IPAC2011 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOOCB01	Study on the Realignment Plan for J-PARC Linac after the Tohoku Earthquake in Japan	DTL, linac, alignment, quadrupole	44
	M. Ikegami KEK, Ibaraki, Japan T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	A 9.0-magnitude earthquake struck eastern Japan on March 11, 2011, and it gave rise to damages to the buildings of the J-PARC facilities. In particular, the earthquake caused a deformation of the J-PARC linac tunnel resulting an alignment error of several tens of millimeters in both horizontal and vertical directions. It also caused a change in the relative position between the linac and other facilities of J-PARC complex. To restore the beam operation, we should establish a reasonable realignment plan for J-PARC linac taking various constraints into account and possibly tolerating some residual misalignment. In this paper, we show a study on the realignment plan for J-PARC linac including evaluation of the effect of residual misalignment with particle simulations.
	Slides MOOCB01 [2.659 MB]

MOODB03	Capture and Transport of the Laser Accelerated Ion Beams for the LIGHT Project	laser, proton, solenoid, ion	59
	S.G. Yaramyshev, W.A. Barth, I. Hofmann, A. Orzhekhovskaya GSI, Darmstadt, Germany B. Zielbauer HIJ, Jena, Germany
	Funding: Work supported by EURATOM (IFK KiT Program) and HIC for FAIR An impressive advantage of Laser Ion Sources is an extremely high beam brilliance. The LIGHT project (Laser Ion Generation, Handling and Transport) is dedicated to the production of protons (ions), accelerated up to 10 MeV by using the GSI PHELIX laser at GSI, and injected into a conventional accelerator. A successful experimental campaign stimulated further investigation of the focusing, transport and collimation of the high energy and high brilliance proton beam. In addition to the advanced codes, describing the very early expansion phase of the proton-electron cloud, the versatile multiparticle code DYNAMION was implemented to perform beam dynamics simulations for different possible transport lines. Potentially transport lines compraises magnetic quadrupole lenses and/or solenoids for transverse beam focusing. A bunch rotation rf cavity decreasing the energy spread of the protons was included into the simulations. The results of the beam dynamics simulations are presented, as well as benchmarking activities with other codes. Further developments of the experimental test stand and the different possibilities of its integration to the GSI accelerators chain are discussed.
	Slides MOODB03 [2.185 MB]

MOPC009	Design of a Pi/2 Mode S-Band Low Energy TW Electron Linear Accelerator	electron, coupling, acceleration, linac	80
	H. Shaker IPM, Tehran, Iran F. Ghasemi sbu, Tehran, Iran H. Shaker CERN, Geneva, Switzerland
	This design is related to a Pi/2 mode S-Band low energy TW electron linear accelerator which is in the construction stage. This project is supported by the school of particles and accelerators, institute for research in fundamental sciences (IPM), Tehran, Iran. This design consists of a buncher and an accelerating structure that are joined and two couplers for the input/output feedings. At each design stage, different methods (analytical or numerical) are used to confirm the results and also to have a better understanding.

MOPC016	Development of a New RF Accelerating Cavity for J-PARC Ring Accelerator	cavity, impedance, ion, controls	98
	Y. Morita, T. Kageyama KEK, Ibaraki, Japan J. Kameda ICRR, Chiba, Japan S. Yamashita ICEPP, Tokyo, Japan
	Funding: Japan Society for the Promotion of Science (JSPS) To enhance the beam power delivered by the J-PARC* ring accelerators, upgrading the accelerating cavities is indispensable. In particular, long term stable operation of the present cavities for the RCS is one of the important issues. Currently, the cavities are loaded with FINEMET* cores cooled by water, where every core is coated with glass cloth and epoxy resin for waterproof. However, it was reported that some of the cores were damaged by thermal stress. We are developing a new cavity loaded with multi ring core modules. Each core module consists of three ring cores concentrically arranged and sandwiched between two glass epoxy plates with flow channels grooved. The ring cores without waterproof coating are cooled by the turbulent flow of a chemically inert liquid (Fluorinert), since FINEMET is subject to corrosion in water. We have designed and built a high power prototype cavity loaded with a single core module, then carried out low level measurement and high power test. Finally, the cavity has been stably operated up to an average power loss of 10 kW per core module, which is 1.7 times higher than that for the present RCS cavity. Japan Proton Accelerator Research Complex Rapid-Cycling Synchrotron **FINEMET is an iron-based magnetic alloy produced by Hitachi Metals, Ltd..

MOPC023	Design of a C-band 6 MeV Standing-wave Linear Accelerating Structure	coupling, electron, bunching, impedance	119
	J.H. Shao, H. Chen, Q.Z. Xing TUB, Beijing, People's Republic of China
	We design a C-band standing-wave biperiodic on-axis coupled linear accelerating structure for industrial and medical applications. It’s less than 300mm long; consists of 3 bunching cells and 9 normal cells. It can accelerate electrons to 6MeV and the pulsed beam current is 100mA. The RF power source is a 2.5MW magnetron. We implement 2D cells geometry optimization by SUPERFISH, beam dynamics study by PARMELA and full scale 3D calculations by MAFIA codes.

MOPC026	MA Cavity for HIRFL-CSR	cavity, impedance, plasma, radio-frequency	125
	L.R. Mei, Z. Xu, Y.J. Yuan, H.W. Zhao IMP, Lanzhou, People's Republic of China
	To meet the requirements of conducting high energy density physics and plasma physics research at HIRFL-CSR. The higher accelerating gap voltage was required. A magnetic alloy (MA)-core loaded radio frequency (RF) cavity which can provide higher accelerating gap voltage has been studied in Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS), Lanzhou. To select proper MA material to load the RF cavity, measurement for MA cores has been conducted. The MA core with higher shunt impedance and lower than 1 quality factor (Q value) should be selected. The theoretical calculation and simulation for the MA-core loaded RF cavity can be consistent with each other well. Finally 1000kW power was needed to meet 50-kV accelerating gap voltage by calculation.

MOPC029	Development of Injector for Compact FEL Tera-hertz Source in CAEP	gun, electron, FEL, booster	131
	W. Bai, M. Li, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	This paper introducs the development of a injector for compact FEL tera-hertz source at Institute of Applied Electronics in China Academy of Engineering Physics (IAE/CAEP). The injector consist of a main accelerator for energy booster section and a multicavity thermionic-cathode rf gun with low back bombardment, with total length no more than one meter. Numerical simulation result shows that the back bombardment power is less for the thermionic-cathode rf gun of the injector and the main accelerator has a good performance, which can provide high quality electron beam with emittance about 10 pi mm mrad, energy about 7 MeV and energy spread about 1%. At present, the preliminary hot test experiment on the injector has been done. The test results indicate that the mainly tested parameters agree well with the theoretical design ones. The process of the preliminary hot test experiment on the injector is present in this paper.

MOPC031	Performance of a 13 MHz Cavity for an RF Implanter at PEFP*	cavity, coupling, ion, ion-source	136
	T.A. Trinh UST, Daejeon, Republic of Korea Y.-S. Cho, J.-H. Jang, D.I. Kim, H.S. Kim, H.-J. Kwon, B.-S. Park, K.T. Seol KAERI, Daejon, Republic of Korea
	Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government A 13 MHz - normal conducting cavity for an rf implanter has been successfully developed at PEFP (Proton Engineering Frontier Project). It consists of an inductive coil, accelerating electrodes and a ground electrode for the inductor. Quality factor of 2074 and critical coupling were achieved at resonant frequency of 12.658 MHz. Rf power of 1 kW was forwarded to the cavity without any spark in the cavity. Beam test was then carried out with a 27 keV helium beam generated from a Duoplasmatron ion source. The results showed that the helium beam was accelerated to final energy of 120 keV with energy spread of 1%. Detail experiments and results are addressed in this presentation.

MOPC034	Design of a 0.6-cell Cell Photocathode RF Gun for FED	gun, electron, cathode, solenoid	145
	Y.W. Parc, M.S. Chae, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea
	Final goal of this study is the development of single cell radio-frequency (RF) electron gun which is optimized to the femotosecond electron diffraction. This study will open new technology basis for the laboratory research in the femto-second (fs) chemistry at the university. RF electron gun will be fabricated with single cell which will reduce the cost and effort. We will also conduct a simulation study to find an optimized operation condition of the RF gun to provide the best electron beam to the femtosecond electron diffraction experimentalist. In this presentation, we will show the status of the RF gun development. The results with the simulation code PARMELA will be presented to find the optimal operation condition of the single cell RF gun for FED.

MOPC036	Design of RF Cavity for Compact 9 MeV Cyclotron	cavity, cyclotron, resonance, acceleration	151
	H.S. Song, J.-S. Chai, H.W. Kim, B.N. Lee, J.H. Oh SKKU, Suwon, Republic of Korea
	The number of PET facility is rapidly increasing worldwide. To get PET image, circular accelerator such as cyclotron is needed. Compact 9 MeV H-cyclotron, which has a diameter of 1.25m is being designed at Sungkyunkwan University starting from July 2010 for getting F-18. It is expected to be constructed by next year. In this paper, RF system of 9 MeV cyclotron including design processes and detail analysis of result is reported. RF system mainly describes RF cavity design.

MOPC040	The Measurement of Transversal Shunt Impedance of RF Deflector	cavity, impedance, dipole, emittance	163
	A.Yu. Smirnov, M.V. Lalayan, N.P. Sobenin MEPhI, Moscow, Russia A.A. Zavadtsev Nano, Moscow, Russia
	This paper presents the results of transverse shunt impedance measurement performed using field perturbation technique and comparison with numerical MWS simulations. The structure under test is the S-band 3-cell deflecting cavity. The mentioned cavity operates with a dipole TM11-like mode with a phase shift of 120 deg per cell. The analyses were carried out with use of two types of perturbing beads: dielectric beads and metallic rings. The latter type perturbs the on-axis magnetic field much stronger than the electric field, which allows us calculating transversal shunt impedance using on-axis EM fields values.

MOPC044	Design of the Radiofrequency Quadrupole Coldmodel for the ESS-BILBAO Linear Accelerator	rfq, quadrupole, dipole, radio-frequency	175
	A. Velez, I. Bustinduy, N. Garmendia, O. Gonzalez, J.L. Munoz, D. de Cos ESS Bilbao, Bilbao, Spain F.J. Bermejo Bilbao, Faculty of Science and Technology, Bilbao, Spain V. Etxebarria, J. Portilla University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	This work will present the design of the ESS-Bilbao LINAC RFQ cold model. The process goes through the electromagnetic design of the cavity by properly setting the resonant quadrupole and dipole modes, as well as the resonance frequency. The prototype includes the vane modulation designed to accelerate a 75 mA proton beam from 75 keV to 3 MeV, with an operating frequency of 352.2 MHz. To this end, electromagnetic and electrostatic simulations have been performed by means of the commercial software COMSOL. Furthemore, results for the three components of the electrical field distribution will be presented and compared to those calculated by evaluating the 8-term multipole expansion.

MOPC046	CaCo: A Cavity Combiner for IOTs Amplifiers	cavity, storage-ring, high-voltage, HOM	181
	B. Bravo, F. Mares, F. Pérez, P. Sanchez CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain M.L. Langlois ESRF, Grenoble, France
	The ALBA storage ring uses six room temperature cavities; each one fed by two 80 kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. One of the design requirements of CaCo was that it continued working safely and with a good efficiency in the case of an IOT failure (asymmetrical mode). During the first asymmetric full power tests, in May 2010, with an active IOT and the other passive, the result was dramatic, the passive IOT broke in two parts after few hours of operation. This paper presents the experimental results and the electromagnetic field simulations of the asymmetrical operation mode of CaCo, i.e. one active IOT and the other passive, and analyze why the ceramic of the output tube of the passive IOT broke during the first performance of this mode. Also, it reports a possible solution to solve this problem.

MOPC050	Multipacting Analysis for the Superconducting RF Cavity HOM Couplers in ESS	cavity, electron, HOM, superconducting-RF	190
	S. Molloy ESS, Lund, Sweden R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom R.J.M.Y. Ruber Uppsala University, Uppsala, Sweden
	The European Spallation Source (ESS) linac will consist of three families superconducting RF cavities to accelerate protons to the required 5 MW for collision with the target. If it is determined that HOM damping is required to limit the effect of beam induced modes, it is quite likely that HOM couplers will be installed. Multipacting in these couplers is a concern as thermally induced detuning of the fundamental notch filter has limited the achievable gradient in other high power machines. It is therefore important to avoid potential multipacting conditions during the design phase. Presented here are simulations using the Track3P code developed at SLAC. Multipacting regions are highlighted, electron trajectories are shown, and suitability of the proposed HOM coupler design is discussed.

MOPC056	The Linac4 Power Coupler	cavity, linac, coupling, vacuum	208
	F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner CERN, Geneva, Switzerland
	Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC059	The Plane Wave Transformer Linac Development at NSRRC	linac, impedance, cavity, electron	217
	A. Sadeghipanah, J.-Y. Hwang, W.K. Lau NSRRC, Hsinchu, Taiwan T.H. Chang NTHU, Hsinchu, Taiwan
	A Plane-Wave-Transformer (PWT), standing wave linac operating at S-band frequency (2.9979 GHz) is being developed at NSRRC. This structure offers the advantages of high efficiency, compactness, fabrication simplicity and cost. The PWT prototype at NSRRC consists of three cells with two half-cells at the ends, separated by a set of four flat disks suspended and cooled by four water tubes inside a large cylindrical tank. To fully understand its physical properties, numerical modeling of the PWT prototype has been carried out by using the 2-D code SUPERFISH and 3-D code MAFIA. In this paper, we describe the principle properties of this structure, the electric parameters obtained from numerical simulations, and heat dissipation calculation. The mechanical design for prototype linac is also reported.

MOPC061	Simulations to Flatten the Field of the FETS RFQ	rfq, cavity, dipole, quadrupole	223
	S.R. Lawrie, A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	A high performance Radio Frequency Quadrupole (RFQ) is the next major component to be installed on the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. The beam dynamics, RF, thermal and mechanical designs of the RFQ are almost complete and so the copper has recently been purchased with a view to start cutting metal near Summer-time. This report summarizes the simulation work performed to ensure the RF design is sound. This includes performance studies of the end-wall dipole suppression fingers, tuning the frequency of the input and output vane end regions and implementing a simple solution to remove modulation induced field tilt.

MOPC065	Ion Motion in the Vicinity of Microprotrusions in Accelerating Structures	ion, electron, plasma, background	232
	D.G. Kashyn, T.M. Antonsen, I. Haber, G.S. Nusinovich UMD, College Park, Maryland, USA
	Funding: This work is supported by Office of High Energy Physics of the U.S. Department of Energy. It is known that newly fabricated accelerating structures have almost ideally smooth surface. However, ‘post mortem’ examination of these structures reveals that their surface can be significantly modified after high-gradient operation. This surface modification can be caused by the appearance of microscopic protrusions. One of the factors leading to heating, melting and evaporation of these protrusions (factors resulting in the RF breakdown) is ion bombardment. In our study we analyze ion motion in the vicinity of microprotrusions both analytically and numerically. First, we study the ion motion in the RF electric field magnified by the protrusion in the absence of electron field emitted current and show that most of the ions do not reach the structure surface. Then we add into consideration the interaction of ions with Fowler-Nordheim current emitted from the tip of protrusion (dark current). First, we develop a model describing this interaction and then we supplement it with numerical results using PIC code WARP*. We show that the ions move towards the area occupied by the dark current, but this does not increase the bombardment of micro-protrusions. R.B. Palmer,et al, Phys. Rev ST Accel. Beams 12, 031002 (2009). P. Wilson, AIP Conf. Proc., 877, Melville, New York, 2006, p. 27. *J.-L. Vay, et al, Physics of Plasmas, 11, 2928 (2004).

MOPC073	A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields	cavity, electron, radio-frequency, vacuum	247
	A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515 RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.

MOPC082	Status of the 325 MHz SC CH-Cavity at IAP Frankfurt	cavity, linac, status, electron	265
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg, K. Aulenbacher HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: BMBF contract no. 06FY161I At the Institute for Applied Physics (IAP), University of Frankfurt, a s.c. 325 MHz CH-Cavity is under development for future beam tests at GSI UNILAC, Darmstadt. The cavity with 7 accelerating cells has a geometrical beta of 0.15 corresponding to 11.4 AMeV. The design gradient is 5 MV/m. The geometry of this resonator was optimized with respect to a compact design, low peak fields, surface processing, power coupling and tuning. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper rf simulations, multipacting analysis as well as thermal calculations will be presented.

MOPC083	Structural Mechanics of Superconducting CH Cavities	cavity, controls, linac, resonance	268
	M. Amberg, K. Aulenbacher HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany
	The superconducting CH-structure (Crossbar-H-mode) is a multi-cell drift tube cavity for the low and medium energy range operated in the H21-mode, which has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. With respect to different high power applications two types of superconducting CH-structures (f = 325 MHz, β = 0.16, seven cells and f = 217 MHz, β = 0.059, 15 cells) are presently under construction and accordingly under development. The structural mechanical simulation is a very important aspect of the cavity design. Furthermore, several simulations with ANSYS Workbench have been performed to predict the deformation of the cavity walls due to the cavity cool-down, pressure effects and mechanical vibrations. To readjust the fast frequency changes in consequence of the cavity shape deformation, a new concept for the dynamic frequency tuning has been investigated, including a novel type of bellow-tuner.

MOPC089	RF Simulations for the QWR Cavities of PIAVE-ALPI	cavity, ion, linac, beam-losses	283
	M. Comunian, F. Grespan, A. Palmieri INFN/LNL, Legnaro (PD), Italy
	The PIAVE-ALPI linac is composed of several families of QWR cavities. In order to have a thorough description of the accelerator in terms of beam dynamics, a detailed field mapping of the accelerating cavities is necessary, including non-linear behavior of the off-axis fields, as well as the steering and dispersion effects due to transverse components. For such a purpose, a set of RF simulation was accomplished, with the codes HFSS and COMSOL. The details about these simulations and the main outcomes and results will be described in this article.

MOPC096	Design and Fabrication of a 5-Cell High Current Superconducting Cavity	cavity, HOM, dipole, quadrupole	301
	Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu PKU/IHIP, Beijing, People's Republic of China R. Nassiri ANL, Argonne, USA
	Funding: National High Technology Research and Development program 863 (2009AA03Z206) Energy recovery linacs (ERL) is promising to achieve high average current with superior beam quality. The key component for accelerating such high current beams is the superconducting radio frequency (SRF) cavity. The design of a 1.3 GHz 5-cell high current superconducting cavity has been carried out under the cooperation between Peking University (PKU) and Argonne National Laboratory (ANL). RF properties, damping of the HOMs, multipacting and mechanical features of this cavity have been discussed and the final design is presented.

MOPC106	Study of the Variation of Transverse Voltage in the 4 Rod Crab Cavity for LHC	cavity, luminosity, HOM, dipole	322
	B.D.S. Hall, P.K. Ambattu, G. Burt, C. Lingwood Cockcroft Institute, Lancaster University, Lancaster, United Kingdom P. Goudket, C. Hill STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The planned high luminosity upgrade to LHC will utilise crab cavities to rotate the beam in order to increase the luminosity in the presence of a finite crossing angle. A compact design is required in order for the cavities to fit between opposing beam-lines. In this paper we discuss we discuss one option for the LHC crab cavity based on a 4 rod TEM deflecting cavity. Due to the large transverse size of the LHC beam the cavity is required to have a large aperture while maintaining a constant transverse voltage across the aperture. The cavity has been optimised to minimise the variation of the transverse voltage while keeping the peak surface electric and magnetic fields low for a given kick. This is achieved while fitting within the strict design space of the LHC. The variation of deflecting voltage across the aperture has been studied numerically and compared with numerical and analytical estimates of other deflecting cavity types. Performance measurements an aluminium prototype of this cavity are presented and compared to the simulated design.

MOPC107	HOM and FP Coupler Design for the NLSF High Gradient SC Cavity	cavity, HOM, SRF, damping	325
	R.M. Jones, N. Juntong UMAN, Manchester, United Kingdom
	The design of both higher order mode (HOM) and fundamental power (FP) couplers for the New Low Surface Field (NLSF) cavity* is presented. Here we study using the ILC baseline couplers for this new superconducting cavity. A Balleyguier method** of calculating external quality factor is used and the results validated using both Microwave studio and HFSS. * N. Juntong and R.M. Jones, SRF2009, THPPO024, 2009. ** P. Balleyguier, LINAC98, MO4037, 1998

MOPC109	Suppression of Coupler Kicks in 7-Cell Main Linac Cavities for Cornell's ERL	cavity, linac, emittance, resonance	331
	N.R.A. Valles, M. Liepe, V.D. Shemelin CLASSE, Ithaca, New York, USA
	Funding: Supported by NSF award DMR-0807731 Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·10⁷, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.

MOPC130	High Power Solid State RF Amplifier Proposal for Iran Light Source Facility (ILSF)	cavity, booster, rf-amplifier, storage-ring	385
	R. safian IPM, Tehran, Iran M. Jafarzadeh ILSF, Tehran, Iran
	Solid state RF amplifiers are being considered for an increasing number of accelerator applications. Their capabilities extend from a few kW of power to several hundred kilo watts and from frequencies less than 100 MHz to above 1 GHz. This paper describes the proposed general scheme for the high power solid state RF generator of the Iran light source facility (ILSF). The maximum expected power of the generator is 200 KW which is used for driving the storage ring cavities. Similar RF generator with lower output power can be used for driving the booster cavities.

MOPC132	Influences of the Inner-conductor on Microwave Characteristics in an L-band Relativistic Backward-wave Oscillator*	resonance, plasma, space-charge, coupling	388
	X.J. Ge, L. Liu, B.L. Qian, J. Zhang, H.H. Zhong National University of Defense Technology, Changsha, Kaifu District, People's Republic of China
	Funding: College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, People’s Republic of China. gexingjun230230@yahoo.com.cn* The influences of the inner-conductor on microwave characteristics in an L-band relativistic backward-wave oscillator (RBWO) are investigated theoretically and experimentally. The numerical results show that the resonance frequency decreases obviously with the increase in the inner-conductor radius. To verify the above conclusions, an L-band coaxial RBWO is investigated in detail with particle-in-cell (PIC) code. It is shown that the frequency is lowered from 1.63 GHz to 1.51 GHz when the inner-conductor radius increases from 0.5 cm to 2.5 cm. And the efficiency varies in the range of 35.4-27.7%. Furthermore, experiments are carried out at the Torch-01 accelerator. When the diode voltage is 887.6 kV and the current is 7.65 kA, the radiated microwave with frequency of 1.61 GHz, power of 2.13 GW and efficiency of 31.3% is generated. It is found that the frequency decreases from 1.64 GHz to 1.58 GHz when the inner-conductor radius increases from 0.5 cm to 1.5 cm. And the efficiency varies in the range of 31.3-29.8%.

MOPC143	A Reduced Gradient Output Design for SLAC's XL4 X-Band Klystron	klystron, cavity, impedance, beam-loading	412
	A. Jensen, C. Adolphsen, A.E. Candel, M.V. Fazio, E.N. Jongewaard, D.W. Sprehn, A.E. Vlieks, F. Wang SLAC, Menlo Park, California, USA
	Funding: This work was supported by the U.S. Department of Energy under contract DE-AC03-76SF00515. X-band klystron work began at SLAC in the mid to late 1980's to develop high frequency (4 times the SLAC S-band klystron), high power RF sources for the linear collider designs under consideration at that time. This work culminated in the current workhorse X-band RF source, the XL4. To date 26 XL4 tubes have been built. The XL4 4-cell disk loaded traveling wave output structure has a high operating gradient. A new 6-cell structure has been designed to reduce breakdown and to further improve the klystron's robustness. Initial simulations show the 6-cell design reduces the gradient roughly 25% and that the structure is stable. A physical XL4 will be retrofitted with the new output cavity and hot tested in the near future.

MOPC158	RF Capture of a Beam with Charge-exchanging Multi-turn Injection	injection, acceleration, closed-orbit, linac	454
	T. Uesugi, Y. Ishi, Y. Kuriyama, J.-B. Lagrange, Y. Mori, R. Nakano, T. Planche, B. Qin, E. Yamakawa KURRI, Osaka, Japan Y. Niwa, K. Okabe, I. Sakai University of Fukui, Faculty of Engineering, Fukui, Japan
	Funding: This work was supported by MEXT of Japan in the framework of a task entitled ”Research and Development for an Accelerator-Driven Sub-critical System Using an FFAG Accelerator”. In the fixed field alternating gradient (FFAG) synchrotron in Kyoto university research reactor Institute (KURRI), charge exchange injection was adopted since 2011. The charge stripping foil is located on the closed orbit of the injection energy, and no bump orbit system is used. Instead, the injected beam escapes from the stripping foil according to the closed-orbit shift due to acceleration. In this scheme, it is important to minimize the number of foil hitting, which causes emittance growth and foil heating. In this paper, the rf capture is studied by means of simulation.

MOPO001	Interaction Point Feedback Design and Integrated Simulations to Stabilize the CLIC Final Focus*	controls, feedback, quadrupole, ground-motion	475
	G. Balik, L. Brunetti, G. Deleglise, A. Jeremie, L. Pacquet IN2P3-LAPP, Annecy-le-Vieux, France A. Badel, B. Caron, R. Le Breton SYMME, Annecy-le-Vieux, France A. Latina, J. Pfingstner, D. Schulte, J. Snuverink CERN, Geneva, Switzerland
	The Compact Linear Collider (CLIC) accelerator has strong precision requirements on offset position between the beams. The beam which is sensitive to ground motion needs to be stabilized to unprecedented requirements. Different Beam Based Feedback (BBF) algorithms such as Orbit Feedback (OFB) and Beam-Beam Offset Feedback (BBOF) have been designed. This paper focuses on the BBOF control which could be added to the CLIC baseline. It has been tested for different ground motion models in the presence of noises or disturbances and uses digital linear control with or without an adaptive loop. The simulations demonstrate that it is possible to achieve the required performances and quantify the maximum allowed noise level. This amount of admitted noises and disturbances is given in terms of an equivalent disturbance on the position of the magnet that controls the beam offset. Due to the limited sampling frequency of the process, the control loop is in a very small bandwidth. The study shows that these disturbances have to be lowered by other means in the higher frequency range.

MOPO004	A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA	cavity, kicker, feedback, impedance	484
	N. Heurich, W. Hillert, A. Roth, R. Zimmermann ELSA, Bonn, Germany
	At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented.

MOPO007	Resonant Strip-line Type Longitudinal Kicker	kicker, impedance, feedback, wakefield	493
	T. Nakamura JASRI/SPring-8, Hyogo-ken, Japan
	The longitudinal feedback for the SPring-8 storage ring is under consideration as the device for suppression of the longitudinal instabilities driven by higher order modes of cavities, observed at test operation with 4 to 6 GeV low energy beam. As the beam energy and the ring circumference are rather high, and the length of the space for the longitudinal kickers is limited, high efficiency kicker per length is required in the our case. As a candidate of such kicker, we propose a resonant strip-line type longitudinal kicker with drive frequency of 13/4 of RF frequency. The shut impedance per length is higher than over-loaded cavities and the drive circuits can be simplified because of higher drive frequency. The design consideration, the result of the simulation and measurement of the prototype model, and the detail of the drive circuit will be reported in the presentation.

MOPO008	Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ	kicker, impedance, feedback, vacuum	496
	W.B. Li, P. Lu, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design.

MOPO010	Orbit Feedback System for the MAX IV 3 GeV Storage Ring	feedback, vacuum, power-supply, storage-ring	499
	M. Sjöström, J. Ahlbäck, M.A.G. Johansson, S.C. Leemann, R. Nilsson MAX-lab, Lund, Sweden
	The paper describes the current orbit correction system design for the 3 GeV storage ring at the MAX IV laboratory, a light source facility under construction in Lund, Sweden. The orbit stability requirements for the 3 GeV storage ring are tight at roughly 200 nm vertical position stability in the insertion device (ID) straight sections. To meet this the ring will be equipped with 200 beam position monitors (BPMs) and 380 dipole corrector magnets, 200 in the horizontal and 180 in the vertical plane. The feedback loop solution, one slow orbit feedback (SOFB) loop and one fast orbit feedback (FOFB) loop in fast acquisition mode at 10,000 samples/second, will be presented. The paper will also discuss the various boundary conditions specific to the MAX IV 3 GeV storage ring design, such as a Cu vacuum chamber, and the impact on the corrector design.

MOPO013	Suppression of Emittance Growth by Excited Magnet Noise with the Transverse Damper in LHC in Simulations and Experiment	pick-up, feedback, emittance, betatron	508
	W. Höfle, G. Arduini, R. De Maria, G. Kotzian, D. Valuch CERN, Geneva, Switzerland V.A. Lebedev Fermilab, Batavia, USA
	The LHC transverse dampers initially build to control transverse instabilities are also a good remedy to suppress the oscillations causing emittance growth excited by electro-magnetic noises at the frequencies of betatron sidebands. To prevent the emittance growth excited by magnet noise using the damper this system has to have extremely low noise properties. The paper discusses simulation results on the effectiveness of the transverse feedback system to suppress such oscillations and the experimental results from a damper point of view as they were gained during the 2010 LHC run. Possible improvements in the damper system to enhance its effectiveness with respect to the suppression of emittance blow-up are also discussed.

MOPO014	SVD-based Filter Design for the Trajectory Feedback of CLIC	ground-motion, feedback, luminosity, controls	511
	J. Pfingstner, D. Schulte, J. Snuverink CERN, Geneva, Switzerland M. Hofbaur UMIT, Hall in Tirol, Austria
	The orbit feedback of the Compact Linear Collider (CLIC) is the basic counter-measure against ground motion effects below 1 Hz in the beam delivery system and the main linac of CLIC. In this paper we present significant improvements of the orbit feedback design, by using time-dependent and spatial filters. The design procedure is based on a singular value decomposition (SVD) of the orbit response matrix and on loop-shaping techniques. This modified design has essential advantages compared to previous ones. The required beam position monitor resolution in the beam delivery system could be relaxed by a factor of five. At the same time the suppression of ground motion effects is improved. As a consequence, the tight tolerances for the allowable luminosity loss due to ground motion effects in CLIC can be met. The presented methods can be easily adapted to other accelerators in order to relax sensor tolerances and to efficiently suppress ground motion effects.

MOPO030	Theoretical and Practical Feasibility Demonstration of a Micrometric Remotely Controlled Pre-alignment System for the CLIC Linear Collider	alignment, linac, target, controls	547
	H. Mainaud Durand, M. Anastasopoulos, N.C. Chritin, J. Kemppinen, M. Sosin, S. griffet CERN, Geneva, Switzerland T. Touzé ENSTA, Brest, France
	The active pre-alignment of the Compact Linear Collider (CLIC) is one of the key points of the project: the components must be pre-aligned w.r.t. to a straight line within a few microns over a sliding window of 200 m, along the two linacs of 20 km each. The proposed solution consists of stretched wires of more than 200 m, overlapping over half of their length, which will be the reference of alignment. Wire Positioning Sensors (WPS), coupled to the supports to be pre-aligned, will perform precise and accurate measurements within a few microns, w.r.t. these wires. A micrometric fiducialisation of the components and a micrometric alignment of the components on common supports will make the strategy of pre-alignment complete. In this paper, the global strategy of active pre-alignment is detailed and illustrated by the latest results demonstrating the feasibility of the proposed solution.

MOPS001	Electron-cloud Pinch Dynamics in Presence of Lattice Magnet Fields	electron, proton, cyclotron, quadrupole	586
	G. Franchetti GSI, Darmstadt, Germany F. Zimmermann CERN, Geneva, Switzerland
	The pinch of the electron cloud due to a passing proton bunch was extensively studied in a field free region and in a dipolar magnetic field. For the latter study, a strong field approximation helped to formulate the equations of motion and to understand the complex electron pinch dynamics, which exhibited some similarities with the field-free situation. Here we extend the analysis to the case of electron pinch in quadrupoles and in sextupoles. We discuss the limits of validity for the strong field approximation and we evaluate the relative magnitude of the peak tune shift along the bunch expected for the different fields.

MOPS002	Mitigation of Space Charge and Nonlinear Resonance Induced Beam Loss in SIS100	beam-losses, resonance, space-charge, acceleration	589
	G. Franchetti GSI, Darmstadt, Germany
	The control of beam loss in SIS100 is essential for avoiding vacuum instability and guarantee the delivery of the foreseen beam intensity. On the other hand simulations show that the simultaneous presence of space charge and lattice resonances creates during 1 second cycle a progressive beam loss exceeding the limit of 5%. Until now the mechanism of periodic resonance crossing were suspected to be, in conjunction with pure dynamic aperture effects, at the base of the beam loss. In this proceeding we present the state of the art in the beam loss prediction and we prove that the periodic resonance crossing is the deteriorating mechanism, and show that the compensation of a relevant resonance intercepting the space charge tune spread sensibly mitigate the beam loss. A short discussion on beam loss during acceleration is addressed as well.

MOPS003	Coherent Beam-beam Resonances in SuperB with Asymmetric Rings	resonance, luminosity, collider, dynamic-aperture	592
	M. Zobov INFN/LNF, Frascati (Roma), Italy Y. Zhang IHEP Beijing, Beijing, People's Republic of China
	One of the latest options of SuperB foresees exploiting rings with unequal circumferences. In such a configuration additional coherent beam-beam resonances can arise. In this paper we discuss the possible impact of the resonances on beam dynamics in SuperB, maximum achievable tune shifts and working point choice.

MOPS005	Beam Dynamics Simulations of J-PARC Main Ring for Upgrade Plan of Fast Extraction Operation	beam-losses, injection, proton, power-supply	598
	Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori, M. Tomizawa KEK, Ibaraki, Japan H. Hotchi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Beam loss simulations under space charge effects are necessary to seek higher intensity proton beams. This paper presents simulations for fast extraction operation of Japan Proton Accelerator Research Complex (J-PARC) Main Ring. For upgrade plan, increasing protons per bunch and making higher repetition pattern are considered. Their optimal balance is discussed to minimize beam losses for aimed beam power considering space charge effects. We found that to optimize RF voltage pattern is a strong key to reduce beam losses for higher repetition. As benchmark works, we compare our simulations with the measured beam loss in our past operation.

MOPS008	Simulation of Longitudinal Emittance Control in J-PARC RCS for 400 MeV Injection	extraction, emittance, injection, bunching	607
	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 injection energy upgrade of the J-PARC RCS from 181 MeV to 400 MeV is scheduled, this is necessary to achieve the design beam intensity. The high intensity beam is delivered to the MR, and the space charge effect at the MR injection should be alleviated by optimizing the longitudinal beam emittance at RCS extraction. This is realized by matching the shape of the beam emittance between the RCS and the MR. We describe the results of particle tracking simulation with the longitudinal emittance control during the whole acceleration period of the RCS.

MOPS011	Impact of Low Transition Energy Optics to the Electron Cloud Instability of LHC Beams in the SPS	electron, optics, synchrotron, emittance	616
	H. Bartosik, E. Benedetto, K.S.B. Li, Y. Papaphilippou, G. Rumolo CERN, Geneva, Switzerland
	One of the main limitations for high intensity multi-bunch LHC proton beams in the SPS is imposed by electron cloud instabilities. A new optics of the SPS with lower transition energy was implemented and successfully tested in machine studies. The significant increase of the slippage factor that it provides at injection energy results in the expected increase of the single bunch instability thresholds. In this paper, the impact of this new optics on the electron cloud instability threshold is estimated by using numerical simulations, taking into account the change of the optics functions and the faster synchrotron motion due to the reduced transition energy.

MOPS017	Simulation Studies of Macro-particles Falling into the LHC Proton Beam	proton, beam-losses, injection, vacuum	634
	F. Zimmermann, T. Baer, M. Giovannozzi, E.B. Holzer, E. Nebot Del Busto, A. Nordt, M. Sapinski CERN, Geneva, Switzerland N. Fuster Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain Z. Yang EPFL, Lausanne, Switzerland
	We report updated simulations on the interaction of macro-particles falling from the top of the vacuum chamber into the circulating LHC proton beam. The path and charge state of micron size micro-particles are computed together with the resulting beam losses, which – if high enough - can lead to the local quench of SC magnets. The simulated time evolution of the beam loss is compared with observations in order to constrain some macro-particle parameters. We also discuss the possibility of a "multiple crossing" by the same macro-particle, the effect of a strong dipole field, and the dependence of peak loss rate and loss duration on beam current and on beam size.

MOPS018	Simulation and Measurement of Half Integer Resonance in Coasting Beams on the ISIS Ring	resonance, emittance, injection, space-charge	637
	C.M. Warsop STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom D.J. Adams, B. Jones, B.G. Pine, H. V. Smith, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on an 800 MeV rapid cycling synchrotron (RCS), which provides 3·10¹³ protons per pulse at 50 Hz, corresponding to a beam power of 0.2 MW. In common with many lower energy, high intensity proton rings, a key loss mechanism on ISIS is half integer resonance under space charge. This paper summarises experimental and simulation work studying half integer resonance in a “2D” coasting beam in the ISIS ring: understanding this is an essential prerequisite for explaining the more complicated case of RCS operation. For coasting beam experiments, the ring is reconfigured to storage ring mode with RF off and main magnets powered on DC current only. A 70 MeV beam is injected, painted appropriately, and manipulated so as to approach resonance. Understanding how the resonant condition develops is central to explaining observations, so realistic simulations of resonance, including injection, ramping of intensity and tunes are being developed. Results from the ORBIT code are presented and compared with experimental and theoretical results. Finally, future plans are summarized.

MOPS019	High Intensity Longitudinal Dynamics Studies for Higher Energy Injection into the ISIS Synchrotron	injection, bunching, space-charge, linac	640
	R.E. Williamson, D.J. Adams, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	ISIS is the world’s most productive pulsed neutron and muon source, at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss-limited 50 Hz proton synchrotron which accelerates 3·10¹³ protons per pulse from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Present studies on ISIS upgrades are focussed on a new linac for higher energy injection into the existing ring, potentially increasing beam current through reduction in space charge and optimized injection. Studies assume injection of a chopped beam at 180 MeV and offer the possibility of beam powers in the 0.5 MW regime. A critical aspect of such an upgrade is the longitudinal dynamics, associated RF parameters, space charge levels and stringent requirements on beam loss. This paper outlines studies optimizing longitudinal parameters including key design requirements such as bunching factor and satisfying the Keil-Schnell-Boussard stability criterion throughout acceleration. Work developing and benchmarking the in-house longitudinal dynamics code used for these studies is also summarized.

MOPS023	An Analytical Lagrangian Model for Analyzing Temperature Effects in Intense Non-neutral Beams*	emittance, focusing, controls, space-charge	646
	E.G. Souza, A. Endler, R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil
	High-intensity charged-particle beams are used in several areas of physics. We can mention as an illustration, high-energy colliders, particle accelerators and vacuum electron devices. In all cases quoted above, the beam lose particles in the acceleration process, between its production to its final destination. These ejected particles, generally, produce a surrounding structure around the beam core, called halo. This undesirable structure is seen in simulation as well as in actual linacs, and its formation has been one of the main sources of energy loss in the acceleration devices. For this reason, the need for an advance in understand the mechanism that produce the halo becomes necessary. In view of the whole problem, we contruct a 1D Lagrangian warm-fluid model for describe the behavior of inhomogeneous charged-particle beam in solenoidal focusing magnetic field. The equations of motion are derived for an adiabatic process with a state equation originated from the ideal gas law. In the end, the model is compared with self-consistent simulation and is used to explain emittance growth and jets of particle, even when the system is out of equilibrium.

MOPS025	Studies of Emittance Measurement by Quadrupole Variation for the IFMIF-EVEDA High Space Charge Beam	emittance, quadrupole, space-charge, beam-transport	652
	P.A.P. Nghiem, E. Counienc CEA/DSM/IRFU, France N. Chauvin CEA/IRFU, Gif-sur-Yvette, France C. Oliver CIEMAT, Madrid, Spain
	For the high-power (1 MW) beam of the IFMIF-EVEDA prototype accelerator, emittance measurements at nearly full power are only possible in a non-interceptive way. The method of quadrupole variation is explored here. Due to the high space charge regime, beam transport is strongly non-linear, and the classical matrix inversion is no more relevant. Inverse calculations using a multiparticle code is mandatory. In this paper, such emittance measurements are studied, aiming at checking its feasibility and evaluating its precision, taking into account the constraints of losses and quadrupole limitations.

MOPS026	Start-to-end Beam Dynamics Simulations for the Prototype Accelerator of the IFMIF/EVEDA Project	rfq, linac, quadrupole, solenoid	655
	N. Chauvin CEA/IRFU, Gif-sur-Yvette, France M. Comunian INFN/LNL, Legnaro (PD), Italy O. Delferrière, R.D. Duperrier, R. Gobin, A. Mosnier, P.A.P. Nghiem, D. Uriot CEA/DSM/IRFU, France C. Oliver CIEMAT, Madrid, Spain
	The EVEDA (Engineering Validation and Engineering Design Activities) phase of the IFMIF (International Fusion Materials Irradiation Facility) project consists in building, testing and operating a 125 mA/9 MeV prototype accelerator in Rokkasho-Mura (Japan). Because of high beam intensity and power, the different sections of the accelerator (injector, RFQ, MEBT, Superconducting Radio-Frequency linac and HEBT) have been optimized with the twofold objective of minimizing losses along the machine and keeping a good beam quality. Extensive start-to-end multi-particles simulations have been performed to validate the prototype accelerator design. A Monte Carlo error analysis has been carried out to study the effects of misalignments and field variations. In this paper, the results of theses beam dynamics simulations, in terms of beam emittance, halo formation and beam losses, are presented.

MOPS028	An Ion Beam Matching to a Linac Accelerating-focusing Channel	rfq, linac, ion, emittance	661
	A. Orzhekhovskaya, W.A. Barth, G. Clemente, L.A. Dahl, P. Gerhard, L. Groening, M. Kaiser, M.T. Maier, S. Mickat, B. Schlitt, H. Vormann, S.G. Yaramyshev GSI, Darmstadt, Germany U. Ratzinger IAP, Frankfurt am Main, Germany
	Funding: Work supported by HIC for FAIR A modern linear accelerator of ions is a long chain of different accelerating-focusing structures. The design of new linacs, as well as an upgrade and optimization of operating facilities, requires precise and reliable beam matching with the subsequent sections. Proper matching of the beam to the channel allows to improve the performance of the whole linac and to reduce the specific costs. Additionally it helps to avoide particle loss in high energy high intensity linacs. Generally a matching algorithm combines precisely measured or calculated accelerating-focusing external fields and experimentally obtained details of the beam parameters with an advanced code for beam dynamics simulations including space charge effects. Experimental results are introduced into a code as input data. The described algorithm has already been successfully implemented for several GSI projects: an upgrade of the GSI heavy ion linac UNILAC, an ion linac for the cancer therapy, the proton linac for the FAIR facility, a facility for laser acceleration of ions and others. Measured data and results of beam dynamics simulations leading to an achieved improvement of the linac performance are presented.

MOPS029	Experiments with a Fast Chopper System for Intense Ion Beams	ion, electron, space-charge, high-voltage	664
	H. Dinter, M. Droba, M. Lotz, O. Meusel, I. Müller, D. Noll, U. Ratzinger, K. Schulte, C. Wagner, C. Wiesner IAP, Frankfurt am Main, Germany
	Chopper systems are used to pulse charged particle beams. In most cases, electric deflection systems are used to generate beam pulses of defined lengths and appropriate repetition rates. At high beam intensities, the field distribution of the chopper system needs to be adapted precisely to the beam dynamics in order to avoid aberrations. An additional challenge is a robust design which guarantees reliable operation. For the Frankfurt Neutron Source FRANZ, an E×B chopper system is being developed which combines static magnetic deflection with a pulsed electric field in a Wien filter configuration. It will generate proton pulses with a flat top of 50 ns at a repetition rate of 250 kHz for 120 keV, 200 mA beams. For the electric deflection, pre-experiments with static and pulsed fields were performed using a helium ion beam. In pulsed mode operation, ion beams of different energies were deflected with voltages of up to ±6 kV and the resulting response was measured using a beam current transformer. A comparison between experiments and theoretical calculations as well as numerical simulations are presented.

