xu, L. Zeng, F.X. Zhao
IHEP, Beijing, People's Republic of China

We compared the 3-D nonlinear macro- particle code IMPACT simulations with the measured beam-core profiles obtained by the wire-scanners in the beam-core matching experiment. Quadrupole scans were used to determinate the transverse properties of the RFQ output beam. The Gaussian distribution was chosen as the initial particle distribution, which is well fit with the measured beam-core profile. We matched the beam using the least-squares fitting procedure that adjusted the first four matching quadrupoles to produce equal rms beam size in the last six wire scanners. Simulations had been fairly successful in reproducing the core of the measured matched beam profiles.

THPWO044

Error Analysis and Beam Loss Control in C-ADS Main Linac

linac, emittance, cavity, solenoid

3866

C. Meng, Z. Li, J.Y. Tang, F. Yan
IHEP, Beijing, People's Republic of China

The China ADS (C-ADS) driver linac is defined to deliver a CW proton beam of 1.5 GeV in energy and 10 mA in current. To meet the extremely high reliability and availability, it is very important and imperative to perform detailed error analysis to simulate the real machine, where the errors always exist. The error studies are by very intense macro-particle simulations by both Trace-Win and TRACK codes with space charge effects included. Through error analysis the proper closed-orbit correction scheme and the maximum tolerable hardware and alignment errors can be found. This paper presents the method to optimize the apertures of elements in the C-ADS main linac. According to the detailed sensitivity analysis of different errors, the static and dynamic errors for the main linac are proposed. The basic lattice scheme has also been re-optimized based on the error studies. The correction scheme is also described, and with the correction scheme the residual orbit can be controlled very well. The influence of the correctors and BPM failures on the correction scheme is also studied.

THPWO047

The LLRF Measurement and Analysis of the SSC-LINAC RFQ

rfq, cavity, linac, LLRF

3875

G. Liu, J.E. Chen, S.L. Gao, Y.R. Lu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
X. Du, Y. He, G. Pan, Y.Q. Yang, X. Yin, Y.J. Yuan, Z.L. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: Supported by NSFC(11079001)
The manufacturing process of the SSC-LINAC RFQ went to end and the LLRF measurement has been done. The frequency of the RFQ is 53.557 MHz without tuning, which is not far from the design value 53.667 MHz. The unflatness of the field along the beam axis is less than ±4%, which meets the simulation results. The dipole field is in the acceptable margin as well. The frequency will be adjusted by tuning plungers in operation. In this paper, the field distribution along the cavity has been measured and compared with the modulated electrodes simulation. The difference and its influences on the beam transmission have been analyzed.

THPWO048

A CW High Charge State Heavy Ion RFQ for SSC-LINAC

rfq, ion, heavy-ion, cavity

3878

Y.R. Lu, J.E. Chen, S.L. Gao, G. Liu, Z. Wang, X.Q. Yan, K. Zhu
PKU, Beijing, People's Republic of China
Y. He, L.P. Sun, J.W. Xia, Y.Q. Yang, X. Yin, Y.J. Yuan, Z.L. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: Supported by NSFC 11079001
To improve the super heavy ion beam injection efficiency and supply high current heavy ion beam for Separated Sector Cyclotron, A CW RFQ for heavy ion with high charge state has been designed and manufactured in the last two years. This RFQ will operate at 53.667MHz, will accelerate super heavy ions such as 238U³⁴⁺ to 143keV/u. This paper will introduce the SSC-LINAC components, especially the RFQ beam dynamics, full length structure design, tuning and cooling method. Furthermore RF system and RF commissioning with full power for the RFQ power cavity will also be presented.

THPWO049

Preliminary Beam Dynamics and Structure Design of One 50mA/CW RFQ with Ramped Inter-vane Voltage

rfq, radio-frequency, linac, quadrupole

3881

L. Du, X. Guan, C.-X. Tang, Q.Z. Xing
TUB, Beijing, People's Republic of China

Funding: Work supported by National Natural Scienccontracte Foundation of China (Major Research Plan Grant No. 91126003 and Project 11175096).
The beam dynamics and structure design of a ramped-voltage CW RFQ (Radio Frequency Quadrupole) accelerator for a NSFC (National Natural Science Foundation of China) Project at Tsinghua University is presented in this paper. The ramped-voltage RFQ, in which the inter-vane voltage increases from the low-energy end to the high-energy end, is compact and efficient. The RFQ, with the operating frequency of 325 MHz, will capture a 50 mA/CW, 50 keV proton beam from the RF source and accelerate it to 3 MeV, an energy suitable for chopping and injecting the beam in a conventional Drift Tube Linac. After optimization, the total length is as short as 2.9 m and the transmission rate is above 97%. The design of RFQ structure including the undercuts will also be shown.