MOPS030	Beam Dynamics of the FRANZ Bunch Compressor using Realistic Fields with a Focus on the Rebuncher Cavities	cavity, linac, dipole, focusing	667
	D. Noll, L.P. Chau, M. Droba, O. Meusel, H. Podlech, U. Ratzinger, C. Wiesner IAP, Frankfurt am Main, Germany
	Funding: Work supported by HIC for FAIR. The ARMADILLO bunch compressor currently being designed at IAP is capable of reaching a longitudinal pulse compression ratio of 45 for proton beams of 150 mA at 2 MeV. It will provide one nanosecond proton pulses with a peak current of 7.7 A. The system guides nine linacμbunches deflected by a 5 MHz rf kicker and uses four dipole magnets - two homogeneous and two with field gradients - to merge them on the target. For longitudinal focusing and an energy variation of ±200 keV two multitrack rf cavities are included. ARMADILLO will be installed at the end of the Frankfurt Neutron Source FRANZ making use of the unique 250 kHz time structure. This contribution will provide an overview of the layout of the system as well as recent advances in component design and beam dynamics of the compressor.

MOPS033	Beam Dynamics Studies on the 100 MeV/100 kW Electron Linear Accelerator for NSC KIPT Neutron Source	linac, electron, dipole, gun	673
	S. Pei, Y.L. Chi, M. Hou, W.B. Liu, G. Pei, S.H. Wang, Z.S. Zhou IHEP Beijing, Beijing, People's Republic of China N. Aizatsky, I.M. Karnaukhov, V.A. Kushnir, V. Mitrochenco, A.Y. Zelinsky NSC/KIPT, Kharkov, Ukraine
	We designed one 100MeV/100kW electron linear accelerator for NSC KIPT, which will be used to drive a neutron source on the base of subcritical assembly. Beam dynamics studies has been conducted to reach the design requirement (E=100MeV, P=100kW, dE/E<1% for 99% particles). In this paper, we will present the progress of the design and dynamics simulation results. For high intensity and long beam pulse linear accelerators, BBU effect is one big issue; special care has been taken in the accelerating structure design. To satisfy the energy spread requirement at the linac exit, the particles with large energy difference from the synchronous particle should be eliminated at low energy stage to ease the design of the collimation system and radiation shielding. A dispersion free chicane with 4 bending magnets is introduced at the downstream of the 1st accelerating section; the unwanted particles will be collimated there.

MOPS037	High Intensity Transient Beam Dynamic Study in Travelling Wave Electron Accelerators with Accounting of Beam Loading Effect	beam-loading, linac, space-charge, electron	682
	S.M. Polozov, T.V. Bondarenko, E.S. Masunov, V.I. Rashchikov, A.V. Voronkov MEPhI, Moscow, Russia
	The beam loading effect is one of main problems limiting the beam current. The methods of beam dynamic simulation taking into account the beam loading effect were discussed previously. Simulation methods and the especial code version BEAMDULAD-BL was described in the paper. The beam loading effect was considered only for traveling wave linacs and for stationary beam only. Now it is important to study the beam dynamics of short current pulses, i.e. for transient process. We can consider only one beam bunch (or a packet of bunches) in a long external RF field pulse in stationary case. The beam radiation and wave fields can be calculated in the quasi-statically approximation. This approximation can not be used for transient mode. The methods of beam dynamics simulation will be discussed in this paper for transient mode. New code version BEAMDULAC-BLNS will be described. The simple test simulations will be carried out. A.V. Voronkov et al., "Beam Loading Effect of High Current Trawling Wave Accelerator Dynamic Study", Proc. of IPAC’10, Kyoto, Japan, TUPEA012, p. 1348 (2010).

MOPS038	3D Beam Dynamic Simulation in Heavy Ion Superconducting Drift Tube Linac	cavity, focusing, ion, linac	685
	A.V. Samoshin, S.M. Polozov MEPhI, Moscow, Russia
	The superconducting (SC) linac conventionally consists of some different classes of the identical cavities. Each cavity is based on a SC structure with a high accelerating gradient. The low charge state beams require stronger transverse focusing. This focusing can be reached with the help of SC solenoid lenses. In this paper beam dynamics simulation obtain by smooth approximation and full field. Traditionally only the Coulomb field is taken into account for low energy beams. In this paper the computer simulation of heavy ion beam dynamics in superconducting (SC) linac will carried out by means of the "particle-in-cell" method. Simulation results will present.

MOPS040	Intra-Bunch Energy Spread of Electrons in Powerful RF Linacs for Nuclear Physics Research*	linac, target, electron, HOM	691
	V.V. Mytrochenko, M.I. Ayzatskiy, V.A. Kushnir, A. Opanasenko, S.A. Perezhogin, V.L. Uvarov NSC/KIPT, Kharkov, Ukraine
	Funding: Ukrainian State program of fundamental and applied studies on the use of nuclear materials, nuclear and radiation technologies in the fields of economics (YaMRT project No. 826/35) There are some particles in RF electron linacs with energy that may be significantly different from that of particles within a core of the bunch. Loss of these particles at average beam power of tens of kilowatts can cause radiation and thermal problems. Filtration of such particles during the initial stage of acceleration, at energies below the threshold of photonuclear reactions, is important. The paper analyzes several ways to perform such type of filtration in the injector part of a powerful electron linac using a RF chopper or magnetic systems.

MOPS042	One-Dimensional Adiabatic Child-Langmuir Flow	electron, emittance, gun, plasma	694
	C. Chen MIT, Cambridge, Massachusetts, USA R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil
	Funding: Research supported in part by US Department of Energy, Grant No. DE-FG02-95ER40919, CNPq, FAPERGS, INCTFCx of Brazil, and US Air Force Office of Scientific Research, Grant No. FA9550-09-1-0283. A theory is presented that describes steady-state one-dimensional Child-Langmuir flow at a self-consistent finite temperature distribution. In particular, warm-fluid equations and adiabatic equation of state are used to derive the self-consistent Poisson equation. The profiles of the charged-particle density, the velocity, the electrostatic potential, the pressure and the temperature are computed. Results are compared with self-consistent simulations.

MOPS043	Beam Performance in H⁻ Injector of LANSCE	emittance, space-charge, beam-transport, ion-source	697
	Y.K. Batygin, C. Pillai, L. Rybarcyk LANL, Los Alamos, New Mexico, USA
	During beam development time in 2010 we performed a series of beam emittance and beam profile scans along 750-keV H⁻ beam transport and 800-MeV linac. The purpose of the measurements was to determine the effects of space charge, slow-wave intensity modulation or chopping, RF buncher fields, and vacuum conditions on beam performance. As previously reported, from our observation and analysis we concluded that the 750 keV H⁻ beam transport is space-charge uncompensated. This presentation will look at the relative importance of space-charge, chopping, and RF-buncher on the observed emittance growth for beam in the short and long pulse regime as well as the effects of beam line vacuum degradation on beam size and emittance at the end of the linac. Y. Batygin et al., “Space-charge effects in H⁻ Low-Energy Beam Transport of LANSCE,” to be published in Proc. of the 2011 Particle Accelerator Conference, March 28-April 1, 2011, New York, NY.

MOPS049	Study of Ion-induced Instabilities and Transverse Feedback Performance at SOLEIL	ion, feedback, vacuum, electron	712
	R. Nagaoka, L. Cassinari, M.D. Diop, J.-M. Filhol, M.-P. Level, A. Loulergue, P. Marchand, R. Sreedharan SOLEIL, Gif-sur-Yvette, France
	Experimental studies indicate that the SOLEIL storage ring at its maximum designed current of 500 mA is under a large influence of ions, potentially capable of inducing the so called fast beam-ion instability. To avoid it, the following three conditions have been empirically found effective: A reduced RF voltage, uniform filling and a large vertical chromaticity. While the choice of uniform filling appears contradictory to raising the ion instability threshold, it goes well with lowering of the RF voltage if outgassing due to beam-induced heating of the vacuum components is the primary source of ions. Additional difficulties associated are frequent occurrence of sudden beam blowups despite the presence of transverse feedback, which are large enough to trigger machine interlocks leading to complete beam losses. These blow ups may even take place horizontally inside in-vacuum insertion devices. The present paper reports on the results and findings obtained through experimental and simulation studies carried out on the collective beam dynamics and the transverse feedback performance, which are deeply interlinked, in order to clarify the mechanism of the encountered phenomena.

MOPS053	Electron Cloud Effects in Coasting Heavy-ion Beams*	electron, ion, accumulation, dipole	724
	F.B. Petrov, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany O. Boine-Frankenheim GSI, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 06DA9022I. During slow extraction of intense ion beams electron clouds (EC) can accumulate in the circulating coasting beam and reduce the extraction efficiency. This is a concern for the existing SIS-18 heavy ion synchrotron at GSI and for the projected SIS-100 as part of the FAIR project. For medium energy heavy-ion beams the production of electrons from residual gas ionization is very effective. The electron density is limited due to Coulomb scattering by the beam ions. Above a threshold beam intensity the two-stream instability and the resulting coherent beam oscillations limit the electron density. Below this threshold the electron cloud can lead to observable deformations of the Schottky side-bands. To avoid EC build-up one can introduce a gap in the beam using barrier rf bucket. The reduction of the build-up efficiency caused by the gap is studied in details based on the solution of the Hill's equation for electrons. Finally we estimate the saturation level for the electron cloud density.

MOPS054	Impedance of the Pulse Power Converter for the SIS100 Bipolar Extraction Kicker System	impedance, kicker, coupling, extraction	727
	K. Samuelsson, V. Hinrichsen TU Darmstadt, Darmstadt, Germany U. Blell, P.J. Spiller GSI, Darmstadt, Germany
	SIS100 will be operated with high intensity heavy-ion and proton beams. The reduction of ring impedances is therefore of great importance in order to avoid coherent beam instabilities. The kicker system is one of the main contributors to the overall ring impedance in SIS100. This paper will focus on the contribution of the external network to the kicker impedance. Calculations as well as experimental impedance measurements of the network contribution have already been carried out for the SIS18 and ESR kickers. The SIS100 will be equipped with a bipolar kicker system, which uses a Pulse Forming Network (PFN) as energy storage. For potential detachment purposes an insulation transformer will be installed. Since this setup is new in several ways it is important to know its contribution to the coupling impedance of the kicker system. In this contribution the corresponding numerical calculation is presented.

MOPS056	An Analytical Formula of the Electron Cloud Linear Map Coefficient in a Strong Dipole	electron, dipole, vacuum, storage-ring	733
	T. Demma INFN/LNF, Frascati (Roma), Italy S. Petracca, A. Stabile U. Sannio, Benevento, Italy G. Rumolo CERN, Geneva, Switzerland
	Electron cloud effects have been indentified as one of the most serious bottleneck for reaching design performances in presently running and proposed future storage rings. The analysis of these effects is usually performed with very time consuming simulation codes. An alternative analytic approach, based on a cubic map model for the bunch-to-bunch evolution of the electron cloud density, could be useful to determine regions in parameters space compatible with safe machine operations. In this communication we derive a simple approximate formula relating the quadratic coefficient in the electron cloud density map to the parameters relevant for the electron cloud evolution in a strong vertical magnetic field. Results are compared with simulations with particular reference to the LHC dipoles.

MOPS057	Beam-beam Interaction under External Force Oscillation	luminosity, positron, electron, kicker	736
	K. Ohmi KEK, Ibaraki, Japan
	Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.

MOPS058	KEKB Linac Wakefield Studies of Comparing Theoretical Calculation, Simulation and Experimental Measurement*	emittance, wakefield, linac, injection	739
	L. Zang, N. Iida, Y. Ogawa, M. Satoh, M. Yoshida, D.M. Zhou KEK, Ibaraki, Japan
	For superKEKB, in order to achieve aiming luminosity machine need to run with a nano-beam scheme so that a small beam emittance is critical important. During the beam propagation, the short-range wake field in the accelerating structure will cause the beam instability and emittance growth. In practical, injecting beam with certain offset could compensate wakfield. And beam emittance could be measured by tuning the quadruple known as quadscan method. In this paper, wakefield theoretical calculation, simulation results will be presented. And then the wakefield impact to beam emittance and wakefield compensation will be discussed. Finally, we will show the comparison of the results getting from theoretical calculation and experimental measurement.

MOPS060	Study on Resistive Wall Instability in CSNS/RCS	injection, impedance, wakefield, extraction	745
	L. Huang, Y.D. Liu, S. Wang IHEP Beijing, Bejing, People's Republic of China
	Rapid Cycling Synchrotron of the China Spallation Neutron Source is a high intensity proton accelerator, with average beam power of 100kW. The collective effects caused by the coupling impedance may be the limit to beam power. The impedance estimation for components on beam line shows that the resistive wall impedance and its instability are more serious than any others. Based on the impedance budget, the instability is theoretically estimated. And a simple resistive wall wake field model is used to simulate the bunch oscillation and the growth rate instability. In this model, the continuous resistive wall wake field is equivalent to a point wake field and long bunch is sliced into many micro-bunches. By tracking the dynamics of the macro-bunches, the transverse growth rate are obtained and the result are analyzed.

MOPS068	Localization of Transverse Impedance Sources in the SPS using HEADTAIL Macroparticle Simulations	impedance, quadrupole, lattice, ion	757
	N. Biancacci, G. Arduini, E. Métral, D. Quatraro, G. Rumolo, B. Salvant, R. Tomás CERN, Geneva, Switzerland N. Biancacci, M. Migliorati, L. Palumbo Rome University La Sapienza, Roma, Italy R. Calaga BNL, Upton, Long Island, New York, USA
	In particle accelerators, beam coupling impedance is one of the main contributors to instability phenomena that lead to particle losses and beam quality deterioration. For this reason these machines are continuously monitored and the global and local amount of impedance needs to be evaluated. In this work we present our studies on the local transverse impedance detection algorithm. The main assumptions behind the algorithm are described in order to understand limits in reconstructing the impedance location. The phase advance response matrix is analyzed in particular for the SPS lattice, studying the different response from 90,180,270 degrees phase advance sections. The thin lenses scheme is also implemented and new analytical formulas for phase advance beating were derived. This avails us to put reconstructing lenses everywhere in the lattice, and to study their positioning scheme. Limits in linear response are analyzed. This sets the upper and lower limits in reconstruction to the phase advance measurement accuracy and the linear response regime limit.

MOPS069	Review of Beam Instabilities in the Presence of Electron Clouds in the LHC	emittance, electron, injection, luminosity	760
	K.S.B. Li, G. Rumolo CERN, Geneva, Switzerland
	Recent observations at the LHC indicate the build-up of electron clouds when 50 ns spaced beams are injected into the machine at nominal intensity. These electron clouds are a source of coherent beam instabilities and incoherent emittance growth and limit the achievable luminosity. To better understand the influence of electron clouds on the beam dynamics, simulations have been carried out to study both the coherent and the incoherent effects on the beam. The simulations are performed with the HeadTail tracking code; the usage of new post-processing software allows determining not only the beam intensity thresholds in terms of the central electron cloud density but also the footprint of the beam in tune space. In this paper we review instability thresholds and tune footprints for beams with different emittances and interacting with an electron cloud in field-free or dipole regions.

MOPS070	Electromagnetic Modeling of C Shape Ferrite Loaded Kickers	impedance, kicker, vacuum, ion	763
	C. Zannini EPFL, Lausanne, Switzerland E. Métral, G. Rumolo, B. Salvant, V.G. Vaccaro, C. Zannini CERN, Geneva, Switzerland
	The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, analytical approach and CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of models of ferrite loaded kickers. It turns out that the existing models are not sufficient to characterize correctly these components from the coupling impedance point of view. In particular the results show that below few hundred MHz the real C-structure of the magnet cannot be neglected. Therefore an analytical model was developed and benchmarked with EM simulations to take into account the C-shape of the magnet.

MOPS071	Simulations of the Impedance of the New PS Wire Scanner Tank	impedance, beam-losses, extraction, vacuum	766
	B. Salvant EPFL, Lausanne, Switzerland W. Andreazza, F. Caspers, A. Grudiev, J.F. Herranz Alvarez, E. Métral, G. Rumolo CERN, Geneva, Switzerland
	The CERN PS is equipped with 4 wire scanners. It was identified that the small aperture of the current wire scanner tank causes beam losses and a new tank design was needed. The interaction of the PS bunches with the beam coupling impedance of this new tank may lead to beam degradation and wire damage. This contribution presents impedance studies of the current PS tank as well as the new design in order to assess the need to modify the design and/or install lossy materials plates dedicated to damp higher order cavity modes and reduce the total power deposited by the beam in the tank.

MOPS072	Broadband Electromagnetic Characterization of Materials for Accelerator Components	impedance, kicker, damping, RF-structure	769
	C. Zannini, A. Grudiev, E. Métral, T. Pieloni, G. Rumolo CERN, Geneva, Switzerland G. De Michele PSI, Villigen, Switzerland C. Zannini EPFL, Lausanne, Switzerland
	Electromagnetic (EM) characterization of materials up to high frequencies is a major requirement for the correct modeling of many accelerator components: collimators, kickers, high order modes damping devices for accelerating cavities. In this scenario, the coaxial line method has gained much importance compared to other methods because of its applicability in a wide range of frequencies. In this paper we describe a new coaxial line method that allows using only one measurement setup to characterize the material in a range of frequency from few MHz up to several GHz. A coaxial cable fed at one side is filled with the material under test and closed on a known load on the other side. The properties of the material are obtained from the measured reflection coefficient by using it as input for a transmission line (TL) model or for 3D EM simulations, which describe the measurements setup. We have applied this method to characterize samples of SiC (Silicon Carbide) which could be used for LHC collimators and for CLIC accelerating structures and NiZn ferrite used for kicker magnets.

MOPS074	Stabilization of the LHC Single-bunch Transverse Instability at High-energy by Landau Octupoles	octupole, beam-losses, emittance, single-bunch	775
	E. Métral, B. Salvant CERN, Geneva, Switzerland N. Mounet EPFL, Lausanne, Switzerland
	When the first ramp was tried on Saturday 15/05/2010 with a single bunch of about nominal intensity (i.e. ~ 10¹1 p/b), the bunch became unstable in the horizontal plane at ~ 2 TeV. The three main observations were: (i) a “Christmas tree” in the transverse tune measurement application (with many synchrotron sidebands excited), (ii) beam losses (few tens of percents) in IR7, and (iii) an increase of the bunch length. This transverse coherent instability has been stabilized successfully with Landau octupoles. Comparing all the measurements performed during this first year of LHC commissioning with the theoretical and simulation predictions reveals a good agreement.

MOPS075	Simulation of Multibunch Motion with the HEADTAIL Code and Application to the CERN SPS and LHC	impedance, wakefield, synchrotron, coupling	778
	N. Mounet EPFL, Lausanne, Switzerland N. Mounet, E. Métral, G. Rumolo CERN, Geneva, Switzerland
	Multibunch instabilities due to beam-coupling impedance can be a critical limitation for synchrotrons operating with many bunches. It is particularly true for the LHC under nominal conditions, where according to theoretical predictions the 2808 bunches rely entirely on the performance of the transverse feedback system to remain stable. To study these instabilities, the HEADTAIL code has been extended to simulate the motion of many bunches under the action of wake fields. All the features already present in the single-bunch version of the code, such as synchrotron motion, chromaticity, amplitude detuning due to octupoles and the ability to load any kind of wake fields through tables, have remained available. This new code has been then parallelized in order to track thousands of bunches in a reasonable amount of time. The code was benchmarked against theory and exhibited a good agreement. We also show results for bunch trains in the LHC and compare them with beam-based measurements.

MOPS076	Long Range Wakefields in the SwissFEL C-band Linac	wakefield, HOM, linac, impedance	781
	A. Citterio, M. Aiba, R. Zennaro PSI, Villigen, Switzerland
	The SwissFEL main linac consists of more than hundred constant gradient C-band accelerating structures which boost the beam energy from 410 MeV at the injector to the final nominal energy of 5.8 GeV. With a repetition rate of 100 Hz, two bunches per pulse can be accelerated with a spacing of 28 ns to feed simultaneously two different FEL arms. Rising of the long range wakefields, both longitudinal and transverse, could affect this multibunch operation, causing degenerative effects on the quality of the second bunch. A direct computation of the longitudinal and transverse wakes by means of time domain simulations is compared with a model based on the computation of the dispersion curves of the wake modes by frequency domain simulations. A good agreement is obtained for both the synchronous frequency and impedance of all the main modes contributing to the wakefields. Moreover, the total longitudinal wake at 28 ns is below the thighter tolerances required by the beam dynamics, so that neither Higher Order Modes (HOMs) either beam loading require compensation. The effects on the beam of the long range transverse wakefields are also negligeable. R. Ganter et al, SwissFEL CDR, PSI report n. 10-04; http://www.psi.ch/swissfel/CurrentSwissFELPublicationsEN/SwissFEL_CDR_{_}v19₀3.03.11-small.pdf

MOPS078	Coaxial Wire Measurements of Ferrite Kicker Magnets	impedance, kicker, injection, extraction	784
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant, C. Zannini CERN, Geneva, Switzerland
	Fast kicker magnets are used to inject beam into and eject beam out of the CERN accelerator rings. These kickers are generally transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the yoke can provoke significant beam induced heating, especially for high intensities. In addition the impedance may contribute to beam instabilities. The results of longitudinal and transverse impedance measurements, for various kicker magnets, are presented and compared with analytical calculations: in addition predictions from a numerical analysis are discussed.

MOPS079	Simulations of Coaxial Wire Measurements of the Impedance of Asymmetric Structures	impedance, coupling, kicker, synchrotron	787
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom F. Caspers, H.A. Day, E. Métral CERN, Geneva, Switzerland
	Coaxial wire measurements have provided a simple and effective way to measure the beam coupling impedance of accelerator structures for a number of years. It has been known how to measure the longitudinal and dipolar transverse impedance using one and two wires for some time. Recently the ability to measure the quadrupolar impedance of structures exhibiting top/bottom and left/right symmetry has been demonstrated. A method for measuring the beam coupling impedance of asymmetric structures using displaced single wires and two wire measurements is proposed. Simulations of the measurement system are presented with further work proposed.

MOPS080	Comparison of the Current LHC Collimators and the SLAC Phase 2 Collimator Impedances	impedance, coupling, cavity, collimation	790
	H.A. Day, R.M. Jones UMAN, Manchester, United Kingdom F. Caspers, H.A. Day, E. Métral, B. Salvant CERN, Geneva, Switzerland
	One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.

MOPS082	Some Considerations on the Choice of Frequency and Geometrical Beta in High Power Proton Linacs in the Context of Higher Order Modes	cavity, HOM, linac, proton	793
	M. Schuh, F. Gerigk CERN, Geneva, Switzerland M. Schuh MPI-K, Heidelberg, Germany C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Several high power superconducting (SC) proton linear accelerators are currently in the design stage around the world, such as for example the European Spallation Source (ESS) in Lund, Project X at Fermilab, the European ADS demonstrator MYRRAH in Mol and the Superconducting Proton linac (SPL) at CERN. In this contribution, the influence of Higher Order Modes (HOMs) in elliptical SC cavities is discussed as a function of the operation frequency, the number of cells and the geometrical beta of the cavity. Based on cavity design data beam dynamics simulations are executed for different linac layouts to quantify the influence of HOMs.

MOPS086	Beam Breakup Simulation for the PEP-X ERL	HOM, cavity, emittance, recirculation	805
	Y. Jiao, Y. Cai, A. Chao SLAC, Menlo Park, California, USA
	Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515. The transverse beam breakup (BBU) is one of the dominant factors in ERL for the available beam current. A tracking code built in Matlab is developed and benchmarked by comparing with the analytical solutions with the simple model. Study on the threshold current and emittance growth due to the transverse BBU for PEP-X ERL are presented in this paper.

MOPS088	Simulation of Electron Cloud Beam Dynamics for CesrTA	emittance, electron, betatron, positron	808
	K.G. Sonnad, G. Dugan, M.A. Palmer, G. Ramirez, H.A. Williams CLASSE, Ithaca, New York, USA K.R. Butler Cornell University, Ithaca, New York, USA M.T.F. Pivi SLAC, Menlo Park, California, USA
	This presentation provides a comprehensive set of results obtained using the simulation program CMAD. CMAD is being used for studying electron cloud induced beam dynamics issues for CesrTA, which is a test facility for studying physics associated with electron and positron damping rings. In particular, we take a closer look at electron cloud induced effects on positron beams, including head-tail motion, emittance growth and incoherent tune shifts for parameters specific to ongoing experimental studies at CesrTA. The correspondence between simulation and experimental results will also be discussed. Work supported by US Department of Energy grant number DE-FC02-08ER41538 and the National Science Foundation grant number PHY-0734867

MOPS089	Identification of Bunch Dynamics in the Presence of E-cloud and TMCI for the CERN SPS Ring	controls, feedback, coupling, kicker	811
	O. Turgut, J.D. Fox, C.H. Rivetta, S. Uemura SLAC, Menlo Park, California, USA W. Höfle CERN, Geneva, Switzerland
	Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). Measurements and multi-particle simulation codes (i.e. HEAD-TAIL, WARP, CMAD) indicate that bunched particle beams show unstable motions induced by electron-clouds and strong head-tail interactions. The bunch dynamics exhibits highly non-linear, complex and unstable behavior under certain operating conditions. Feedback control systems have been proposed to mitigate these instabilities in the CERN SPS ring. The design of feedback systems requires the knowledge of a reduced dynamic model of the bunch. It allows to include and quantify the effect of noise and signal perturbations, as well as system robustness to parameter variation. Identification techniques are used to estimate those models based on bunch motion measurements. In this work we present reduced mathematical models representing the transverse bunch dynamics and identification techniques to extract the model parameters based on measurements. These techniques are validated using time domain simulations of the bunch motion conducted using multi-particle simulation codes. For that, different sections of the bunch are driven by random signals, and the vertical motion of those areas is used to estimate the reduced model.

MOPS091	Study of Electron Cloud for MEIC	electron, emittance, luminosity, dipole	817
	S. Ahmed, J.D. Dolph, G.A. Krafft, T. Satogata, B.C. Yunn JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The Medium Energy Electron Ion Collider (MEIC) at Jefferson Lab has been envisioned as a future high energy particle accelerator beyond the 12 GeV upgrade of the existing Continuous Electron Beam Accelerator Facility (CEBAF). Synchrotron radiation from the closely spaced proton bunches in MEIC can generate photoelectrons inside the vacuum chamber and cause secondary emission due to multipacting in the presence of beam's electric field. This phenomenon can lead to fast build up of electron density, known as electron cloud effect – resulting into beam instability coupled to multi-bunches in addition to a single bunch. For MEIC, the estimated threshold value of the electron-cloud density is approximately 5 x 10¹² m-3. In this paper, we would like to report the self-consistent simulation studies of electron cloud formation for MEIC. The code has been benchmarked against the published data of electron cloud effects observed in LHC. Our first simulations predict increase of electron clouds with the increase of repetition rate. The detailed simulations are under progress and will be reported.

MOPZ001	MuSIC, the World's Highest Intensity DC Muon Beam using a Pion Capture System	proton, solenoid, target, dipole	820
	A. Sato, Y. Kuno, H. Sakamoto Osaka University, Osaka, Japan S. Cook, R.T.P. D'Arcy UCL, London, United Kingdom M. Fukuda, K. Hatanaka RCNP, Osaka, Japan Y. Hino, N.H. Tran, N.M. Truong Osaka University, Graduate School of Science, Osaka, Japan Y. Mori KURRI, Osaka, Japan T. Ogitsu, A. Yamamoto, M.Y. Yoshida KEK, Tokai, Ibaraki, Japan
	MuSIC is a project to provide the world's highest-intensity muon beam with continuous time structure at Research Center of Nuclear Physics (RCNP) of Osaka University, Japan. A pion capture system using a superconducting solenoid magnet and a part of superconducting muon transport solenoid channel have been build in 2010. The highest muon production efficiency was demonstrated by the beam test carried out in February 2011. The result concludes that the MuSIC can provide more than 10⁹ muons/sec using a 400 W proton beam. The pion capture system is one of very important technologies for future muon programs such as muon to electron conversion searches, neutrino factories, and a muon collider. The MuSIC built the first pion capture system and demonstrate its potential to provide an intense muon beam. The construction on the entire beam channel of the MuSIC will be finished in five years. We plan to carry out not only an experiment to search the lepton flavor violating process but also other experiments for muon science and their applications using the intense muon beam at RCNP.

MOPZ008	Particle Production Simulations for the Neutrino Factory Target	target, proton, shielding, factory	835
	J.J. Back University of Warwick, Coventry, United Kingdom X.P. Ding UCLA, Los Angeles, California, USA I. Efthymiopoulos, S.S. Gilardoni, O.M. Hansen, G. Prior CERN, Geneva, Switzerland H.G. Kirk, N. Souchlas BNL, Upton, Long Island, New York, USA R.J. Weggel Particle Beam Lasers, Inc., Northridge, California, USA
	Funding: EU FP7 EUROnu WP3 In the International Design Study for the Neutrino Factory (IDS-NF), a proton beam with a kinetic energy between 5 and 15 GeV interacts with a liquid mercury jet target in order to produce pions that will decay to muons, which in turn decay to neutrinos. The target is situated in a solenoidal field tapering from 20 T down to 1.5 T over a length of several metres, allowing for an optimised capture of pions in order to produce a useful muon beam for the machine. We present results of target particle production calculations using MARS, FLUKA and G4BEAMLINE simulation codes.

MOPZ010	An Accelerator Design Tool for the International Design Study for the Neutrino Factory	factory, lattice, solenoid, HOM	841
	A. Kurup Imperial College of Science and Technology, Department of Physics, London, United Kingdom P. Bonnal, B. Daudin, J. De Jonghe, M. Dutour CERN, Geneva, Switzerland
	A tool has been developed to simplify the accelerator design process from the lattice design, through tracking simulations with engineering features, to costing the facility. The aim of this tool is to facilitate going through the design loop efficiently and thus allow engineering features to be included early on in the design process without hindering the development of the lattice design. The tool uses a spreadsheet to store information about the accelerator and can generate MADX input files, G4beamline input files and interfaces with the costing tool developed by CERN. Having one source for the information simplifies going between lattice simulations, tracking simulations and costing calculations and eliminates the possibility of introducing discrepancies in the design. The application of this tool to cost the Neutrino Factory, which is part of the IDS-NF and EUROnu studies for delivering the Reference Design Report, will be presented.

MOPZ013	MAUS: MICE Analysis User Software	emittance, controls, extraction, factory	850
	C.D. Tunnell JAI, Oxford, United Kingdom C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The Muon Ionization Cooling Experiment (MICE) is unique because it measures accelerator physics quantities using particle physics methods. It follows that the software that forms the theoretical model of MICE needs to be able to not only propagate beam envelopes and optical parameters but also model detector responses and matter effects for cooling. MICE addresses this dichotomy with the software framework MAUS in order to maximize its physics sensitivity whilst providing the conveniences of, for example, a common data structure. The diversity of challenges that MICE provides from the analysis perspective means that appropriately defining the software scope and layout is critical to the correctness and maintainability of the final accelerator physics analyses. MICE has structured its code into a Map-Reduce framework to enable better parallelization whilst also introducing unit, functional, and integration tests to ensure code reliability and correctness. These methods can apply to other experiments.

MOPZ016	MICE Step I: First Measurement of Emittance with Particle Physics Detectors*	emittance, quadrupole, collider, factory	853
	L. Coney UCR, Riverside, California, USA M. Popovic Fermilab, Batavia, USA M.A. Rayner DPNC, Genève, Switzerland
	The muon ionization cooling experiment (MICE) is a strategic R&D project intending to demonstrate the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. MICE is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam is measured in the upstream magnetic spectrometer with a sci-fiber tracker. A cooling cell will then follow, alternating energy loss in Li-H absorbers and RF acceleration. A second spectrometer identical to the first and a second muon identification system measure the outgoing emittance. In the 2010 run the beam and most detectors have been fully commissioned and a first measurement of the emittance of a beam with particle physics (time-of-flight) detectors has been performed. The analysis of these data should be completed by the time of the Conference. The next steps of more precise measurements, of emittance and emittance reduction (cooling), that will follow in 2011 and later, will also be outlined. Abstract is submitted by the MICE Speakers Bureau. If accepted, most likely Dr. Kaplan will present it. As a first result in a novel sector, we propose it for an oral presentation

MOPZ028	Solid Absorber Program Status for MICE Step IV	emittance, status, insertion, cavity	859
	P. Snopok IIT, Chicago, Illinois, USA J.H. Cobb JAI, Oxford, United Kingdom G.T. Kafka Illinois Institute of Technology, Chicago, Illinois, USA C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	Funding: Work is supported by the Science and Technology Facilities Council and the U.S. Department of Energy. In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material and then through RF cavities to compensate for the energy loss, which reduces the transverse emittance. In addition to demonstrating the transverse emittance reduction using flat solid absorbers, it is also planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge-shaped absorber in MICE Step IV. The current status of the simulation and design effort for both flat and wedge-shaped solid absorbers is summarized.

MOPZ036	Ionization Cooling in MICE Step IV	emittance, scattering, solenoid, factory	877
	T. Carlisle, J.H. Cobb JAI, Oxford, United Kingdom R.R.M. Fletcher UCR, Riverside, California, USA
	The international Muon Ionization Cooling Experiment (MICE), under construction at RAL, will test and characterize a prototype cooling channel for a future Neutrino Factory or Muon Collider. The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance. The change in 4D emittance will be determined with a relative accuracy of 1% by measuring muons individually. These include two scintillating fibre trackers embedded within 4 T solenoid fields, TOF counters and a muon ranger. Step IV of MICE will begin in 2012, producing the experiment's first precise emittance-reduction measurements. Multiple scattering in candidate Step IV absorber materials was studied in G4MICE, based on GEANT4. Equilibrium emittances for low-Z materials from hydrogen to aluminium can be studied experimentally in Step IV of MICE, and compared with simulations.

TUOAA02	Status of UA9, the Crystal Collimation Experiment in the SPS	collimation, ion, proton, beam-losses	897
	W. Scandale LAL, Orsay, France
	Funding: CERN, IHEP-Protvino, Imperial-College, INFN, JINR-Dubna, LBNL, PNPI-Gartchina, SLAC UA9 was operated in the CERN-SPS for more than two years in view of investigating the feasibility of the halo collimation with bent crystals. Silicon crystals 2 mm long with bending angles of about 150 urad were used as primary collimators. The crystal collimation process was steadily achieved through channeling with high efficiency. The crystal orientation was easily set and optimized with the installed goniometer which has an angular reproducibility of about ± 10 μrad. In channeling orientation, the loss rate of the halo particles interacting with the crystal is reduced by a factor of ten, whilst the residual off-momentum halo escaping from the crystal-collimator area is reduced by a factor five. The crystal channeling efficiency of about 75 % is reasonably consistent with simulations and with single pass data collected in the North Area of the SPS. The accumulated observations, shown in this paper, support our expectation that the coherent deflection of the beam halo by a bent crystal should considerably help in enhancing the collimation efficiency in LHC.
	Slides TUOAA02 [4.297 MB]

TUYA03	Stochastic Cooling of a High Energy Collider	kicker, pick-up, cavity, luminosity	913
	M. Blaskiewicz, J.M. Brennan, R.C. Lee, K. Mernick BNL, Upton, Long Island, New York, USA
	Three dimensional stochastic cooling was successfully implemented at the Relativistic Heavy Ion Collider to overcome emittance growth from intra-beam scattering. The talk reports on the experience of operating a collider with continuous cooling. The application of such techniques to other hadron machine (e.g. LHC) will be discussed.
	Slides TUYA03 [1.350 MB]

TUOAB03	Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization	lattice, sextupole, dynamic-aperture, storage-ring	948
	Z. Bai, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	Particle swarm optimization (PSO) is a computational intelligence algorithm for global optimization. Obtaining adequate dynamic and momentum aperture is crucial for high injection efficiency and long beam lifetime in low emittance electron storage rings. Different from nonlinear driving terms optimization, we have made direct optimization of dynamic and momentum aperture by PSO algorithm. It is critical to make a criterion for comparison of dynamic and momentum aperture tracking results in the direct optimization procedure. Thus, in this paper we first propose a quantitative criterion of dynamic aperture. Then we apply PSO to the optimization of chromatic and harmonic sextupoles to find the optimum sextupole settings for enlarging the dynamic aperture. Taking the momentum aperture into consideration, we make joint optimization of dynamic and momentum aperture. Also, the momentum aperture has its quantitative criterion. As an example of application, the dynamic and momentum aperture of an FBA lattice studied in the design of storage ring of Hefei Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.
	Slides TUOAB03 [0.313 MB]

TUODB03	Innovative Design of the Fast Switching Power Supplies for the SOLEIL EMPHU Insertion and its Fast Correctors	power-supply, controls, undulator, permanent-magnet	982
	F. Bouvet, D. Aballea, R. Ben El Fekih, S. Bobault, M. Bol, Y. Bouanani, Y. Dietrich, A. Hardy, F. Marteau SOLEIL, Gif-sur-Yvette, France
	A new electromagnetic/permanent magnets helical undulator has been designed and is under commissioning at SOLEIL. For a fast switching of the photon polarization, it requires a power supply able to switch between +/350 A within 50 ms, without any current overshoot and with a very good current resolution over the full scale (50 ppm). The in-house design is based on two full switching bridges with interleaved commands. Combined with a regulation scheme using sophisticated algorithms, such a design enables to reach a high control bandwidth, permitting fast transitions. Such a fast and accurate system needs well performing digital control electronics. We chose the digital control cards developed at Paul Scherrer Institute (Villigen CH) for the SLS (Swiss Light Source). The components, measurements, interlocks, control interfaces, and electronic cards were developed and assembled together at SOLEIL. This paper will present the main lines of this development and the performances achieved during the EMPHU insertion commissioning. The design of the fast power supplies (±20 A) needed for corrector magnets of this insertion will also be presented.
	Slides TUODB03 [3.017 MB]

TUPC001	Simulations of the Interaction Point for TeV-scale e⁺ e− Colliders	photon, electron, collider, radiation	985
	J. Esberg Aarhus University, Aarhus, Denmark
	The design of a detector and post collisional line of a future linear collider calls for detailed knowledge of the beam-beam dynamics at the interaction point. We here describe the implementation and results of new simulation tools in the program GUINEA-PIG. The subjects are direct trident production relevant in the deep quantum-regime, incoherent muon generation, synchrotron radiation from secondary particles and depolarization effects. We choose beam parameters in the range relevant for CLIC and comment on the implications for the design of such a machine.

TUPC004	The Luminosity for the ILC Travelling Focus Regime with Offsets and Angle Scans*	luminosity, emittance, collider, wakefield	991
	L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, A. Ushakov University of Hamburg, Hamburg, Germany K. Buesser, A.F. Hartin, G.A. Moortgat-Pick, N.J. Walker DESY, Hamburg, Germany S. Riemann, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	One of the crucial challenges of a future linear collider is to provide high luminosity. In the current ILC design a luminosity of 2x10³⁴ is foreseen. In order to enhance the luminosity, use of the “travelling focus” scheme is under discussion. Within this regime the hourglass effect at the interaction point can be effectively overcome by judiciously arranging for the head and tail of the bunches to be focused at a proportionally displaced longitudinal position. The effect is further enhanced by the strong beam-beam interaction which continuously focuses the bunches during collision. In principle travelling focus could provide an additional 30% luminosity. Nevertheless the regime is highly sensitive to beam-beam transverse and angular offsets at the collision point. The study of the luminosity stability for various ILC parameters using traveling focus will be presented.

TUPC013	Simulation of Phase Stability at the Flat Top of the CLIC Drive Beam	linac, luminosity, kicker, collider	1018
	A. Gerbershagen, D. Schulte CERN, Geneva, Switzerland P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Funding: University of Oxford The drive beam phase stability is one of the critical issues of the Compact Linear Collider (CLIC). In this paper the generation and propagation of drive beam phase errors is studied for effects that vary during the drive beam pulse. This includes the influence of drive beam current and phase errors as well as of drive beam accelerator RF phase and amplitude errors on the drive beam phase after the compressor chicanes and the analysis of the propagation of these errors through the drive beam combination scheme. The impact of the imperfections on the main beam is studied including the possible correction with help of a feedforward system.

TUPC014	System Control for the CLIC Main Beam Quadrupole Stabilization and Nano-positioning*	feedback, quadrupole, luminosity, ground-motion	1021
	S.M. Janssens, K. Artoos, C.G.R.L. Collette, M. Esposito, P. Fernandez Carmona, M. Guinchard, C. Hauviller, A.M. Kuzmin, R. Leuxe, J. Pfingstner, D. Schulte, J. Snuverink CERN, Geneva, Switzerland
	The conceptual design of the active stabilization and nano-positioning of the CLIC main beam quadrupoles was validated in models and experimentally demonstrated on test benches. Although the mechanical vibrations were reduced to within the specification of 1.5 nm at 1 Hz, additional input for the stabilization system control was received from integrated luminosity simulations that included the measured stabilization transfer functions. Studies are ongoing to obtain a transfer function which is more compatible with beam based orbit feedback; it concerns the controller layout, new sensors and their combination. In addition, the gain margin must be increased in order to reach the requirements from a higher vibration background. For this purpose, the mechanical support is adapted to raise the frequency of some resonances in the system and the implementation of force sensors is considered. Furthermore, this will increase the speed of repositioning the magnets between beam pulses. This paper describes the improvements and their implementation from a controls perspective.

TUPC015	Comparative Wakefield Analysis of a First Prototype of a DDS Structure for CLIC Main Linac	wakefield, impedance, dipole, damping	1024
	A. D'Elia, A. Grudiev, V.F. Khan, W. Wuensch CERN, Geneva, Switzerland R.M. Jones UMAN, Manchester, United Kingdom
	A Damped Detuned Structure (DDS) for CLIC main linac has been proposed as an alternative to the present baseline design which is based on heavy damping. A first prototype, CLIC_DDS_A, for high power tests has been already designed and is under construction. It is also foreseen to design a further prototype, CLIC_DDS_B, to test both the wakefield suppression and high power performances. Wakefield calculations for DDS are, in the early design stage, based on single infinitely periodic cells. Though cell-to-cell interaction is taken into account to calculate the wakefields, it is important to study full structure properties using computational tools. In particular this is fundamental for defining the input parameters for the HOM coupler that is crucial for the performances of DDS. In the following a full analysis of wakefields and impedances based on simulations conducted with finite difference based electromagnetic computer code GdfidL will be presented.

TUPC018	Progress on Modelling of the Thermo-Mechanical Behavior of the CLIC Two-Beam Module	vacuum, RF-structure, linac, collider	1033
	R.J. Raatikainen, K. Osterberg HIP, University of Helsinki, Finland T.O. Niinikoski, G. Riddone CERN, Geneva, Switzerland
	The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module will be tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the FEA model developed for CLIC prototype module is described. The thermal and structural results for the new module configuration are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done during 2011 and 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behaviour and they will be propagated back to the present thermo-mechanical model.

TUPC019	Beam-based Alignment of CLIC Drive Beam Decelerator using Girders Movers	quadrupole, alignment, dipole, extraction	1036
	G. Sterbini, D. Schulte CERN, Geneva, Switzerland
	The CLIC drive beams will provide the rf power to accelerate the colliding beams: in order to reach the design performance, an efficient transport of the drive beam has to be ensured in spite of its challenging energy spread and large current intensity. As shown in previous studies, the specifications can be met by coupling a convenient optics design with the state-of-the-art of pre-alignment and beam-based alignment techniques. In this paper we consider a novel beam-based alignment scheme that does not require quadrupole movers or dipole correctors but uses the motors already foreseen for the pre-alignment system. This implies potential savings in terms of complexity and cost at the expense of the alignment flexibility: the performance, limitations and sensitivity to pre-alignment tolerances of this method are discussed.

TUPC023	Status of Ground Motion Mitigation Techniques for CLIC	luminosity, feedback, quadrupole, ground-motion	1048
	J. Snuverink, K. Artoos, C.G.R.L. Collette, F. Duarte Ramos, A. Gaddi, H. Gerwig, S.M. Janssens, J. Pfingstner, D. Schulte CERN, Geneva, Switzerland G. Balik, L. Brunetti, A. Jeremie IN2P3-LAPP, Annecy-le-Vieux, France P. Burrows Oxford University, Physics Department, Oxford, Oxon, United Kingdom B. Caron SYMME, Annecy-le-Vieux, France J. Resta-López IFIC, Valencia, Spain
	The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion. A number of mitigation techniques are proposed - quadrupole stabilisation and positioning, final doublet stabilisation as well as beam based orbit and interaction point (IP) feedback. Integrated studies of the impact of the ground motion on the CLIC Main Linac (ML) and Beam Delivery System (BDS) have been performed, which model the hardware and beam performance in detail. Based on the results future improvements of the mitigation techniques are suggested and simulated. It is shown that with the current design the tight luminosity budget for ground motion effects is fulfilled and accordingly, an essential feasibility issue of CLIC has been addressed.

TUPC025	Calibration Errors in the Cavity Beam Position Monitor System at the ATF2	cavity, radio-frequency, lepton, closed-orbit	1051
	F.J. Cullinan, S.T. Boogert, N.Y. Joshi, A. Lyapin JAI, Egham, Surrey, United Kingdom
	It has been shown at the Accelerator Test Facility at KEK, that it is possible to run a system of 37 cavity beam position monitors (BPMs) and achieve high working resolution. However, stability of the calibration constants (position scale and radio frequency (RF) phase) over a three/four week running period is yet to be demonstrated. During the calibration procedure, random beam jitter gives rise to a statistical error in the position scale and slow orbit drift in position and tilt causes systematic errors in both the position scale and RF phase. These errors are dominant and have been evaluated for each BPM. The results are compared with the errors expected after a tested method of beam jitter subtraction has been applied.

TUPC027	CLIC Post-Collision Line Luminosity Monitoring	photon, luminosity, monitoring, feedback	1057
	R. Appleby UMAN, Manchester, United Kingdom A. Apyan, L.C. Deacon, E. Gschwendtner CERN, Geneva, Switzerland
	The CLIC post collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14 MW to the main beam dump. Full Monte Carlo simulation has been done for the description of the Compact Linear Collider (CLIC) luminosity monitoring at the post collision line. One method of the luminosity diagnostic is based on the detection of high energy muons produced by the beamsstrahlung photons in the main beam dump. The disrupted beam and the beamsstrahlung photons produce at the order of 10⁶ muons per bunch crossing, with energies greater than 10 GeV. Currently threshold Cherenkov counters are considered after the beam dump for the detection of these high energy muons. A second method using the direct detection of the beamsstrahlung photons is also considered.

TUPC028	Background and Energy Deposition Studies for the CLIC Post-Collision Line*	photon, radiation, positron, electron	1060
	R. Appleby, M.D. Salt UMAN, Manchester, United Kingdom L.C. Deacon, E. Gschwendtner CERN, Geneva, Switzerland
	The CLIC post-collision line is designed to transport the spent-beam products of collision to their respective dumps, with minimal losses and thus minimal background contributions. With nanometre spot-sizes at TeV energies, large beam-beam effects induce divergence and dispersion of the outgoing beams, with a large production cross-section of Beamstrahlung photons and subsequently coherent pairs. The post-collision line should provide sufficient divergence of the beam to avoid damage to the vacuum exit and dump entrance windows. In this study, the beam losses are investigated, with the production of secondary particles from the interaction with matter simulated. The particle flux leakage from absorbers and dumps is modelled to determine the total energy deposited on magnets of the post-collision line. Finally, both electromagnetic and hadronic backgrounds at the CLIC experiment are considered.

TUPC050	Impedance Effects in the CLIC Damping Rings	impedance, wiggler, damping, vacuum	1111
	E. Koukovini, K.S.B. Li, N. Mounet, G. Rumolo, B. Salvant CERN, Geneva, Switzerland
	Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity proved that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive-wall wake fields on the transverse impedance budget is finally discussed.

TUPC052	Normal Mode BPM Calibration for Ultralow-Emittance Tuning in Lepton Storage Rings	emittance, quadrupole, coupling, alignment	1114
	A. Wolski The University of Liverpool, Liverpool, United Kingdom D. L. Rubin, D. Sagan, J.P. Shanks CLASSE, Ithaca, New York, USA
	BPMs capable of high-resolution turn-by-turn measurements offer the possibility of new techniques for tuning for ultra-low beam emittance. In this paper, we describe how signals collected from individual buttons during resonant beam excitation can be used to calibrate BPMs to read the beam position in a normal mode coordinate system. This allows for rapid minimization of the mode II emittance, simply by correcting the mode II dispersion. Simulations indicate that the technique is effective and robust, and has the benefit of being insensitive to BPM gain and alignment errors that can limit the effectiveness of other techniques.

TUPC055	Strongly Space Charge Dominated Beam Transport at 50 keV	solenoid, beam-transport, space-charge, electron	1123
	D. Heiliger, W. Hillert, B. Neff ELSA, Bonn, Germany
	Funding: supported by DFG (SFB/TR16) A pulsed (100 nC in 1 us), low energetic beam of polarized electrons is routinely provided by an inverted source of polarized electrons at ELSA. The beam transport to the linear accelerator is strongly space charge dominated due to the beam energy of 50 keV. Thus, the actual beam current has an impact on the beam dynamics, and the optics of the transfer line to the linear accelerator must be optimized with respect to the chosen beam intensity. Numerical simulations of the beam transport demonstrate that an intensity upgrade from 100 mA to 200 mA is feasible. In order to successfully adjust the focussing strength of the magnets according to the final results of the simulation, dedicated beam diagnostics like wire scanners suitable for extreme-high vacuum applications are required.

TUPC063	Energy Verification in Ion Beam Therapy	proton, synchrotron, ion, closed-orbit	1141
	F. Moser ATI, Wien, Austria M. Benedikt, U. Dorda EBG MedAustron, Wr. Neustadt, Austria
	Funding: Austrian Federal Ministry for Science and Research, CERN Technology Doctoral Student Program The adoption of synchrotrons for medical applications necessitates a comprehensive on-line verification of all beam parameters, autonomous of common beam monitors. In particular for energy verification, the required precision of down to 0.1 MeV, in absolute terms, poses a special challenge regarding the betatron-core driven 3rd order extraction mechanism which is intended to be used at MedAustron. Two different energy verification options have been studied and their limiting factors were investigated: 1) A time-of-flight measurement inside the synchrotron, limited by the orbit circumference information and measurement duration as well as extraction uncertainties. 2) A calorimeter-style system in the extraction line, limited by radiation hardness and statistical fluctuations. The paper discusses in detail the benefits and specific aspects of each method.

TUPC067	Simulations of Effects of Detector Materials and Geometry to the Beam Properties of Super-FRS	diagnostics, ion, extraction, antiproton	1153
	M. Kalliokoski HIP, University of Helsinki, Finland
	The Super-FRS is a superconducting fragment separator that will be built as part of the FAIR facility. For the slow-extraction part of the beam diagnostics system a total of 32 detectors are needed for the beam monitoring, tracking and characterization of the produced ions. GEM-TPC detectors are planned to be used for the diagnostics at slow extraction mode of the separator,. The detectors will be placed in focal planes along the separator. Simulations have been made to study the effects of the detector materials and geometries in order minimize their influence to the performance of the separator. Results of the optimization using different simulation tools will be presented. F. Garcia et al., 2009 IEEE NSS Conference Record, Orlando, USA, N13-7 (2009). ** M. Kalliokoski et al., Proc. of IPAC'10, Kyoto, Japan, p.888 (2010).

TUPC077	Investigations on High Sensitive Sensor Cavity for Longitudinal and Transversal Schottky for the CR at FAIR	cavity, coupling, dipole, resonance	1180
	M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany P. Hülsmann GSI, Darmstadt, Germany
	Funding: Funded by the Federal Ministry of Education and Research (BMBF): 06DA90351 For the Collector Ring (CR) at the FAIR (Facility for Antiproton and Ion Research) accelerator complex a sensitive Schottky sensor is required. The CR covers different modes of operation, like pre-cooling of antiprotons at 3 GeV, pre-cooling of rare isotope beams at 740 MeV/u and an isochronous mode for mass measurements. For longitudinal Schottky measurements the concept of a resonant cavity had been introduced [Hansli2011]. Due to limited space inside the ring, the integration of transversal Schottky analysis into this cavity is desired. In this paper the demands and required changes to implement also transversal Schottky measurements are discussed. An analysis of the expected signal characteristics featuring equivalent circuit is shown, as well as numerical full wave simulations of the cavity. * M. Hansli, A. Penirschke, R. Jakoby, W. Kaufmann, W. Ackermann, T. Weiland, "Conceptual Design of a High Sensitive Versatile Schottky Sensor for the Collector Ring at FAIR", DIPAC2011.

TUPC079	Sensitivity and Tolerance Analysis of a New Bunch Arrival-time Monitor Pickup Design for FLASH and XFEL	pick-up, laser, electron, free-electron-laser	1186
	A. Kuhl, A. Angelovski, R. Jakoby, A. Penirschke, S. Schnepp TU Darmstadt, Darmstadt, Germany M. Bousonville, H. Schlarb DESY, Hamburg, Germany T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Supported by the Graduate School of Computational Engineering at TU Darmstadt and the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors" The Free Electron Laser in Hamburg (FLASH) is equipped with Bunch Arrival Time Monitors (BAM), which provide for a time resolution of less than 10 fs for bunch charges higher than 0.2 nC. Future experiments, however, will aim at generating FEL light pulses from a broad range of bunch charges down to 10 pC. In these circumstances the requirements on the time resolution will no longer be fulfilled, which demands for a larger bandwidth of the pickup system. A new cone-shaped pickup, which has a bandwidth greater than 40 GHz has been proposed. At high frequencies, small manufacturing tolerances might have great influence on the pickup signal. A sensitivity analysis of several manufacturing tolerances in the pickup design regarding their influence on the output signal was carried out (by means of CST PARTICLE STUDIO®). These results are utilized for setting limits to the manufacturing tolerances. M.K. Bock et al., IPAC2010, WEOCMH02, Kyoto, Japan, 2010. ** A. Kuhl et al., "Design eines hochauflösenden Ankunftszeitmonitor für FLASH", DPG Frühjahrstagung 2011, Karlsruhe, Germany.

TUPC080	Pickup Design with Beta Matching	pick-up, impedance, resonance, kicker	1189
	J.A. Tsemo Kamga, W.F.O. Müller, K.K. Stavrakakis, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by GSI The main goal of this project is to investigate the Schottky noise of an ion beam in the frequency range from 3 to 5 GHz. In order to accomplish this task, a pickup design is required. For an efficient study of this Schottky noise the pickup sensitivity for low beta must be increased. A design for such a problem has been developed by McGinnis for a fixed beam velocity but can also be used for variable beta by using a tunable material (ferroelectric) inside the waveguide. Since such tunable materials like for instance BST (Barium Strontium Titanate) are lossy, the impact of dielectric losses on the pickup sensitivity will also be investigated in this work. Additionally to the classical parameter studies where multiple simulation runs based on the original numerical model are initiated to characterize the various design parameters it is also possible to utilize a reduced model instead. In particular one is interested in a fast evaluation of the frequency response while taking also material variations into account. In this work, a multivariate parameterized dynamical system is set up and used complementary to the full model for the required beam characterization.

TUPC081	Diagnostics of Femtosecond Low-charge Electron Bunches at REGAE	electron, photon, diagnostics, laser	1192
	S. Bayesteh Uni HH, Hamburg, Germany H. Delsim-Hashemi DESY, Hamburg, Germany
	A new linac is constructed at DESY as the electron source fo "Relativistic Electron Gun for Atomic Exploration (REGAE)". REGAE is mainly established for a Femtosecond electron diffraction experiment presenting structural information on atomic transition states occurring in the sub-hundred femtosecond time-scale. REGAE comprises a photo-cathode gun followed by normal conducting 1.5 cell RF cavity to provide sub pico-Coulomb charge of 2 to 5 MeV energy with a coherent length in the range of 30nm. In order to produce and maintain such high quality electron bunches, sophisticated single-shot diagnostics is mandatory to monitor the properties. Diagnostics include emittance, energy, energy spread and bunch length measurement. In this paper the conceptual ideas and steps toward realization of these diagnostics are presented with a detailed focus on transverse diagnostics. As for photon source of transversal diagnostics, scintillators are studied. Simulation results show which material suits the best for REGAE parameters. Layout of a home-made intensified camera is presented. The method discussed in this paper would also be advantageous for low-charge Free Electron Lasers.

TUPC083	Comparative Studies into 3D Beam Loss Simulations	photon, beam-losses, electron, positron	1198
	M. Panniello MPI-K, Heidelberg, Germany C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the Helmholtz Association and GSI under contract VH-NG-328. A detailed understanding and monitoring of potential beam loss mechanisms is crucial for every particle accelerator. The main motivation in low energy facilities, such as the Ultra-low energy Storage Ring (USR) at the future Facility of Low energy Antiproton and Ion Research (FLAIR), comes from the very low number of particles available which in such machine ought to be conserved. In High Energy accelerators it is the concern about activation or even physical damage of machine parts which has to be taken into serious account. The CLIC Test Facility (CTF3) at CERN provides an ideal testing ground for studies into novel BLM systems and is well suited for benchmarking the results from numerical simulations in experiments. This contribution summarizes the three-dimensional beam loss pattern as found with the commonly used codes FLUKA and Géant4. The results from these codes are compared and analyzed in detail and used for the identification of optimum beam loss monitor locations.

TUPC098	Beam Profile Measurement using Flying Wire Monitors at the J-PARC Main Ring*	injection, space-charge, proton, emittance	1239
	S. Igarashi, K. Ohmi, Y. Sato, M.J. Shirakata, M. Tejima, T. Toyama KEK, Ibaraki, Japan Y. Hashimoto, K. Satou J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Transverse beam profiles have been measured using flying wire monitors at the main ring of the Japan Proton Accelerator Research Complex (J-PARC). The flying wire is a beam profile monitor using a thin carbon fiber as a target. The beam is scanned with the wire target at the maximum speed of 5 m/s. The secondary particles from the beam-wire scattering are detected using a scintillation counter as a function of the wire position. The measurement has revealed a characteristic temporal change of the beam profile during the injection period of 120 ms. A multiparticle tracking simulation program, SCTR, taking account of space charge effects has successfully reproduced the beam profiles.

TUPC100	Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac	beam-losses, cavity, linac, injection	1245
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan A. Miura, G.H. Wei JAEA/J-PARC, Tokai-mura, Japan H. Sako JAEA, Ibaraki-ken, Japan
	We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC102	Measurement of Beam Loss Tracks by Scintillating Fibers at J-PARC Linac	beam-losses, linac, background, gun	1251
	H. Sako, T. Maruta, A. Miura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Highest beam loss in the J-PARC linac has been observed that the ACS (Annular-Coupled Structure linac) section. Since the observed beam loss is proportional to the residual gas pressure, the source of the beam loss is considered as H0 produced in an interaction of H⁻ beams with remnant gas. If this assumption is valid, H0 hits the beam duct and changes into H⁺ and escapes from the beam duct. We constructed scintillation fiber hodoscopes to detect H⁺s and eventually identify the particle species as H⁺. The hodoscopes are made of 4 planes of hodoscopes which consists of 16 scintillation fibers of 64mm long and with 4mmx4mm cross section. We installed the hodoscopes at the upstream part of the ACS section and measured beam loss. The results are shown in this paper.

TUPC104	Beam Loss Detected by Scintillation Monitor	beam-losses, linac, cavity, hadron	1257
	A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako JAEA/J-PARC, Tokai-mura, Japan Z. Igarashi, M. Ikegami, T. Miyao KEK, Ibaraki, Japan
	Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

TUPC108	Beam Diagnostics Based on Higher Order Mode for High Repetition Beam	HOM, cavity, diagnostics, single-bunch	1269
	X. Luo, X.Y. Lu, F. Wang PKU/IHIP, Beijing, People's Republic of China F.S. He JLAB, Newport News, Virginia, USA
	The signals from the HOM ports on superconducting cavities can be used as beam position monitors. The HOM amplitude of dipole mode is proportional to the beam offset. For high repetition bunches operation, the spectrum is consist of the HOMs peaks and the peaks which is integer times of the bunch repetition. The HOMs amplitudes should be separated from the two kinds of peaks. Based on the simulation from a TESLA 2-cell cavity, the transform matrix between the HOMs amplitudes and beam offsets has been found, as well as the cavity axis. The simulation results have demonstrated that beam diagnostics based on HOMs is feasible while high repetition bunches operation.

TUPC109	Electron Bunch Slice Emittance Measurement with the Space Charge Effects*	solenoid, emittance, space-charge, electron	1272
	C. Li, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan TUB, Beijing, People's Republic of China
	Funding: supported by the National Natural Science Foundation of China (Grant Nos. 10735050, 10805031, 10875070 and 10925523), and the National Basic Research Program of China (Grant No. 2007CB815102). Since slice transverse emittance of the electron beam is critical to a high-gain short-wavelength FEL, its characterization is very important. For space charge dominated electron beam, conventional emittance measurement techniques, such as solenoid scanning and quadruple scanning, without considering space charge forces lead to large errors of emittance evaluations. This essay introduces a modified solenoid-scan method of slice emittance measurement for space charge dominated beam, and simulations show that the new method brings the emittance evaluations much closer to actual values.

TUPC119	A Comprehensive Study of Nanometer Resolution of the IPBPM at ATF2*	cavity, dipole, coupling, extraction	1296
	Y.I. Kim, H. Park Kyungpook National University, Daegu, Republic of Korea S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom J.C. Frisch, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White, M. Woodley SLAC, Menlo Park, California, USA Y. Honda, R. Sugahara, T. Tauchi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515. High-resolution beam position monitors (IPBPMs) have been developed in order to measure the electron beam position at the focus point of ATF2 to a few nanometers in the vertical plane. To date, the IPBPM system has operated in test mode with a highest demonstrated resolution of 8.7 nm in the ATF extraction line during 2008. After expected noise source calculations there still remains 7.9 nm of noise of unexplained origin. We summarize the experimental work on the IPBPM system since this measurement and outline the possible origins of these sources. We then present a study plan to be performed at the ATF2 facility designed to identify and to improve the resolution performance and comment on the expected ultimate resolution of this system.

TUPC127	Optical Transition Radiation System for ATF2	emittance, target, coupling, radiation	1317
	J. Alabau-Gonzalvo, C. Blanch Gutierrez, A. Faus-Golfe, J.J. García-Garrigós IFIC, Valencia, Spain J. Cruz, D.J. McCormick, G.R. White, M. Woodley SLAC, Menlo Park, California, USA
	Funding: Funding Agency: FPA2010-21456-C02-01 Work supported in part by Department of Energy Contract DE-AC02-76SF00515 In this paper we present the first measurements performed during the fall 2010 and early 2011 runs. Software development, simulations and hardware improvements to the Multi-Optical Transition Radiation System installed in the beam diagnostic section of the Extraction (EXT) line of ATF2 are described. 2D emittance measurements have been performed and the system is being routinely used for coupling correction. Realistic beam simulations have been made and compared with the measurements. A 4D emittance procedure, yet to be implemented, is also discussed. A demagnifier lens system to improve the beam finding procedure has been designed and will be implemented in a future run. Finally, we discuss further verification work planned for the next run period of ATF.

TUPC128	Transverse Beam Jitter Propagation in Multi-bunch Operation at ATF2	extraction, feedback, kicker, lattice	1320
	J. Resta-López, J. Alabau-Gonzalvo IFIC, Valencia, Spain P. Burrows, G.B. Christian JAI, Oxford, United Kingdom B. Constance CERN, Geneva, Switzerland
	Pulse-to-pulse orbit jitter, if not controlled, can drastically degrade the luminosity in future linear colliders. The second goal of the ATF2 project at the KEK accelerator test facility is to stabilize the vertical beam position down to approximately 5% of the nominal rms vertical beam size at the virtual interaction point (IP). This will require control of the orbit to better than 1 micrometer at the entrance of the ATF2 final focus system. In this paper, by means of computer simulations, we study the vertical jitter propagation along the ATF2 from the start of the extraction line to the IP. For this study pulse-to-pulse vertical jitter measurements using three stripline beam position monitors are used as initial inputs. This study is performed for the case of a bunch-train with three bunches, but could easily be extended for a larger number of bunches. The cases with and without intra-train orbit feedback correction in the extraction line of ATF2 are compared.

TUPC137	UFOs in the LHC	beam-losses, injection, kicker, acceleration	1347
	T. Baer, M.J. Barnes, B. Goddard, E.B. Holzer, J.M. Jimenez, A. Lechner, V. Mertens, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, B. Velghe, J. Wenninger, F. Zimmermann CERN, Geneva, Switzerland

Paper

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MOOCB01

Study on the Realignment Plan for J-PARC Linac after the Tohoku Earthquake in Japan

DTL, linac, alignment, quadrupole

44

M. Ikegami
KEK, Ibaraki, Japan
T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

A 9.0-magnitude earthquake struck eastern Japan on March 11, 2011, and it gave rise to damages to the buildings of the J-PARC facilities. In particular, the earthquake caused a deformation of the J-PARC linac tunnel resulting an alignment error of several tens of millimeters in both horizontal and vertical directions. It also caused a change in the relative position between the linac and other facilities of J-PARC complex. To restore the beam operation, we should establish a reasonable realignment plan for J-PARC linac taking various constraints into account and possibly tolerating some residual misalignment. In this paper, we show a study on the realignment plan for J-PARC linac including evaluation of the effect of residual misalignment with particle simulations.

Slides MOOCB01 [2.659 MB]

MOODB03

Capture and Transport of the Laser Accelerated Ion Beams for the LIGHT Project

laser, proton, solenoid, ion

59

S.G. Yaramyshev, W.A. Barth, I. Hofmann, A. Orzhekhovskaya
GSI, Darmstadt, Germany
B. Zielbauer
HIJ, Jena, Germany

Funding: Work supported by EURATOM (IFK KiT Program) and HIC for FAIR
An impressive advantage of Laser Ion Sources is an extremely high beam brilliance. The LIGHT project (Laser Ion Generation, Handling and Transport) is dedicated to the production of protons (ions), accelerated up to 10 MeV by using the GSI PHELIX laser at GSI, and injected into a conventional accelerator. A successful experimental campaign stimulated further investigation of the focusing, transport and collimation of the high energy and high brilliance proton beam. In addition to the advanced codes, describing the very early expansion phase of the proton-electron cloud, the versatile multiparticle code DYNAMION was implemented to perform beam dynamics simulations for different possible transport lines. Potentially transport lines compraises magnetic quadrupole lenses and/or solenoids for transverse beam focusing. A bunch rotation rf cavity decreasing the energy spread of the protons was included into the simulations. The results of the beam dynamics simulations are presented, as well as benchmarking activities with other codes. Further developments of the experimental test stand and the different possibilities of its integration to the GSI accelerators chain are discussed.

Slides MOODB03 [2.185 MB]

MOPC009

Design of a Pi/2 Mode S-Band Low Energy TW Electron Linear Accelerator

electron, coupling, acceleration, linac

80

H. Shaker
IPM, Tehran, Iran
F. Ghasemi
sbu, Tehran, Iran
H. Shaker
CERN, Geneva, Switzerland

This design is related to a Pi/2 mode S-Band low energy TW electron linear accelerator which is in the construction stage. This project is supported by the school of particles and accelerators, institute for research in fundamental sciences (IPM), Tehran, Iran. This design consists of a buncher and an accelerating structure that are joined and two couplers for the input/output feedings. At each design stage, different methods (analytical or numerical) are used to confirm the results and also to have a better understanding.

MOPC016

Development of a New RF Accelerating Cavity for J-PARC Ring Accelerator

cavity, impedance, ion, controls

98

Y. Morita, T. Kageyama
KEK, Ibaraki, Japan
J. Kameda
ICRR, Chiba, Japan
S. Yamashita
ICEPP, Tokyo, Japan

Funding: Japan Society for the Promotion of Science (JSPS)
To enhance the beam power delivered by the J-PARC* ring accelerators, upgrading the accelerating cavities is indispensable. In particular, long term stable operation of the present cavities for the RCS** is one of the important issues. Currently, the cavities are loaded with FINEMET*** cores cooled by water, where every core is coated with glass cloth and epoxy resin for waterproof. However, it was reported that some of the cores were damaged by thermal stress. We are developing a new cavity loaded with multi ring core modules. Each core module consists of three ring cores concentrically arranged and sandwiched between two glass epoxy plates with flow channels grooved. The ring cores without waterproof coating are cooled by the turbulent flow of a chemically inert liquid (Fluorinert), since FINEMET is subject to corrosion in water. We have designed and built a high power prototype cavity loaded with a single core module, then carried out low level measurement and high power test. Finally, the cavity has been stably operated up to an average power loss of 10 kW per core module, which is 1.7 times higher than that for the present RCS cavity.
*Japan Proton Accelerator Research Complex
**Rapid-Cycling Synchrotron
***FINEMET is an iron-based magnetic alloy produced by Hitachi Metals, Ltd..

MOPC023

Design of a C-band 6 MeV Standing-wave Linear Accelerating Structure

coupling, electron, bunching, impedance

119

J.H. Shao, H. Chen, Q.Z. Xing
TUB, Beijing, People's Republic of China

We design a C-band standing-wave biperiodic on-axis coupled linear accelerating structure for industrial and medical applications. It’s less than 300mm long; consists of 3 bunching cells and 9 normal cells. It can accelerate electrons to 6MeV and the pulsed beam current is 100mA. The RF power source is a 2.5MW magnetron. We implement 2D cells geometry optimization by SUPERFISH, beam dynamics study by PARMELA and full scale 3D calculations by MAFIA codes.

MOPC026

MA Cavity for HIRFL-CSR

cavity, impedance, plasma, radio-frequency

125

L.R. Mei, Z. Xu, Y.J. Yuan, H.W. Zhao
IMP, Lanzhou, People's Republic of China

To meet the requirements of conducting high energy density physics and plasma physics research at HIRFL-CSR. The higher accelerating gap voltage was required. A magnetic alloy (MA)-core loaded radio frequency (RF) cavity which can provide higher accelerating gap voltage has been studied in Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS), Lanzhou. To select proper MA material to load the RF cavity, measurement for MA cores has been conducted. The MA core with higher shunt impedance and lower than 1 quality factor (Q value) should be selected. The theoretical calculation and simulation for the MA-core loaded RF cavity can be consistent with each other well. Finally 1000kW power was needed to meet 50-kV accelerating gap voltage by calculation.

MOPC029

Development of Injector for Compact FEL Tera-hertz Source in CAEP

gun, electron, FEL, booster

131

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

This paper introducs the development of a injector for compact FEL tera-hertz source at Institute of Applied Electronics in China Academy of Engineering Physics (IAE/CAEP). The injector consist of a main accelerator for energy booster section and a multicavity thermionic-cathode rf gun with low back bombardment, with total length no more than one meter. Numerical simulation result shows that the back bombardment power is less for the thermionic-cathode rf gun of the injector and the main accelerator has a good performance, which can provide high quality electron beam with emittance about 10 pi mm mrad, energy about 7 MeV and energy spread about 1%. At present, the preliminary hot test experiment on the injector has been done. The test results indicate that the mainly tested parameters agree well with the theoretical design ones. The process of the preliminary hot test experiment on the injector is present in this paper.

MOPC031

Performance of a 13 MHz Cavity for an RF Implanter at PEFP*

cavity, coupling, ion, ion-source

136

T.A. Trinh
UST, Daejeon, Republic of Korea
Y.-S. Cho, J.-H. Jang, D.I. Kim, H.S. Kim, H.-J. Kwon, B.-S. Park, K.T. Seol
KAERI, Daejon, Republic of Korea

Funding: This work is supported by the Ministry of Education, Science and Technology of the Korean Government
A 13 MHz - normal conducting cavity for an rf implanter has been successfully developed at PEFP (Proton Engineering Frontier Project). It consists of an inductive coil, accelerating electrodes and a ground electrode for the inductor. Quality factor of 2074 and critical coupling were achieved at resonant frequency of 12.658 MHz. Rf power of 1 kW was forwarded to the cavity without any spark in the cavity. Beam test was then carried out with a 27 keV helium beam generated from a Duoplasmatron ion source. The results showed that the helium beam was accelerated to final energy of 120 keV with energy spread of 1%. Detail experiments and results are addressed in this presentation.

MOPC034

Design of a 0.6-cell Cell Photocathode RF Gun for FED

gun, electron, cathode, solenoid

145

Y.W. Parc, M.S. Chae, I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea

Final goal of this study is the development of single cell radio-frequency (RF) electron gun which is optimized to the femotosecond electron diffraction. This study will open new technology basis for the laboratory research in the femto-second (fs) chemistry at the university. RF electron gun will be fabricated with single cell which will reduce the cost and effort. We will also conduct a simulation study to find an optimized operation condition of the RF gun to provide the best electron beam to the femtosecond electron diffraction experimentalist. In this presentation, we will show the status of the RF gun development. The results with the simulation code PARMELA will be presented to find the optimal operation condition of the single cell RF gun for FED.

MOPC036

Design of RF Cavity for Compact 9 MeV Cyclotron

cavity, cyclotron, resonance, acceleration

151

H.S. Song, J.-S. Chai, H.W. Kim, B.N. Lee, J.H. Oh
SKKU, Suwon, Republic of Korea

The number of PET facility is rapidly increasing worldwide. To get PET image, circular accelerator such as cyclotron is needed. Compact 9 MeV H-cyclotron, which has a diameter of 1.25m is being designed at Sungkyunkwan University starting from July 2010 for getting F-18. It is expected to be constructed by next year. In this paper, RF system of 9 MeV cyclotron including design processes and detail analysis of result is reported. RF system mainly describes RF cavity design.

MOPC040

The Measurement of Transversal Shunt Impedance of RF Deflector

cavity, impedance, dipole, emittance

163

A.Yu. Smirnov, M.V. Lalayan, N.P. Sobenin
MEPhI, Moscow, Russia
A.A. Zavadtsev
Nano, Moscow, Russia

This paper presents the results of transverse shunt impedance measurement performed using field perturbation technique and comparison with numerical MWS simulations. The structure under test is the S-band 3-cell deflecting cavity. The mentioned cavity operates with a dipole TM11-like mode with a phase shift of 120 deg per cell. The analyses were carried out with use of two types of perturbing beads: dielectric beads and metallic rings. The latter type perturbs the on-axis magnetic field much stronger than the electric field, which allows us calculating transversal shunt impedance using on-axis EM fields values.

MOPC044

Design of the Radiofrequency Quadrupole Coldmodel for the ESS-BILBAO Linear Accelerator

rfq, quadrupole, dipole, radio-frequency

175

A. Velez, I. Bustinduy, N. Garmendia, O. Gonzalez, J.L. Munoz, D. de Cos
ESS Bilbao, Bilbao, Spain
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

This work will present the design of the ESS-Bilbao LINAC RFQ cold model. The process goes through the electromagnetic design of the cavity by properly setting the resonant quadrupole and dipole modes, as well as the resonance frequency. The prototype includes the vane modulation designed to accelerate a 75 mA proton beam from 75 keV to 3 MeV, with an operating frequency of 352.2 MHz. To this end, electromagnetic and electrostatic simulations have been performed by means of the commercial software COMSOL. Furthemore, results for the three components of the electrical field distribution will be presented and compared to those calculated by evaluating the 8-term multipole expansion.

MOPC046

CaCo: A Cavity Combiner for IOTs Amplifiers

cavity, storage-ring, high-voltage, HOM

181

B. Bravo, F. Mares, F. Pérez, P. Sanchez
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
M.L. Langlois
ESRF, Grenoble, France

The ALBA storage ring uses six room temperature cavities; each one fed by two 80 kW IOTs amplifiers at 499.654 MHz. The power of the pair of transmitters is combined by a cavity combiner, CaCo. One of the design requirements of CaCo was that it continued working safely and with a good efficiency in the case of an IOT failure (asymmetrical mode). During the first asymmetric full power tests, in May 2010, with an active IOT and the other passive, the result was dramatic, the passive IOT broke in two parts after few hours of operation. This paper presents the experimental results and the electromagnetic field simulations of the asymmetrical operation mode of CaCo, i.e. one active IOT and the other passive, and analyze why the ceramic of the output tube of the passive IOT broke during the first performance of this mode. Also, it reports a possible solution to solve this problem.

MOPC050

Multipacting Analysis for the Superconducting RF Cavity HOM Couplers in ESS

cavity, electron, HOM, superconducting-RF

190

S. Molloy
ESS, Lund, Sweden
R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

The European Spallation Source (ESS) linac will consist of three families superconducting RF cavities to accelerate protons to the required 5 MW for collision with the target. If it is determined that HOM damping is required to limit the effect of beam induced modes, it is quite likely that HOM couplers will be installed. Multipacting in these couplers is a concern as thermally induced detuning of the fundamental notch filter has limited the achievable gradient in other high power machines. It is therefore important to avoid potential multipacting conditions during the design phase. Presented here are simulations using the Track3P code developed at SLAC. Multipacting regions are highlighted, electron trajectories are shown, and suitability of the proposed HOM coupler design is discussed.

MOPC056

The Linac4 Power Coupler

cavity, linac, coupling, vacuum

208

F. Gerigk, J.-M. Giguet, E. Montesinos, B. Riffaud, P. Ugena Tirado, R. Wegner
CERN, Geneva, Switzerland

Linac4 employs 3 types of accelerating structures after the RFQ: a Drift Tube Linac (DTL), a Cell-Coupled DTL (CCDTL), and a Pi-Mode Structure (PIMS) to accelerate the beam to 160 MeV. The structures are designed for a peak power of 1 MW per coupler, which consists of two parts: a ceramic window, which separates the cavity vacuum from the air in the wave-guides, and a so-called "coupling T", which couples the RF power through an iris to the cavity. In the frame of the Linac4 R&D both devices have been significantly improved with respect to their commonly used design. On the coupler side, the wave-guide short circuit with its matched length has been replaced by a fixed length λ/4 short circuit. The RF matching is done by a simple piston tuner, which allows a quick matching to different cavity quality factors. In the window part, which usually consists of a ceramic disc and 2 pieces of wave-guides with matching elements, the wave-guide sections could be completely suppressed, so that the window became very compact, lightweight, and much simpler to manufacture. In this paper we present electromagnetic simulations, and tests on first prototypes, which were constructed at CERN.

MOPC059

The Plane Wave Transformer Linac Development at NSRRC

linac, impedance, cavity, electron

217

A. Sadeghipanah, J.-Y. Hwang, W.K. Lau
NSRRC, Hsinchu, Taiwan
T.H. Chang
NTHU, Hsinchu, Taiwan

A Plane-Wave-Transformer (PWT), standing wave linac operating at S-band frequency (2.9979 GHz) is being developed at NSRRC. This structure offers the advantages of high efficiency, compactness, fabrication simplicity and cost. The PWT prototype at NSRRC consists of three cells with two half-cells at the ends, separated by a set of four flat disks suspended and cooled by four water tubes inside a large cylindrical tank. To fully understand its physical properties, numerical modeling of the PWT prototype has been carried out by using the 2-D code SUPERFISH and 3-D code MAFIA. In this paper, we describe the principle properties of this structure, the electric parameters obtained from numerical simulations, and heat dissipation calculation. The mechanical design for prototype linac is also reported.

MOPC061

Simulations to Flatten the Field of the FETS RFQ

rfq, cavity, dipole, quadrupole

223

S.R. Lawrie, A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

A high performance Radio Frequency Quadrupole (RFQ) is the next major component to be installed on the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. The beam dynamics, RF, thermal and mechanical designs of the RFQ are almost complete and so the copper has recently been purchased with a view to start cutting metal near Summer-time. This report summarizes the simulation work performed to ensure the RF design is sound. This includes performance studies of the end-wall dipole suppression fingers, tuning the frequency of the input and output vane end regions and implementing a simple solution to remove modulation induced field tilt.

MOPC065

Ion Motion in the Vicinity of Microprotrusions in Accelerating Structures

ion, electron, plasma, background

232

D.G. Kashyn, T.M. Antonsen, I. Haber, G.S. Nusinovich
UMD, College Park, Maryland, USA

Funding: This work is supported by Office of High Energy Physics of the U.S. Department of Energy.
It is known that newly fabricated accelerating structures have almost ideally smooth surface. However, ‘post mortem’ examination of these structures reveals that their surface can be significantly modified after high-gradient operation. This surface modification can be caused by the appearance of microscopic protrusions*. One of the factors leading to heating, melting and evaporation of these protrusions (factors resulting in the RF breakdown) is ion bombardment**. In our study we analyze ion motion in the vicinity of microprotrusions both analytically and numerically. First, we study the ion motion in the RF electric field magnified by the protrusion in the absence of electron field emitted current and show that most of the ions do not reach the structure surface. Then we add into consideration the interaction of ions with Fowler-Nordheim current emitted from the tip of protrusion (dark current). First, we develop a model describing this interaction and then we supplement it with numerical results using PIC code WARP***. We show that the ions move towards the area occupied by the dark current, but this does not increase the bombardment of micro-protrusions.
* R.B. Palmer,et al, Phys. Rev ST Accel. Beams 12, 031002 (2009).
** P. Wilson, AIP Conf. Proc., 877, Melville, New York, 2006, p. 27.
***J.-L. Vay, et al, Physics of Plasmas, 11, 2928 (2004).

MOPC073

A Dual-mode Accelerating Cavity to Test RF Breakdown Dependence on RF Magnetic Fields

cavity, electron, radio-frequency, vacuum

247

A.D. Yeremian, V.A. Dolgashev, J. Neilson, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: * Work Supported by Doe Contract No. DE-AC02-76SF00515
RF Breakdown experiments on short accelerating structures at SLAC have shown that increased rf magnetic fields increase the probability of rf breakdowns. Moreover, the breakdown rate is highly correlated with the peak pulse-heating in soft-copper single-cell standing-wave structures of disk-loaded waveguide type. In these geometries the rf electric and magnetic fields are highly correlated. To separate effects of rf magnetic and electric fields on the rf breakdown rate, we have designed an X-band cavity with a geometry as close to that of a standing-wave accelerator cell as practically possible. This cavity supports two modes: an accelerating TM mode and a TE mode with no-surface-electric field but with a strong magnetic field. The cavity will be constructed and tested at the Accelerator Structure Test Area (ASTA) at SLAC.

MOPC082

Status of the 325 MHz SC CH-Cavity at IAP Frankfurt

cavity, linac, status, electron

265

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: BMBF contract no. 06FY161I
At the Institute for Applied Physics (IAP), University of Frankfurt, a s.c. 325 MHz CH-Cavity is under development for future beam tests at GSI UNILAC, Darmstadt. The cavity with 7 accelerating cells has a geometrical beta of 0.15 corresponding to 11.4 AMeV. The design gradient is 5 MV/m. The geometry of this resonator was optimized with respect to a compact design, low peak fields, surface processing, power coupling and tuning. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper rf simulations, multipacting analysis as well as thermal calculations will be presented.

MOPC083

Structural Mechanics of Superconducting CH Cavities

cavity, controls, linac, resonance

268

M. Amberg, K. Aulenbacher
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany

The superconducting CH-structure (Crossbar-H-mode) is a multi-cell drift tube cavity for the low and medium energy range operated in the H21-mode, which has been developed at the Institute for Applied Physics (IAP) of Frankfurt University. With respect to different high power applications two types of superconducting CH-structures (f = 325 MHz, β = 0.16, seven cells and f = 217 MHz, β = 0.059, 15 cells) are presently under construction and accordingly under development. The structural mechanical simulation is a very important aspect of the cavity design. Furthermore, several simulations with ANSYS Workbench have been performed to predict the deformation of the cavity walls due to the cavity cool-down, pressure effects and mechanical vibrations. To readjust the fast frequency changes in consequence of the cavity shape deformation, a new concept for the dynamic frequency tuning has been investigated, including a novel type of bellow-tuner.

MOPC089

RF Simulations for the QWR Cavities of PIAVE-ALPI

cavity, ion, linac, beam-losses

283

M. Comunian, F. Grespan, A. Palmieri
INFN/LNL, Legnaro (PD), Italy

The PIAVE-ALPI linac is composed of several families of QWR cavities. In order to have a thorough description of the accelerator in terms of beam dynamics, a detailed field mapping of the accelerating cavities is necessary, including non-linear behavior of the off-axis fields, as well as the steering and dispersion effects due to transverse components. For such a purpose, a set of RF simulation was accomplished, with the codes HFSS and COMSOL. The details about these simulations and the main outcomes and results will be described in this article.

MOPC096

Design and Fabrication of a 5-Cell High Current Superconducting Cavity

cavity, HOM, dipole, quadrupole

301

Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu
PKU/IHIP, Beijing, People's Republic of China
R. Nassiri
ANL, Argonne, USA

Funding: National High Technology Research and Development program 863 (2009AA03Z206)
Energy recovery linacs (ERL) is promising to achieve high average current with superior beam quality. The key component for accelerating such high current beams is the superconducting radio frequency (SRF) cavity. The design of a 1.3 GHz 5-cell high current superconducting cavity has been carried out under the cooperation between Peking University (PKU) and Argonne National Laboratory (ANL). RF properties, damping of the HOMs, multipacting and mechanical features of this cavity have been discussed and the final design is presented.

MOPC106

Study of the Variation of Transverse Voltage in the 4 Rod Crab Cavity for LHC

cavity, luminosity, HOM, dipole

322

B.D.S. Hall, P.K. Ambattu, G. Burt, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket, C. Hill
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The planned high luminosity upgrade to LHC will utilise crab cavities to rotate the beam in order to increase the luminosity in the presence of a finite crossing angle. A compact design is required in order for the cavities to fit between opposing beam-lines. In this paper we discuss we discuss one option for the LHC crab cavity based on a 4 rod TEM deflecting cavity. Due to the large transverse size of the LHC beam the cavity is required to have a large aperture while maintaining a constant transverse voltage across the aperture. The cavity has been optimised to minimise the variation of the transverse voltage while keeping the peak surface electric and magnetic fields low for a given kick. This is achieved while fitting within the strict design space of the LHC. The variation of deflecting voltage across the aperture has been studied numerically and compared with numerical and analytical estimates of other deflecting cavity types. Performance measurements an aluminium prototype of this cavity are presented and compared to the simulated design.

MOPC107

HOM and FP Coupler Design for the NLSF High Gradient SC Cavity

cavity, HOM, SRF, damping

325

R.M. Jones, N. Juntong
UMAN, Manchester, United Kingdom

The design of both higher order mode (HOM) and fundamental power (FP) couplers for the New Low Surface Field (NLSF) cavity* is presented. Here we study using the ILC baseline couplers for this new superconducting cavity. A Balleyguier method** of calculating external quality factor is used and the results validated using both Microwave studio and HFSS.
* N. Juntong and R.M. Jones, SRF2009, THPPO024, 2009.
** P. Balleyguier, LINAC98, MO4037, 1998

MOPC109

Suppression of Coupler Kicks in 7-Cell Main Linac Cavities for Cornell's ERL

cavity, linac, emittance, resonance

331

N.R.A. Valles, M. Liepe, V.D. Shemelin
CLASSE, Ithaca, New York, USA

Funding: Supported by NSF award DMR-0807731
Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·10⁷, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.

MOPC130

High Power Solid State RF Amplifier Proposal for Iran Light Source Facility (ILSF)

cavity, booster, rf-amplifier, storage-ring

385

R. safian
IPM, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

Solid state RF amplifiers are being considered for an increasing number of accelerator applications. Their capabilities extend from a few kW of power to several hundred kilo watts and from frequencies less than 100 MHz to above 1 GHz. This paper describes the proposed general scheme for the high power solid state RF generator of the Iran light source facility (ILSF). The maximum expected power of the generator is 200 KW which is used for driving the storage ring cavities. Similar RF generator with lower output power can be used for driving the booster cavities.

MOPC132

Influences of the Inner-conductor on Microwave Characteristics in an L-band Relativistic Backward-wave Oscillator*

resonance, plasma, space-charge, coupling

388

X.J. Ge, L. Liu, B.L. Qian, J. Zhang, H.H. Zhong
National University of Defense Technology, Changsha, Kaifu District, People's Republic of China

Funding: College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, People’s Republic of China. *gexingjun230230@yahoo.com.cn
The influences of the inner-conductor on microwave characteristics in an L-band relativistic backward-wave oscillator (RBWO) are investigated theoretically and experimentally. The numerical results show that the resonance frequency decreases obviously with the increase in the inner-conductor radius. To verify the above conclusions, an L-band coaxial RBWO is investigated in detail with particle-in-cell (PIC) code. It is shown that the frequency is lowered from 1.63 GHz to 1.51 GHz when the inner-conductor radius increases from 0.5 cm to 2.5 cm. And the efficiency varies in the range of 35.4-27.7%. Furthermore, experiments are carried out at the Torch-01 accelerator. When the diode voltage is 887.6 kV and the current is 7.65 kA, the radiated microwave with frequency of 1.61 GHz, power of 2.13 GW and efficiency of 31.3% is generated. It is found that the frequency decreases from 1.64 GHz to 1.58 GHz when the inner-conductor radius increases from 0.5 cm to 1.5 cm. And the efficiency varies in the range of 31.3-29.8%.