THPWO066

Beam Commissioning of KOMAC Linac

DTL, linac, proton, rfq

3909

J.-H. Jang, Y.-S. Cho, D.I. Kim, H.S. Kim, H.-J. Kwon, B.-S. Park, J.Y. Ryu, K.T. Seol, Y.-G. Song, S.P. Yun
KAERI, Daejon, Republic of Korea

Funding: This work was supported by the Ministry of Education, Science and Technology of the Korean Government.
The proton engineering frontier project (PEFP), which is the first phase of Korea multi-purpose accelerator complex (KOMAC), developed a 100-MeV proton linac which consists of a 50 keV injector, a 3-MeV radio frequency quadrupole (RFQ) and a 100-MeV drift tube linac (DTL). The installation of the linac was finished in 2012. The goal of the beam commissioning in spring 2013 is accelerating 100-MeV proton beams with the beam power of 1 kW to the beam dump which is located downstream of the linac. This work summarized the beam commissioning result for the linac.

THPWO083

Simulation of a Beam Rotation System for the SINQ Spallation Source at PSI

target, proton, neutron, optics

3954

D. Reggiani, T. Reiss, M. Seidel, V. Talanov, M. Wohlmuther
PSI, Villigen PSI, Switzerland

With a nominal beam power of nearly 1 MW on target, the PSI-SINQ ranks among the world's most powerful neutron spallation sources. The proton beam transport to the SINQ target is carried out exclusively by means of linear elements. As a consequence, at the SINQ target entrance the beam presents Gaussian transverse x and y distributions with tails cut short by collimators. This leads to a highly uneven temperature distribution inside the SINQ zircaloy target, giving rise to thermal and mechanical stress. In view of a future beam intensity upgrade, the possibility of homogenizing the beam distribution by means of a fast beam rotation system is currently under study. Important aspects of this method concern the resulting neutron spectrum and flux distribution. The simulations of the beam distribution achievable thanks to this technique as well as its consequences in terms of neutron production are presented in this contribution.

THPWO085

Numerical and Experimental Study for the Characterization of the Spallation Target Performance of the Ultracold Neutron Source at the Paul Scherrer Institut

neutron, target, shielding, proton

3960

V. Talanov, M. Wohlmuther
PSI, Villigen PSI, Switzerland

Results of numerical calculation and experimental characterization of the neutron flux profile in the vicinity of the ultracold neutron source (UCN) at the Paul Scherrer Institut (PSI) are presented. At first, the MCNPX-based model of the Monte-Carlo simulation with its detailed description of the so-called ‘Cannelloni’-type spallation target assembly and the realistic proton beam profile modeling is described. Thereafter the experimental determination of the thermal neutron flux profile using the gold foil activation, along the height of the UCN vacuum tank, starting from the proton beam plane, is presented. Both calculations and measurements were performed for the standard operation mode, with several seconds of the full proton beam on the target. Finally, a comparison of simulation and experimental results is discussed.

THPWO087

Measurement of Resonant Space Charge Effects in the J-PARC Linac

emittance, linac, resonance, space-charge

3966

D.C. Plostinar
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Liu, T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan

Traditionally, high intensity linac designs follow the “equipartitioning condition”, a strict control of the transverse and longitudinal tune ratios throughout the linac that ensures space-charge driven emittance exchange between the longitudinal and transverse planes is minimised. However, equipartitioning imposes strict rules on the linac design, thus limiting the design options and increasing the overall construction cost. More recently, practical tools have been developed that offer guidelines in designing non-equipartitioned linacs, by charting the stable regions in a tune ratio diagram (Hofmann’s Charts). While these stability diagrams have been backed by extensive multiparticle simulations and some experimental evidence, questions still remain regarding the practical consequences of crossing the resonances. In this paper preliminary results are presented from an experimental study conducted in the J-PARC linac, where for the first time we measured both the transverse and longitudinal emittance for different linac working points. A detailed analysis will be presented as well as a discussion on the wider implications of this experiment.

THPWO094

Electromagnetic and Multi-particle Beam Dynamics Modeling of 4-Rod RFQs

rfq, vacuum, quadrupole, cavity

3978

S.S. Kurennoy, R.W. Garnett, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

Detailed 3D modeling of the recently commissioned FNAL 4-rod RFQ was performed with the CST Studio Suite. The RFQ model is based on the CAD files used for its fabrication, which are imported in CST Studio. The electromagnetic (EM) analysis was done with MicroWave Studio (MWS) and the beam dynamics modeled with Particle Studio (PS) using the MWS-calculated fields. Realistic matched input CW beam distributions, generated externally with up to 10K particles per RF period and up to 70 RF periods long, are injected in the RFQ for PS simulations. The EM analysis reveals some interesting features of the RFQ fields; their origin and influence on the beam parameters is studied. In particular, the end-gap longitudinal field, which is usually not taken into account when an RFQ is designed with standard codes, can change the output beam energy. Our CST modeling results helped explain and successfully resolve some problems encountered in the FNAL RFQ commissioning. We plan to use a similar approach to evaluate a new 4-rod RFQ that will become a part of an upgraded front end of the LANSCE linac.