MOPC143

A Reduced Gradient Output Design for SLAC's XL4 X-Band Klystron

klystron, cavity, impedance, beam-loading

412

A. Jensen, C. Adolphsen, A.E. Candel, M.V. Fazio, E.N. Jongewaard, D.W. Sprehn, A.E. Vlieks, F. Wang
SLAC, Menlo Park, California, USA

Funding: This work was supported by the U.S. Department of Energy under contract DE-AC03-76SF00515.
X-band klystron work began at SLAC in the mid to late 1980's to develop high frequency (4 times the SLAC S-band klystron), high power RF sources for the linear collider designs under consideration at that time. This work culminated in the current workhorse X-band RF source, the XL4. To date 26 XL4 tubes have been built. The XL4 4-cell disk loaded traveling wave output structure has a high operating gradient. A new 6-cell structure has been designed to reduce breakdown and to further improve the klystron's robustness. Initial simulations show the 6-cell design reduces the gradient roughly 25% and that the structure is stable. A physical XL4 will be retrofitted with the new output cavity and hot tested in the near future.

MOPC158

RF Capture of a Beam with Charge-exchanging Multi-turn Injection

injection, acceleration, closed-orbit, linac

454

T. Uesugi, Y. Ishi, Y. Kuriyama, J.-B. Lagrange, Y. Mori, R. Nakano, T. Planche, B. Qin, E. Yamakawa
KURRI, Osaka, Japan
Y. Niwa, K. Okabe, I. Sakai
University of Fukui, Faculty of Engineering, Fukui, Japan

Funding: This work was supported by MEXT of Japan in the framework of a task entitled ”Research and Development for an Accelerator-Driven Sub-critical System Using an FFAG Accelerator”.
In the fixed field alternating gradient (FFAG) synchrotron in Kyoto university research reactor Institute (KURRI), charge exchange injection was adopted since 2011. The charge stripping foil is located on the closed orbit of the injection energy, and no bump orbit system is used. Instead, the injected beam escapes from the stripping foil according to the closed-orbit shift due to acceleration. In this scheme, it is important to minimize the number of foil hitting, which causes emittance growth and foil heating. In this paper, the rf capture is studied by means of simulation.

MOPO001

Interaction Point Feedback Design and Integrated Simulations to Stabilize the CLIC Final Focus*

controls, feedback, quadrupole, ground-motion

475

G. Balik, L. Brunetti, G. Deleglise, A. Jeremie, L. Pacquet
IN2P3-LAPP, Annecy-le-Vieux, France
A. Badel, B. Caron, R. Le Breton
SYMME, Annecy-le-Vieux, France
A. Latina, J. Pfingstner, D. Schulte, J. Snuverink
CERN, Geneva, Switzerland

The Compact Linear Collider (CLIC) accelerator has strong precision requirements on offset position between the beams. The beam which is sensitive to ground motion needs to be stabilized to unprecedented requirements. Different Beam Based Feedback (BBF) algorithms such as Orbit Feedback (OFB) and Beam-Beam Offset Feedback (BBOF) have been designed. This paper focuses on the BBOF control which could be added to the CLIC baseline. It has been tested for different ground motion models in the presence of noises or disturbances and uses digital linear control with or without an adaptive loop. The simulations demonstrate that it is possible to achieve the required performances and quantify the maximum allowed noise level. This amount of admitted noises and disturbances is given in terms of an equivalent disturbance on the position of the magnet that controls the beam offset. Due to the limited sampling frequency of the process, the control loop is in a very small bandwidth. The study shows that these disturbances have to be lowered by other means in the higher frequency range.

MOPO004

A Longitudinal Kicker Cavity for a Bunch-by-bunch Feedback System at ELSA

cavity, kicker, feedback, impedance

484

N. Heurich, W. Hillert, A. Roth, R. Zimmermann
ELSA, Bonn, Germany

At the Electron Stretcher Facility ELSA of Bonn University, a longitudinal bunch-by-bunch feedback system is currently being installed in order to damp multibunch instabilities and to enable a future intensity upgrade of up to 200 mA. As a main component, a longitudinal kicker cavity was developed and manufactured. The kicker requires a bandwidth of 250~MHz taking into account the bunch spacing of 2 ns at ELSA. Existing designs used at other facilities were optimized in view of the considerably larger bunch lenght at ELSA. The choice of 1.125 GHz as a center frequency is a result of these considerations. With the resulting low quality factor, the design had to be optimized in order to maximize the shunt impedance. The longitudinal feedback is succesfully working with the prototype installed in the stretcher ring. The design and detailed simulations of the geometry are discussed and laboratory measurements are presented.

MOPO007

Resonant Strip-line Type Longitudinal Kicker

kicker, impedance, feedback, wakefield

493

T. Nakamura
JASRI/SPring-8, Hyogo-ken, Japan

The longitudinal feedback for the SPring-8 storage ring is under consideration as the device for suppression of the longitudinal instabilities driven by higher order modes of cavities, observed at test operation with 4 to 6 GeV low energy beam. As the beam energy and the ring circumference are rather high, and the length of the space for the longitudinal kickers is limited, high efficiency kicker per length is required in the our case. As a candidate of such kicker, we propose a resonant strip-line type longitudinal kicker with drive frequency of 13/4 of RF frequency. The shut impedance per length is higher than over-loaded cavities and the drive circuits can be simplified because of higher drive frequency. The design consideration, the result of the simulation and measurement of the prototype model, and the detail of the drive circuit will be reported in the presentation.

MOPO008

Design and Simulation of the Transverse Feedback Kicker for the HLSⅡ

kicker, impedance, feedback, vacuum

496

W.B. Li, P. Lu, B.G. Sun, F.F. Wu, Y.L. Yang, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

In order to suppress the coupled bunch instabilities in the HLSⅡ storage ring, a transverse feedback system is required. The vital component of the system is the kicker that is the feedback actuator. We design a stripline kicker for the HLSⅡ. The horizontal and vertical electrodes are combined in a structure on account of the space limit. In addition to the design issues, this paper focuses on the simulation results for the kicker using the computer codes. By the 2D code POSSION, we calculate and optimize the characteristic impedance of the stripline kicker to match the 50Ω external transmission lines so as to reduce the reflected power. The reflection coefficient and the shunt impedance in the working frequency range are obtained by the 3D code HFSS. The simulation results provide many important supports for the structure design.

MOPO010

Orbit Feedback System for the MAX IV 3 GeV Storage Ring

feedback, vacuum, power-supply, storage-ring

499

M. Sjöström, J. Ahlbäck, M.A.G. Johansson, S.C. Leemann, R. Nilsson
MAX-lab, Lund, Sweden

The paper describes the current orbit correction system design for the 3 GeV storage ring at the MAX IV laboratory, a light source facility under construction in Lund, Sweden. The orbit stability requirements for the 3 GeV storage ring are tight at roughly 200 nm vertical position stability in the insertion device (ID) straight sections. To meet this the ring will be equipped with 200 beam position monitors (BPMs) and 380 dipole corrector magnets, 200 in the horizontal and 180 in the vertical plane. The feedback loop solution, one slow orbit feedback (SOFB) loop and one fast orbit feedback (FOFB) loop in fast acquisition mode at 10,000 samples/second, will be presented. The paper will also discuss the various boundary conditions specific to the MAX IV 3 GeV storage ring design, such as a Cu vacuum chamber, and the impact on the corrector design.

MOPO013

Suppression of Emittance Growth by Excited Magnet Noise with the Transverse Damper in LHC in Simulations and Experiment

pick-up, feedback, emittance, betatron

508

W. Höfle, G. Arduini, R. De Maria, G. Kotzian, D. Valuch
CERN, Geneva, Switzerland
V.A. Lebedev
Fermilab, Batavia, USA

The LHC transverse dampers initially build to control transverse instabilities are also a good remedy to suppress the oscillations causing emittance growth excited by electro-magnetic noises at the frequencies of betatron sidebands. To prevent the emittance growth excited by magnet noise using the damper this system has to have extremely low noise properties. The paper discusses simulation results on the effectiveness of the transverse feedback system to suppress such oscillations and the experimental results from a damper point of view as they were gained during the 2010 LHC run. Possible improvements in the damper system to enhance its effectiveness with respect to the suppression of emittance blow-up are also discussed.

MOPO014

SVD-based Filter Design for the Trajectory Feedback of CLIC

ground-motion, feedback, luminosity, controls

511

J. Pfingstner, D. Schulte, J. Snuverink
CERN, Geneva, Switzerland
M. Hofbaur
UMIT, Hall in Tirol, Austria

The orbit feedback of the Compact Linear Collider (CLIC) is the basic counter-measure against ground motion effects below 1 Hz in the beam delivery system and the main linac of CLIC. In this paper we present significant improvements of the orbit feedback design, by using time-dependent and spatial filters. The design procedure is based on a singular value decomposition (SVD) of the orbit response matrix and on loop-shaping techniques. This modified design has essential advantages compared to previous ones. The required beam position monitor resolution in the beam delivery system could be relaxed by a factor of five. At the same time the suppression of ground motion effects is improved. As a consequence, the tight tolerances for the allowable luminosity loss due to ground motion effects in CLIC can be met. The presented methods can be easily adapted to other accelerators in order to relax sensor tolerances and to efficiently suppress ground motion effects.

MOPO030

Theoretical and Practical Feasibility Demonstration of a Micrometric Remotely Controlled Pre-alignment System for the CLIC Linear Collider

alignment, linac, target, controls

547

H. Mainaud Durand, M. Anastasopoulos, N.C. Chritin, J. Kemppinen, M. Sosin, S. griffet
CERN, Geneva, Switzerland
T. Touzé
ENSTA, Brest, France

The active pre-alignment of the Compact Linear Collider (CLIC) is one of the key points of the project: the components must be pre-aligned w.r.t. to a straight line within a few microns over a sliding window of 200 m, along the two linacs of 20 km each. The proposed solution consists of stretched wires of more than 200 m, overlapping over half of their length, which will be the reference of alignment. Wire Positioning Sensors (WPS), coupled to the supports to be pre-aligned, will perform precise and accurate measurements within a few microns, w.r.t. these wires. A micrometric fiducialisation of the components and a micrometric alignment of the components on common supports will make the strategy of pre-alignment complete. In this paper, the global strategy of active pre-alignment is detailed and illustrated by the latest results demonstrating the feasibility of the proposed solution.

MOPS001

Electron-cloud Pinch Dynamics in Presence of Lattice Magnet Fields

electron, proton, cyclotron, quadrupole

586

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Geneva, Switzerland

The pinch of the electron cloud due to a passing proton bunch was extensively studied in a field free region and in a dipolar magnetic field. For the latter study, a strong field approximation helped to formulate the equations of motion and to understand the complex electron pinch dynamics, which exhibited some similarities with the field-free situation. Here we extend the analysis to the case of electron pinch in quadrupoles and in sextupoles. We discuss the limits of validity for the strong field approximation and we evaluate the relative magnitude of the peak tune shift along the bunch expected for the different fields.

MOPS002

Mitigation of Space Charge and Nonlinear Resonance Induced Beam Loss in SIS100

beam-losses, resonance, space-charge, acceleration

589

G. Franchetti
GSI, Darmstadt, Germany

The control of beam loss in SIS100 is essential for avoiding vacuum instability and guarantee the delivery of the foreseen beam intensity. On the other hand simulations show that the simultaneous presence of space charge and lattice resonances creates during 1 second cycle a progressive beam loss exceeding the limit of 5%. Until now the mechanism of periodic resonance crossing were suspected to be, in conjunction with pure dynamic aperture effects, at the base of the beam loss. In this proceeding we present the state of the art in the beam loss prediction and we prove that the periodic resonance crossing is the deteriorating mechanism, and show that the compensation of a relevant resonance intercepting the space charge tune spread sensibly mitigate the beam loss. A short discussion on beam loss during acceleration is addressed as well.

MOPS003

Coherent Beam-beam Resonances in SuperB with Asymmetric Rings

resonance, luminosity, collider, dynamic-aperture

592

M. Zobov
INFN/LNF, Frascati (Roma), Italy
Y. Zhang
IHEP Beijing, Beijing, People's Republic of China

One of the latest options of SuperB foresees exploiting rings with unequal circumferences. In such a configuration additional coherent beam-beam resonances can arise. In this paper we discuss the possible impact of the resonances on beam dynamics in SuperB, maximum achievable tune shifts and working point choice.

MOPS005

Beam Dynamics Simulations of J-PARC Main Ring for Upgrade Plan of Fast Extraction Operation

beam-losses, injection, proton, power-supply

598

Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori, M. Tomizawa
KEK, Ibaraki, Japan
H. Hotchi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Beam loss simulations under space charge effects are necessary to seek higher intensity proton beams. This paper presents simulations for fast extraction operation of Japan Proton Accelerator Research Complex (J-PARC) Main Ring. For upgrade plan, increasing protons per bunch and making higher repetition pattern are considered. Their optimal balance is discussed to minimize beam losses for aimed beam power considering space charge effects. We found that to optimize RF voltage pattern is a strong key to reduce beam losses for higher repetition. As benchmark works, we compare our simulations with the measured beam loss in our past operation.

MOPS008

Simulation of Longitudinal Emittance Control in J-PARC RCS for 400 MeV Injection

extraction, emittance, injection, bunching

607

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 injection energy upgrade of the J-PARC RCS from 181 MeV to 400 MeV is scheduled, this is necessary to achieve the design beam intensity. The high intensity beam is delivered to the MR, and the space charge effect at the MR injection should be alleviated by optimizing the longitudinal beam emittance at RCS extraction. This is realized by matching the shape of the beam emittance between the RCS and the MR. We describe the results of particle tracking simulation with the longitudinal emittance control during the whole acceleration period of the RCS.

MOPS011

Impact of Low Transition Energy Optics to the Electron Cloud Instability of LHC Beams in the SPS

electron, optics, synchrotron, emittance

616

H. Bartosik, E. Benedetto, K.S.B. Li, Y. Papaphilippou, G. Rumolo
CERN, Geneva, Switzerland

One of the main limitations for high intensity multi-bunch LHC proton beams in the SPS is imposed by electron cloud instabilities. A new optics of the SPS with lower transition energy was implemented and successfully tested in machine studies. The significant increase of the slippage factor that it provides at injection energy results in the expected increase of the single bunch instability thresholds. In this paper, the impact of this new optics on the electron cloud instability threshold is estimated by using numerical simulations, taking into account the change of the optics functions and the faster synchrotron motion due to the reduced transition energy.

MOPS017

Simulation Studies of Macro-particles Falling into the LHC Proton Beam

proton, beam-losses, injection, vacuum

634

F. Zimmermann, T. Baer, M. Giovannozzi, E.B. Holzer, E. Nebot Del Busto, A. Nordt, M. Sapinski
CERN, Geneva, Switzerland
N. Fuster
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
Z. Yang
EPFL, Lausanne, Switzerland

We report updated simulations on the interaction of macro-particles falling from the top of the vacuum chamber into the circulating LHC proton beam. The path and charge state of micron size micro-particles are computed together with the resulting beam losses, which – if high enough - can lead to the local quench of SC magnets. The simulated time evolution of the beam loss is compared with observations in order to constrain some macro-particle parameters. We also discuss the possibility of a "multiple crossing" by the same macro-particle, the effect of a strong dipole field, and the dependence of peak loss rate and loss duration on beam current and on beam size.

MOPS018

Simulation and Measurement of Half Integer Resonance in Coasting Beams on the ISIS Ring

resonance, emittance, injection, space-charge

637

C.M. Warsop
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
D.J. Adams, B. Jones, B.G. Pine, H. V. Smith, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on an 800 MeV rapid cycling synchrotron (RCS), which provides 3·10¹³ protons per pulse at 50 Hz, corresponding to a beam power of 0.2 MW. In common with many lower energy, high intensity proton rings, a key loss mechanism on ISIS is half integer resonance under space charge. This paper summarises experimental and simulation work studying half integer resonance in a “2D” coasting beam in the ISIS ring: understanding this is an essential prerequisite for explaining the more complicated case of RCS operation. For coasting beam experiments, the ring is reconfigured to storage ring mode with RF off and main magnets powered on DC current only. A 70 MeV beam is injected, painted appropriately, and manipulated so as to approach resonance. Understanding how the resonant condition develops is central to explaining observations, so realistic simulations of resonance, including injection, ramping of intensity and tunes are being developed. Results from the ORBIT code are presented and compared with experimental and theoretical results. Finally, future plans are summarized.

MOPS019

High Intensity Longitudinal Dynamics Studies for Higher Energy Injection into the ISIS Synchrotron

injection, bunching, space-charge, linac

640

R.E. Williamson, D.J. Adams, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the world’s most productive pulsed neutron and muon source, at the Rutherford Appleton Laboratory in the UK. Operation is centred on a loss-limited 50 Hz proton synchrotron which accelerates 3·10¹³ protons per pulse from 70 MeV to 800 MeV, delivering a mean beam power of 0.2 MW. Present studies on ISIS upgrades are focussed on a new linac for higher energy injection into the existing ring, potentially increasing beam current through reduction in space charge and optimized injection. Studies assume injection of a chopped beam at 180 MeV and offer the possibility of beam powers in the 0.5 MW regime. A critical aspect of such an upgrade is the longitudinal dynamics, associated RF parameters, space charge levels and stringent requirements on beam loss. This paper outlines studies optimizing longitudinal parameters including key design requirements such as bunching factor and satisfying the Keil-Schnell-Boussard stability criterion throughout acceleration. Work developing and benchmarking the in-house longitudinal dynamics code used for these studies is also summarized.

MOPS023

An Analytical Lagrangian Model for Analyzing Temperature Effects in Intense Non-neutral Beams*

emittance, focusing, controls, space-charge

646

E.G. Souza, A. Endler, R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

High-intensity charged-particle beams are used in several areas of physics. We can mention as an illustration, high-energy colliders, particle accelerators and vacuum electron devices. In all cases quoted above, the beam lose particles in the acceleration process, between its production to its final destination. These ejected particles, generally, produce a surrounding structure around the beam core, called halo. This undesirable structure is seen in simulation as well as in actual linacs, and its formation has been one of the main sources of energy loss in the acceleration devices. For this reason, the need for an advance in understand the mechanism that produce the halo becomes necessary. In view of the whole problem, we contruct a 1D Lagrangian warm-fluid model for describe the behavior of inhomogeneous charged-particle beam in solenoidal focusing magnetic field. The equations of motion are derived for an adiabatic process with a state equation originated from the ideal gas law. In the end, the model is compared with self-consistent simulation and is used to explain emittance growth and jets of particle, even when the system is out of equilibrium.

MOPS025

Studies of Emittance Measurement by Quadrupole Variation for the IFMIF-EVEDA High Space Charge Beam

emittance, quadrupole, space-charge, beam-transport

652

P.A.P. Nghiem, E. Counienc
CEA/DSM/IRFU, France
N. Chauvin
CEA/IRFU, Gif-sur-Yvette, France
C. Oliver
CIEMAT, Madrid, Spain

For the high-power (1 MW) beam of the IFMIF-EVEDA prototype accelerator, emittance measurements at nearly full power are only possible in a non-interceptive way. The method of quadrupole variation is explored here. Due to the high space charge regime, beam transport is strongly non-linear, and the classical matrix inversion is no more relevant. Inverse calculations using a multiparticle code is mandatory. In this paper, such emittance measurements are studied, aiming at checking its feasibility and evaluating its precision, taking into account the constraints of losses and quadrupole limitations.

MOPS026

Start-to-end Beam Dynamics Simulations for the Prototype Accelerator of the IFMIF/EVEDA Project

rfq, linac, quadrupole, solenoid

655

N. Chauvin
CEA/IRFU, Gif-sur-Yvette, France
M. Comunian
INFN/LNL, Legnaro (PD), Italy
O. Delferrière, R.D. Duperrier, R. Gobin, A. Mosnier, P.A.P. Nghiem, D. Uriot
CEA/DSM/IRFU, France
C. Oliver
CIEMAT, Madrid, Spain

The EVEDA (Engineering Validation and Engineering Design Activities) phase of the IFMIF (International Fusion Materials Irradiation Facility) project consists in building, testing and operating a 125 mA/9 MeV prototype accelerator in Rokkasho-Mura (Japan). Because of high beam intensity and power, the different sections of the accelerator (injector, RFQ, MEBT, Superconducting Radio-Frequency linac and HEBT) have been optimized with the twofold objective of minimizing losses along the machine and keeping a good beam quality. Extensive start-to-end multi-particles simulations have been performed to validate the prototype accelerator design. A Monte Carlo error analysis has been carried out to study the effects of misalignments and field variations. In this paper, the results of theses beam dynamics simulations, in terms of beam emittance, halo formation and beam losses, are presented.

MOPS028

An Ion Beam Matching to a Linac Accelerating-focusing Channel

rfq, linac, ion, emittance

661

A. Orzhekhovskaya, W.A. Barth, G. Clemente, L.A. Dahl, P. Gerhard, L. Groening, M. Kaiser, M.T. Maier, S. Mickat, B. Schlitt, H. Vormann, S.G. Yaramyshev
GSI, Darmstadt, Germany
U. Ratzinger
IAP, Frankfurt am Main, Germany

Funding: Work supported by HIC for FAIR
A modern linear accelerator of ions is a long chain of different accelerating-focusing structures. The design of new linacs, as well as an upgrade and optimization of operating facilities, requires precise and reliable beam matching with the subsequent sections. Proper matching of the beam to the channel allows to improve the performance of the whole linac and to reduce the specific costs. Additionally it helps to avoide particle loss in high energy high intensity linacs. Generally a matching algorithm combines precisely measured or calculated accelerating-focusing external fields and experimentally obtained details of the beam parameters with an advanced code for beam dynamics simulations including space charge effects. Experimental results are introduced into a code as input data. The described algorithm has already been successfully implemented for several GSI projects: an upgrade of the GSI heavy ion linac UNILAC, an ion linac for the cancer therapy, the proton linac for the FAIR facility, a facility for laser acceleration of ions and others. Measured data and results of beam dynamics simulations leading to an achieved improvement of the linac performance are presented.

MOPS029

Experiments with a Fast Chopper System for Intense Ion Beams

ion, electron, space-charge, high-voltage

664

H. Dinter, M. Droba, M. Lotz, O. Meusel, I. Müller, D. Noll, U. Ratzinger, K. Schulte, C. Wagner, C. Wiesner
IAP, Frankfurt am Main, Germany

Chopper systems are used to pulse charged particle beams. In most cases, electric deflection systems are used to generate beam pulses of defined lengths and appropriate repetition rates. At high beam intensities, the field distribution of the chopper system needs to be adapted precisely to the beam dynamics in order to avoid aberrations. An additional challenge is a robust design which guarantees reliable operation. For the Frankfurt Neutron Source FRANZ, an E×B chopper system is being developed which combines static magnetic deflection with a pulsed electric field in a Wien filter configuration. It will generate proton pulses with a flat top of 50 ns at a repetition rate of 250 kHz for 120 keV, 200 mA beams. For the electric deflection, pre-experiments with static and pulsed fields were performed using a helium ion beam. In pulsed mode operation, ion beams of different energies were deflected with voltages of up to ±6 kV and the resulting response was measured using a beam current transformer. A comparison between experiments and theoretical calculations as well as numerical simulations are presented.

MOPS030

Beam Dynamics of the FRANZ Bunch Compressor using Realistic Fields with a Focus on the Rebuncher Cavities

cavity, linac, dipole, focusing

667

D. Noll, L.P. Chau, M. Droba, O. Meusel, H. Podlech, U. Ratzinger, C. Wiesner
IAP, Frankfurt am Main, Germany

Funding: Work supported by HIC for FAIR.
The ARMADILLO bunch compressor currently being designed at IAP is capable of reaching a longitudinal pulse compression ratio of 45 for proton beams of 150 mA at 2 MeV. It will provide one nanosecond proton pulses with a peak current of 7.7 A. The system guides nine linacμbunches deflected by a 5 MHz rf kicker and uses four dipole magnets - two homogeneous and two with field gradients - to merge them on the target. For longitudinal focusing and an energy variation of ±200 keV two multitrack rf cavities are included. ARMADILLO will be installed at the end of the Frankfurt Neutron Source FRANZ making use of the unique 250 kHz time structure. This contribution will provide an overview of the layout of the system as well as recent advances in component design and beam dynamics of the compressor.

MOPS033

Beam Dynamics Studies on the 100 MeV/100 kW Electron Linear Accelerator for NSC KIPT Neutron Source

linac, electron, dipole, gun

673

S. Pei, Y.L. Chi, M. Hou, W.B. Liu, G. Pei, S.H. Wang, Z.S. Zhou
IHEP Beijing, Beijing, People's Republic of China
N. Aizatsky, I.M. Karnaukhov, V.A. Kushnir, V. Mitrochenco, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

We designed one 100MeV/100kW electron linear accelerator for NSC KIPT, which will be used to drive a neutron source on the base of subcritical assembly. Beam dynamics studies has been conducted to reach the design requirement (E=100MeV, P=100kW, dE/E<1% for 99% particles). In this paper, we will present the progress of the design and dynamics simulation results. For high intensity and long beam pulse linear accelerators, BBU effect is one big issue; special care has been taken in the accelerating structure design. To satisfy the energy spread requirement at the linac exit, the particles with large energy difference from the synchronous particle should be eliminated at low energy stage to ease the design of the collimation system and radiation shielding. A dispersion free chicane with 4 bending magnets is introduced at the downstream of the 1st accelerating section; the unwanted particles will be collimated there.

MOPS037

High Intensity Transient Beam Dynamic Study in Travelling Wave Electron Accelerators with Accounting of Beam Loading Effect

beam-loading, linac, space-charge, electron

682

S.M. Polozov, T.V. Bondarenko, E.S. Masunov, V.I. Rashchikov, A.V. Voronkov
MEPhI, Moscow, Russia

The beam loading effect is one of main problems limiting the beam current. The methods of beam dynamic simulation taking into account the beam loading effect were discussed previously. Simulation methods and the especial code version BEAMDULAD-BL was described in the paper*. The beam loading effect was considered only for traveling wave linacs and for stationary beam only. Now it is important to study the beam dynamics of short current pulses, i.e. for transient process. We can consider only one beam bunch (or a packet of bunches) in a long external RF field pulse in stationary case. The beam radiation and wave fields can be calculated in the quasi-statically approximation. This approximation can not be used for transient mode. The methods of beam dynamics simulation will be discussed in this paper for transient mode. New code version BEAMDULAC-BLNS will be described. The simple test simulations will be carried out.
* A.V. Voronkov et al., "Beam Loading Effect of High Current Trawling Wave Accelerator Dynamic Study", Proc. of IPAC’10, Kyoto, Japan, TUPEA012, p. 1348 (2010).

MOPS038

3D Beam Dynamic Simulation in Heavy Ion Superconducting Drift Tube Linac

cavity, focusing, ion, linac

685

A.V. Samoshin, S.M. Polozov
MEPhI, Moscow, Russia

The superconducting (SC) linac conventionally consists of some different classes of the identical cavities. Each cavity is based on a SC structure with a high accelerating gradient. The low charge state beams require stronger transverse focusing. This focusing can be reached with the help of SC solenoid lenses. In this paper beam dynamics simulation obtain by smooth approximation and full field. Traditionally only the Coulomb field is taken into account for low energy beams. In this paper the computer simulation of heavy ion beam dynamics in superconducting (SC) linac will carried out by means of the "particle-in-cell" method. Simulation results will present.

MOPS040

Intra-Bunch Energy Spread of Electrons in Powerful RF Linacs for Nuclear Physics Research*

linac, target, electron, HOM

691

V.V. Mytrochenko, M.I. Ayzatskiy, V.A. Kushnir, A. Opanasenko, S.A. Perezhogin, V.L. Uvarov
NSC/KIPT, Kharkov, Ukraine

Funding: Ukrainian State program of fundamental and applied studies on the use of nuclear materials, nuclear and radiation technologies in the fields of economics (YaMRT project No. 826/35)
There are some particles in RF electron linacs with energy that may be significantly different from that of particles within a core of the bunch. Loss of these particles at average beam power of tens of kilowatts can cause radiation and thermal problems. Filtration of such particles during the initial stage of acceleration, at energies below the threshold of photonuclear reactions, is important. The paper analyzes several ways to perform such type of filtration in the injector part of a powerful electron linac using a RF chopper or magnetic systems.

MOPS042

One-Dimensional Adiabatic Child-Langmuir Flow

electron, emittance, gun, plasma

694

C. Chen
MIT, Cambridge, Massachusetts, USA
R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

Funding: Research supported in part by US Department of Energy, Grant No. DE-FG02-95ER40919, CNPq, FAPERGS, INCTFCx of Brazil, and US Air Force Office of Scientific Research, Grant No. FA9550-09-1-0283.
A theory is presented that describes steady-state one-dimensional Child-Langmuir flow at a self-consistent finite temperature distribution. In particular, warm-fluid equations and adiabatic equation of state are used to derive the self-consistent Poisson equation. The profiles of the charged-particle density, the velocity, the electrostatic potential, the pressure and the temperature are computed. Results are compared with self-consistent simulations.

MOPS043

Beam Performance in H⁻ Injector of LANSCE

emittance, space-charge, beam-transport, ion-source

697

Y.K. Batygin, C. Pillai, L. Rybarcyk
LANL, Los Alamos, New Mexico, USA

During beam development time in 2010 we performed a series of beam emittance and beam profile scans along 750-keV H⁻ beam transport and 800-MeV linac. The purpose of the measurements was to determine the effects of space charge, slow-wave intensity modulation or chopping, RF buncher fields, and vacuum conditions on beam performance. As previously reported*, from our observation and analysis we concluded that the 750 keV H⁻ beam transport is space-charge uncompensated. This presentation will look at the relative importance of space-charge, chopping, and RF-buncher on the observed emittance growth for beam in the short and long pulse regime as well as the effects of beam line vacuum degradation on beam size and emittance at the end of the linac.
* Y. Batygin et al., “Space-charge effects in H⁻ Low-Energy Beam Transport of LANSCE,” to be published in Proc. of the 2011 Particle Accelerator Conference, March 28-April 1, 2011, New York, NY.

MOPS049

Study of Ion-induced Instabilities and Transverse Feedback Performance at SOLEIL

ion, feedback, vacuum, electron

712

R. Nagaoka, L. Cassinari, M.D. Diop, J.-M. Filhol, M.-P. Level, A. Loulergue, P. Marchand, R. Sreedharan
SOLEIL, Gif-sur-Yvette, France

Experimental studies indicate that the SOLEIL storage ring at its maximum designed current of 500 mA is under a large influence of ions, potentially capable of inducing the so called fast beam-ion instability. To avoid it, the following three conditions have been empirically found effective: A reduced RF voltage, uniform filling and a large vertical chromaticity. While the choice of uniform filling appears contradictory to raising the ion instability threshold, it goes well with lowering of the RF voltage if outgassing due to beam-induced heating of the vacuum components is the primary source of ions. Additional difficulties associated are frequent occurrence of sudden beam blowups despite the presence of transverse feedback, which are large enough to trigger machine interlocks leading to complete beam losses. These blow ups may even take place horizontally inside in-vacuum insertion devices. The present paper reports on the results and findings obtained through experimental and simulation studies carried out on the collective beam dynamics and the transverse feedback performance, which are deeply interlinked, in order to clarify the mechanism of the encountered phenomena.

MOPS053

Electron Cloud Effects in Coasting Heavy-ion Beams*

electron, ion, accumulation, dipole

724

F.B. Petrov, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim
GSI, Darmstadt, Germany

Funding: Work supported by BMBF under contract 06DA9022I.
During slow extraction of intense ion beams electron clouds (EC) can accumulate in the circulating coasting beam and reduce the extraction efficiency. This is a concern for the existing SIS-18 heavy ion synchrotron at GSI and for the projected SIS-100 as part of the FAIR project. For medium energy heavy-ion beams the production of electrons from residual gas ionization is very effective. The electron density is limited due to Coulomb scattering by the beam ions. Above a threshold beam intensity the two-stream instability and the resulting coherent beam oscillations limit the electron density. Below this threshold the electron cloud can lead to observable deformations of the Schottky side-bands. To avoid EC build-up one can introduce a gap in the beam using barrier rf bucket. The reduction of the build-up efficiency caused by the gap is studied in details based on the solution of the Hill's equation for electrons. Finally we estimate the saturation level for the electron cloud density.

MOPS054

Impedance of the Pulse Power Converter for the SIS100 Bipolar Extraction Kicker System

impedance, kicker, coupling, extraction

727

K. Samuelsson, V. Hinrichsen
TU Darmstadt, Darmstadt, Germany
U. Blell, P.J. Spiller
GSI, Darmstadt, Germany

SIS100 will be operated with high intensity heavy-ion and proton beams. The reduction of ring impedances is therefore of great importance in order to avoid coherent beam instabilities. The kicker system is one of the main contributors to the overall ring impedance in SIS100. This paper will focus on the contribution of the external network to the kicker impedance. Calculations as well as experimental impedance measurements of the network contribution have already been carried out for the SIS18 and ESR kickers. The SIS100 will be equipped with a bipolar kicker system, which uses a Pulse Forming Network (PFN) as energy storage. For potential detachment purposes an insulation transformer will be installed. Since this setup is new in several ways it is important to know its contribution to the coupling impedance of the kicker system. In this contribution the corresponding numerical calculation is presented.

MOPS056

An Analytical Formula of the Electron Cloud Linear Map Coefficient in a Strong Dipole

electron, dipole, vacuum, storage-ring

733

T. Demma
INFN/LNF, Frascati (Roma), Italy
S. Petracca, A. Stabile
U. Sannio, Benevento, Italy
G. Rumolo
CERN, Geneva, Switzerland

Electron cloud effects have been indentified as one of the most serious bottleneck for reaching design performances in presently running and proposed future storage rings. The analysis of these effects is usually performed with very time consuming simulation codes. An alternative analytic approach, based on a cubic map model for the bunch-to-bunch evolution of the electron cloud density, could be useful to determine regions in parameters space compatible with safe machine operations. In this communication we derive a simple approximate formula relating the quadratic coefficient in the electron cloud density map to the parameters relevant for the electron cloud evolution in a strong vertical magnetic field. Results are compared with simulations with particular reference to the LHC dipoles.

MOPS057

Beam-beam Interaction under External Force Oscillation

luminosity, positron, electron, kicker

736

K. Ohmi
KEK, Ibaraki, Japan

Beam-ion interaction is strongly nonlinear. Response for external oscillation applied to beam shows characteristic feature. Simulations for external frequency scan becomes feasible for the recent computer power. We show the frequency response for beam-ion system in KEK-PF and recent low emittance rings.

MOPS058

KEKB Linac Wakefield Studies of Comparing Theoretical Calculation, Simulation and Experimental Measurement*

emittance, wakefield, linac, injection

739

L. Zang, N. Iida, Y. Ogawa, M. Satoh, M. Yoshida, D.M. Zhou
KEK, Ibaraki, Japan

For superKEKB, in order to achieve aiming luminosity machine need to run with a nano-beam scheme so that a small beam emittance is critical important. During the beam propagation, the short-range wake field in the accelerating structure will cause the beam instability and emittance growth. In practical, injecting beam with certain offset could compensate wakfield. And beam emittance could be measured by tuning the quadruple known as quadscan method. In this paper, wakefield theoretical calculation, simulation results will be presented. And then the wakefield impact to beam emittance and wakefield compensation will be discussed. Finally, we will show the comparison of the results getting from theoretical calculation and experimental measurement.

MOPS060

Study on Resistive Wall Instability in CSNS/RCS

injection, impedance, wakefield, extraction

745

L. Huang, Y.D. Liu, S. Wang
IHEP Beijing, Bejing, People's Republic of China

Rapid Cycling Synchrotron of the China Spallation Neutron Source is a high intensity proton accelerator, with average beam power of 100kW. The collective effects caused by the coupling impedance may be the limit to beam power. The impedance estimation for components on beam line shows that the resistive wall impedance and its instability are more serious than any others. Based on the impedance budget, the instability is theoretically estimated. And a simple resistive wall wake field model is used to simulate the bunch oscillation and the growth rate instability. In this model, the continuous resistive wall wake field is equivalent to a point wake field and long bunch is sliced into many micro-bunches. By tracking the dynamics of the macro-bunches, the transverse growth rate are obtained and the result are analyzed.

MOPS068

Localization of Transverse Impedance Sources in the SPS using HEADTAIL Macroparticle Simulations

impedance, quadrupole, lattice, ion

757

N. Biancacci, G. Arduini, E. Métral, D. Quatraro, G. Rumolo, B. Salvant, R. Tomás
CERN, Geneva, Switzerland
N. Biancacci, M. Migliorati, L. Palumbo
Rome University La Sapienza, Roma, Italy
R. Calaga
BNL, Upton, Long Island, New York, USA

In particle accelerators, beam coupling impedance is one of the main contributors to instability phenomena that lead to particle losses and beam quality deterioration. For this reason these machines are continuously monitored and the global and local amount of impedance needs to be evaluated. In this work we present our studies on the local transverse impedance detection algorithm. The main assumptions behind the algorithm are described in order to understand limits in reconstructing the impedance location. The phase advance response matrix is analyzed in particular for the SPS lattice, studying the different response from 90,180,270 degrees phase advance sections. The thin lenses scheme is also implemented and new analytical formulas for phase advance beating were derived. This avails us to put reconstructing lenses everywhere in the lattice, and to study their positioning scheme. Limits in linear response are analyzed. This sets the upper and lower limits in reconstruction to the phase advance measurement accuracy and the linear response regime limit.

MOPS069

Review of Beam Instabilities in the Presence of Electron Clouds in the LHC

emittance, electron, injection, luminosity

760

K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Recent observations at the LHC indicate the build-up of electron clouds when 50 ns spaced beams are injected into the machine at nominal intensity. These electron clouds are a source of coherent beam instabilities and incoherent emittance growth and limit the achievable luminosity. To better understand the influence of electron clouds on the beam dynamics, simulations have been carried out to study both the coherent and the incoherent effects on the beam. The simulations are performed with the HeadTail tracking code; the usage of new post-processing software allows determining not only the beam intensity thresholds in terms of the central electron cloud density but also the footprint of the beam in tune space. In this paper we review instability thresholds and tune footprints for beams with different emittances and interacting with an electron cloud in field-free or dipole regions.

MOPS070

Electromagnetic Modeling of C Shape Ferrite Loaded Kickers

impedance, kicker, vacuum, ion

763

C. Zannini
EPFL, Lausanne, Switzerland
E. Métral, G. Rumolo, B. Salvant, V.G. Vaccaro, C. Zannini
CERN, Geneva, Switzerland

The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of an intensity upgrade of the LHC. In this paper, analytical approach and CST Particle Studio time domain electromagnetic simulations are performed to obtain the longitudinal and transverse impedances/wake potentials of models of ferrite loaded kickers. It turns out that the existing models are not sufficient to characterize correctly these components from the coupling impedance point of view. In particular the results show that below few hundred MHz the real C-structure of the magnet cannot be neglected. Therefore an analytical model was developed and benchmarked with EM simulations to take into account the C-shape of the magnet.

MOPS071

Simulations of the Impedance of the New PS Wire Scanner Tank

impedance, beam-losses, extraction, vacuum

766

B. Salvant
EPFL, Lausanne, Switzerland
W. Andreazza, F. Caspers, A. Grudiev, J.F. Herranz Alvarez, E. Métral, G. Rumolo
CERN, Geneva, Switzerland

The CERN PS is equipped with 4 wire scanners. It was identified that the small aperture of the current wire scanner tank causes beam losses and a new tank design was needed. The interaction of the PS bunches with the beam coupling impedance of this new tank may lead to beam degradation and wire damage. This contribution presents impedance studies of the current PS tank as well as the new design in order to assess the need to modify the design and/or install lossy materials plates dedicated to damp higher order cavity modes and reduce the total power deposited by the beam in the tank.

MOPS072

Broadband Electromagnetic Characterization of Materials for Accelerator Components

impedance, kicker, damping, RF-structure

769

C. Zannini, A. Grudiev, E. Métral, T. Pieloni, G. Rumolo
CERN, Geneva, Switzerland
G. De Michele
PSI, Villigen, Switzerland
C. Zannini
EPFL, Lausanne, Switzerland

Electromagnetic (EM) characterization of materials up to high frequencies is a major requirement for the correct modeling of many accelerator components: collimators, kickers, high order modes damping devices for accelerating cavities. In this scenario, the coaxial line method has gained much importance compared to other methods because of its applicability in a wide range of frequencies. In this paper we describe a new coaxial line method that allows using only one measurement setup to characterize the material in a range of frequency from few MHz up to several GHz. A coaxial cable fed at one side is filled with the material under test and closed on a known load on the other side. The properties of the material are obtained from the measured reflection coefficient by using it as input for a transmission line (TL) model or for 3D EM simulations, which describe the measurements setup. We have applied this method to characterize samples of SiC (Silicon Carbide) which could be used for LHC collimators and for CLIC accelerating structures and NiZn ferrite used for kicker magnets.

MOPS074

Stabilization of the LHC Single-bunch Transverse Instability at High-energy by Landau Octupoles

octupole, beam-losses, emittance, single-bunch

775

E. Métral, B. Salvant
CERN, Geneva, Switzerland
N. Mounet
EPFL, Lausanne, Switzerland

When the first ramp was tried on Saturday 15/05/2010 with a single bunch of about nominal intensity (i.e. ~ 10¹1 p/b), the bunch became unstable in the horizontal plane at ~ 2 TeV. The three main observations were: (i) a “Christmas tree” in the transverse tune measurement application (with many synchrotron sidebands excited), (ii) beam losses (few tens of percents) in IR7, and (iii) an increase of the bunch length. This transverse coherent instability has been stabilized successfully with Landau octupoles. Comparing all the measurements performed during this first year of LHC commissioning with the theoretical and simulation predictions reveals a good agreement.

MOPS075

Simulation of Multibunch Motion with the HEADTAIL Code and Application to the CERN SPS and LHC

impedance, wakefield, synchrotron, coupling

778

N. Mounet
EPFL, Lausanne, Switzerland
N. Mounet, E. Métral, G. Rumolo
CERN, Geneva, Switzerland

Multibunch instabilities due to beam-coupling impedance can be a critical limitation for synchrotrons operating with many bunches. It is particularly true for the LHC under nominal conditions, where according to theoretical predictions the 2808 bunches rely entirely on the performance of the transverse feedback system to remain stable. To study these instabilities, the HEADTAIL code has been extended to simulate the motion of many bunches under the action of wake fields. All the features already present in the single-bunch version of the code, such as synchrotron motion, chromaticity, amplitude detuning due to octupoles and the ability to load any kind of wake fields through tables, have remained available. This new code has been then parallelized in order to track thousands of bunches in a reasonable amount of time. The code was benchmarked against theory and exhibited a good agreement. We also show results for bunch trains in the LHC and compare them with beam-based measurements.

MOPS076

Long Range Wakefields in the SwissFEL C-band Linac

wakefield, HOM, linac, impedance

781

A. Citterio, M. Aiba, R. Zennaro
PSI, Villigen, Switzerland

The SwissFEL main linac consists of more than hundred constant gradient C-band accelerating structures which boost the beam energy from 410 MeV at the injector to the final nominal energy of 5.8 GeV. With a repetition rate of 100 Hz, two bunches per pulse can be accelerated with a spacing of 28 ns to feed simultaneously two different FEL arms*. Rising of the long range wakefields, both longitudinal and transverse, could affect this multibunch operation, causing degenerative effects on the quality of the second bunch. A direct computation of the longitudinal and transverse wakes by means of time domain simulations is compared with a model based on the computation of the dispersion curves of the wake modes by frequency domain simulations. A good agreement is obtained for both the synchronous frequency and impedance of all the main modes contributing to the wakefields. Moreover, the total longitudinal wake at 28 ns is below the thighter tolerances required by the beam dynamics, so that neither Higher Order Modes (HOMs) either beam loading require compensation. The effects on the beam of the long range transverse wakefields are also negligeable.
*R. Ganter et al, SwissFEL CDR, PSI report n. 10-04; http://www.psi.ch/swissfel/CurrentSwissFELPublicationsEN/SwissFEL_CDR_{_}v19₀3.03.11-small.pdf

MOPS078

Coaxial Wire Measurements of Ferrite Kicker Magnets

impedance, kicker, injection, extraction

784

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant, C. Zannini
CERN, Geneva, Switzerland

Fast kicker magnets are used to inject beam into and eject beam out of the CERN accelerator rings. These kickers are generally transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the yoke can provoke significant beam induced heating, especially for high intensities. In addition the impedance may contribute to beam instabilities. The results of longitudinal and transverse impedance measurements, for various kicker magnets, are presented and compared with analytical calculations: in addition predictions from a numerical analysis are discussed.

MOPS079

Simulations of Coaxial Wire Measurements of the Impedance of Asymmetric Structures

impedance, coupling, kicker, synchrotron

787

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
F. Caspers, H.A. Day, E. Métral
CERN, Geneva, Switzerland

Coaxial wire measurements have provided a simple and effective way to measure the beam coupling impedance of accelerator structures for a number of years. It has been known how to measure the longitudinal and dipolar transverse impedance using one and two wires for some time. Recently the ability to measure the quadrupolar impedance of structures exhibiting top/bottom and left/right symmetry has been demonstrated. A method for measuring the beam coupling impedance of asymmetric structures using displaced single wires and two wire measurements is proposed. Simulations of the measurement system are presented with further work proposed.

MOPS080

Comparison of the Current LHC Collimators and the SLAC Phase 2 Collimator Impedances

impedance, coupling, cavity, collimation

790

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
F. Caspers, H.A. Day, E. Métral, B. Salvant
CERN, Geneva, Switzerland

One of the key sources of transverse impedance in the LHC has been the secondary graphite collimators that sit close to the beam at all energies. This limits the stable bunch intensity due to transverse coupled-bunch instabilities and transverse mode coupling instability. To counteract this, new secondary collimators have been proposed for the phase II upgrade of the LHC collimation system. A number of designs based on different jaw materials and mechanical designs have been proposed. A comparison of the beam coupling impedance of these different designs derived from simulations are presented, with reference to the existing phase I secondary collimator design.

MOPS082

Some Considerations on the Choice of Frequency and Geometrical Beta in High Power Proton Linacs in the Context of Higher Order Modes

cavity, HOM, linac, proton

793

M. Schuh, F. Gerigk
CERN, Geneva, Switzerland
M. Schuh
MPI-K, Heidelberg, Germany
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Several high power superconducting (SC) proton linear accelerators are currently in the design stage around the world, such as for example the European Spallation Source (ESS) in Lund, Project X at Fermilab, the European ADS demonstrator MYRRAH in Mol and the Superconducting Proton linac (SPL) at CERN. In this contribution, the influence of Higher Order Modes (HOMs) in elliptical SC cavities is discussed as a function of the operation frequency, the number of cells and the geometrical beta of the cavity. Based on cavity design data beam dynamics simulations are executed for different linac layouts to quantify the influence of HOMs.

MOPS086

Beam Breakup Simulation for the PEP-X ERL

HOM, cavity, emittance, recirculation

805

Y. Jiao, Y. Cai, A. Chao
SLAC, Menlo Park, California, USA

Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515.
The transverse beam breakup (BBU) is one of the dominant factors in ERL for the available beam current. A tracking code built in Matlab is developed and benchmarked by comparing with the analytical solutions with the simple model. Study on the threshold current and emittance growth due to the transverse BBU for PEP-X ERL are presented in this paper.

MOPS088

Simulation of Electron Cloud Beam Dynamics for CesrTA

emittance, electron, betatron, positron

808

K.G. Sonnad, G. Dugan, M.A. Palmer, G. Ramirez, H.A. Williams
CLASSE, Ithaca, New York, USA
K.R. Butler
Cornell University, Ithaca, New York, USA
M.T.F. Pivi
SLAC, Menlo Park, California, USA

This presentation provides a comprehensive set of results obtained using the simulation program CMAD. CMAD is being used for studying electron cloud induced beam dynamics issues for CesrTA, which is a test facility for studying physics associated with electron and positron damping rings. In particular, we take a closer look at electron cloud induced effects on positron beams, including head-tail motion, emittance growth and incoherent tune shifts for parameters specific to ongoing experimental studies at CesrTA. The correspondence between simulation and experimental results will also be discussed.
Work supported by US Department of Energy grant number DE-FC02-08ER41538
and the National Science Foundation grant number PHY-0734867

MOPS089

Identification of Bunch Dynamics in the Presence of E-cloud and TMCI for the CERN SPS Ring

controls, feedback, coupling, kicker

811

O. Turgut, J.D. Fox, C.H. Rivetta, S. Uemura
SLAC, Menlo Park, California, USA
W. Höfle
CERN, Geneva, Switzerland

Funding: Work is supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
Measurements and multi-particle simulation codes (i.e. HEAD-TAIL, WARP, CMAD) indicate that bunched particle beams show unstable motions induced by electron-clouds and strong head-tail interactions. The bunch dynamics exhibits highly non-linear, complex and unstable behavior under certain operating conditions. Feedback control systems have been proposed to mitigate these instabilities in the CERN SPS ring. The design of feedback systems requires the knowledge of a reduced dynamic model of the bunch. It allows to include and quantify the effect of noise and signal perturbations, as well as system robustness to parameter variation. Identification techniques are used to estimate those models based on bunch motion measurements. In this work we present reduced mathematical models representing the transverse bunch dynamics and identification techniques to extract the model parameters based on measurements. These techniques are validated using time domain simulations of the bunch motion conducted using multi-particle simulation codes. For that, different sections of the bunch are driven by random signals, and the vertical motion of those areas is used to estimate the reduced model.

MOPS091

Study of Electron Cloud for MEIC

electron, emittance, luminosity, dipole

817

S. Ahmed, J.D. Dolph, G.A. Krafft, T. Satogata, B.C. Yunn
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Medium Energy Electron Ion Collider (MEIC) at Jefferson Lab has been envisioned as a future high energy particle accelerator beyond the 12 GeV upgrade of the existing Continuous Electron Beam Accelerator Facility (CEBAF). Synchrotron radiation from the closely spaced proton bunches in MEIC can generate photoelectrons inside the vacuum chamber and cause secondary emission due to multipacting in the presence of beam's electric field. This phenomenon can lead to fast build up of electron density, known as electron cloud effect – resulting into beam instability coupled to multi-bunches in addition to a single bunch. For MEIC, the estimated threshold value of the electron-cloud density is approximately 5 x 10¹² m-3. In this paper, we would like to report the self-consistent simulation studies of electron cloud formation for MEIC. The code has been benchmarked against the published data of electron cloud effects observed in LHC. Our first simulations predict increase of electron clouds with the increase of repetition rate. The detailed simulations are under progress and will be reported.

MOPZ001

MuSIC, the World's Highest Intensity DC Muon Beam using a Pion Capture System

proton, solenoid, target, dipole

820

A. Sato, Y. Kuno, H. Sakamoto
Osaka University, Osaka, Japan
S. Cook, R.T.P. D'Arcy
UCL, London, United Kingdom
M. Fukuda, K. Hatanaka
RCNP, Osaka, Japan
Y. Hino, N.H. Tran, N.M. Truong
Osaka University, Graduate School of Science, Osaka, Japan
Y. Mori
KURRI, Osaka, Japan
T. Ogitsu, A. Yamamoto, M.Y. Yoshida
KEK, Tokai, Ibaraki, Japan

MuSIC is a project to provide the world's highest-intensity muon beam with continuous time structure at Research Center of Nuclear Physics (RCNP) of Osaka University, Japan. A pion capture system using a superconducting solenoid magnet and a part of superconducting muon transport solenoid channel have been build in 2010. The highest muon production efficiency was demonstrated by the beam test carried out in February 2011. The result concludes that the MuSIC can provide more than 10⁹ muons/sec using a 400 W proton beam. The pion capture system is one of very important technologies for future muon programs such as muon to electron conversion searches, neutrino factories, and a muon collider. The MuSIC built the first pion capture system and demonstrate its potential to provide an intense muon beam. The construction on the entire beam channel of the MuSIC will be finished in five years. We plan to carry out not only an experiment to search the lepton flavor violating process but also other experiments for muon science and their applications using the intense muon beam at RCNP.

MOPZ008

Particle Production Simulations for the Neutrino Factory Target

target, proton, shielding, factory

835

J.J. Back
University of Warwick, Coventry, United Kingdom
X.P. Ding
UCLA, Los Angeles, California, USA
I. Efthymiopoulos, S.S. Gilardoni, O.M. Hansen, G. Prior
CERN, Geneva, Switzerland
H.G. Kirk, N. Souchlas
BNL, Upton, Long Island, New York, USA
R.J. Weggel
Particle Beam Lasers, Inc., Northridge, California, USA

Funding: EU FP7 EUROnu WP3
In the International Design Study for the Neutrino Factory (IDS-NF), a proton beam with a kinetic energy between 5 and 15 GeV interacts with a liquid mercury jet target in order to produce pions that will decay to muons, which in turn decay to neutrinos. The target is situated in a solenoidal field tapering from 20 T down to 1.5 T over a length of several metres, allowing for an optimised capture of pions in order to produce a useful muon beam for the machine. We present results of target particle production calculations using MARS, FLUKA and G4BEAMLINE simulation codes.

MOPZ010

An Accelerator Design Tool for the International Design Study for the Neutrino Factory

factory, lattice, solenoid, HOM

841

A. Kurup
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
P. Bonnal, B. Daudin, J. De Jonghe, M. Dutour
CERN, Geneva, Switzerland

A tool has been developed to simplify the accelerator design process from the lattice design, through tracking simulations with engineering features, to costing the facility. The aim of this tool is to facilitate going through the design loop efficiently and thus allow engineering features to be included early on in the design process without hindering the development of the lattice design. The tool uses a spreadsheet to store information about the accelerator and can generate MADX input files, G4beamline input files and interfaces with the costing tool developed by CERN. Having one source for the information simplifies going between lattice simulations, tracking simulations and costing calculations and eliminates the possibility of introducing discrepancies in the design. The application of this tool to cost the Neutrino Factory, which is part of the IDS-NF and EUROnu studies for delivering the Reference Design Report, will be presented.

MOPZ013

MAUS: MICE Analysis User Software

emittance, controls, extraction, factory

850

C.D. Tunnell
JAI, Oxford, United Kingdom
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The Muon Ionization Cooling Experiment (MICE) is unique because it measures accelerator physics quantities using particle physics methods. It follows that the software that forms the theoretical model of MICE needs to be able to not only propagate beam envelopes and optical parameters but also model detector responses and matter effects for cooling. MICE addresses this dichotomy with the software framework MAUS in order to maximize its physics sensitivity whilst providing the conveniences of, for example, a common data structure. The diversity of challenges that MICE provides from the analysis perspective means that appropriately defining the software scope and layout is critical to the correctness and maintainability of the final accelerator physics analyses. MICE has structured its code into a Map-Reduce framework to enable better parallelization whilst also introducing unit, functional, and integration tests to ensure code reliability and correctness. These methods can apply to other experiments.

MOPZ016

MICE Step I: First Measurement of Emittance with Particle Physics Detectors*

emittance, quadrupole, collider, factory

853

L. Coney
UCR, Riverside, California, USA
M. Popovic
Fermilab, Batavia, USA
M.A. Rayner
DPNC, Genève, Switzerland

The muon ionization cooling experiment (MICE) is a strategic R&D project intending to demonstrate the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. MICE is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam is measured in the upstream magnetic spectrometer with a sci-fiber tracker. A cooling cell will then follow, alternating energy loss in Li-H absorbers and RF acceleration. A second spectrometer identical to the first and a second muon identification system measure the outgoing emittance. In the 2010 run the beam and most detectors have been fully commissioned and a first measurement of the emittance of a beam with particle physics (time-of-flight) detectors has been performed. The analysis of these data should be completed by the time of the Conference. The next steps of more precise measurements, of emittance and emittance reduction (cooling), that will follow in 2011 and later, will also be outlined.
Abstract is submitted by the MICE Speakers Bureau.
If accepted, most likely Dr. Kaplan will present it.
As a first result in a novel sector, we propose it for an oral presentation

MOPZ028

Solid Absorber Program Status for MICE Step IV

emittance, status, insertion, cavity

859

P. Snopok
IIT, Chicago, Illinois, USA
J.H. Cobb
JAI, Oxford, United Kingdom
G.T. Kafka
Illinois Institute of Technology, Chicago, Illinois, USA
C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Funding: Work is supported by the Science and Technology Facilities Council and the U.S. Department of Energy.
In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material and then through RF cavities to compensate for the energy loss, which reduces the transverse emittance. In addition to demonstrating the transverse emittance reduction using flat solid absorbers, it is also planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge-shaped absorber in MICE Step IV. The current status of the simulation and design effort for both flat and wedge-shaped solid absorbers is summarized.

MOPZ036

Ionization Cooling in MICE Step IV

emittance, scattering, solenoid, factory

877

T. Carlisle, J.H. Cobb
JAI, Oxford, United Kingdom
R.R.M. Fletcher
UCR, Riverside, California, USA

The international Muon Ionization Cooling Experiment (MICE), under construction at RAL, will test and characterize a prototype cooling channel for a future Neutrino Factory or Muon Collider. The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance. The change in 4D emittance will be determined with a relative accuracy of 1% by measuring muons individually. These include two scintillating fibre trackers embedded within 4 T solenoid fields, TOF counters and a muon ranger. Step IV of MICE will begin in 2012, producing the experiment's first precise emittance-reduction measurements. Multiple scattering in candidate Step IV absorber materials was studied in G4MICE, based on GEANT4. Equilibrium emittances for low-Z materials from hydrogen to aluminium can be studied experimentally in Step IV of MICE, and compared with simulations.

TUOAA02

Status of UA9, the Crystal Collimation Experiment in the SPS

collimation, ion, proton, beam-losses

897

W. Scandale
LAL, Orsay, France

Funding: CERN, IHEP-Protvino, Imperial-College, INFN, JINR-Dubna, LBNL, PNPI-Gartchina, SLAC
UA9 was operated in the CERN-SPS for more than two years in view of investigating the feasibility of the halo collimation with bent crystals. Silicon crystals 2 mm long with bending angles of about 150 urad were used as primary collimators. The crystal collimation process was steadily achieved through channeling with high efficiency. The crystal orientation was easily set and optimized with the installed goniometer which has an angular reproducibility of about ± 10 μrad. In channeling orientation, the loss rate of the halo particles interacting with the crystal is reduced by a factor of ten, whilst the residual off-momentum halo escaping from the crystal-collimator area is reduced by a factor five. The crystal channeling efficiency of about 75 % is reasonably consistent with simulations and with single pass data collected in the North Area of the SPS. The accumulated observations, shown in this paper, support our expectation that the coherent deflection of the beam halo by a bent crystal should considerably help in enhancing the collimation efficiency in LHC.

Slides TUOAA02 [4.297 MB]

TUYA03

Stochastic Cooling of a High Energy Collider

kicker, pick-up, cavity, luminosity

913

M. Blaskiewicz, J.M. Brennan, R.C. Lee, K. Mernick
BNL, Upton, Long Island, New York, USA

Three dimensional stochastic cooling was successfully implemented at the Relativistic Heavy Ion Collider to overcome emittance growth from intra-beam scattering. The talk reports on the experience of operating a collider with continuous cooling. The application of such techniques to other hadron machine (e.g. LHC) will be discussed.

Slides TUYA03 [1.350 MB]

TUOAB03

Enlarging Dynamic and Momentum Aperture by Particle Swarm Optimization

lattice, sextupole, dynamic-aperture, storage-ring

948

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

Particle swarm optimization (PSO) is a computational intelligence algorithm for global optimization. Obtaining adequate dynamic and momentum aperture is crucial for high injection efficiency and long beam lifetime in low emittance electron storage rings. Different from nonlinear driving terms optimization, we have made direct optimization of dynamic and momentum aperture by PSO algorithm. It is critical to make a criterion for comparison of dynamic and momentum aperture tracking results in the direct optimization procedure. Thus, in this paper we first propose a quantitative criterion of dynamic aperture. Then we apply PSO to the optimization of chromatic and harmonic sextupoles to find the optimum sextupole settings for enlarging the dynamic aperture. Taking the momentum aperture into consideration, we make joint optimization of dynamic and momentum aperture. Also, the momentum aperture has its quantitative criterion. As an example of application, the dynamic and momentum aperture of an FBA lattice studied in the design of storage ring of Hefei Advanced Light Source were optimized, and the results have shown the power of PSO algorithm.

Slides TUOAB03 [0.313 MB]

TUODB03

Innovative Design of the Fast Switching Power Supplies for the SOLEIL EMPHU Insertion and its Fast Correctors

power-supply, controls, undulator, permanent-magnet

982

F. Bouvet, D. Aballea, R. Ben El Fekih, S. Bobault, M. Bol, Y. Bouanani, Y. Dietrich, A. Hardy, F. Marteau
SOLEIL, Gif-sur-Yvette, France

A new electromagnetic/permanent magnets helical undulator has been designed and is under commissioning at SOLEIL. For a fast switching of the photon polarization, it requires a power supply able to switch between +/350 A within 50 ms, without any current overshoot and with a very good current resolution over the full scale (50 ppm). The in-house design is based on two full switching bridges with interleaved commands. Combined with a regulation scheme using sophisticated algorithms, such a design enables to reach a high control bandwidth, permitting fast transitions. Such a fast and accurate system needs well performing digital control electronics. We chose the digital control cards developed at Paul Scherrer Institute (Villigen CH) for the SLS (Swiss Light Source). The components, measurements, interlocks, control interfaces, and electronic cards were developed and assembled together at SOLEIL. This paper will present the main lines of this development and the performances achieved during the EMPHU insertion commissioning. The design of the fast power supplies (±20 A) needed for corrector magnets of this insertion will also be presented.

Slides TUODB03 [3.017 MB]

TUPC001

Simulations of the Interaction Point for TeV-scale e⁺ e− Colliders

photon, electron, collider, radiation

985

J. Esberg
Aarhus University, Aarhus, Denmark

The design of a detector and post collisional line of a future linear collider calls for detailed knowledge of the beam-beam dynamics at the interaction point. We here describe the implementation and results of new simulation tools in the program GUINEA-PIG. The subjects are direct trident production relevant in the deep quantum-regime, incoherent muon generation, synchrotron radiation from secondary particles and depolarization effects. We choose beam parameters in the range relevant for CLIC and comment on the implications for the design of such a machine.

TUPC004

The Luminosity for the ILC Travelling Focus Regime with Offsets and Angle Scans*

luminosity, emittance, collider, wakefield

991

L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, A. Ushakov
University of Hamburg, Hamburg, Germany
K. Buesser, A.F. Hartin, G.A. Moortgat-Pick, N.J. Walker
DESY, Hamburg, Germany
S. Riemann, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

One of the crucial challenges of a future linear collider is to provide high luminosity. In the current ILC design a luminosity of 2x10³⁴ is foreseen. In order to enhance the luminosity, use of the “travelling focus” scheme is under discussion. Within this regime the hourglass effect at the interaction point can be effectively overcome by judiciously arranging for the head and tail of the bunches to be focused at a proportionally displaced longitudinal position. The effect is further enhanced by the strong beam-beam interaction which continuously focuses the bunches during collision. In principle travelling focus could provide an additional 30% luminosity. Nevertheless the regime is highly sensitive to beam-beam transverse and angular offsets at the collision point. The study of the luminosity stability for various ILC parameters using traveling focus will be presented.

TUPC013

Simulation of Phase Stability at the Flat Top of the CLIC Drive Beam

linac, luminosity, kicker, collider

1018

A. Gerbershagen, D. Schulte
CERN, Geneva, Switzerland
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Funding: University of Oxford
The drive beam phase stability is one of the critical issues of the Compact Linear Collider (CLIC). In this paper the generation and propagation of drive beam phase errors is studied for effects that vary during the drive beam pulse. This includes the influence of drive beam current and phase errors as well as of drive beam accelerator RF phase and amplitude errors on the drive beam phase after the compressor chicanes and the analysis of the propagation of these errors through the drive beam combination scheme. The impact of the imperfections on the main beam is studied including the possible correction with help of a feedforward system.

TUPC014

System Control for the CLIC Main Beam Quadrupole Stabilization and Nano-positioning*

feedback, quadrupole, luminosity, ground-motion

1021

S.M. Janssens, K. Artoos, C.G.R.L. Collette, M. Esposito, P. Fernandez Carmona, M. Guinchard, C. Hauviller, A.M. Kuzmin, R. Leuxe, J. Pfingstner, D. Schulte, J. Snuverink
CERN, Geneva, Switzerland

The conceptual design of the active stabilization and nano-positioning of the CLIC main beam quadrupoles was validated in models and experimentally demonstrated on test benches. Although the mechanical vibrations were reduced to within the specification of 1.5 nm at 1 Hz, additional input for the stabilization system control was received from integrated luminosity simulations that included the measured stabilization transfer functions. Studies are ongoing to obtain a transfer function which is more compatible with beam based orbit feedback; it concerns the controller layout, new sensors and their combination. In addition, the gain margin must be increased in order to reach the requirements from a higher vibration background. For this purpose, the mechanical support is adapted to raise the frequency of some resonances in the system and the implementation of force sensors is considered. Furthermore, this will increase the speed of repositioning the magnets between beam pulses. This paper describes the improvements and their implementation from a controls perspective.

TUPC015

Comparative Wakefield Analysis of a First Prototype of a DDS Structure for CLIC Main Linac

wakefield, impedance, dipole, damping

1024

A. D'Elia, A. Grudiev, V.F. Khan, W. Wuensch
CERN, Geneva, Switzerland
R.M. Jones
UMAN, Manchester, United Kingdom

A Damped Detuned Structure (DDS) for CLIC main linac has been proposed as an alternative to the present baseline design which is based on heavy damping. A first prototype, CLIC_DDS_A, for high power tests has been already designed and is under construction. It is also foreseen to design a further prototype, CLIC_DDS_B, to test both the wakefield suppression and high power performances. Wakefield calculations for DDS are, in the early design stage, based on single infinitely periodic cells. Though cell-to-cell interaction is taken into account to calculate the wakefields, it is important to study full structure properties using computational tools. In particular this is fundamental for defining the input parameters for the HOM coupler that is crucial for the performances of DDS. In the following a full analysis of wakefields and impedances based on simulations conducted with finite difference based electromagnetic computer code GdfidL will be presented.

TUPC018

Progress on Modelling of the Thermo-Mechanical Behavior of the CLIC Two-Beam Module

vacuum, RF-structure, linac, collider

1033

R.J. Raatikainen, K. Osterberg
HIP, University of Helsinki, Finland
T.O. Niinikoski, G. Riddone
CERN, Geneva, Switzerland

The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module will be tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the FEA model developed for CLIC prototype module is described. The thermal and structural results for the new module configuration are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done during 2011 and 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behaviour and they will be propagated back to the present thermo-mechanical model.

TUPC019

Beam-based Alignment of CLIC Drive Beam Decelerator using Girders Movers

quadrupole, alignment, dipole, extraction

1036

G. Sterbini, D. Schulte
CERN, Geneva, Switzerland

The CLIC drive beams will provide the rf power to accelerate the colliding beams: in order to reach the design performance, an efficient transport of the drive beam has to be ensured in spite of its challenging energy spread and large current intensity. As shown in previous studies, the specifications can be met by coupling a convenient optics design with the state-of-the-art of pre-alignment and beam-based alignment techniques. In this paper we consider a novel beam-based alignment scheme that does not require quadrupole movers or dipole correctors but uses the motors already foreseen for the pre-alignment system. This implies potential savings in terms of complexity and cost at the expense of the alignment flexibility: the performance, limitations and sensitivity to pre-alignment tolerances of this method are discussed.

TUPC023

Status of Ground Motion Mitigation Techniques for CLIC

luminosity, feedback, quadrupole, ground-motion

1048

J. Snuverink, K. Artoos, C.G.R.L. Collette, F. Duarte Ramos, A. Gaddi, H. Gerwig, S.M. Janssens, J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland
G. Balik, L. Brunetti, A. Jeremie
IN2P3-LAPP, Annecy-le-Vieux, France
P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
B. Caron
SYMME, Annecy-le-Vieux, France
J. Resta-López
IFIC, Valencia, Spain

The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion. A number of mitigation techniques are proposed - quadrupole stabilisation and positioning, final doublet stabilisation as well as beam based orbit and interaction point (IP) feedback. Integrated studies of the impact of the ground motion on the CLIC Main Linac (ML) and Beam Delivery System (BDS) have been performed, which model the hardware and beam performance in detail. Based on the results future improvements of the mitigation techniques are suggested and simulated. It is shown that with the current design the tight luminosity budget for ground motion effects is fulfilled and accordingly, an essential feasibility issue of CLIC has been addressed.

TUPC025

Calibration Errors in the Cavity Beam Position Monitor System at the ATF2

cavity, radio-frequency, lepton, closed-orbit

1051

F.J. Cullinan, S.T. Boogert, N.Y. Joshi, A. Lyapin
JAI, Egham, Surrey, United Kingdom

It has been shown at the Accelerator Test Facility at KEK, that it is possible to run a system of 37 cavity beam position monitors (BPMs) and achieve high working resolution. However, stability of the calibration constants (position scale and radio frequency (RF) phase) over a three/four week running period is yet to be demonstrated. During the calibration procedure, random beam jitter gives rise to a statistical error in the position scale and slow orbit drift in position and tilt causes systematic errors in both the position scale and RF phase. These errors are dominant and have been evaluated for each BPM. The results are compared with the errors expected after a tested method of beam jitter subtraction has been applied.

TUPC027

CLIC Post-Collision Line Luminosity Monitoring

photon, luminosity, monitoring, feedback

1057

R. Appleby
UMAN, Manchester, United Kingdom
A. Apyan, L.C. Deacon, E. Gschwendtner
CERN, Geneva, Switzerland

The CLIC post collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14 MW to the main beam dump. Full Monte Carlo simulation has been done for the description of the Compact Linear Collider (CLIC) luminosity monitoring at the post collision line. One method of the luminosity diagnostic is based on the detection of high energy muons produced by the beamsstrahlung photons in the main beam dump. The disrupted beam and the beamsstrahlung photons produce at the order of 10⁶ muons per bunch crossing, with energies greater than 10 GeV. Currently threshold Cherenkov counters are considered after the beam dump for the detection of these high energy muons. A second method using the direct detection of the beamsstrahlung photons is also considered.

TUPC028

Background and Energy Deposition Studies for the CLIC Post-Collision Line*

photon, radiation, positron, electron

1060

R. Appleby, M.D. Salt
UMAN, Manchester, United Kingdom
L.C. Deacon, E. Gschwendtner
CERN, Geneva, Switzerland

The CLIC post-collision line is designed to transport the spent-beam products of collision to their respective dumps, with minimal losses and thus minimal background contributions. With nanometre spot-sizes at TeV energies, large beam-beam effects induce divergence and dispersion of the outgoing beams, with a large production cross-section of Beamstrahlung photons and subsequently coherent pairs. The post-collision line should provide sufficient divergence of the beam to avoid damage to the vacuum exit and dump entrance windows. In this study, the beam losses are investigated, with the production of secondary particles from the interaction with matter simulated. The particle flux leakage from absorbers and dumps is modelled to determine the total energy deposited on magnets of the post-collision line. Finally, both electromagnetic and hadronic backgrounds at the CLIC experiment are considered.

TUPC050

Impedance Effects in the CLIC Damping Rings

impedance, wiggler, damping, vacuum

1111

E. Koukovini, K.S.B. Li, N. Mounet, G. Rumolo, B. Salvant
CERN, Geneva, Switzerland

Due to the unprecedented brilliance of the beams, the performance of the Compact Linear Collider (CLIC) damping rings is affected by collective effects. Single bunch instability thresholds based on a broad-band resonator model and the associated coherent tune shifts have been evaluated with the HEADTAIL code. Simulations performed for positive and negative values of chromaticity proved that higher order bunch modes can be potentially dangerous for the beam stability. This study also includes the effects of high frequency resistive wall impedance due to different coatings applied on the chambers of the wigglers for e-cloud mitigation and/or ultra-low vacuum pressure. The impact of the resistive-wall wake fields on the transverse impedance budget is finally discussed.

TUPC052

Normal Mode BPM Calibration for Ultralow-Emittance Tuning in Lepton Storage Rings

emittance, quadrupole, coupling, alignment

1114

A. Wolski
The University of Liverpool, Liverpool, United Kingdom
D. L. Rubin, D. Sagan, J.P. Shanks
CLASSE, Ithaca, New York, USA

BPMs capable of high-resolution turn-by-turn measurements offer the possibility of new techniques for tuning for ultra-low beam emittance. In this paper, we describe how signals collected from individual buttons during resonant beam excitation can be used to calibrate BPMs to read the beam position in a normal mode coordinate system. This allows for rapid minimization of the mode II emittance, simply by correcting the mode II dispersion. Simulations indicate that the technique is effective and robust, and has the benefit of being insensitive to BPM gain and alignment errors that can limit the effectiveness of other techniques.

TUPC055

Strongly Space Charge Dominated Beam Transport at 50 keV

solenoid, beam-transport, space-charge, electron

1123

D. Heiliger, W. Hillert, B. Neff
ELSA, Bonn, Germany

Funding: supported by DFG (SFB/TR16)
A pulsed (100 nC in 1 us), low energetic beam of polarized electrons is routinely provided by an inverted source of polarized electrons at ELSA. The beam transport to the linear accelerator is strongly space charge dominated due to the beam energy of 50 keV. Thus, the actual beam current has an impact on the beam dynamics, and the optics of the transfer line to the linear accelerator must be optimized with respect to the chosen beam intensity. Numerical simulations of the beam transport demonstrate that an intensity upgrade from 100 mA to 200 mA is feasible. In order to successfully adjust the focussing strength of the magnets according to the final results of the simulation, dedicated beam diagnostics like wire scanners suitable for extreme-high vacuum applications are required.

TUPC063

Energy Verification in Ion Beam Therapy

proton, synchrotron, ion, closed-orbit

1141

F. Moser
ATI, Wien, Austria
M. Benedikt, U. Dorda
EBG MedAustron, Wr. Neustadt, Austria

Funding: Austrian Federal Ministry for Science and Research, CERN Technology Doctoral Student Program
The adoption of synchrotrons for medical applications necessitates a comprehensive on-line verification of all beam parameters, autonomous of common beam monitors. In particular for energy verification, the required precision of down to 0.1 MeV, in absolute terms, poses a special challenge regarding the betatron-core driven 3rd order extraction mechanism which is intended to be used at MedAustron. Two different energy verification options have been studied and their limiting factors were investigated: 1) A time-of-flight measurement inside the synchrotron, limited by the orbit circumference information and measurement duration as well as extraction uncertainties. 2) A calorimeter-style system in the extraction line, limited by radiation hardness and statistical fluctuations. The paper discusses in detail the benefits and specific aspects of each method.

TUPC067

Simulations of Effects of Detector Materials and Geometry to the Beam Properties of Super-FRS

diagnostics, ion, extraction, antiproton

1153

M. Kalliokoski
HIP, University of Helsinki, Finland

The Super-FRS is a superconducting fragment separator that will be built as part of the FAIR facility. For the slow-extraction part of the beam diagnostics system a total of 32 detectors are needed for the beam monitoring, tracking and characterization of the produced ions. GEM-TPC detectors are planned to be used for the diagnostics at slow extraction mode of the separator*,**. The detectors will be placed in focal planes along the separator. Simulations have been made to study the effects of the detector materials and geometries in order minimize their influence to the performance of the separator. Results of the optimization using different simulation tools will be presented.
* F. Garcia et al., 2009 IEEE NSS Conference Record, Orlando, USA, N13-7 (2009).
** M. Kalliokoski et al., Proc. of IPAC'10, Kyoto, Japan, p.888 (2010).

TUPC077

Investigations on High Sensitive Sensor Cavity for Longitudinal and Transversal Schottky for the CR at FAIR

cavity, coupling, dipole, resonance

1180

M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
P. Hülsmann
GSI, Darmstadt, Germany

Funding: Funded by the Federal Ministry of Education and Research (BMBF): 06DA90351
For the Collector Ring (CR) at the FAIR (Facility for Antiproton and Ion Research) accelerator complex a sensitive Schottky sensor is required. The CR covers different modes of operation, like pre-cooling of antiprotons at 3 GeV, pre-cooling of rare isotope beams at 740 MeV/u and an isochronous mode for mass measurements. For longitudinal Schottky measurements the concept of a resonant cavity had been introduced [Hansli2011]. Due to limited space inside the ring, the integration of transversal Schottky analysis into this cavity is desired. In this paper the demands and required changes to implement also transversal Schottky measurements are discussed. An analysis of the expected signal characteristics featuring equivalent circuit is shown, as well as numerical full wave simulations of the cavity.
* M. Hansli, A. Penirschke, R. Jakoby, W. Kaufmann, W. Ackermann, T. Weiland, "Conceptual Design of a High Sensitive Versatile Schottky Sensor for the Collector Ring at FAIR", DIPAC2011.

TUPC079

Sensitivity and Tolerance Analysis of a New Bunch Arrival-time Monitor Pickup Design for FLASH and XFEL

pick-up, laser, electron, free-electron-laser

1186

A. Kuhl, A. Angelovski, R. Jakoby, A. Penirschke, S. Schnepp
TU Darmstadt, Darmstadt, Germany
M. Bousonville, H. Schlarb
DESY, Hamburg, Germany
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Supported by the Graduate School of Computational Engineering at TU Darmstadt and the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors"
The Free Electron Laser in Hamburg (FLASH) is equipped with Bunch Arrival Time Monitors (BAM)*, which provide for a time resolution of less than 10 fs for bunch charges higher than 0.2 nC. Future experiments, however, will aim at generating FEL light pulses from a broad range of bunch charges down to 10 pC. In these circumstances the requirements on the time resolution will no longer be fulfilled, which demands for a larger bandwidth of the pickup system. A new cone-shaped pickup, which has a bandwidth greater than 40 GHz has been proposed**. At high frequencies, small manufacturing tolerances might have great influence on the pickup signal. A sensitivity analysis of several manufacturing tolerances in the pickup design regarding their influence on the output signal was carried out (by means of CST PARTICLE STUDIO®). These results are utilized for setting limits to the manufacturing tolerances.
* M.K. Bock et al., IPAC2010, WEOCMH02, Kyoto, Japan, 2010.
** A. Kuhl et al., "Design eines hochauflösenden Ankunftszeitmonitor für FLASH", DPG Frühjahrstagung 2011, Karlsruhe, Germany.

TUPC080

Pickup Design with Beta Matching

pick-up, impedance, resonance, kicker

1189

J.A. Tsemo Kamga, W.F.O. Müller, K.K. Stavrakakis, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by GSI
The main goal of this project is to investigate the Schottky noise of an ion beam in the frequency range from 3 to 5 GHz. In order to accomplish this task, a pickup design is required. For an efficient study of this Schottky noise the pickup sensitivity for low beta must be increased. A design for such a problem has been developed by McGinnis for a fixed beam velocity but can also be used for variable beta by using a tunable material (ferroelectric) inside the waveguide. Since such tunable materials like for instance BST (Barium Strontium Titanate) are lossy, the impact of dielectric losses on the pickup sensitivity will also be investigated in this work. Additionally to the classical parameter studies where multiple simulation runs based on the original numerical model are initiated to characterize the various design parameters it is also possible to utilize a reduced model instead. In particular one is interested in a fast evaluation of the frequency response while taking also material variations into account. In this work, a multivariate parameterized dynamical system is set up and used complementary to the full model for the required beam characterization.

TUPC081

Diagnostics of Femtosecond Low-charge Electron Bunches at REGAE

electron, photon, diagnostics, laser

1192

S. Bayesteh
Uni HH, Hamburg, Germany
H. Delsim-Hashemi
DESY, Hamburg, Germany

A new linac is constructed at DESY as the electron source fo "Relativistic Electron Gun for Atomic Exploration (REGAE)". REGAE is mainly established for a Femtosecond electron diffraction experiment presenting structural information on atomic transition states occurring in the sub-hundred femtosecond time-scale. REGAE comprises a photo-cathode gun followed by normal conducting 1.5 cell RF cavity to provide sub pico-Coulomb charge of 2 to 5 MeV energy with a coherent length in the range of 30nm. In order to produce and maintain such high quality electron bunches, sophisticated single-shot diagnostics is mandatory to monitor the properties. Diagnostics include emittance, energy, energy spread and bunch length measurement. In this paper the conceptual ideas and steps toward realization of these diagnostics are presented with a detailed focus on transverse diagnostics. As for photon source of transversal diagnostics, scintillators are studied. Simulation results show which material suits the best for REGAE parameters. Layout of a home-made intensified camera is presented. The method discussed in this paper would also be advantageous for low-charge Free Electron Lasers.

TUPC083

Comparative Studies into 3D Beam Loss Simulations

photon, beam-losses, electron, positron

1198

M. Panniello
MPI-K, Heidelberg, Germany
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the Helmholtz Association and GSI under contract VH-NG-328.
A detailed understanding and monitoring of potential beam loss mechanisms is crucial for every particle accelerator. The main motivation in low energy facilities, such as the Ultra-low energy Storage Ring (USR) at the future Facility of Low energy Antiproton and Ion Research (FLAIR), comes from the very low number of particles available which in such machine ought to be conserved. In High Energy accelerators it is the concern about activation or even physical damage of machine parts which has to be taken into serious account. The CLIC Test Facility (CTF3) at CERN provides an ideal testing ground for studies into novel BLM systems and is well suited for benchmarking the results from numerical simulations in experiments. This contribution summarizes the three-dimensional beam loss pattern as found with the commonly used codes FLUKA and Géant4. The results from these codes are compared and analyzed in detail and used for the identification of optimum beam loss monitor locations.

TUPC098

Beam Profile Measurement using Flying Wire Monitors at the J-PARC Main Ring*

injection, space-charge, proton, emittance

1239

S. Igarashi, K. Ohmi, Y. Sato, M.J. Shirakata, M. Tejima, T. Toyama
KEK, Ibaraki, Japan
Y. Hashimoto, K. Satou
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Transverse beam profiles have been measured using flying wire monitors at the main ring of the Japan Proton Accelerator Research Complex (J-PARC). The flying wire is a beam profile monitor using a thin carbon fiber as a target. The beam is scanned with the wire target at the maximum speed of 5 m/s. The secondary particles from the beam-wire scattering are detected using a scintillation counter as a function of the wire position. The measurement has revealed a characteristic temporal change of the beam profile during the injection period of 120 ms. A multiparticle tracking simulation program, SCTR, taking account of space charge effects has successfully reproduced the beam profiles.

TUPC100

Longitudinal Beam Profile Measurement at J-PARC Separated Drift Tube Linac

beam-losses, cavity, linac, injection

1245

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-mura, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

We measured longitudinal beam profile at Separated Drift Tube Linac (SDTL) injection part by scanning beam transmission and beamloss at the downstream of SDTL section by changing SDTL injection phase. As the beam goes to acceptance edge, part of the beam which is out of acceptance isn't accelerate and finally it is lost by hitting to beam duct. Thus beam transmission shows sliced bunch shape by acceptance edge, it is possible to reconstruct the beam bunch shape. The result shows about 60% wider profile in both phi and E direction against to design.

TUPC102

Measurement of Beam Loss Tracks by Scintillating Fibers at J-PARC Linac

beam-losses, linac, background, gun

1251

H. Sako, T. Maruta, A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Highest beam loss in the J-PARC linac has been observed that the ACS (Annular-Coupled Structure linac) section. Since the observed beam loss is proportional to the residual gas pressure, the source of the beam loss is considered as H0 produced in an interaction of H⁻ beams with remnant gas. If this assumption is valid, H0 hits the beam duct and changes into H⁺ and escapes from the beam duct. We constructed scintillation fiber hodoscopes to detect H⁺s and eventually identify the particle species as H⁺. The hodoscopes are made of 4 planes of hodoscopes which consists of 16 scintillation fibers of 64mm long and with 4mmx4mm cross section. We installed the hodoscopes at the upstream part of the ACS section and measured beam loss. The results are shown in this paper.

TUPC104

Beam Loss Detected by Scintillation Monitor

beam-losses, linac, cavity, hadron

1257

A. Miura, K. Hasegawa, T. Maruta, N. Ouchi, H. Sako
JAEA/J-PARC, Tokai-mura, Japan
Z. Igarashi, M. Ikegami, T. Miyao
KEK, Ibaraki, Japan

Ar gas proportional BLMs have measured the beam loss through operations, but they are also sensitive to background noise of X-ray emitted from RF cavities. We have tried to measure the beam loss using scintillation monitors which would bring more accurate beam loss measurements with suppression of X-ray noise. We measured beam loss using scintillation beam loss monitors. Because this scintillation BLM is sensitive for low energy gamma-rays and fast neutrons, small signals from X-rays would be also detected. As the measurement results, a good signal to noise ratio is observed for the scintillation monitor with quite low sensitivity to the background X-ray. And many single events are observed in the intermediate pulse bunch with about 600 ns as pulse width. In addition, because we fabricated the filter and integrated circuit, total amount of X-ray noise can become smaller. We obtained the good performances of scintillation BLM with small effect of X-ray noise. This monitor can be used for beam loss measurement and a knob for tuning. Furthermore, because the detail structure can be detected, this monitor could be employed for another diagnostic device.

TUPC108

Beam Diagnostics Based on Higher Order Mode for High Repetition Beam

HOM, cavity, diagnostics, single-bunch

1269

X. Luo, X.Y. Lu, F. Wang
PKU/IHIP, Beijing, People's Republic of China
F.S. He
JLAB, Newport News, Virginia, USA

The signals from the HOM ports on superconducting cavities can be used as beam position monitors. The HOM amplitude of dipole mode is proportional to the beam offset. For high repetition bunches operation, the spectrum is consist of the HOMs peaks and the peaks which is integer times of the bunch repetition. The HOMs amplitudes should be separated from the two kinds of peaks. Based on the simulation from a TESLA 2-cell cavity, the transform matrix between the HOMs amplitudes and beam offsets has been found, as well as the cavity axis. The simulation results have demonstrated that beam diagnostics based on HOMs is feasible while high repetition bunches operation.

TUPC109

Electron Bunch Slice Emittance Measurement with the Space Charge Effects*

solenoid, emittance, space-charge, electron

1272

C. Li, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan
TUB, Beijing, People's Republic of China

Funding: supported by the National Natural Science Foundation of China (Grant Nos. 10735050, 10805031, 10875070 and 10925523), and the National Basic Research Program of China (Grant No. 2007CB815102).
Since slice transverse emittance of the electron beam is critical to a high-gain short-wavelength FEL, its characterization is very important. For space charge dominated electron beam, conventional emittance measurement techniques, such as solenoid scanning and quadruple scanning, without considering space charge forces lead to large errors of emittance evaluations. This essay introduces a modified solenoid-scan method of slice emittance measurement for space charge dominated beam, and simulations show that the new method brings the emittance evaluations much closer to actual values.

TUPC119

A Comprehensive Study of Nanometer Resolution of the IPBPM at ATF2*

cavity, dipole, coupling, extraction

1296

Y.I. Kim, H. Park
Kyungpook National University, Daegu, Republic of Korea
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
J.C. Frisch, D.J. McCormick, J. Nelson, T.J. Smith, G.R. White, M. Woodley
SLAC, Menlo Park, California, USA
Y. Honda, R. Sugahara, T. Tauchi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515.
High-resolution beam position monitors (IPBPMs) have been developed in order to measure the electron beam position at the focus point of ATF2 to a few nanometers in the vertical plane. To date, the IPBPM system has operated in test mode with a highest demonstrated resolution of 8.7 nm in the ATF extraction line during 2008. After expected noise source calculations there still remains 7.9 nm of noise of unexplained origin. We summarize the experimental work on the IPBPM system since this measurement and outline the possible origins of these sources. We then present a study plan to be performed at the ATF2 facility designed to identify and to improve the resolution performance and comment on the expected ultimate resolution of this system.

TUPC127

Optical Transition Radiation System for ATF2

emittance, target, coupling, radiation

1317

J. Alabau-Gonzalvo, C. Blanch Gutierrez, A. Faus-Golfe, J.J. García-Garrigós
IFIC, Valencia, Spain
J. Cruz, D.J. McCormick, G.R. White, M. Woodley
SLAC, Menlo Park, California, USA

Funding: Funding Agency: FPA2010-21456-C02-01 Work supported in part by Department of Energy Contract DE-AC02-76SF00515
In this paper we present the first measurements performed during the fall 2010 and early 2011 runs. Software development, simulations and hardware improvements to the Multi-Optical Transition Radiation System installed in the beam diagnostic section of the Extraction (EXT) line of ATF2 are described. 2D emittance measurements have been performed and the system is being routinely used for coupling correction. Realistic beam simulations have been made and compared with the measurements. A 4D emittance procedure, yet to be implemented, is also discussed. A demagnifier lens system to improve the beam finding procedure has been designed and will be implemented in a future run. Finally, we discuss further verification work planned for the next run period of ATF.

TUPC128

Transverse Beam Jitter Propagation in Multi-bunch Operation at ATF2

extraction, feedback, kicker, lattice

1320

J. Resta-López, J. Alabau-Gonzalvo
IFIC, Valencia, Spain
P. Burrows, G.B. Christian
JAI, Oxford, United Kingdom
B. Constance
CERN, Geneva, Switzerland

Pulse-to-pulse orbit jitter, if not controlled, can drastically degrade the luminosity in future linear colliders. The second goal of the ATF2 project at the KEK accelerator test facility is to stabilize the vertical beam position down to approximately 5% of the nominal rms vertical beam size at the virtual interaction point (IP). This will require control of the orbit to better than 1 micrometer at the entrance of the ATF2 final focus system. In this paper, by means of computer simulations, we study the vertical jitter propagation along the ATF2 from the start of the extraction line to the IP. For this study pulse-to-pulse vertical jitter measurements using three stripline beam position monitors are used as initial inputs. This study is performed for the case of a bunch-train with three bunches, but could easily be extended for a larger number of bunches. The cases with and without intra-train orbit feedback correction in the extraction line of ATF2 are compared.

TUPC137

UFOs in the LHC

beam-losses, injection, kicker, acceleration

1347

T. Baer, M.J. Barnes, B. Goddard, E.B. Holzer, J.M. Jimenez, A. Lechner, V. Mertens, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, B. Velghe, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland

One of the major known limitations for the performance of the Large Hadron Collider are so called UFOs (”Unidentified Falling Objects”). UFOs were first observed in July 2010 and have since caused numerous protection beam dumps. UFOs are thought to be micrometer sized dust particles which lead to fast beam losses with a duration of about 10 turns when they interact with the beam. In 2011, the diagnostics for such events was significantly improved which allows estimates of the properties, dynamics and production mechanisms of the dust particles. The state of knowledge and mitigation strategies are presented.

TUPC148

Measuring Emittance with the MICE Scintillating Fibre Trackers

emittance, photon, alignment, factory

1374

D. Adey
University of Warwick, Coventry, United Kingdom

The Muon Ionization Cooling Experiment (MICE) aims to measure a 10% reduction in a muon beam emittance to within 0.1%. To achieve this two scintillating fibre trackers will be placed within a 4T solenoidal field. The trackers utilize fibres with a diameter of 350 microns to provide a position resolution of less than 0.5 mm. Details of the tracker hardware, electronics and its calibration and reconstruction methods will be presented, along with the measured performance under cosmic ray tests and the simulated performance in MICE.

TUPC149

Measurements at the ALICE Tomography Section

quadrupole, emittance, injection, background

1377

M.G. Ibison, K.M. Hock, D.J. Holder, B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Korostelev
The University of Liverpool, Liverpool, United Kingdom

Funding: STFC
This paper reports the results of tomography measurements of the electron beam transverse phase space distribution in the ALICE accelerator at Daresbury Laboratory. These measurements have two main aims. The first is to give a detailed picture of the phase space distribution of the electron beam injected from ALICE into the EMMA prototype non-scaling FFAG accelerator. The second is to provide data for the development and testing of a variety of techniques for tomographic reconstruction. We summarize the measurement results which we have obtained and discuss the advantages and disadvantages of some different tomography methods.

TUPC150

The Effect of Space-Charge on the Tomographic Measurement of Transverse Phase-Space in the EMMA Injection Line

space-charge, quadrupole, injection, emittance

1380

M.G. Ibison, M. Korostelev
The University of Liverpool, Liverpool, United Kingdom
K.M. Hock, D.J. Holder, B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: STFC
Phase-space tomography for particle beams depends upon detailed knowledge of the particle transport through specified sections of a beam line. In the simplest case, only the effects of magnets (such as quadrupoles) and drift spaces need to be taken into account; however, in certain parameter regimes (high charge density and low energy) space charge forces may play a significant role. The ALICE accelerator is the electron source for EMMA, a prototype ns-FFAG machine. Results are presented of investigations into these effects on phase-space tomography in the injection line between ALICE and EMMA. The application of suitable correction techniques* to the EMMA injection line tomography measurements in the presence of space-charge is also discussed.
* D. Stratakis et al., Phys. Rev. ST Accel. Beams 9, 112801 (2006).

TUPC154

Commissioning of the Detection System for a Supersonic Gas-jets Based Transverse Beam Profile Monitor

ion, extraction, storage-ring, electron

1392

M. Putignano, D. Borrows, A. Intermite
The University of Liverpool, Liverpool, United Kingdom
M. Putignano, M.R.F. Siggel-King, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328.
We present the commissioning results of the Micro-Channel-Plate (MCP) based, ion extraction and detection system currently in use for an experimental test stand aimed at demonstrating the operation of a least-interceptive transverse beam profile monitor based on a planar supersonic gas-jet. This monitoring design features least-interceptive operation under excellent vacuum conditions and provides fast acquisition of a fully bi-dimensional transverse profile. It bears application for ultra-low energy particle beams at future storage rings, but also for e.g. linacs at high currents and light source injectors. For instance, the Ultra-low energy Storage Ring (USR), part of the Facility for Antiproton and Ion Research (FAIR) in Germany will store antiprotons at energies of 20-300 keV. In this contribution, we report numerical simulations and experimental results obtained by calibration of the detection system with a low energy electron beam to demonstrate a 1 mm imaging resolution only limited by recoiling ion drift.

TUPC163

Experimental Results from Test Measurements with the USR Beam Position Monitoring System

pick-up, storage-ring, vacuum, alignment

1416

J. Harasimowicz, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J. Harasimowicz, I. Takov
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by STFC, the EU under GA-ITN-215080, the Helmholtz Association and GSI under VH-NG-328.
A diagonal-cut capacitive pick-up (PU) was optimised for monitoring slow (v < 0.025c), long (~1 m) bunches consisting of only about 10⁶ antiprotons at the future Ultra-low energy Storage Ring (USR). Ultra-low noise (0.5 nV/Hz⁰.5) FET pre-amplifiers are used to allow detection of the weak signals generated in the PU plates. The amplified signals are then digitized by a 16-bit, 200 MS/s ADC and processed in a digital manner. The following contribution presents the beam monitoring system as it was tested with a stretched-wire method and compares the measurements with the results from 3D electromagnetic simulations.

TUPC168

Results from the LHC BRAN Luminosity Monitor at Increased Luminosities

luminosity, emittance, radiation, injection

1428

R. Miyamoto
BNL, Upton, Long Island, New York, USA
E. Bravin
CERN, Geneva, Switzerland
H.S. Matis, A. Ratti, W.C. Turner, H. Yaver, T. stezelberger
LBNL, Berkeley, California, USA

Funding: This work supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The LHC BRAN luminosity monitors are used to monitor and optimize the luminosity at the LHC high luminosity interaction points IP1 and IP5. The Argon gas ionization chambers detect showers produced in the TAN absorbers by neutral particles emerging from pp collisions. The detectors have been operated during the 2010 run by counting the shower rate. As the current 2011 run has the multiplicity of proton-proton collisions per bunch crossing near ten, the detector sees more than one collision per bunch crossing. Therefore, the operation of the detector has been switched to pulse height mode to detect the average shower flux. This paper presents results from recent pulse height mode measurements, including the total and bunch-by-bunch luminosity as well as a determination of the crossing angle at these IPs. Comparisons with luminosity measurements from ATLAS and CMS are also presented.

TUPC171

2D Optical Streaking for Ultra-short Electron Beam Diagnostics

laser, electron, diagnostics, linac

1437

L. Wang, Y.T. Ding, Z. Huang
SLAC, Menlo Park, California, USA

We propose a novel approach to measure the short electron bunch profile at micrometer level. Low energy electrons generated during beam-gas ionization are simultaneously modulated by the transverse electric field of a circularly-polarized laser, and then they are collected at a down-stream screen where the angular modulation are converted to a circular shape there. The longitudinal bunch profile is simply represented by the angular distribution of the electrons on the screen. We only need to know the laser wavelength for calibration and there is no phase synchronization problem. Meanwhile the required laser power is also relatively low in this setup. Some simulations examples and resolution of this method will be discussed.

TUPC172

Evaluation and Correction of the Non-linear Distortion of CEBAF Beam Position Monitors

electron, pick-up, radiation

1440

M. Spata, T.L. Allison, K.E. Cole, J. Musson, J. Yan
JLAB, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The beam position monitors at CEBAF have four antenna style pickups that are used to measure the location of the beam. There is a strong nonlinear response when the beam is far from the electrical center of the device. In order to conduct beam experiments at large orbit excitation we need to correct for this nonlinearity. The correction algorithm is presented and compared to measurements from our stretched wire BPM test stand.

TUPO023

Narrow Spectral Bandwidth Optimization of Compton Scattering Sources

electron, laser, scattering, emittance

1488

F. Albert, S.G. Anderson, S.M. Betts, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu
LLNL, Livermore, California, USA

We will be presenting the theoretical and numerical design and optimization of Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering sources. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. We will review the potential sources of spectral broadening, in particular due to the electron beam properties. While it is also known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics based on given laser and electron beam distributions, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

TUPO034

Longitudinal Stability of ERL with Two Accelerating RF Structures

linac, cavity, electron, RF-structure

1509

Ya.V. Getmanov, O.A. Shevchenko
BINP SB RAS, Novosibirsk, Russia
N. Vinokurov
NSU, Novosibirsk, Russia

Modern ERL projects use superconductive accelerating RF structures. Their RF quality is typically very high. Therefore, the RF voltage induced by electron beam is also high. In ERL the RF voltage induced by the accelerating beam is almost canceled by the RF voltage induced by the decelerating beam. But, a small variation of the RF voltage may cause the deviations of the accelerating phases. These deviations then may cause further voltage variation. Thus the system may be unstable. The stability conditions for ERL with one accelerating structure are well known [*, **]. The ERL with split RF structure was discussed recently [***, ****]. The stability conditions for such ERLs are discussed in this paper.
* L. Merminga et al.,Annu. Rev.Nucl. Part. Sci. 53 (2003) 387.
** N.A. Vinokurov et al.,Proc. SPIE 2988 (1997) 221.
*** D. Douglas, ICFA BD-Nl 26 (2001) 40.
****N.A. Vinokurov et al.,Proc. IPAC’10.

TUPO035

Beam Dynamics at the ALICE Accelerator R&D Facility

linac, FEL, booster, cavity

1512

F. Jackson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science and Technology Facilities Council
ALICE is an energy recovery accelerator which drives an infrared free electron laser (IR FEL), based at STFC Daresbury Laboratory. Beam dynamics are of primary importance for the operation of the IR FEL, to ensure sufficient peak current with minimal energy spread and transverse emittance. Measurements of beam parameters are presented and compared with particle tracking simulations. Of particular interest in the ALICE machine is the relatively long injection line where space charge and velocity bunching effects can be significant.

TUPS009

SEY of Al Samples from the Dipole Chamber of PETRA III at DESY

electron, emittance, synchrotron, synchrotron-radiation

1533

D. R. Grosso, R. Cimino, M. Commisso
INFN/LNF, Frascati (Roma), Italy
R. Flammini
CNR-IMIP, Monterotondo Stazione RM, Italy
R. Larciprete
ISM-CNR, Rome, Italy
R. Wanzenberg
DESY, Hamburg, Germany

At the synchrotron radiation facility PETRA III, tune spectra have been measured with some characteristics which are typically observed at other storage rings in connection with electron cloud effects. For some bunch filling patterns, an increase of the vertical emittance has been observed. To estimate such effects with the available e-cloud simulation codes, the detailed knowledge of the SEY (Secondary Electron Yield) of the Al chamber, is required. To the purpose, representative PETRA III Al samples, were studied in detail at the INFN-LNF Surface Science Laboratory. XPS (X-ray photoelectron spectroscopy) and SEY measurements were performed as a function of electron and argon ion conditioning. The SEY of the as received samples shows a maximum value of δmax ≅ 2.8. Electron conditioning at 500 eV kinetic energy, reduces the SEY to values between δmax ≅ 1.8 to 1.4 (depending on the actual sample analyzed). The XPS characterization of the sample surface, after several cycles of argon ion sputtering, shows clearly that the SEY variation is closely related to the oxidation state of the Al sample, reaching a δmax value as low as 1.3 for our cleanest surface.

TUPS014

Vacuum Performance Simulation of C-band Accelerating Structures

vacuum, cavity, linac, free-electron-laser

1548

H. Lee, M.-H. Cho, S.H. Kim, C.H. Yi
POSTECH, Pohang, Kyungbuk, Republic of Korea
W. Namkung, C.D. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work is partly supported by the MEST and POSTECH Physics BK21 program.
A C-band accelerating structure has a higher accelerating gradient than that of the S-band structure. It provides a good advantage of a shorter machine length. In order to effectively use RF power and for cost reduction, the accelerating structure should be as long as possible. We propose a 2.2-m long structure compared to 1.8-m at SACLA (SPring-8 Angstrom Compact free electron LAser). However, a longer accelerating structure has worse vacuum performance than a shorter accelerating structure. Thus, the vacuum conductance of 2.2-m long structure has to be checked. We calculate vacuum performance of the accelerating structure by 1-D analytical method and 3-D finite element method (FEM). It is shown that the vacuum performance for the 2.2-m long accelerating structure is safe enough for the XFEL LINAC.

TUPS018

Observations of Electron Cloud Effects with the LHC Vacuum System

vacuum, electron, solenoid, ion

1560

V. Baglin, G. Bregliozzi, P. Chiggiato, P. Cruikshank, B. Henrist, J.M. Jimenez, G. Lanza
CERN, Geneva, Switzerland

In autumn 2010, during the LHC beam commissioning, electron-cloud effects producing pressure rise in common and single vacuum beam pipes, were observed. To understand the potential limitations for future operation, dedicated machine studies were performed with beams of 50 and 75 ns bunch spacing at energy of 450 GeV. In order to push further the LHC performances, a scrubbing run was held in spring 2011. This paper summarizes the vacuum observations made during these periods. The effects of bunch intensity and different filling schemes on the vacuum levels are discussed. Simulations taking into account the effective pumping speed at the location of the vacuum gauge are introduced. As a consequence, the different vacuum levels observed along the LHC ring could be explained. Finally, the results obtained during the scrubbing run are shown together with an estimation of pressure profiles during the 2011 run.

TUPS021

Simulations and Vacuum Tests of a CLIC Accelerating Structure

vacuum, cavity, ion, damping

1569

C. Garion
CERN, Geneva, Switzerland

The Compact LInear Collider, under study, is based on room temperature high gradient structures. The vacuum specificities of these cavities are low conductance, large surface areas and a non-baked system. The main issue is to reach UHV conditions (typically 10^-7 Pa) in a system where the residual vacuum is driven by water outgassing. A finite element model based on an analogy thermal/vacuum has been built to estimate the vacuum profile in an accelerating structure. Vacuum tests are carried out in a dedicated set-up, the vacuum performances of different configurations are presented and compared with the predictions.

TUPS035

LHC Collimators with Embedded Beam Position Monitors: A New Advanced Mechanical Design

alignment, collimation, pick-up, radiation

1611

A. Dallocchio, A. Bertarelli, C.B. Boccard, F. Carra, M. Gasior, L. Gentini, M.A. Timmins
CERN, Geneva, Switzerland

The LHC collimation system, ensuring both functions of beam cleaning and machine protection, is potentially submitted to high-energy beam impacts. Currently the collimators setup is performed by monitoring beam losses generated by the collimator jaws when approaching the particle beam. This procedure is applied to all LHC collimators (almost one hundred), taking several hours, and needs to be repeated if beam settings change significantly. Furthermore, during the beam-based alignment, the LHC tertiary collimators are potentially exposed to abnormal losses entailing possible damage to their tungsten jaws. To improve the efficiency of the machine operation and better control the particle beam a new advanced design embedding Beam Position Monitors (BPM) into the movable collimator jaws has been developed. This paper describes the mechanical design of various types of future collimators with embedded BPMs. Experimental measurements performed on a simplified functional prototype installed in the CERN SPS showed that, thanks to on-board BPMs, the collimator could be precisely, rapidly, and safely aligned and the beam position accurately measured.

TUPS036

High Energy Beam Impacts on Beam Intercepting Devices: Advanced Numerical Methods and Experimental Set-up

emittance, impedance

1614

A. Bertarelli, V. Boccone, F. Carra, F. Cerutti, A. Dallocchio, N. Mariani, M.A. Timmins
CERN, Geneva, Switzerland
L. Peroni, M. Scapin
Politecnico di Torino, Torino, Italy

Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behavior of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC Tungsten Collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedicated experimental program is proposed, relying on the HiRadMat test facility at CERN. Experimental aspects such as sample-holder design and test set-up are described.

TUPS037

Preliminary Assessment of Beam Impact Consequences on LHC Collimators

proton, collimation, controls, beam-losses

1617

M. Cauchi, R.W. Assmann, A. Bertarelli, R. Bruce, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi, N.J. Sammut
CERN, Geneva, Switzerland
M. Cauchi, P. Mollicone
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain

The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, the robustness of the collimators plays an important role. An accident which causes the proton beam to hit a collimator might result in severe beam-induced damage and, in some cases, replacement of the collimator, with consequent downtime for the machine. In this paper, several case studies representing different realistic beam impact scenarios are shown. A preliminary analysis of the thermal response of tertiary collimators to beam impact is presented, from which the most critical cases can be identified. Such work will also help to give an initial insight on the operational constraints of the LHC by taking into account all relevant collimator damage limits.

TUPS039

Reduction of Magnetic Interference on the Position Sensors of the LHC Collimators

shielding, radiation, dipole

1623

A. Masi, M. Lamberti, R. Losito, M. Martino
CERN, Geneva, Switzerland

The jaws of the LHC collimators have to be positioned with respect to the beam with an accuracy of 20 μm. On some collimators, installed in the LHC transfer lines from SPS, huge reading errors of several tens of micrometers have been observed on the Linear Variable Differential Transformer (LVDT) positioning sensors in synchronization with the variable magnetic field produced by the feed cables of the pulsed resistive dipoles of the transfer line. In this paper we introduce and describe in detail the problem, the model developed using FLUXTM for the simulation of the magnetic flux density generated by the current cables in the complex environment of an LHC transfer line, and the magnetic shielding we designed and implemented. Finally, we compare the results of simulations with experimental measurements taken during on-line pulsed magnets test campaigns.

TUPS041

Thermo-mechanical Study of a CLIC Bunch Train hitting a Beryllium Energy Spoiler Model

radiation, collimation, wakefield, linac

1629

J.-L. Fernández-Hernando, D. Angal-Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J. Resta-López
IFIC, Valencia, Spain

A thermo-mechanical study of the impact a CLIC bunch train has over a beryllium energy spoiler has been made. Beryllium has a high electrical and thermal conductivity which together with a large radiation length compared to other metals makes it an optimal candidate for a long tapered design spoiler that will not generate high wakefields, which might degrade the orbit stability and affect the collider luminosity. This paper shows the progress made from the paper presented last year in IPAC 2010. While in the aforementioned paper the study of the temperature and stress was made for the duration of the bunch train this time the study shows the evolution of the stress in the spoiler body 3 microseconds after the bunch train hit.

TUPS050

Target Optimisation Studies for MuSR Applications

target, proton, beam-losses, neutron

1641

A. Bungau, C. Bungau, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom
P.J.C. King, J.S. Lord
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

Considering the ISIS muon target as a reference, Geant4 simulations have been performed to optimise the target parameters with respect to muon and pion yield. Previous studies suggested that the muon production can be optimised by using a thin graphite slab target with an incident proton energy significantly lower than initially considered. The current paper discusses a possible target design fully optimised for MuSR studies.

TUPS054

Beam-power Deposition in a 4-MW Target Station for a Muon Collider or a Neutrino Factory

target, proton, solenoid, factory

1653

H.G. Kirk
BNL, Upton, Long Island, New York, USA
J.J. Back
University of Warwick, Coventry, United Kingdom
X.P. Ding
UCLA, Los Angeles, California, USA
V.B. Graves
ORNL, Oak Ridge, Tennessee, USA
K.T. McDonald
PU, Princeton, New Jersey, USA
N. Souchlas, R.J. Weggel
Particle Beam Lasers, Inc., Northridge, California, USA

Funding: This work is supported in part by the US DOE Contract NO. DE-AC02-98CH10886.
We present the results of power deposition in various components of the baseline target station of a Muon Collider or a Neutrino Factory driven by a 4-MW proton beam.

TUPS056

Synchronizing GEANT and 3D CAD - A Collaborative Engineering Study at ILD

free-electron-laser, laser, electron

1659

L. Hagge, S. Eucker, B. List, S. Sühl, N. Welle
DESY, Hamburg, Germany

The design of a detector for a high-energy physics experiment is a complex task, driven by two different communities: The scientists aim to optimize the detector performance, while engineers are tasked to provide a design that can actually be built. Both groups have their own specific tools (e.g. GEANT versus 3D CAD systems) that are employed to model the detector and improve its design. The ensuing models need to be compared and synchronized at regular intervals, so that optimizations made to the physics simulation model are propagated to the engineering world, and engineering solutions are reflected properly in the physics simulation. Based on experience from the European XFEL project, DESY is providing tools and processes for establishing this synchronization at a very early stage in the design of the International Large Detector (ILD) for the International Linear Collider (ILC). They have been used to analyze compliance and differences of the ILD engineering design and physics simulation models. The poster introduces tools and process and presents first results and lessons learned.

TUPS067

Photon-stimulated Desorption Experiment for a TPS Crotch Absorber

synchrotron, photon, vacuum, radiation

1692

Y.T. Cheng, G.-Y. Hsiung, C.K. Kuan, A. Sheng, H.Y. Yan
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

National Synchrotron Radiation Research Center (NSRRC) is constructing a large third-generation synchrotron accelerator in Taiwan, the so-called Taiwan Photon Source (TPS). This 3-GeV, 500-mA machine will generate high-density bending-magnet radiation, of which 90 % of the power is absorbed by the crotch absorber in the storage ring. To understand better the beam-cleaning and photon-desorption phenomena of a copper crotch absorber, we have performed a PSD (photon-stimulated desorption) test in Taiwan Light Source (TLS) at Beam line 19 (BL19). Some mathematical modelling, experimental designs and results are also presented here.

TUPS070

An Experiment at HiRadMat: Irradiation of High-Z Materials

target, proton, collider, ion

1698

J. Blanco, C. Maglioni, R. Schmidt
CERN, Geneva, Switzerland
N.A. Tahir
GSI, Darmstadt, Germany

Calculations of the impact of dense high intensity proton beams at SPS and LHC into material have been presented in several papers*,**,***. This paper presents the plans for an experiment to validate the theoretical results with experimental data. The experiment will be performed at the High Radiation to Materials (HiRadMat) facility at the CERN-SPS. The HiRadMat facility is dedicated to shock beam impact experiments. It allows testing of accelerator components with respect to the impact of high-intensity pulsed beams. It will provide a 440 GeV proton beam with a focal size down to 0.1 mm, thus providing very dense beam (energy/cross section). The transversal profile of the beam is considered to be Gaussian with a tunable σ from 0.1 mm to 2 mm. This facility will allow to study “high energy density” physics as the energy density will be high enough to create strong coupled plasma in the core of high-Z materials (copper, tungsten) and to produce strong enough shock waves to create a density depletion channel along the beam axis (tunneling effect). The paper introduces the layout of the experiment and the monitoring system to detect tunneling of protons through the target.
* N.A.Tahir et al. HB2010 Proc., Morschach, Switzerland.
** N.A.Tahir et al. NIMA 606(1-2) 2009 186.
*** N.A.Tahir et al. 11th EPAC, Genoa, Italy, 2008, WEPP073.

TUPS075

Experimental determination of impedance and delay time of the 100 Ω meander transmission line for the SPIRAL2 Single Bunch Selector

impedance, ion, single-bunch, site

1710

M. Di Giacomo
GANIL, Caen, France
P. Balleyguier
CEA/DAM/DPTA/SP2A, Bruyères-le-Châtel, France
A.C. Caruso, F. Consoli
INFN/LNS, Catania, Italy
A. Longhitano
ALTEK, San Gregorio (CATANIA), Italy

The Spiral2 driver requires a Single Bunch Selector to reduce the bunch repetition rate at the experimental targets. A 100 Ω meander line is used in the beta 0.04 medium energy line of the Spiral2 driver. The non standard characteristic impedance figure helps to reduce the pulsed power but introduces the problem of calibrated measurements. The paper describes the results of the different methods used to measure the impedance and the delay of the electrodes.

TUPS081

3D Visualization, Simulation and Virtual Reality in Accelerator Development

linear-collider, collider, site

1728

L. Hagge, A. Herz, J. Kreutzkamp, S. Lang, V. Rupprecht, S. Sühl, N. Welle
DESY, Hamburg, Germany

Visualizing complex beamline designs, animating installation procedures and virtually walking through planned facilities - 3D modelling is a powerful tool with a broad range of applications in accelerator development. The poster describes established and emerging 3D modelling applications at the European XFEL and their benefits: 3D visualization enables inspection and compliance analysis of interfacing systems and components. Simulations enable early verification of e.g. safety and transportation concepts. Digital humans can be inserted into accelerator models to perform e.g. reachability and field-of-sight studies for installation works. Movies of transport and installation procedures can be created for staff training. And ultimately, stereo projection can be used to inspect and simulate designs and processes in virtual environments. 3D modelling helps discovering and resolving design issues earlier and leads to large savings in time and cost.

TUPS102

Design of an FPGA-based Radiation Tolerant Agent for WorldFIP Fieldbus

radiation, controls, target, status

1780

G. Penacoba Fernandez, P. Alvarez, E. Gousiou, S.T. Page, J.P. Palluel, J. Serrano, E. Van der Bij
CERN, Geneva, Switzerland

CERN makes extensive use of the WorldFIP field-bus interface in the LHC and other accelerators in the pre-injectors chain. Following the decision of the provider of the components to stop the developments in this field and foreseeing the potential problems in the subsequent support, CERN decided to purchase the design information of these components and in-source the future developments using this technology. The first in-house design concerns a replacement for the MicroFIP chip whose last version was manufactured in an IC feature size found to be more vulnerable to radiation of high energy particles than the previous versions. NanoFIP is a CERN design based on a Flash FPGA implementing a subset of the functionality allowed by the communication standard, fitting the requirements of the different users and including the robustness against radiation as a design constraint. The development presented involved several groups at CERN working together in the framework of the Open Hardware Repository collaboration, and aiming at maximizing the interoperability and reliability of the final product.

TUPS103

High Temperature Radio Frequency Loads

coupling, vacuum, instrumentation, impedance

1783

S. Federmann, F. Caspers, A. Grudiev, E. Montesinos, I. Syratchev
CERN, Geneva, Switzerland

In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet with 150 deg C and more than 20 bar has a certain value. Normal RF power loads containing dielectric and sensitive windows usually do not permit going much higher than 50 deg C. Here we present and discuss several design concepts for narrow-band “metal only” RF high power loads. One concept is the application of normal steel corrugated waveguides structures near cutoff .This concept could find practical use above several GHz. Another solution are resonant structures made of normal magnetic steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage the rather high losses of normal steel may also be used in coaxial line geometries with large dimensions.

TUPZ003

Simulation of Electron-cloud Build-Up for the Cold Arcs of the LHC and Comparison with Measured Data

electron, dipole, vacuum, injection

1801

G.H.I. Maury Cuna
CINVESTAV, Mérida, Mexico
G. Arduini, G. Rumolo, L.J. Tavian, F. Zimmermann
CERN, Geneva, Switzerland

The electron cloud generated by synchrotron radiation or residual gas ionization is a concern for LHC operation and performance. We report the results of simulations studies which examine the electron cloud build-up, at injection energy, 3.5 TeV for various operation parameters In particular we determine the value of the secondary emission yield corresponding to the multipacting threshold, and investigate the electron density, and heat as a function of bunch intensity for dipoles and field-free regions. We also include a comparison between simulations results and measured heat-load data from the LHC scrubbing runs in 2011

TUPZ007

First Ion Collimation Commissioning Results at the LHC

ion, collimation, betatron, proton

1813

G. Bellodi, R.W. Assmann, R. Bruce, M. Cauchi, J.M. Jowett, G. Valentino, D. Wollmann
CERN, Geneva, Switzerland

First commissioning of the LHC Pb ion beams to 1.38 A TeV energy was successfully achieved in November 2010. Ion collimation has been predicted to be less efficient than for protons at the LHC, because of the complexity of the physical processes involved: nuclear fragmentation and electromagnetic dissociation in the primary collimators creating fragments with a wide range of Z/A ratios, that are not intercepted by the secondary collimators but lost in the dispersion suppressor sections of the ring. In this article we present first comparisons of measured loss maps with theoretical predictions from simulation runs with the ICOSIM code. An extrapolation to define the ultimate intensity limit for Pb beams is attempted. The scope of possible improvements in collimation efficiency coming from the installation of new collimators in the cold dispersion suppressors and combined betatron and momentum cleaning is also explored.

TUPZ011

LHC Collimation with a Reduced Beam Pipe Radius in ATLAS

optics, collimation, scattering, background

1822

R. Bruce, R.W. Assmann
CERN, Geneva, Switzerland

Based on SixTrack simulations, we investigate the effect from collimation of a reduced beam pipe in the ATLAS experiment in the LHC. Several running scenarios are studied with range of different beam pipe radii and in each case we conclude on the minimum allowed aperture, which does not cause beam losses inside the detectors.

TUPZ012

Machine-induced Showers entering the ATLAS and CMS Detectors in the LHC

proton, background, collimation, beam-losses

1825

R. Bruce, R.W. Assmann, V. Boccone, H. Burkhardt, F. Cerutti, A. Ferrari, M. Huhtinen, W. Kozanecki, Y.I. Levinsen, A. Mereghetti, A. Rossi, Th. Weiler
CERN, Geneva, Switzerland
N.V. Mokhov
Fermilab, Batavia, USA

One source of experimental background in the LHC is showers induced by particles hitting the upstream collimators or particles that have been scattered on the residual gas. We estimate the flux and distribution of particles entering the ATLAS and CMS detectors through FLUKA simulations originating from tertiary collimator hits and inelastic beam-gas interactions. Comparisons to MARS results are also presented.

TUPZ015

Electron Cloud Parameterization Studies in the LHC

electron, vacuum, emittance, beam-losses

1834

C.O. Domínguez, G. Arduini, V. Baglin, G. Bregliozzi, J.M. Jimenez, E. Métral, G. Rumolo, D. Schulte, F. Zimmermann
CERN, Geneva, Switzerland

During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. the secondary emission yield; 2. the incident electron energy at which the yield is maximum; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmark of measurements and these simulations is used to infer the secondary-emission properties of the beam-pipe at different locations around the ring and at various stages of the surface conditioning. In this paper we present the methodology and first results from applying the technique to the LHC.

TUPZ017

Luminosity and Beam Parameter Evolution for Lead Ion Beams in the LHC

luminosity, emittance, ion, heavy-ion

1840

J.M. Jowett, R. Bruce, T. Mertens
CERN, Geneva, Switzerland

Heavy ion beams in the LHC are subject to strong blow-up and debunching effects from intra-beam scattering and luminosity-driven beam losses. The large nuclear charge is at the origin of these effects, both in the cross sections for simple Coulomb scattering and the ultraperipheral interactions occurring in the collisions. We compare predictions from our models with data on luminosity, beam size and intensity evolution from the first heavy ion run of the LHC. This analysis has to take account of the varying capabilities of the LHC beam instrumentation between injection and collision energies.

TUPZ027

Beta* Measurement in the LHC Based on K-modulation

quadrupole, optics, luminosity, lattice

1864

R. Calaga, R. Miyamoto
BNL, Upton, Long Island, New York, USA
R. Tomás
CERN, Geneva, Switzerland
G. Vanbavinckhove
NIKHEF, Amsterdam, The Netherlands

Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
Accurate knowledge of the collision point optics is crucial to equalize the luminosities at the different experiments. K-modulation was successfully applied at several accelerators for measuring the lattice beta functions. In the LHC, it was proposed as an alternative method to compute the beta* at the collision points. Results of beta* measurements in the LHC based on the K-modulation technique are presented with comparisons to nominal segment-by-segment method.

TUPZ028

Beam Based Optimization of the Squeeze at the LHC

feedback, optics, beam-losses, controls

1867

X. Buffat
EPFL, Lausanne, Switzerland
M. Lamont, S. Redaelli, J. Wenninger
CERN, Geneva, Switzerland

The betatron squeeze is a critical operational phase for the LHC because it is carried out at top energy, with the maximum stored energy and with reduced aperture margins in the superconducting triplets. A stable operation with minimum beam losses must be achieved in order to ensure a safe and efficient operation. The operational experience at the LHC showed that this is possible. The operation in 2010 is reviewed. In particular, orbit, tune and chromaticity measurements are investigated and correlated to beam losses. Different optimizations are then proposed towards a more efficient and robust operation. The improvements obtained for the operation in 2011 are presented.

TUPZ029

Observation of Coherent Beam-beam Effects in the LHC

emittance, damping, beam-beam-effects, collider

1870

X. Buffat
EPFL, Lausanne, Switzerland
R. Calaga, S.M. White
BNL, Upton, Long Island, New York, USA
R. Giachino, W. Herr, G. Papotti, T. Pieloni
CERN, Geneva, Switzerland

Early collisions in the LHC with a very limited number of bunches with high intensities indicated the presence of coherent beam-beam driven oscillations. Here we discuss the experimental results and compare with the expectations.

TUPZ030

Simulation of Linear Beam Parameters to Minimize the Duration of the Squeeze at the LHC

optics, controls, collider, acceleration

1873

X. Buffat
EPFL, Lausanne, Switzerland
G.J. Müller, S. Redaelli, M. Strzelczyk
CERN, Geneva, Switzerland

The betatron squeeze allows to increase the luminosity of a collider by reducing the β function at the interaction points. This operation has shown to be very critical in previous colliders. In this state of mind, the squeezing was performed extremely safely during the first year of operation of the Large Hadron Collider, at the expense of the duration of the process. As the turnaround time is a relevant parameter for the integrated luminosity, a squeeze of shorter duration is proposed for 2011 and further. MadX simulation of linear beam parameters based on settings extracted from the LHC control system are used to justify the proposal. Further optimization of the squeeze setting generation is also discussed.

TUPZ031

Near Beam-gas Backgrounds for LHCb at 3.5 TeV

proton, background, hadron, vacuum

1876

D.R. Brett, R. Appleby
UMAN, Manchester, United Kingdom
F. Alessio, G. Corti, R. Jacobsson
CERN, Geneva, Switzerland
M.H. Lieng
UNIDO, Dortmund, Germany
V. Talanov
IHEP Protvino, Protvino, Moscow Region, Russia

Funding: STFC
We consider the machine induced backgrounds for LHCb arising from collisions of the beam with residual gas in the long straight sections of the LHC close to the experiment. We concentrate on the background particle fluxes initiated by inelastic beam-gas interactions with a direct line of sight to the experiment, with the potential impact on the experiment increasing for larger beam currents and changing gas pressures. In this paper we calculate the background rates for parameters foreseen with LHC running in 2011, using realistic residual pressure profiles. We also discuss the effect of using a pressure profile formulated in terms of equivalent hydrogen, through weighting of other residual gases by their cross section, upon the radial fluxes from the machine and the detector response. We present the expected rates and the error introduced through this approximation.

TUPZ032

LHC Luminosity Upgrade with Large Piwinski Angle Scheme: A Recent Look

luminosity, collider, emittance, single-bunch

1879

C.M. Bhat
Fermilab, Batavia, USA
F. Zimmermann
CERN, Geneva, Switzerland

Funding: Work is supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and US LARP.
Luminosity upgrade at the LHC collider using bunches with constant line charge density (longitudinally flat bunches) but with same beam-beam tune shift at collision, the so called large Piwinski angle scheme* is being studied with renewed interest in recent years**. By design the total beam-beam tune shift at the LHC is less than 0.015. But the initial operational experience at the LHC indicates the possibility of operating with beam-beam tune shifts as high as 0.02. In view of this development we have revisited the requirements for the Large Piwinski Angle scheme at the LHC. In this paper we present a new parameter list supported by 1) calculations on the luminosity gain, 2) reduction of e-cloud issues on nearly flat bunches and 3) longitudinal beam dynamics simulations. We also make some remarks on the needed upgrades on the LHC injector accelerators.
* F. Ruggiero and F. Zimmermann, PRST-AB 5, 061001 (2002).
** C. M. Bhat, CERN-2009-004, pp. 10⁶-114.
Thanks to O.Bruning, E.Shaposhnikova, H.Damerau, E.Mahner, F.Caspers & CERN BE/ABP & RF Depts.

TUPZ039

Modelling of the AGS Using Zgoubi - Status

dipole, multipole, quadrupole, resonance

1897

F. Méot, L. A. Ahrens, Y. Dutheil, J.W. Glenn, H. Huang, T. Roser, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Models of the Alternating Gradient Synchrotron, based on stepwise ray-tracing methods using both mathematical modelling or ﬁeld maps so to represent the optical elements, including the siberian snakes, are being developed based on stepwise ray-tracing numerical tools. The topic is introduced in earlier PAC and IPAC publications, a status is given here.

WEOAA03

Approach to a Start-to-end Simulation of 2-loop Compact Energy Recovery Linac

electron, emittance, linac, optics

1909

M. Shimada, K. Harada, Y. Kobayashi, T. Miyajima, N. Nakamura, S. Sakanaka
KEK, Ibaraki, Japan
R. Hajima
JAEA, Ibaraki-ken, Japan

Transport of an extreme low emittance electron beam is critical issue in an energy recovery linac. In particlar, the space charge effect on an electron bunch in the injector with lower than 5 - 10 MeV induces a large emittance growth. To suppress the emittance growth by such as an optimization of the solenoid magnets, a nonlinear effect should be clarified by a three dimensional tracking simulation. The cons is that it consumes a enormous simulation time. The approach is not suitable for a double loop circulation because the simulation time depends on the transport length. Therefore the beam dynamics and optics are calculated by a start-to-end (S2E) simulation, in which the simulation code is switched after the full acceleration. We used 'general particle tracking (GPT)' for injector electron beam and 'elegant' for a circulator electron beam.

Slides WEOAA03 [3.951 MB]

WEOBB02

Bunch Length Diagnostic with Sub-femtosecond Resolution for High Brightness Electron Beams

laser, undulator, electron, cavity

1967

G. Andonian, E. Hemsing, P. Musumeci, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
A.Y. Murokh
RadiaBeam, Santa Monica, USA
D. Xiang
SLAC, Menlo Park, California, USA

Next generation light sources require electron beams with high peak currents, typically achieved by compression techniques. The temporal diagnosis of these ultra-short beams demands enhanced resolution. We describe a scheme to achieve a temporal resolution on the order of sub-femtoseconds. The scheme is based on encoding the longitudinal profile of the beam on a transverse angular modulation, based on an interaction between the electron beam and a high-power laser in an undulator. This imposes a fast-sweep of the beam, on the order of sub-femtoseconds. A subsequent sweep in the orthogonal dimension by an rf deflecting cavity, imposes a "slow-sweep" on the order of sub-picoseconds. In this paper, we demonstrate applicability of this diagnostic scheme at the BNL ATF and specify the techniques required for practical applicability.

Slides WEOBB02 [1.120 MB]

WEPC003

Low-Beta Empirical Models used in Online Modeling and High Level Applications

space-charge, cavity, solenoid, controls

2001

Y.-C. Chao, G. Goh
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Using empirically models for elements generated by simulations codes such as Astra in low-beta beamline to provide efficient and more accurate models for machine diagnostic and tuning is discussed. Experience of such application in the framework of XAL may also be presented.

WEPC004

Comparison of the Action and Phase Analysis on LHC Orbits with Other Techniques

quadrupole, interaction-region, coupling, optics

2004

J.F. Cardona
UNAL, Bogota D.C, Colombia
R. Calaga, R. Miyamoto
BNL, Upton, Long Island, New York, USA
R. Tomás
CERN, Geneva, Switzerland
G. Vanbavinckhove
NIKHEF, Amsterdam, The Netherlands

Funding: DIB-Universidad Nacional de Colombia
Recently acquired turn-by-turn data of the LHC is analyzed using the action and phase jump technique. The results of this analysis show a visible variation of the action and phase plots at the interaction regions from which optic error estimations can be done. In this paper error estimations will be presented and comparisons with other existing techniques in the LHC, such as the recently implemented Segment-by-segment technique, will be discussed.

WEPC012

Steering-corrected 88 MHz QWRs for SARAF Phase II

cavity, linac, proton, lattice

2028

J. Rodnizki, J. Ashkenazy, D. Berkovits, Z. Horvitz
Soreq NRC, Yavne, Israel
A. Kolomiets, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work is partially supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
SARAF phase II linac is designed for 5 mA 40 MeV proton and deuteron beams. One option is to base the design on Quarter Wave Resonators (QWR). It is suggested to compensate the QWR non-symmetric magnetic field component by introducing a drift tube face tilt angle*. Here we explore the applicability of this steering correction scheme to the acceleration of a CW high current low β light ion beam in an end-to-end 88 MHz QWR lattice. This can serve as a case study for multi-megawatt machines that are currently being designed by ANL. An analytical approximation is used to evaluate the on-axis beam steering behavior. Two 88 MHz QWR cavities, β=0.08 and 0.15, were designed, field and beam dynamics were simulated and optimized. Using the tube face tilt angle concept the beam steering along a QWR can be reduced to the order of 0.1 mrad. Beam dynamics lattice examination including error analysis demonstrated an efficient high performance 40 MeV linac based on 3 superconducting modules with 19 QWRs (Ep < 35 MV/m and Bp < 70 mT). The fields obtained at recent ANL tests for a 73 MHz QWR (70 MV/m and 10⁵ mT) imply that Ep is not a real limiting factor.
* P.N. Ostroumov and K. W. Shepard, PRST-AB 4, 110101 (2001).

WEPC013

Tests for Low Vertical Emittance at Diamond using LET Algorithm

coupling, quadrupole, emittance, lattice

2031

S.M. Liuzzo, M.E. Biagini, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
R. Bartolini
JAI, Oxford, United Kingdom

We present measurements recently performed at the Diamond Light Source, aimed at the achievement of low vertical emittance using the Low Emittance Tuning (LET) algorithm developed for a SuperB factory project presently in progress. The tests have been focused on the comparison between this method and the LOCO algorithm currently used at Diamond. Beam position monitor tilts estimate and multiple coupling response matrices have been introduced in the algorithm in order to optimize the procedure. After few iterations using vertical correctors and skew quadrupoles, very low vertical dispersion and emittance coupling, comparable to those obtained by LOCO, have been measured.

WEPC014

Beam Dynamics Simulations of the PIAVE-ALPI Linac

linac, cavity, rfq, diagnostics

2034

M. Comunian, E. Fagotti, F. Grespan, A. Palmieri, A. Pisent, C. Roncolato
INFN/LNL, Legnaro (PD), Italy

At the Legnaro National Laboratories it is operating a SuperConducting linac for nuclear studies. The ALPI linac is injected either by a XTU tandem, up to 14 MV, or by the s-c PIAVE injector, made with 2 SC-RFQ. The main part of the linac (at the present 64 cavities for a total voltage up to 48 MV) is build up in two branches connected by an achromatic and isochronous U-bend. The PIAVE-ALPI complex is able to accelerate beams up to A/q = 7. The layout of the linac ALPI is, from the point of beam dynamics, quite complex due the presence of RFQs, cavities, dipoles, magnets, etc. These elements behaviors are entirely not linear, so a small change on the settings can induce a big change in the Linac beam dynamics. An automatic tuning procedure and a full field maps description are mandatory to handle a so high number of active components. The program used at this scope is TraceWin that is able to do an envelope simulation and a full multiparticles simulation.

WEPC017

Vertical Beam Size Correction at the SSRF Storage Ring

coupling, quadrupole, betatron, emittance

2043

M.Z. Zhang, J. Hou, B.C. Jiang, H.H. Li, S.Q. Tian
SINAP, Shanghai, People's Republic of China

Vertical beam size is an important parameter for 3rd generation light source. Correcting the vertical beam size is a realistic way to increase brightness or beam lifetime without any additional equipments in a machine under operation. The main sources of vertical beam size are betatron coupling and vertical dispersion. At the SSRF storage ring, LOCO is used for vertical dispersion and coupling measurements and corrections. The betatron coupling and vertical dispersion is corrected by skew quadrupoles that calculated by LOCO. Vertical beam size can be changed from 10s um to several um for different purposes. Touschek lifetime is also measured to testify the vertical beam size. Simulations show that if smaller vertical beam size is required, more skew quadrupoles are needed.

WEPC023

Beam Dynamics Simulations for the ESS-Bilbao H⁻ Ion Source

extraction, ion, ion-source, emittance

2052

I. Bustinduy, F.J. Bermejo, D. Fernandez-Cañoto, J.L. Munoz, I. Rodríguez
ESS Bilbao, Bilbao, Spain
M. Eguiraun, J. Feuchtwanger, Z. Izaola
ESS-Bilbao, Zamudio, Spain

Simulations are performed for the Ion Source Test Stand (ITUR) of the ESS-Bilbao research accelerator facility. The beam dynamics is investigated as a function of the extraction voltages, the ion current, and the inclination angle of the ion source. The ITUR Penning H− ion source has the plasma aperture plate and extraction electrode inclined a certain angle with respect to the vertical axis to compensate for the Penning magnets field. The negative charged particles are extracted through a rectangular slit of 10×6 mm2. The extraction system is mainly composed of two devices, a rectangular extraction electrode and a refrigerated trumpet shaped device acting as an Einzel lens to focus the beam, and also, as a trap for neutral cesium atoms exiting from the source. Results are calculated and analyzed at the DC Current Transformer and pepperpot positions located at 245 mm and 882 mm from the ion source.

WEPC029

Accuracy of the LHC Optics Measurement based on AC Dipoles

dipole, optics, quadrupole, focusing

2064

R. Miyamoto, R. Calaga
BNL, Upton, Long Island, New York, USA
R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The tight tolerances in the LHC requires optics measurement with very good accuracy. Therefore, AC dipoles are employed as the primary devices to measure the LHC optics. The accuracy of the measurement is mainly determined by the length of the coherent signal, signal-to-noise ratio of the measurement, and the data processing to effectively suppress the noise. This paper presents numerical and experimental studies of how these factors affect the accuracy of the LHC optics measurement using the AC dipoles.

WEPC032

First Measurements of Higher Order Optics Parameters in the LHC

optics, resonance, injection, kicker

2073

G. Vanbavinckhove
NIKHEF, Amsterdam, The Netherlands
M. Aiba
PSI, Villigen, Switzerland
R. Bartolini
Diamond, Oxfordshire, United Kingdom
R. Calaga, R. Miyamoto
BNL, Upton, Long Island, New York, USA
M. Giovannozzi, F. Schmidt, R. Tomás
CERN, Geneva, Switzerland
E.H. Maclean
JAI, Oxford, United Kingdom

Higher order effects can play an important role in the performance of the LHC. Lack of knowledge of these parameters can increase the tune footprint and compromise the beam lifetime. First measurements of these parameters at injection and flattop have been conducted. Detailed simulations are compared to the measurements together with discussions on the measurement limitations.

WEPC039

Modelling of the FETS MEBT Line using GPT

emittance, rfq, ion, linac

2094

D.C. Plostinar
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
R. Enparantza, M. Larrañaga
Fundación TEKNIKER, Eibar (Gipuzkoa), Spain

The Front End Test Stand project (FETS) currently under construction at Rutherford Appleton Laboratory (RAL) will accelerate a 60 mA, 2 ms, 50 pps H⁻ beam up to 3 MeV. It consists of an H⁻ ion source, a three-solenoid low energy beam transport line (LEBT), an RFQ and a medium energy beam transport line (MEBT) with a fast-slow beam chopping system. As part of the MEBT development, a GPT simulation model has been prepared. The aim is to analyse and understand the transport of intense beams and the beam behaviour in the space-charge dominated regime. The beam quality is then evaluated in terms of RMS emittance growth, beam loss, chopping efficiency and halo development. Results previously obtained with different simulation codes are discussed throughout the paper.

WEPC040

Initial 2D Investigations into the Design and Parameters of an EM Quadrupole for FETS

quadrupole, ion, linac, rfq

2097

M. Larrañaga, R. Enparantza
Fundación TEKNIKER, Eibar (Gipuzkoa), Spain
D.C. Plostinar
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The Medium Energy Beam Transport (MEBT) line for the Front End Test Stand (FETS) at Rutherford Appleton Laboratory (RAL) consists of a number of quadrupoles, re-bunching cavities and a fast-slow chopping system with dedicated beam dumps, as well as diagnostics. The type and design of the quadrupoles to be used merits special attention. Due to space restrictions, a hybrid quadrupole solution has been proposed in the past. However, because of the limited range of field adjustability achievable, this approach is not ideal. In this paper, a very preliminary investigation of an electromagnetic quadrupole (EMQ) design is presented. Magnetic simulations results performed with a 2D simulation code will be discussed including magnet optimisation details.

WEPC045

Transverse Emittance Reduction with Tapered Foil

emittance, scattering, electron, target

2112

Y. Jiao, Y. Cai, A. Chao
SLAC, Menlo Park, California, USA

Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515.
The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In present paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio.

WEPC048

Calibrating Transport Lines using LOCO Techniques

quadrupole, dipole, optics, focusing

2118

Y. Roblin
JLAB, Newport News, Virginia, USA

Funding: Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
With the 12GeV upgrade underway at CEBAF, there is a need to recharacterize the beamlines after the modifications made to it to accommodate running at higher energies. We present a linear perturbation approach to calibrating the optics model of transport lines. This method is adapted from the LOCO method in use for storage rings. We consider the effect of quadrupole errors, dipole construction errors as well as beam position monitors and correctors calibrations. The ideal model is expanded to first order in Taylor series of the quadrupole errors. A set of difference orbits obtained by exciting the correctors along the beamline is taken, yielding the measured response matrix. An iterative procedure is invoked and the quadrupole errors as well as beam position monitors and corrector calibration factors are obtained. Here we present details of the method and results of first measurements at CEBAF in early 2011 Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes

WEPC054

Amplitude Dependent Tune Spread in the CR Operated as an Antiproton Collector

sextupole, quadrupole, beam-losses, antiproton

2136

A. Dolinskii, C. Dimopoulou, O.E. Gorda, S.A. Litvinov, F. Nolden, M. Steck
GSI, Darmstadt, Germany

The Collector Ring is planned to be built for efficient cooling of antiprotons and rare isotopes beams. In order to accept hot antiproton beams coming from a separator large aperture magnets are required. This paper examines the effects which, may influence on the beam dynamic because of both large both betatron amplitude oscillations (240 mm mrad) and momentum spread (6%). Using analytic expressions the amplitude-dependent tune shifts driven by sextupole magnets, fringe field of quadrupole magnets and kinematics effects have been calculated. The results are compared with numerical simulations. Tracking studies for the CR operated as an antiproton collector have been performed considering the real shape of the magnetic field of the wide aperture quadrupole. We report on quantitative studies of the effects on the tune spread and its influence on the beam losses.

WEPC058

Field Properties of the ESR Magnets and their Influence on Beam Optics

dipole, quadrupole, betatron, sextupole

2148

O.E. Gorda, C. Dimopoulou, A. Dolinskii, S.A. Litvinov, F. Nolden, M. Steck
GSI, Darmstadt, Germany

Machine experiments at the experimental storage ring (ESR) demonstrated that the ring acceptance is strongly restricted by field errors. Higher-order field harmonics of the dipole and quadrupole magnets have been calculated and then used in particle tracking simulations in order to find out the dynamic aperture of the ESR. To benchmark the results of numerical calculations, betatron tune measurements have been performed with a uranium beam at the energy of 400 MeV/u. The results of the magnetic field simulations for the ESR magnets and a comparison between the measured and calculated tune behavioгr are presented.

WEPC066

High Order Non-linear Motion in Electrostatic Rings

lattice, focusing, proton, storage-ring

2172

D. Zyuzin, R. Maier, Y. Senichev
FZJ, Jülich, Germany

The advantages of an electrostatic storage ring as compared to a magnetic ring are obvious from the point of view to search for the proton electric dipole moment (pEDM). However the magnetic and electrostatic fields have the different nature and, consequently, different features. In particular, particles moving in electrostatic field, can change their own kinetic energy as electrical field coincides with the direction of motion, which is not so for the magnetic field, where the force is always perpendicular to the direction of motion. The electrostatic rings found many applications in the atomic physics and partly the beam dynamics has been already investigated. However in EDM ring some additional specific features are added, which are considered in this paper.

WEPC067

The Spin Aberration of Polarized Beam in Electrostatic Rings

cavity, emittance, lattice, dipole

2175

Y. Senichev, A. Lehrach, R. Maier, D. Zyuzin
FZJ, Jülich, Germany

For a beam with nonzero transverse emittance and momentum spread passing through an electric field, for example an electric focusing lens or deflector, the orientation of a spin vector becomes a function of 6D initial phase coordinates that leads to spin aberrations. We investigate this process analytically and numerically.

WEPC068

Amplitude Dependent Betatron Oscillation Center Shift by Non-linearity and Beam Instability Interlock

betatron, insertion, insertion-device, sextupole

2178

T. Nakamura, K. Kobayashi, J. Schimizu, T. Seike, K. Soutome, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan
T. Hara
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

The center of the betatron oscillation in storage rings shifts as the amplitude of the oscillation increases. This effect is produced by non-linear components like sextupole magnets with its first-order perturbation. This shift can be observed as the shift of the closed orbit with usual slow beam position monitor (BPM) for closed orbit measurement. At the SPring-8 storage ring, the insertion devices (IDs) have their dedicated BPMs for monitoring the beam axis in the IDs. If some amount of the shift of beam axis is observed, the beam is aborted to avoid the damage by the irradiation of the ring components by ID radiation. When a betatron oscillation is excited by a beam transverse instability, the beam axis also oscillates and might produce the damage. Though it is not easy to detect the oscillation amplitude in various bunch current and filling patterns like in SPring-8, the oscillation produces the shift of the center of the betatron oscillation and can be observed by the BPM of IDs, and the beam is aborted. Calculation, tracking simulation and observation will be reported.

WEPC077

Beam Based Measurements with the Modified Wigglers in DAΦNE

wiggler, closed-orbit, octupole, multipole

2196

S. Bettoni
CERN, Geneva, Switzerland
A. Drago, S. Guiducci, C. Milardi, M.A. Preger, P. Raimondi
INFN/LNF, Frascati (Roma), Italy

A novel idea to minimize the odd high order non-linearities in periodic magnets has been presented in other articles in the past. The optimization of this method on the wigglers of the main rings in DAΦNE has been performed by means of multipolar and tracking analysis. After the magnetic measurements on a spare wiggler confirmed the magnetic model used to optimize the DAΦNE wigglers, all the insertion devices in the main rings have been modified accordingly. In fall last year tune variation measurements as a function of closed orbit bumps around the wigglers confirmed the validity of the method. In this paper the beam based measurement results with the new configuration are discussed and compared with those obtained in the previous configurations.

WEPC081

Beam-Beam Induced Orbit Effects at LHC

luminosity, closed-orbit, beam-beam-effects, collider

2208

M. Schaumann, R. Alemany-Fernandez
CERN, Geneva, Switzerland

For high bunch intensities the beam-beam force is strong enough to expect orbit effects if the two beams do not collide head-on but with a crossing angle or with a given offset. As a consequence the closed orbit changes. The closed orbit of an unperturbed machine with respect to a machine where the beam-beam force becomes more and more important has been studied and the results are presented in this paper.

WEPC087

Dark Current Simulations for the Cornell ERL

cavity, linac, electron, cryomodule

2214

C.E. Mayes, C.S. Chiu, G.H. Hoffstaetter, V.O. Kostroun, D. Sagan
CLASSE, Ithaca, New York, USA
L.M. Nash
North Carolina University, Chapel Hill, North Carolina, USA

Funding: Supported by NSF award DMR-0807731
Charged particles unintentionally transported through an accelerator, collectively called the dark current, can be lost in the beam chamber and create a radiation hazard for both equipment and personnel. Here we simulate the creation of particles by field emission in the superconducting accelerating cavities of the Cornell Energy Recovery Linac, and track them to their loss points. These lost particles can then be used to simulate background radiation. The presented calculations are therefore an essential step in the design of appropriate radiation-shielding of components around the linac.

WEPC088

Embedding Finite Element Results for Accelerator Components in a Moment Approach Beam Dynamics Code*

quadrupole, dipole, electron, sextupole

2217

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''.
A moment based beam dynamics code has particular advantages, i.e. accuracy and efficiency, over macro-particle tracking and full particle-in-cell (PIC) codes respectively. Instead of embedding analytical descriptions of the accelerator components in the beam dynamics model, it is proposed to insert a surrogate model obtained from the finite element model of individual accelerator components. We apply the V-Code, which accepts moments up to the sixth order and accounts for space charge effects. We construct and calculate finite element and finite difference time domain models using the CST Studio Suite 2011 software package. An interface is implemented using VBA and MATLAB. As an example of the accuracy of this cascadic simulation approach, we compare the beam dynamics of an S-DALINAC quadrupole obtained by directly tracking particles to the calculated fields with the results for the cascadic approach with the V-Code.
This work was performed during a three month research visit at the Technische Universität Darmstadt, Institut für Theorie Elektromagnetischer Felder, Darmstadt, Germany.

WEPC092

Moment-Based Simulation of the S-DALINAC Recirculations*

recirculation, linac, quadrupole, cavity

2223

S. Franke, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
R. Eichhorn, F. Hug, C. Klose, N. Pietralla, M. Platz
TU Darmstadt, Darmstadt, Germany

Funding: Work supported by DFG under contract SFB 634.
The Superconducting Linear Accelerator S-DALINAC installed at the institute of nuclear physics (IKP) at TU Darmstadt is designed as a re-circulating linear accelerator. The length of the beam line and the numerous accelerating structures as well as dipole and quadrupole magnets require a highly efficient numerical simulation tool in order to assist the operators by providing a detailed and almost instantaneous insight into the actual machine status. A suitable approach which enables a fast online calculation of the beam dynamics is given by the so-called moment approach where the particle distribution is represented by means of a discrete set of moments or by multiple discrete sets of moments in a multi-ensemble environment. Following this approach the V-Code simulation tool has been implemented at the Computational Electromagnetics Laboratory (TEMF) at TU Darmstadt. In this contribution an overview of the numerical model is presented together with new V-Code simulation results regarding the S-DALINAC recirculation sections.

WEPC093

Various Approaches to Electromagnetic Field Simulations for RF Cavities

cavity, impedance, HOM, higher-order-mode

2226

C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by BMBF under contract 05H09RD5
In the Superconducting Proton Linac (SPL) cavity, there is not only the fundamental mode for the particle acceleration but also many higher order modes (HOMs), which can lead to particle beam instabilities. This is very dangerous for SPL cavity. Therefore it is necessary to simulate the electromagnetic field in the SPL cavity, so that the field distribution and the shunt impedance for every higher order mode can be precisely calculated. At TEMF this research work can be done in three different ways: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain and field simulation with tetrahedral mesh and higher order curvilinear elements. Finally the HOM coupler will be considered for the effective damping of higher order modes in the SPL cavity.

WEPC094

Energy Loss and Longitudinal Wakefield of Relativistic Short Ion Bunches in Electron Clouds

electron, ion, wakefield, plasma

2229

F. Yaman, O. Boine-Frankenheim, E. Gjonaj, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany
G. Rumolo
CERN, Geneva, Switzerland

Funding: Work supported by BMBF under contract 06DA9022I
The aim of our study is the numerical computation of the wakefield, impedance and energy loss for an energetic, short (< 10 ns) ion bunch penetrating an electron cloud plasma residing in the beam pipe. We use a 3-D self-consistent and higher order PIC code based on the full-wave solution of the Maxwell equations in the time domain. In our simulations we observe the induced density oscillations in the electron cloud in the longitudinal as well as in the transverse directions. A special numerical procedure is applied to compute the longitudinal wake potential and the broadband coupling impedance due to the beam-electron cloud interaction. The code is applied to the case of the CERN SPS and the projected SIS-100 at GSI. The effects of the beam pipe, electron density, bunch intensity and external magnetic dipole fields are studied. The results are compared to analytical and numerical models of reduced complexity.

WEPC095

Simulations of the Microbunching Instability at ANKA using a Vlasov-Fokker-Planck Solver

radiation, electron, synchrotron, impedance

2232

M. Klein, A.-S. Müller
KIT, Karlsruhe, Germany
K.G. Sonnad
CLASSE, Ithaca, New York, USA

In order to produce coherent synchrotron radiation the ANKA light source is operated frequently in short bunch mode. It is known that during this procedure strong self fields caused by high electron densities can enforce initial density fluctuations and thus lead to microbunching. The build-up of those substructures is accompanied by bursting radiation which provides higher radiation power for the users. Damping and diffusion due to incoherent radiation smoothens the bunch shape again and hence lead to periodic or chaotic bursting cycles. The evolution of the electron bunch density under the influence of self fields can be described by the Vlasov-Fokker-Plank (VFP) equation. We present results from a numerical solution of the VFP-equation for parameters used in standard short bunch mode at ANKA.

WEPC099

Coupler Design and Optimization by GPU-Accelerated DG-FEM

HOM, scattering, higher-order-mode, linac

2244

C. Potratz, H.-W. Glock, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

The numerical optimization of rf-components like couplers is a common task during the design phase of particle accelerators. Typically, these optimizations involve the simulation of a multitude of very similar structures with minor geometric variations. Nevertheless, this process is in its entire extend rather demanding on both the invested time and hardware budget. With recent advancements in the field of numerical electromagnetic field simulation and consumer graphic processors, an interesting alternative for the time-consuming simulation part of the optimization is available. In this contribution we show, how the Discontinuous Galerkin FEM method in conjunction with consumer graphic cards can be used to build moderately prized cluster solutions for the parallel simulation of rf-components. The contribution will mainly focus on, but is not limited to, Higher Order Mode couplers as a typical application example, where the DG-FEM method accelerated by a graphic processor might be used to significantly reduce the overall time necessary for the optimization.

WEPC100

Simulation of the Single Bunch Instability due to the Electron Cloud Effect by Tracking with a Pre-computed 2D Wake Matrix*

electron, dipole, single-bunch, positron

2247

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

Funding: Supported by DFG Contract Nr. RI 814/20-1.
The passage of a positron bunch through an initially homogeneous electron cloud (e-cloud) changes the distribution of the e-cloud in a way that the concentration of electrons in the proximity of the beam axis grows rapidly. The electrons are primarily moving in the transverse plane and are very sensitive on the beam centroid position in that plane. Thus the transverse kick of the e-cloud on the tail particles depends on the centroid position of the head particles of the same bunch. A PIC simulation of the interaction of a positron beam with an e-cloud yields the wake kick from the electrons on the tail particles for a certain offset in the transverse centroid position of the head parts of the bunch. With such a pre-computed 2D wake matrix, for a certain e-cloud density, we investigate the stability of a single bunch by tracking it through the linear optics of the storage ring while at each turn applying the kick from the e-cloud. We examine the positron bunch stability of KEKB-LER and PETRAIII for a certain electron cloud density.

WEPC101

Simulation of the Interaction of an Electron Beam with Ionized Residual Gas

ion, electron, space-charge, emittance

2250

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
Light sources of the next generation such as ERLs require minimal beam losses as well as a stable beam position and emittance over the time. Instabilities caused by ion accumulation have to be avoided. In Rostock the tracking code MOEVE PIC Tracking has been developed for the simulation of space charge influenced beam dynamics, which is recently applied for simulations of the interaction beam - e-cloud. In this paper we apply MOEVE PIC Tracking for simulation of the interaction of the ionized residual gas with an electron bunch. We demonstrate numerical results with parameters planed for the ERL BERLinPro.

WEPC102

Recent Developments for Efficient 3D Space Charge Computations Based on Adaptive Multigrid Discretizations

space-charge, brightness, injection, optics

2253

G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
M.J. de Loos
TUE, Eindhoven, The Netherlands
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

Funding: Partly supported by BMBF under contract number 05K10HRC
Efficient and accurate space-charge computations are essential for the design of high-brightness charged particle sources. Recently a new adaptive meshing strategy based on multigrid was implemented in GPT and the capabilities were demonstrated. This new meshing scheme uses the solution of an intermediate step in the multigrid algorithm itself to define optimal mesh line positions. In this paper we discuss further developments of this adaptive meshing strategy. We compare the new algorithm with the current meshing scheme of GPT, where the mesh line positions are based upon the projected charge density.

WEPC105

Multiparticle Simulation of Intrabeam Scattering for SuperB

emittance, damping, scattering, lattice

2259

T. Demma, M.E. Biagini, M. Boscolo
INFN/LNF, Frascati (Roma), Italy
K.L.F. Bane, A. Chao, M.T.F. Pivi
SLAC, Menlo Park, California, USA

Intrabeam scattering (IBS) is associated with multiple small angle scattering events leading to emittance growth. In most electron storage rings, the growth rates arising from IBS are much longer than damping times due to synchrotron radiation, and the effect on emittance growth is negligible. However, IBS growth rates increase with increasing bunch charge density, and for storage rings such as SuperB, that operate with high bunch charges and very low vertical emittance, the IBS growth rates can be large enough to produce significant emittance increase. Several formalisms have been developed for calculating IBS growth rates in storage rings*. However these models, based on Gaussian bunch distributions, cannot investigate some interesting aspects of IBS such as its evolution during the damping process and its effect on the beam distribution. We developed a multiparticle tracking code, based on the Binary Collision Model**, to investigate these effects. In this communication we present the structure of the code and simulation results obtained with particular reference to the SuperB parameters. Simulation results are compared with those of conventional IBS theories.
* A. Piwinski, Lect. Notes Phys. 296 (1988); J.D. Bjorken and S.K. Mtingwa, Part. Accel. 13 (1983); K. Kubo et al., Phys. Rev. ST-AB 8 (2005).
** Peicheng Yu et al., Phys. Rev. ST–AB 12 (2009).

WEPC106

Touschek Effect at DAΦNE for the New KLOE Run in the Crab-Waist Scheme

background, vacuum, scattering, lattice

2262

M. Boscolo, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
E. Paoloni
University of Pisa and INFN, Pisa, Italy
A. Perez
INFN-Pisa, Pisa, Italy

Funding: Work supported by the EuCARD research programme within the 'Assessment of Novel Accelerator Concepts' work package (ANAC-WP11)
The innovative crab-waist collision scheme has been recently implemented at DAΦNE for a new KLOE run. This scheme requires special attention to the Touschek effect, both for the lifetime and the machine induced backgrounds into the detector. These two aspects have been handled starting from the same Monte Carlo simulation. The DAΦNE optical model has been tuned to keep the effects of Touschek scattering under control with a trade-off between critical parameters, following the indications given by simulations. Connections between numerical results and lattice modifications are discussed here. Dedicated lifetime measurements have been carried out to validate these studies. Particle losses at the IR have been minimized by means of the same optical knobs, but in addition proper shieldings have been implemented to further decrease their impact on the detector performance. IR distributions of the Touschek particle losses have been tracked from the beam pipe into KLOE for direct comparison of measured and expected backgrounds. Moreover, these studies are carried out with the same software tools used for the SuperB factory design, allowing a direct validation test of this approach.

WEPC107

Development of a Steady State Simulation Code for Klystron Amplifiers

cavity, space-charge, klystron, electromagnetic-fields

2265

C. Marrelli
CERN, Geneva, Switzerland
M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
B. Spataro
INFN/LNF, Frascati (Roma), Italy
S.G. Tantawi
SLAC, Menlo Park, California, USA

The design of klystrons is based on the intensive utilization of simulation codes, which can evaluate the complete beam-cavities interaction in the case of large signals. In the present work, we present the development of a 2-D steady state simulation code that can self-consistently evaluate the effects of the electromagnetic field on the particles and of the particles back on the field. The algorithm is based on the iterative solution of the power balance equation in the RF structures and allows determining the amplitude and phase of the electromagnetic field starting from the cavity modes. Some applications of the code to a single cavity and a two cavity klystron are presented and compared with the results obtained from other codes. The effect of the space charge forces in the klystron drift tubes is also evaluated.

WEPC111

Single Particle Tracking Simulation for Compact Cyclotron*

cyclotron, cavity, positron, injection

2274

H.W. Kim, J.-S. Chai, B.N. Lee, Y.S. Lee, K.R. Nam, H.S. Song
SKKU, Suwon, Republic of Korea

Funding: Ministry of Education, Science and Technology, Republic of Korea. Department of Energy Science and School of Information and Communication Engineering of SungKyunKwan University.
Low energy compact cyclotrons for Positron emission tomography (PET) are needed for the production of radio-isotope. In the magnet design for those cyclotrons, single particle tracking simulation after the design is important to check the quality of designed magnetic field of the magnet. The study of single particle tracking simulation for cyclotron magnet is shown in this paper. Maximum beam energy of example cyclotron is 9 MeV for proton and pseudo accelerating gap is adapted for the simulation. 3D CAD program CATIA P3 V5 R18 is used for design the magnet and pseudo accelerating gap. All magnetic and electric field calculations had been performed by OPERA-3D TOSCA and the own-made program OPTICY is used for other calculations - phase slip, radial and axial tune.

WEPC119

PYMAD – Integration of MADX in PYTHON

status, background, lattice, optics

2289

K. Fuchsberger, Y.I. Levinsen
CERN, Geneva, Switzerland

The de-facto standard software for modeling accelerator lattices at CERN is MADX (Methodical Accelerator Design), which is implemented and still maintained in the programming languages C and FORTRAN. For detailed processing, analysis and plotting of MADX results, other programming languages are often used. One very popular scripting language is PYTHON, which is widely used in the physics community and provides powerful numerical libraries and plotting routines. Therefore, access to MADX models from PYTHON is a common demand. Currently, several possible concepts for the realization of such a project are evaluated, including direct access to MADX via CYTHON (C extension of PYTHON) or the re-usage of the existing JMAD Java libraries, benefiting from the already available model-definitions. A first prototype is already in use and the release as an open source project is in preparation. This paper presents the concepts and the current status of the project, as well as some usage examples.

WEPC123

Numerical Algorithm based on the PDE Method for the Solution of the Fokker-Planck Equation

pick-up, kicker, storage-ring, impedance

2298

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

Funding: Work supported by HIC for FAIR
This paper discus a fast and accurate algorithm for numerical solution of Fokker-Planck equation based on the solution of the parabolic Partial Differential Equations (PDE), where the Crank–Nicholson scheme is used. The stability, convergence and round-off errors of the algorithm are studied. The numerical results on Fokker–Planck equation solution with PDE method are compared with other numerical methods. Using the PDE solver, we will be able to predict the stochastic cooling process of notch filter in storage rings.

WEPC125

Higher Order Modes in Coupled Cavities of the FLASH Module ACC39

cavity, HOM, diagnostics, dipole

2301

R.M. Jones, I.R.R. Shinton
UMAN, Manchester, United Kingdom
Z. Li
SLAC, Menlo Park, California, USA

We analyse the higher order modes (HOMs) in the 3.9GHz bunch shaping cavities installed in the FLASH facility at DESY. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations are used to investigate the modes in these cavities. This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39. Coupled inter-cavity modes are simulated together with a limited band of trapped modes.

WEPC128

Application of Dynamical Maps to the FFAG EMMA Commissioning*

lattice, closed-orbit, acceleration, target

2304

Y. Giboudot, R. Nilavalan
Brunel University, Middlesex, United Kingdom
A. Wolski
The University of Liverpool, Liverpool, United Kingdom

Funding: Work supported by the Engineering and Physical Sciences Research Council, UK.
The lattice of the Non Scaling FFAG EMMA has four degrees of freedom (strengths and transverse positions of each of the two quadrupoles in each periodic cell). Dynamical maps computed from an analytical representation of the magnetic field may be used to predict the beam dynamics in any configuration of the lattice. An interpolation technique using a mixed variable generating function representation for the map provides an efficient way to generate the map for any required lattice configuration, while ensuring symplecticity of the map. The interpolation technique is used in an optimisation routine, to identify the lattice configuration most closely machine specified dynamical properties, including the variation of time of flight with beam energy (a key characteristic for acceleration in EMMA).
yoel.giboudot@stfc.ac.uk

WEPC132

Simulations of Surface Effects and Electron Emission from Diamond-Amplifier Cathodes

electron, vacuum, scattering, cathode

2307

D.A. Dimitrov, R. Busby, J.R. Cary, D.N. Smithe
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi
Stony Brook University, Stony Brook, USA
X. Chang, T. Rao, J. Smedley, Q. Wu
BNL, Upton, Long Island, New York, USA
E. Wang
PKU/IHIP, Beijing, People's Republic of China

Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grants DE-SC0004431 (Tech-X Corp.), DE-AC02-98CH10886 (BNL), and DE-SC0005713 (Stony Brook University).
Emission of electrons in diamond experiments based on the promising diamond-amplifier concept* was recently demonstrated**. Transmission mode experiments have shown the potential to realize over two orders of magnitude charge amplification. However, the recent emission experiments indicate that surface effects should be understood in detail to build cathodes with optimal properties. We have made progress in understanding secondary electron generation and charge transport in diamond with models we implemented in the VORPAL particle-in-cell computational framework. We will introduce models that we have been implementing for surface effects (band bending and electron affinity), charge trapping, and electron emission from diamond. Then, we will present results from 3D VORPAL diamond-vacuum simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, charge transport, and then emission of electrons from diamond into vacuum. Finally, we will discuss simulation results on the dependence of the electron emission on diamond surface properties.
* I. Ben-Zvi et al., Secondary emission enhanced photoinjector, C-AD Accel. Phys. Rep. C-A/AP/149, BNL (2004).
** X. Chang et al., Phys. Rev. Lett. 10⁵, 164801 (2010).

WEPC134

Unified Accelerator Modeling Using the Bmad Software Library

lattice, controls, photon, linac

2310

D. Sagan, I.V. Bazarov, J.Y. Chee, J.A. Crittenden, G. Dugan, K. Finkelstein, G.H. Hoffstaetter, C.E. Mayes, S. Milashuk, D. L. Rubin, J.P. Shanks
CLASSE, Ithaca, New York, USA
R. Cope
CSU, Fort Collins, Colorado, USA

Funding: Work supported by the National Science Foundation and by the US Department of Energy under contract numbers PHY-0734867 and DE-FC02-08ER41538.
The Bmad software library has proved to be a useful tool for accelerator simulations owing to its modular, object-oriented design. It is now used in a number of design, simulation and control programs at the Cornell Laboratory for Accelerator-based Sciences and Education. Work is ongoing to expand Bmad in a number of directions. One aim is tohave a complete framework in order to simulate Cornell's Energy Recovery Linac from Gun cathode (including space-charge) to photon generation to photon tracking through to the x-ray experimental end stations. Other work includes synchrotron radiation tracking including reflections from the vacuum chamber walls which is useful for electron cloud investigations, spin tracking, beam break-up instability, intra-beam scattering, etc. This paper will discuss the current state of the Bmad software along with the long-term goals.

WEPC137

Undulator Radiation Simulation by QUINDI

undulator, radiation, electron, polarization

2316

D. Schiller, E. Hemsing, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

QUINDI, a code developed to simulate coherent emission from bending systems, has been upgraded to include undulators as a beamline element. This approach allows us to better model the radiation produced by a relativistic electron bunch propagating through such a device.

WEPC141

Application of the SYNRAD3D Photon-Tracking Model to Shielded Pickup Measurements of Electron Cloud Buildup at CesrTA

photon, scattering, electron, vacuum

2319

L.E. Boon
Purdue University, West Lafayette, Indiana, USA
J.A. Crittenden, T. Ishibashi
CLASSE, Ithaca, New York, USA
K.C. Harkay
ANL, Argonne, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
We present calculations of synchrotron radiation photon reflection in the vacuum chamber at the Cornell Electron Storage Ring Test Accelerator (CesrTA), applying them as input to the electron cloud buildup code ECLOUD to model time-resolved local measurements with shielded pickup detectors. The recently developed SYNRAD3D photon-tracking code employs a reflection model based on data from the Center for X-Ray Optics at LBNL. This study investigates the dependence of electron cloud buildup on the azimuthal position and kinetic energy distribution of photoelectron production on the vacuum chamber wall.

WEPC165

Monte Carlo Simulation of the Total Dose Distribution around the 12 MeV UPC Race-track Microtron and Radiation Shielding Calculations

shielding, radiation, target, beam-losses

2370

C. de la Fuente, M.A. Duch, Yu.A. Kubyshin
UPC, Barcelona, Spain
V.I. Shvedunov
MSU, Moscow, Russia

The Technical University of Catalonia is building a miniature 12 MeV electron race-track microtron for medical applications. In the paper we study the leakage radiation caused by beam losses inside the accelerator head, as well as the bremstrahlung radiation produced by the primary beam in the commissioning setting. Results of Monte Carlo simulations using the PENELOPE code are presented and two shielding schemes, global and local, are studied. The obtained shielding parameters are compared with estimates based on international recommendations of the radiation safety standards.

WEPC171

Requirements of a Beam Loss Monitoring System for the CLIC Two Beam Modules

photon, beam-losses, linac, monitoring

2385

S. Mallows
The University of Liverpool, Liverpool, United Kingdom
E.B. Holzer, A.P. Mechev, J.W. van Hoorne
CERN, Geneva, Switzerland
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

he Compact Linear Collider (CLIC) study investigates the feasibility of a high-energy electron-positron linear collider optimized for a centre of mass energy of 3 TeV. To achieve the high accelerating gradients, the RF power is produced by a novel two-beam acceleration method in which a decelerating drive beam supplies energy to the main accelerating beam. The linacs are arranged in modular structures referred to as the two beam modules which cover 42 km of beamline. Beam losses from either beam can have severe consequences due to the high intensity drive beam and the high energy, small emittance main beam. This paper presents recent developments towards the design of a Cherenkov fiber BLM system and discusses its ability to distinguish losses originating from either beam.

WEPC172

Beam-induced Quench Test of a LHC Main Quadrupole

beam-losses, proton, quadrupole, monitoring

2388

A. Priebe, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, E.B. Holzer, C. Kurfuerst, E. Nebot Del Busto, A. Nordt, M. Sapinski, J. Steckert, A.P. Verweij, C. Zamantzas
CERN, Geneva, Switzerland
A. Priebe
EPFL, Lausanne, Switzerland

Unexpected beam loss might lead to transition of a superconducting accelerator magnet to a normal conducting state. The LHC beam loss monitoring (BLM) system is designed to abort the beam before the energy deposited in the magnet coils reaches a quench-provoking level. In order to verify the threshold settings generated by simulation, a series of beam-induced quench tests at various beam energies have been performed. The beam losses are generated by means of an orbit bump peaked in one of the main quadrupole magnets. The analysis not only includes BLM data but also data from the electrical quench protection and cryogenic systems. The measurements are compared to Geant4 simulations of energy deposition inside the coils and corresponding BLM signal outside the cryostat. The results are also extrapolated to higher beam energies.

WEPC173

LHC Magnet Quench Test with Beam Loss Generated by Wire Scan

beam-losses, proton, electron, quadrupole

2391

M. Sapinski, F. Cerutti, K. Dahlerup-Petersen, B. Dehning, J. Emery, A. Ferrari, A. Guerrero, E.B. Holzer, M. Koujili, A. Lechner, E. Nebot Del Busto, M. Scheubel, J. Steckert, A.P. Verweij, J. Wenninger
CERN, Geneva, Switzerland

Beam losses with millisecond duration have been observed in the LHC in 2010 and 2011. They are expected to be provoked by dust particles falling into the beam. These losses could compromise the LHC availability if they provoke quenches of superconducting magnets. In order to investigate the quench limits for this loss mechanism, a quench test using the wire scanner has been performed, with the wire movement through the beam mimicking a loss with similar spatial and temporal distribution as in the case of dust particles. This paper will show the conclusions reached for millisecond-duration dust-provoked quench limits. It will include details on the maximum energy deposited in the coil as estimated using FLUKA code, showing good agreement with quench limit estimated from the heat transfer code QP3. In addition, information on the damage limit for carbon wires in proton beams will be presented, following electron microscope analysis which revealed strong wire sublimation.

WEPC175

FLUKA Studies of the Asynchronous Beam Dump Effects on LHC Point 6

proton, insertion, quadrupole, dipole

2397

R. Versaci, V. Boccone, B. Goddard, A. Mereghetti, R. Schmidt, V. Vlachoudis
CERN, Geneva, Switzerland

The LHC is a record-breaking machine for beam energy and intensity. An intense effort has therefore been deployed in simulating critical operational scenarios of energy deposition. FLUKA is the most widely used code for this kind of simulations at CERN because of the high reliability of its results and the ease to custom detailed simulations all along hundreds of meters of beam line. We have investigated the effects of an asynchronous beam dump on the LHC Point 6 where, beams with a stored energy of 360 MJ, can instantaneously release up to a few J cm^-3 in the cryogenic magnets which have a quench limit of the order of the mJ cm^-3. In the present paper we will briefly introduce FLUKA, describe the simulation approach, and discuss the evaluated maximum energy release onto the superconducting magnets during an asynchronous beam dump. We will then analyse the shielding provided by collimators installed in the area and discuss safety limits for the operation of the LHC.

WEPC176

Beam Loss Monitoring and Machine Protection System Design and Application for the ALICE Test Accelerator at Daresbury Laboratory

beam-losses, monitoring, radiation, dipole

2400

S.R. Buckley, J.-L. Fernández-Hernando
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

ALICE is a demonstrator accelerator system which has been designed and built at Daresbury Laboratory. The heart of this facility is an ERL accelerator and a powerful multi-terrawatt laser. It serves as an advanced test facility for novel accelerator and photon science applications. Beam loss monitoring and machine protection systems are vital areas for the successful operation of ALICE. These systems are required, both for efficient machine set up and for hardware protection during operation. This paper gives an overview of the system design, commissioning details and a summary of the systems’ effectiveness as a diagnostic tool.

WEPC177

Collimation of High Intensity Ion Beams*

collimation, solenoid, ion, ion-source

2403

J. Pfister, O. Meusel
IAP, Frankfurt am Main, Germany
O.K. Kester
GSI, Darmstadt, Germany

Funding: HIC for FAIR
Intense ion beams with small phase space occupation (high brilliance) are mandatory to keep beam losses low in high current injector accelerators like those planned for FAIR. The low energy beam transport from the ion source towards the linac has to keep the emittance growth low and has to support the optimization of the ion source tune. The Frankfurt Neutron Source Facility FRANZ is currently under construction. An intense beam of protons (2 MeV, 200 mA) will be used for neutron production using the Li⁷(p,n)Be⁷ reaction for studies of the astrophysical s-process. A collimation channel, which can be adjusted to allow the transport of beams with a certain beam emittance, is an ideal tool to optimize the ion source tune in terms of beam brightness. Therefore a collimation channel in the Low Energy Beam Transport section will be used. Through defined apertures and transversal phase space rotation using focusing solenoids the beam halo as well as unwanted H₂⁺ and H₃⁺ fractions will be cut. Theoretical studies which were carried out so far and a first design of the setup will be presented.

WEPO001

Design and Optimization of the MedAustron Synchrotron Main Dipoles

dipole, synchrotron, ion, quadrupole

2406

M. Stockner, B. Langenbeck, C. Siedler
EBG MedAustron, Wr. Neustadt, Austria
Th. Zickler
CERN, Geneva, Switzerland

MedAustron, a future centre for ion-therapy and research in Austria will comprise an accelerator facility based on a synchrotron for the delivery of protons and light ions for cancer treatment and for clinical and non-clinical research. The main dipole for the synchrotron went through an extensive design process to meet the stringent requirements. The local and integrated field quality was optimized. The residual field levels in the magnet gap were calculated and the dynamic behaviour of the dipole magnet was studied, both in 2D and 3D, using OPERA. The pole profile has been optimized to reduce sextupolar components in the integrated field by adjusting the shims on the pole edge. A Rogowski-profile at the pole ends and the use of stainless-steel tension straps will enhance the dynamic behaviour and guarantee a small time constants. Appropriate pole-end shimming will be used to compensate for residual multi-pole components and to fine-tune the magnetic length. The results of this comprehensive design study are summarized in this paper.

WEPO011

Design study of Electromagnet for 13MeV PET Cyclotron

cyclotron, extraction, proton, focusing

2415

B.N. Lee, J.-S. Chai, H.W. Kim, J.H. Oh, H.S. Song
SKKU, Suwon, Republic of Korea

Funding: National Research Foundation of Korea
Cyclotron electromagnet for RI production which is used for PET scanning has been designed. Designed pancake-shape electromagnet is an advanced type of KIRAMS-13's electromagnet which has the H-type electromagnet. The AVF structure with hill and valley was used for getting strong axial focusing and producing the energy of proton beam up to 13MeV with a thin stripper foil. To design and analyse the magnet, 3D CAD (CATIA V5)and TOSCA (OPERA-3D)were used, respectively. To reduce the calculation time, routine files were developed which can generate model, mesh and field map automatically in TOSCA modeller and post processor. The beam dynamics program OPTICY is used for calculation of the tunes.
KIRAMS-13* is the cyclotron had been manufactured by KIRAMS.
KIRAMS is short for Korea Institutes of Radiological and Medical Science.

WEPO014

Magnetic Design of Quadrupoles for the Medium and High Energy Beam Transport line of the LIPAC Accelerator

quadrupole, coupling, beam-transport, dipole

2424

C. Oliver, B. Brañas, A. Ibarra, I. Podadera, F. Toral
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230.
The LIPAC accelerator will be a 9 MeV, 125 mA cw deuteron accelerator which will verify the validity of the design of the future IFMIF accelerator. A Medium Energy Beam Transport line (MEBT) is necessary to handle the high current beam from the RFQ to the Superconducting RF accelerating cavities (SRF) whereas a High Energy Beam Transport line (HEBT) is used to match the beam from the SRF to the beam dump. The high space charge and beam power determine the beam dynamics in both transport lines. As a consequence, magnets with strong fields in a reduced space are required. Along the transport beamlines, there are different types of quadrupoles with steerers and a dipole. Special care is devoted to maximize the integrated fields in the available space. Both 2-D and 3-D magnetic calculations are used to optimize coil configurations. Magnetic performance and cost, both of magnet and power supply, have been taken into account for final choice. In this paper, the design of the resistive quadrupoles of the MEBT and HEBT of the LIPAC accelerator is presented.

WEPO015

MAX IV 3 GeV Storage Ring Prototype Magnet

dipole, storage-ring, magnet-design, lattice

2427

M.A.G. Johansson, L.-J. Lindgren
MAX-lab, Lund, Sweden
B. Anderberg
AMACC, Uppsala, Sweden

The MAX IV facility, currently under construction, will consist of a 3 GeV storage ring, a 1.5 GeV storage ring, and a full energy injector/SPF/FEL driver. The magnet design for the 3 GeV storage ring is conceptually identical to the MAX III storage ring magnets, with all magnet elements within each cell machined into one solid iron block. A prototype of a matching cell magnet block has been manufactured and mechanical and magnetic field measurements have been performed.

WEPO016

Design of the MAX IV/Solaris 1.5 GeV Storage Ring Magnets

lattice, ion, storage-ring, dipole

2430

M.A.G. Johansson
MAX-lab, Lund, Sweden

The MAX IV facility, currently under construction in Lund, Sweden, will consist of a 3 GeV storage ring, a 1.5 GeV storage ring, and a full energy injector/SPF/FEL driver. The Solaris facility, which will be built in Krakow, Poland, will use an identical 1.5 GeV storage ring, injected at 500 MeV. The magnet design for the 1.5 GeV storage ring is conceptually identical to the MAX III and the MAX IV 3 GeV storage ring magnets, with several magnet elements machined into one solid iron block. Detailed design has been done in Opera3D, with a model of the full magnet block being set up and simulated, and iterated against the lattice design.

WEPO018

Status of the New Linac4 Magnets at CERN

linac, quadrupole, solenoid, DTL

2436

Th. Zickler, F. Borgnolutti, O. Crettiez, A. Newborough, L. Vanherpe
CERN, Geneva, Switzerland
A.S. Vorozhtsov
JINR, Dubna, Moscow Region, Russia

Linac4 is a new H⁻ linear accelerator at CERN replacing Linac2 as injector to the PS Booster. Almost 100 electro-magnets of different types are needed for the Linac4 project. Following a detailed analysis of the requirements and constraints, several magnet designs have been studied and are well advanced. This paper presents the design considerations, main parameters and characteristics of the new Linac4 magnets and summarizes the present status.

WEPS011

Application of Orbit Response Matrix Method at CSNS/RCS

closed-orbit, lattice, dipole, alignment

2505

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

The China Spallation Neutron Source(CSNS) consists of a low energy linac and a high energy Rapid Cycling Synchrotron(RCS). RCS accumulates 80MeV beam and accelerates to 1.6GeV with 25Hz repetition rate and the average extraction beam power is 100kW. For controlling beam loss, the closed orbit should be adjusted as flexible as possible. The orbit response matrix(ORM) method is applied to correct the closed orbit distortion in RCS. The simulation study was made by using the code Linear Optics from Closed Orbit(LOCO) for CSNS/RCS, and the results of simulation study are presented.

WEPS016

Update on Comparison of the Particle Production using MARS Simulation Code

target, proton, factory, solenoid

2514

G. Prior, S.S. Gilardoni
CERN, Geneva, Switzerland
X.P. Ding
UCLA, Los Angeles, California, USA
H.G. Kirk, N. Souchlas
BNL, Upton, Long Island, New York, USA

Funding: EU FP7 EUROnu WP3
In the International Design Study for the Neutrino Factory (IDS-NF), a 5-15 GeV (kinetic energy) proton beam impinges a Hg jet target in order to produce pions that will decay into muons. The muons are then captured and transformed into a beam that can be passed to the downstream acceleration system. The target sits in a solenoid field tapering from 20 T down to below 2 T over several meters permitting a optimized capture of the pions that will produce useful muons for the machine. The target and pion capture system have been simulated in MARS simulation code and this work presents an updated comparison of the particles production using the MARS code versions m1507 and m1510.

WEPS025

First Beam Experiments at ISIS with a Low Output-impedance Second Harmonic Cavity

cavity, impedance, proton, synchrotron

2538

Y. Irie, S. Fukumoto, K. Muto, H. Nakanishi, T. Oki, A. Takagi
KEK, Ibaraki, Japan
D. Bayley, I.S.K. Gardner, R.J. Mathieson, A. Seville, J.W.G. Thomason
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.C. Dooling, D. Horan, R. Kustom
ANL, Argonne, USA
M.E. Middendorf
ORNL RAD, Oak Ridge, Tennessee, USA

A Low Output-Impedance (LOI) rf drive, which may be suitable for future high intensity accelerator applications, has been developed jointly by ANL, ISIS and KEK for an ISIS synchrotron second harmonic cavity. The cavity is ferrite-loaded, and is driven by a high-power triode (240 kW plate dissipation) with a plate-to-grid feedback circuit. The impedance is designed to be 20~30 ohms over a 2-6 MHz frequency range. Beam induced voltage has been measured with the ISIS beam, and compared with that calculated from the designed output impedance.

WEPS034

A CW RFQ Prototype

rfq, impedance, linac, vacuum

2559

U. Bartz, A. Schempp
IAP, Frankfurt am Main, Germany

A short RFQ prototype was built for RF-tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The cw-tests with 20 kW/m RF-power and simulations of thermal effects with ALGOR were finished successfully. The optimization of some details of the HF design is on focus now. First results and the status of the project will be presented.

WEPS037

RF Design of a 325 MHz 4-ROD RFQ

dipole, rfq, linac, quadrupole

2568

B. Koubek, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany
L. Groening
GSI, Darmstadt, Germany

Usually 4-ROD Radio Frequency Quadrupoles (RFQ) are built for frequencies up to 216 MHz. For higher frequencies 4-VANE structures are more common. The advantages of 4-Rod structures, the greater flexibility for tuning and being more comfortable for maintenance, are motivating the development of a 4-Rod RFQ for higher frequencies than 216 MHz. In particular a 325 MHz RFQ with an output energy of 3 MeV is needed for the proton linac for the FAIR project of GSI. This paper reports about the design studies and the latest developments of this RFQ.

WEPS041

Tuning of the New 4-Rod RFQ for FNAL

rfq, resonance, pick-up, linac

2580

J.S. Schmidt, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

For the injector upgrade at FNAL a 4-rod Radio Frequency Quadrupole (RFQ) with a resonance frequency of 200 MHz has been build. With this short structure of only 1.3 m a very compact injector design has been realized. Simulations with CST Microwave Studio® were performed for the design. Their results leading to the RF characterizations of the RFQ and the final RF setup which has been accomplished at IAP of the Goethe-University Frankfurt are presented in this paper.

WEPS046

Longitudinal Beam Acceptance of J-PARC Drift Tube Linac

DTL, beam-losses, linac, cavity

2592

T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
KEK, Ibaraki, Japan
A. Miura, G.H. Wei
JAEA/J-PARC, Tokai-mura, Japan
H. Sako
JAEA, Ibaraki-ken, Japan

The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.

WEPS047

Beamloss Study at J-PARC Linac by using Geant4 Simulation

beam-losses, scattering, linac, radiation

2595

T. Maruta
JAEA/J-PARC, Tokai-mura, Japan

Beamloss is one of the key issue for intense hadron beam accelerators. Most of case, origin of beamloss is scattering process between beam particle and residual gas inside vacuum duct. In the case of J-PARC Linac, H⁻ ions emitted from an Ion source are accelerated up to 181 MeV, then the beam is transported to RCS. The H⁻ ion is the system comprised from a proton and two electrons. If the H⁻ ion is scattered with residual gas, these one or two electrons are escaped, then H⁻ becomes H0 or H⁺(proton). H0 or H⁺ is uncontrollable and finally it goes to beam duct. This process is based on physics process, and Geant4 is matched to this kind of simulation study. I programmed SDTL (50 MeV) to L3BT (181 MeV) section at J-PARC Linac by using Geant4 code. I also wrote H⁻ and H0 library which makes it possible for Geant4 to simulate them. I will show the simulation results.

WEPS052

Progress of Linear Injector for SSC at HIRFL

linac, ion, DTL, rfq

2610

Y. He, X. Du, L.P. Sun, Z.J. Wang, C. Xiao, Y.Q. Yang, Y.J. Yuan, X.H. Zhang, Z.L. Zhang
IMP, Lanzhou, People's Republic of China
J.E. Chen, S.L. Gao, G. Liu, Y.R. Lu, K. Zhu
PKU/IHIP, Beijing, People's Republic of China
J. Wang
Lanzhou University of Technology, People's Republic of China

A heavy ion linear accelerator for Separate Sector Cyclotron (SSC) is constructing at Heavy Ion Research Facility at Lanzhou (HIRFL). It is a new injector for SSC to improve its output beam intensity of 2 times for Super Heavy Experiment (SHE) and 10 times for injection of Cooling Storage Ring (CSR) than old Cyclotron. It has a normal conducting linac at upstream of SSC and one superconducting cryomodule at downstream of SSC to shift beam energy. The designed current of the linac is 0.5 mA and output energy is 0.57 MeV/u and 1.02 MeV/u. Beam dynamic study and prototype fabrication are introduced in the paper.

WEPS053

The Conceptual Design of One of Injector II of ADS in China

rfq, solenoid, proton, linac

2613

Y. He, H. Jia, C. Li, Y. Liu, Z.J. Wang, C. Xiao, Y. Yang, B. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

A 10mA / 50 MeV superconducting proton linac as the demo of an ADS driver is designing and constructing in China. One of 10 MeV segments and corresponding prototypes are designed and fabricating at Institute of Modern Physics of the Chinese Academy of Sciences. It consists of 2.5 MeV RFQ and superconducting structure from 2.5 to 10 MeV. The conceptual design and development of prototype are introduced in the paper.

WEPS054

The Comparison of ADS Injector II with HWR Cavity and CH Cavity

cavity, linac, proton, emittance

2616

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

High current superconducting proton linac is being studied for Accelerator-driven System (ADS) Project hold by the Chinese Academic of Sciences (CAS). The injector II, which will accelerate proton beam from 2.1 MeV to 10 MeV, will be operated with superconducting cavity. At low energy part, there are two alternative choose, one is HWR cavity, the other is CH cavity. In this paper, the comparison of design with the two type cavities will be presented in view of beam dynamics.

WEPS056

First Beam Test of 81.5 MHz RFQ for ITEP-TWAC

rfq, ion, emittance, proton

2622

V. Andreev, N.N. Alexeev, A. Kolomiets, B. Kondratyev, V.A. Koshelev, A.M. Kozodaev, V.G. Kuzmichev, Y. Orlov, V. Stolbunov, T. Tretyakova
ITEP, Moscow, Russia

The 4 vane RFQ resonator with magnetic coupling windows as initial part of high-current Heavy Ion Linac for ITEP TWAC Facility is presently under commissioning at ITEP. It was constructed for acceleration of ions with 1/3 charge-to-mass ratio to the energy of 1.57 MeV/u with beam current up to 100 mA. Additional beam dynamics simulations have been carried out for actual fields of the RFQ in order to determine both extreme output beam properties for different ion species with charge-to-mass ratio in the range of 1-0.25 and limitations for high-brightness of the high-current injector. The beam test of RFQ has been started with protons at relatively low electrode voltage for experimental studying the RFQ beam dynamics. First results of the beam test in comparison with beam dynamics simulations are presented.

WEPS069

The C70 ARRONAX and Beam Lines Status

cyclotron, target, proton, quadrupole

2661

F. Poirier, F. Haddad
SUBATECH, Nantes, France
S. Auduc, S. Girault, C. Huet, E. Mace, F. Poirier
Cyclotron ARRONAX, Saint-Herblain, France
J.L. Delvaux
IBA, Louvain-la-Neuve, Belgium

Funding: The cyclotron ARRONAX is supported by the Regional Council of Pays de la Loire, local authorities, the French government and the European Union.
The C70 Arronax project is a high intensity (up to 350 ·10^-6 A) and high energy (70 MeV) multi-particle cyclotron aiming at R&D on material and radiolysis, and production of rare radioisotopes. The project began its hands-on phase in December 2010, and is now undergoing beam lines’ modification in experimental halls for both present and future experiments. Characterization of the beams at the end of the beam lines is of particular importance to determine the capacity of the cyclotron for the end-line experimental users. A program of beam characterization is being performed based on dedicated diagnostics, e.g. beam profilers, Faraday cups, alumina foils, and also on a series of Geant4 beam simulations. The results of the measurements, along with the simulations, are detailed in this report for proton and alpha particle beams, as well as the future prospects of the characterization program.

WEPS087

Dynamics of a Novel Isochronous Non-scaling FFAG

lattice, acceleration, dynamic-aperture, closed-orbit

2712

S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

Many non-scaling FFAG accelerator designs involve magnetic fields that cannot be described in popular accelerator design codes, and complex beam dynamics that require extremely accurate simulations. A recent design of a 1 GeV isochronous non-scaling FFAG is used to compare the codes COSY Infinity and ZGOUBI, both of which are commonly used in FFAG design. Results are presented for the comparison of basic beam dynamics and calculated dynamic aperture.

WEPS088

Space Charge Studies of a 1 GeV Isochronous Non-scaling FFAG Proton Driver

space-charge, acceleration, lattice, emittance

2715

S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The production of very high power proton drivers in the 10 MW range is a considerable challenge to the accelerator community. Non-scaling FFAGs have gained interest in this field, as they may be able to provide smaller, cheaper accelerators than existing options. The recent development of an isochronous non-scaling FFAG is a promising advance, but must be shown to have stable beam dynamics in the presence of space charge. Simulations of this design including space charge are presented and the implications discussed.

WEPS098

Combined Momentum Collimation Method in High-intensity Rapid Cycling Proton Synchrotrons

collimation, synchrotron, scattering, injection

2736

J.F. Chen, J. Tang, Y. Zou
IHEP Beijing, Beijing, People's Republic of China

A new momentum collimation method – so-called combined momentum collimation method in high-intensity synchrotrons is proposed and studied here, which makes use two-stage collimation in both the longitudinal and the transverse phase planes. The primary collimator is placed at a high-dispersion location of an arc, and the longitudinal and transverse secondary collimators are in the same arc and in the down-stream dispersion-free long straight section, respectively. The particles with positive momentum deviations will be scattered and degraded by a carbon scraper and then cleaned mainly by the transverse collimators, whereas the particles with negative momentum deviations will be scattered by a tantalum scraper and mainly cleaned by the longitudinal secondary collimators in the successive turns. Numerical simulation results using TURTLE and ORBIT codes show that this method gives high collimation efficiency for medium-energy synchrotrons. The studies have also shown two interesting effects: one is that the momentum collimation is strongly dependent on the transverse beam correlation; the other is that the material for the primary collimator plays an important role in the method.
This work was supported by the National Natural Science Foundation of China (10975150, 10775153), the CAS Knowledge Innovation Program-“CSNS R&D Studies”.

WEPS104

Transverse Beam Dynamics for the ISIS Synchrotron with Higher Energy Injection

resonance, space-charge, injection, synchrotron

2754

B.G. Pine, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on an 800 MeV rapid cycling synchrotron, which provides 3·10¹³ protons per pulse at 50 Hz, corresponding to a beam power of 200 kW. Studies are underway to increase the energy of the ISIS linac from 70 to 180 MeV. This would reduce space charge in the synchrotron, and enable a larger current to be accumulated, possibly up to 0.5 MW. As part of the study, transverse beam dynamics have been re-examined on ISIS, building up models from incoherent space charge tune shift, through smooth focusing models with space charge to 2D alternating gradient lattice simulations. These later simulations, using the in-house space charge code Set, include harmonic perturbations to the focusing lattice, closed orbits and images. A clearer picture of the dynamics is emerging, where there may be important constraints on the highest intensities, including half integer resonance, image induced structure resonances and transverse instabilities.

WEPS106

Status of Injection Upgrade Studies for the ISIS Synchrotron

injection, space-charge, linac, synchrotron

2760

C.M. Warsop, D.J. Adams, D.J.S. Findlay, I.S.K. Gardner, S.J.S. Jago, B. Jones, R.J. Mathieson, S.J. Payne, B.G. Pine, A. Seville, H. V. Smith, J.W.G. Thomason, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
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. Operation centres on a high intensity proton accelerator, consisting of a 70 MeV linac and an 800 MeV rapid cycling synchrotron, which provides a beam power of 0.2 MW. Obsolescence issues are motivating plans to replace the ageing 70 MeV linac, and this paper summarises the status of studies looking at how a new, higher energy linac (~180 MeV) could be used to increase beam power in the existing synchrotron. Reduced space charge and optimized injection might allow beam powers in the 0.5 MW regime, thus providing a very cost effective upgrade. The key areas of study are: design of a practical injection straight and magnets; injection painting and dynamics; foil specifications; acceleration dynamics; transverse space charge; instabilities; RF beam loading; beam loss and activation; diagnostics and possible damping systems. Results from work on most of these topics suggest that beam powers of ~0.5 MW may well be possible, but a number of topics, particularly transverse stability, still look challenging. Conclusions so far are presented, as is progress on R&D on the main intensity limiting issues.

WEPS107

Phase Space Coating in Synchrotrons: Some Applications*

synchrotron, antiproton, brightness, emittance

2763

C.M. Bhat
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Phase-space painting to produce very high intensity beam in synchrotrons is one of the widely studied topics in accelerator physics. A remarkable example of this is multi-turn beam injection by transverse phase-space painting in spallation sources. Use of barrier buckets at synchrotron storage rings has paved way for further advancements in this field. The Fermilab Recycler, antiproton storage ring, has been augmented with multipurpose broad-band barrier rf systems. Recently we have developed a longitudinal phase-space coating technique over already e-cooled high intensity low longitudinal antiproton beam and demonstrated with beam experiments. This method is extended to map the incoherent synchrotron tune of beam particles in a barrier bucket. Here I review various phase-space painting techniques being used in particle accelerators including some new schemes developed using barrier rf systems and possible new applications.

WEPZ004

Solid Pulse Transforming Line for DWA

impedance, coupling, induction, high-voltage

2769

L. Zhang
CAEP/IFP, Mainyang, Sichuan, People's Republic of China

This paper introduces the research work about solid pulse transforming line for dielectric wall accelerator(DWA). We will discuss the impedence of the solid pulse transforming line due to different material. Some research of PCSS(photoconductive semiconductor switch),which was used for DWA, will also be described.

WEPZ008

Experimental Plans to Explore Dielectric Wakefield Acceleration in the THz Regime

wakefield, acceleration, electron, dipole

2781

F. Lemery, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
C. Behrens, E. Elsen, K. Flöttmann, C. Gerth, G. Kube, B. Schmidt
DESY, Hamburg, Germany
J. Osterhoff
LBNL, Berkeley, California, USA
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work was supported by the Defense Threat Reduction Agency, Basic Research Award \# HDTRA1-10^-1-0051, to Northern Illinois University
Dielectric wakefield accelerators have shown great promise toward high-gradient acceleration. We investigate tow experiments in preparation to explore the performance of cylindrically-symmetric and slab-shaped dielectric-loaded waveguides. The planned experiments at Fermilab and DESY will use unique pulse shaping capabilities offered at these facilities. The superconducting test accelerator at FNAL will ultimately provide flat beams with variable current profiles needed for enhancing the transformer ratio. The FLASH facility at DESY recently demonstrated the generation of a ramped round beam current profile that will enable us to explore the performance of cylindrically-symmetric structures. Finally both of these facilities incorporate superconducting linear accelerator that could generate bunch trains with closely spaced bunches thereby opening the exploration of dynamical effects in dielectric wakefield accelerators. We present the planned layout and simulated experimental performances.

WEPZ009

Parametric-Resonance Ionization Cooling in Twin-Helix

resonance, quadrupole, multipole, betatron

2784

V.S. Morozov, Y.S. Derbenev
JLAB, Newport News, Virginia, USA
A. Afanasev, R.P. Johnson
Muons, Inc, Batavia, USA
B. Erdelyi, J.A. Maloney
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by DOE SBIR grant DE-SC0005589. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Parametric-resonance Ionization Cooling (PIC) is proposed as the final 6D cooling stage of a high-luminosity muon collider. For the implementation of PIC, we developed an epicyclic twin-helix channel with correlated optics. Wedge-shaped absorbers immediately followed by short rf cavities are placed into the twin-helix channel. Parametric resonances are induced in both planes using helical quadrupole harmonics. We demonstrate resonant dynamics and cooling with stochastic effects off using GEANT4/ G4beamline. We illustrate compensation of spherical aberrations and benchmark COSY Infinity, a powerful tool for aberration analysis and compensation.

WEPZ010

Modeling and Experimental Update on Direct Laser Acceleration

laser, electron, plasma, acceleration

2787

I. Jovanovic, M.W. Lin
Penn State University, University Park, Pennsylvania, USA

Funding: This work is supported by the Defense Threat Reduction Agency under contract HDTRA1-11-1-0009.
Moderate-energy, high-repetition-rate electron beams are needed in a variety of applications such as those in security and medicine, while requiring that the acceleration be realized in a compact and relatively inexpensive package. Laser wakefield acceleration is an attractive technology which meets most of those requirements, but it requires the use of relatively high peak power lasers which do not scale readily to high repetition rates. We are developing the theoretical and experimental basis for advancing the science and technology of direct laser acceleration (DLA) of charged particles using the axial component of the electric field of a radially polarized intense laser pulse. DLA is an acceleration method which exhibits no threshold and is thus compatible with the use of lower peak power, but much higher repetition rate lasers. We are currently numerically investigating the conditions for quasi-phase-matched DLA of electrons in plasma waveguides and experimentally implementing the quasi-phase-matched waveguide structure in laser-produced plasmas.

WEPZ021

Self-Consistent Dynamics of Electromagnetic Pulses and Wakefields in Laser-Plasma Interactions

laser, plasma, wakefield, space-charge

2811

A. Bonatto, R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

In the present work we study the stability of laser pulses propagating in a cold relativistic plasma, which can be of interest for particle acceleration schemes. After obtaining a Lagrangian density from the one-dimensional equations for the laser pulse envelope and the plasma electron density, we define a trial function and apply the variational approach in order to obtain an analytical model which allows us to calculate an effective potential for the pulse width. Using this procedure, we analyze the stability of narrow and large laser pulses and then compare its results with numerical solutions for the envelope and density equations.

WEPZ025

Study of Self-injection of an Electron Beam in a Laser-driven Plasma Cavity

electron, plasma, laser, injection

2820

S. Krishnagopal, S.A. Samant, D. Sarkar
BARC, Mumbai, India
P. Jha
Lucknow University, Lucknow, India
A.K. Upadhyay
CBS, Mumbai, India

Over the last few years, remarkable advances in laser wakefield acceleration of electrons have been achieved, including quasi-monoenergetic beams and GeV energy in a few centimeters. However, it is necessary to achieve good beam quality (large current, low energy-spread and low emittance) for applications such as free-electron lasers. We study self-injection in two regimes of the laser-plasma interaction: the moderate intensity, self-guiding regime, and the low intensity, near-injection-threshold regime, both in a homogeneous plasma that completely fills the simulation volume. We find good beam quality with injection of on-axis electrons, especially at lower intensity. We also study the case when the laser has to travel through vacuum before entering the plasma. We find that injection here is completely different, from off-axis electrons, and the beam quality is poorer.

WEPZ028

Status of Plasma Electron Hose Instability Studies in FACET

plasma, electron, ion, emittance

2826

E. Adli
University of Oslo, Oslo, Norway
W. An, W.B. Mori
UCLA, Los Angeles, California, USA
R.J. England, J.T. Frederico, M.J. Hogan, S.Z. Li, M.D. Litos, Y. Nosochkov
SLAC, Menlo Park, California, USA

Funding: This work is supported by the Research Council of Norway, the Fulbright Visiting Scholar Program and US DOE contract DE-AC02-76SF00515.
In the FACET plasma-wakefield acceleration experiments a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability.

WEPZ030

Study on a Gas-filled Capillary Waveguide for Laser Wakefield Acceleration

laser, acceleration, electron, plasma

2829

M.S. Kim, D. Jang, D. Jang, H. Suk
APRI-GIST, Gwangju, Republic of Korea

In gas-filled capillary waveguide for lase wakefield accelerators the gas flows through the two gas feed lines used to sustain constant pressure. Compared to the supersonic gas-jet system operated under high pressure, the gas at low pressure (<1atm) is injected inside capillary waveguide, so that this waveguide has experimental limit to the measurement of the neutral density. In order to investigate the gas pressure in capillary system we used computational fluid dynamics (CFD) simulation. In this paper, we presented the gas pressure changed by a variety of parameters, such as length and sizes of gas feed lines, and the method to decrease the turbulence effect at the ends of capillary.

WEPZ032

Energy Spectrometer Studies for Proton-driven Plasma Acceleration

plasma, proton, electron, acceleration

2835

S. Hillenbrand, R.W. Assmann, F. Zimmermann
CERN, Geneva, Switzerland
S. Hillenbrand, A.-S. Müller
KIT, Karlsruhe, Germany
T. Tückmantel
HHUD, Dusseldorf, Germany

Plasma-based acceleration methods have seen important progress over the last years. Recently, it has been proposed to experimentally study plasma acceleration driven by proton beams, in addition to the established research directions of electron and laser driven plasmas. Here, we present the planned experiment with a focus on the energy spectrometer studies carried out.

WEPZ034

Double Resosnant Plasma Wakefields

plasma, laser, wakefield, electron

2838

B.D. O'Shea, A. Fukasawa, B. Hidding, J.B. Rosenzweig, S. Tochitsky
UCLA, Los Angeles, California, USA
D.L. Bruhwiler
Tech-X, Boulder, Colorado, USA

Present work in Laser Plasma Accelerators focuses on a single laser pulse driving a non-linear wake in a plasma. Such single pulse regimes require ever increasing laser power in order to excite ever increasing wake amplitudes. Such high intensity pulses can be limited by instabilities as well engineering restrictions and experimental constraints on optics. Alternatively we present a look at resonantly driving plasmas using a laser pulse train. In particular we compare analytic, numerical and VORPAL simulation results to characterize a proposed experiment to measure the wake resonantly driven by four Gaussian laser pulses. The current progress depicts the interaction of 4 CO2 laser pulses, λlaser = 10.6μm, of 3 ps full width at half max- imum (FWHM) length separated peak-to-peak by 18 ps, each of normalized vector potential a0 ≃ 0.7. Results con- firm previous discourse (*,**) and show, for a given laser pro- file, an accelerating field on the order of 900 MV/m, for a plasma satisfying the resonant condition, ωp=π/t_fwhm.
* Umstadter, D., et al, Phys. Rev. Lett. 72, 1224
** Umstadter, D., et al, Phys. Rev. E 51, 3484

THOBA01

Electron Cloud Observations in LHC

electron, vacuum, injection, emittance

2862

G. Rumolo, G. Arduini, V. Baglin, H. Bartosik, P. Baudrenghien, N. Biancacci, G. Bregliozzi, S.D. Claudet, R. De Maria, J. Esteban Muller, M. Favier, C. Hansen, W. Höfle, J.M. Jimenez, V. Kain, E. Koukovini, G. Lanza, K.S.B. Li, G.H.I. Maury Cuna, E. Métral, G. Papotti, T. Pieloni, F. Roncarolo, B. Salvant, E.N. Shaposhnikova, R.J. Steinhagen, L.J. Tavian, D. Valuch, W. Venturini Delsolaro, F. Zimmermann
CERN, Geneva, Switzerland
C.M. Bhat
Fermilab, Batavia, USA
U. Iriso
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
N. Mounet, C. Zannini
EPFL, Lausanne, Switzerland

Operation of LHC with bunch trains different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build-up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as a strong instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity and/or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with existing models will be presented. The efficiency of scrubbing and scrubbing strategies to improve the machine running performance will be also briefly discussed.

Slides THOBA01 [2.911 MB]

THOBA03

Dual AC Dipole Excitation for the Measurement of Magnetic Multipole Strength from Beam Position Monitor Data*

dipole, sextupole, kicker, lattice

2865

M. Spata, G.A. Krafft
JLAB, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
An experiment was conducted at Jefferson Lab's Continuous Electron Beam Accelerator Facility to develop a technique for characterizing the nonlinear fields of the beam transport system. Two air-core dipole magnets were simultaneously driven at two different frequencies to provide a time-dependent transverse modulation of the electron beam. Fourier decomposition of beam position monitor data was then used to measure the amplitude of these frequencies at different positions along the beamline. For a purely linear transport system one expects to find solely the frequencies that were applied to the dipoles with amplitudes that depend on the phase advance of the lattice. In the presence of nonlinear fields one expects to also find harmonics of the driving frequencies that depend on the order of the nonlinearity. The technique was calibrated using one of the sextupole magnets in a CEBAF beamline and then applied to a dipole to measure the sextupole and octupole strength of the magnet. A comparison is made between the beam-based measurements, results from TOSCA and data from our Magnet Measurement Facility.

Slides THOBA03 [6.193 MB]

THYB01

Advanced Beam Manipulation Techniques at SPARC

gun, emittance, linac, laser

2877

A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
B. Marchetti
INFN-Roma II, Roma, Italy
M. Migliorati
University of Rome "La Sapienza", Rome, Italy
L. Palumbo
Rome University La Sapienza, Roma, Italy
V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

SPARC in Frascati is a high brightness photo-injector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of sub-picosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.

Slides THYB01 [20.772 MB]

THPPA00

Study of Beam Diagnostics with Trapped Modes in Third Harmonic Superconducting Cavities at FLASH

cavity, dipole, HOM, electron

2891

P. Zhang
DESY, Hamburg, Germany
P. Zhang
UMAN, Manchester, United Kingdom

Contribution selected for EPS-AG Prize d). Off-axis beams passing through an accelerating cavity excite dipole modes among other higher order modes (HOMs). These modes have linear dependence on the transverse beam offset from the cavity axis. Therefore they can be used to monitor the beam position within the cavity. The fifth dipole passband of the third harmonic superconducting cavities at FLASH has modes trapped within each cavity and do not propagate through the adjacent beam pipes, while most other cavity modes do. This could enable the beam position measurement in individual cavities. This paper investigates the possibility to use the fifth dipole band for beam alignment in the third harmonic cavity module. Simulations and measurements both with and without beam-excitations are presented. Various analysis methods are used and compared. A good correlation of HOM signals to the beam position is observed.

Slides THPPA00 [2.740 MB]

THPC007

Laser Electron Interaction Simulation for the Femtosecond Bunch Slicing on SOLEIL Storage Ring

laser, electron, wiggler, storage-ring

2918

J.F. Zhang, M.-E. Couprie, M. Labat, A. Loulergue, A. Nadji
SOLEIL, Gif-sur-Yvette, France

The interaction of an electron bunch and a laser in a wiggler (modulator) to generate a femtosecond slice is simulated for the slicing project on SOLEIL storage ring, using a code based on Monte-Carlo method and GENESIS. The results from these two codes are consistent with the theoretical values. The maximum modulated energy of the electron bunch and the number of electrons above a certain limit are studied for different wiggler and laser parameters. The transport of the 6D distribution of the sliced bunch from the modulator to the radiators are simulated using AT (Accelerator Toolbox) and ELEGANT, with synchrotron radiation on and taking into account the collective effects of the sliced bunch core.

THPC015

A Dedicated THz Beamline at DELTA

laser, electron, radiation, undulator

2939

M. Höner, M. Bakr, H. Huck, S. Khan, R. Molo, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh
DELTA, Dortmund, Germany

Funding: Work supported by DFG, BMBF, and by the Federal State NRW
As a consequence of the new radiation source for ultrashort VUV pulses at DELTA, which is based on the interaction of electrons with fs laser pulses, coherent THz radiation is emitted. Simulations of the laser-electron interaction, particle dynamics and radiation spectrum, as well as the optical and mechanical design of a dedicated THz beamline are presented. First experimental results including laser-electron overlap diagnostics and characterization of the THz radiation are discussed.

THPC028

A Proposal of Short X-ray Pulse Generation from Compressed Bunches by mm-wave iFEL in the SPring-8 Upgrade Plan

storage-ring, wiggler, injection, electron

2969

M. Masaki, K. Fukami, C. Mitsuda, T. Watanabe
JASRI/SPring-8, Hyogo-ken, Japan

In the SPring-8 upgrade plan, short pulse options are prepared for time-resolved experiments of pico-second order with high repetition rate. The best scenario is that selected bunches have equilibrium bunch length of 1 ps or less. A mm-wave storage-ring iFEL may be one possible solution for it. If resonant wavelength of the FEL is a few millimeters, which is about ten times longer than typical short bunch length of 0.3 mm corresponding to 1 ps, almost all electrons of a bunch can be confined in one valley of ponderomotive potentials formed by the FEL mechanism. The system consists of a helical wiggler with period length of several meters and a mm-wave resonator. Numerical simulations with coherent synchrotron radiation effect at bunch charge of 479 pC show that an ultra-short injection bunch is trapped in a mm-wave “bucket” and kept shorter than 1 ps (r.m.s.) even after twice the longitudinal damping time from the injection. The ultra-short bunches need to be injected from the XFEL linac. XFEL-to-Storage Ring beam transport line is designed to suppress dispersions which cause bunch lengthening. Tracking calculations show promising results for bunch qualities at the transport line.

THPC031

Measurement of Longitudinal Dynamics of Injected Beam in a Storage Ring

injection, storage-ring, synchrotron, booster

2978

T. Watanabe, T. Fujita, M. Masaki, K. Soutome, S. Takano, M. Takao, K. Tamura
JASRI/SPring-8, Hyogo-ken, Japan

Experimental observation of longitudinal dynamics of injected beam in a storage ring has been demonstrated. Since the injected beam undergoes synchrotron oscillation in a longitudinal phase space, two projected values, i.e., a bunch duration and an energy spread, oscillate at twice the synchrotron frequency. At SPring-8, the initial energy spread (~0.126%) at the injection goes up and down until it reaches the equilibrium energy spread (~0.11%). If the injection timing should not be optimized, an asymmetrically enhanced oscillation could distort the injection efficiency. The observation of such an oscillation helps make sure that no significant injection loss occurs. More importantly, the scheme is expected to enable us to observe non-linear longitudinal dynamics of ultra-short bunches injected from the XFEL linac; the bunches are in near future going to be transferred from the linac to the storage ring via 600-meter long transports, in which strong coherent synchrotron radiation and other high peak-current effects will not be ignorable. Experimental results obtained by a dual-scan streak camera and other devices as well as numerical simulations will be presented.

THPC076

FEL Performance with Focusing Lattice Magnets Alignment Errors

FEL, quadrupole, radiation, alignment

3071

V.G. Khachatryan, M. Ivanyan
CANDLE, Yerevan, Armenia

At the European XFEL the alignemnet errors of the undulator section quadrupole magnets will be corrected by applying beam based quadrupole alignment methods. Numerical simulations of the SASE process have been conducted to evaluate the FEL power reduction due to residual quadrupole alignment errors. FEL simulations with focusing lattice errors allow choosing an optimal error correction method in terms of FEL performance.

THPC085

Effect of mirror-tilt on the mode-structure in an oscillator FEL

FEL, coupling, cavity, alignment

3092

S. Krishnagopal, S.A. Samant
BARC, Mumbai, India

In an oscillator free-electron laser (FEL) the power coupled out depends strongly on the mode configuration at the out-coupling mirror. This mode configuration is affected by many parameters such as the resonator configuration, FEL wavelength, etc. In addition, mirror alignment also plays an important role in determining the mode structure. In this paper we use three-dimensional simulations (GENESIS+OPC), to study the effect of mirror tilt on the out-coupled power. We find that mirror-tilt can severely distort the mode, and can introduce non-Gaussian, non-axisymmetric modes. In this regard the confocal configuration is more robust compared to the concentric.

THPC087

Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II

laser, electron, FEL, bunching

3098

T. Tanikawa, M. Adachi, M. Katoh, J. Yamazaki, H. Zen
UVSOR, Okazaki, Japan
M. Hosaka, Y. Taira, N. Yamamoto
Nagoya University, Nagoya, Japan

Light source technologies based on laser seeding are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region and also in generating CH with variable polarizations in deep UV*. In previous conference, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependence, and injection laser power dependence on VUV CHs**. This time we have successfully observed saturation on CHs intensities　and have found some interesting phenomena in different harmonic orders. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations***.
*M. Labat et al., Phys. Rev. Lett. 10¹ (2008) 164803.
**T. Tanikawa et al., Proc. IPAC'10, TUPE029, p. 2206 (2010).
***T. Tanikawa et al., Appl. Phys. Express 3 (2010) 122702.

THPC093

Beam Dynamics Simulations for the SwissFEL Injector Test facility

emittance, laser, solenoid, gun

3107

S. Bettoni, M. Pedrozzi, S. Reiche, T. Schietinger
PSI, Villigen, Switzerland

The SwissFEL under study at PSI will produce 0.1 nm to 0.7 nm wavelength coherent x-ray. The design of the injector is based on the invariant envelope matching scheme, developed for other photoinjectors in the past years. According to this technique the emittance at the exit of the injector can be minimized if some conditions at the entrance of the booster are satisfied. A campaign of simulations has been carried out to verify the impact of the errors of the machine components (RF and magnetic) and laser shaping (transverse and longitudinal) on the final SwissFEL injector emittance. These results have to be used to define the tolerances on the machine and laser.

THPC101

Fitting Formulas for Space-charge Dominated Free-electron Lasers

FEL, space-charge, electron, undulator

3122

G. Marcus, E. Hemsing, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

A simple power-fit formula for calculating the gain length of the fundamental Gaussian mode of a free-electron laser having strong space-charge effects in the 3D regime has been obtained. This tool allows for quick evaluation of the free-electron laser performance in the presence of diffraction, uncorrelated energy spread, and longitudinal space-charge effects. Here, we use it to evaluate the performance of high-gain FEL amplifiers considered candidates as high average power light sources. Results are compared with detailed numerical particle simulations using the free-electron laser code Genesis.

THPC103

Beam Dynamics Study of X-band Linac Driven X-ray FELs

linac, electron, FEL, optics

3128

Y. Sun, C. Adolphsen, C. Limborg-Deprey, T.O. Raubenheimer, J. Wu
SLAC, Menlo Park, California, USA

Funding: Work supported by the DOE under Contract DE-AC02-76SF00515
Several linac driven X-ray Free Electron Lasers (XFELs) are being developed to provide high brightness photon beams with very short, tunable wavelengths. In this paper, three XFEL configurations are proposed that achieve LCLS-like performance using X-band linac drivers. These linacs are more versatile, efficient and compact than ones using S-band or C-band rf technology. For each of the designs, the overall accelerator layout and the shaping of the bunch longitudinal phase space are described briefly.

THPC104

Optimization for Single-Spike X-Ray Fels at LCLS with a Low Charge Beam

undulator, laser, FEL, electron

3131

L. Wang, Y.T. Ding, Z. Huang
SLAC, Menlo Park, California, USA

The recently commissioned Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is now operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup. In the soft x-ray regime, with the help of slotted-foil or undulator taper, a single spike x-ray pulse is achievable with peak FEL power of 30 GW.

THPC125

Study of some Design Concepts and Collective Effects in the MAX IV Linac

linac, emittance, sextupole, wakefield

3176

F. Curbis, M. Eriksson, O.E. Karlberg, S. Thorin, S. Werin
MAX-lab, Lund, Sweden
D. Angal-Kalinin, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (phase 2). Compression is done in two double achromats with positive R56. The natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a harmonic cavity for linearization of longitudinal phase space. In this proceeding we present the design of the achromat compressors and results from particle tracking through the MAX IV linac in high brightness mode. We also investigate emittance dilution due to CSR, in the achromat compressors, and transverse wakefields in a high beta function lattice.

THPC131

MAX-IV Linac Injector Simulations including Tolerance and Jitter Analysis

linac, gun, emittance, laser

3191

J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S. Thorin, S. Werin
MAX-lab, Lund, Sweden

The MAX-IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). 100 pC bunches of electrons are created from a 1.5 cell S-band photocathode gun and subsequently accelerated up to 3 GeV by S-band linac sections. Simulations of the dynamics of the space-charge dominated beam up to 100 MeV are presented including an analysis of the tolerances required and the effects of jitter sources.

THPC161

Possible Superconducting Insertion Devices with Period Length Doubling for Beamlines of Third Generation Light Sources

insertion, insertion-device, undulator, photon

3269

D. Saez de Jauregui, T. Baumbach, S. Casalbuoni, S. Gerstl, A.W. Grau, M. Hagelstein, T. Holubek
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

The tunability of an insertion device can be increased by period length switching, which in superconducting insertion devices (IDs) can be achieved by reversing the current in separately powered subsets of the superconducting windings. The feasibility of this concept has been experimentally proven. We study here different possibilities to tailor the needs of beamlines of third generation light sources: FEM simulations performed to compute the magnetic field on axis of such devices with different period lengths are reported together with the spectral simulations.

THPC165

Estimations for Demagnetization of ID Permanent Magnets due to Installation of OTR

electron, permanent-magnet, radiation, undulator

3281

Y. Asano
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Bizen
JASRI/SPring-8, Hyogo, Japan

Demagnetization due to high energy electron irradiation is one of the crucial issues for stable operation of X-ray free electron laser (XFEL) and Synchrotron radiation (SR) facilities. Especially, during the commissioning, electron beam is scattered and then hits permanent magnets of insertion devices due to installation of some instrumentations such as OTR (Optical Transition Radiation) for beam diagnosis so that the estimation of demagnetization is very important to perform the commissioning smoothly. Fortunately, we found the index of demagnetization of Nd2Fe14B permanent magnets due to high energy electron irradiation. Star density produced by high energy photo-neutron reproduces experimental results of demagnetization. At SPring-8, in-vacuum type undulators have been employed for XFEL so that we estimate the demagnetization of the undulators for various cases such as electron energy in ranging from 2 GeV to 8 GeV and the permanent magnet gap from 2 mm to 40 mm. And we also estimate the allowable time to be able to insert the OTR.

THPC168

Field Error Correction for a Superconducting Undulator

undulator, photon, radiation, electron

3290

S. Chunjarean
PAL, Pohang, Kyungbuk, Republic of Korea
C.-S. Hwang, J.C. Jan
NSRRC, Hsinchu, Taiwan
H. Wiedemann
SLAC, Menlo Park, California, USA

To reach higher photon energies in the region of soft or hard x-rays with high photon beam brightness in low energy storage rings, superconducting undulators with very short period length and high magnetic field strength are required. Because undulator radiation comes in a line spectrum, photons up to the 7th harmonic are desired. The photon brightness in such harmonics is strongly dependent on perfect periodicity of the magnetic field. Such imperfections also appear in conventional permanent material undulators, which can be corrected by well developed and efficient shimming. Unfortunately, this method cannot be applied to superconducting undulators. Therefore, we present a new approach to field corrections by modification of the magnetic field saturation in each pole. In this paper it is shown that this approach can reduce not only the magnetic field error but also greatly improves phase errors from period to period. The proposed method works quite local with only small perturbations in neighboring poles. The tenability is preserved for most of the field excitations and is reduced only at extreme parameters.

THPC173

Modelization of Inhomogeneities in Permanent Magnet Blocks

undulator, permanent-magnet, insertion, insertion-device

3305

V. Massana, J. Campmany, J. Marcos
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Nowadays one of the main objectives for insertion devices manufacturers is to reduce the gap of undulators as much as possible while keeping the features of the generated magnetic field. Because of that, the effects of magnetic blocks’ inhomogeneities are playing an increasing role in the quality of the whole device. In this paper we present a modelization of the inhomogeneities of permanent magnet blocks used to build wigglers and undulators. The model is based in splitting individual magnet blocks in different parts which are considered magnetically homogeneous. The model takes into account the relative orientation of magnet blocks assembled into their holders as well as local magnetic properties. We have applied the model to fit magnetic field integrals measured with a fixed stretched wire bench and magnetization data obtained from Helmholtz coils measurements for both single blocks and groups of blocks mounted on a common holder. The results of the model fit with experimental data within an rms error of 6•10^-4 mT•m for individual blocks and 1.5•10^-4 mT•m in the case of magnet groups.

THPC186

Heat Load for the APS Superconducting Undulator

photon, radiation, undulator, shielding

3332

L.E. Boon, A.F. Garfinkel
Purdue University, West Lafayette, Indiana, USA
K.C. Harkay
ANL, Argonne, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Upgrade calls for the development and commissioning of a superconducting undulator (SCU) at the Advanced Photon Source (APS), a 7-GeV electron synchrotron. The first SCU will be installed in June 2012. Until then, simulations such as SYNRAD3D will be used to understand and reduce the heat load on the cryo-system from primary and secondary photons. Current calculations predict that primary photons will distribute 0.5W/m on the chamber walls of the cryostat. SYNRAD3D will be used to calculate the ratio of primary and secondary photons to calculate the heat load due to secondary photons. Previous simulations were of only one sector of the APS accelerator. Simulated here are multiple sectors, to include photons back scattered from downstream photon absorbers.

THPO004

An Active Power Filter Based on Wavelet Analysis

power-supply, controls, electron, background

3341

X.L. Guo
Private Address, Beijing, People's Republic of China
X.L. Guo
IHEP Beijng, Beijing, People's Republic of China

As modern accelerator demands a magnet supply with a much higher stability, it is important to improve the quality of the magnet supply. An effective method to improve the output performance active power filter (APF) applied in current supply is proposed. To lowdown the harmonic constituents, the APF circuit generates a harmonic current, which added to the current from the main power supply, to countervail the ones in the supply’s current. At end of this paper, a simulation result is given to prove the effect of APF.

THPO013

Development of a DSP-based Digital Control Three Phase Shunt Active Power Filter for Magnet Power Supply System

controls, power-supply, sextupole, storage-ring

3361

B.S. Wang, K.-B. Liu, Y.S. Wong
NSRRC, Hsinchu, Taiwan

There will be 240 quadruple and 168 sextuple magnet power supplies installed in TPS storage ring, power factor of these power supplies is an important issue to be concerned. A digital control three-phase shunt active power filter (APF) for quadruple and sextuple magnet power supplies is implemented and the power factor is better than 0.98. The APF power stage employs a three-phase switch-mode rectifier (SMR) to reduce the input current harmonics distortion and correct the power factor. The digital control circuit of the three-phase shunt active power filter is implemented by using a multi-channel 12 bits analog-to-digital converter、high resolution Pulse Width Modulated (PWM) and a TMS320F28335 digital signal processor (DSP). The system configuration is described in three function blocks include principle of compensation、design of the snubber protective circuit and control strategies. Finally, the feasibility and validity of proposed scheme is simulated with Matlab simulink and verified by the homemade digital control three-phase shunt active power filter.

THPO014

Analysis and Compensator Design of Magnet Correction Power Supply

controls, power-supply, feedback

3364

Y.S. Wong, J.C. Huang, K.-B. Liu
NSRRC, Hsinchu, Taiwan

This paper presents a new method for the analysis and design of compensators for magnet correction (MC) power supply. The system has to need controllers to satisfy required gain and phase margin specifications and compensator by adding to circuit controller and switch. The gain-phase margin tester method can transform of the controller and find solutions on the figure. According to circuit frequency response and transfer function by theory analysis and simulation design new method compensators to improved anti-disturbance and stability of the system.

THPO015

External Energy Dump for Superconducting Magnet of the Uni-polar Power System

power-supply, controls, superconductivity, HOM

3367

Y.S. Wong, K.-B. Liu, W.S. Wen
NSRRC, Hsinchu, Taiwan

This thesis focuses on the design of superconducting discharge energy circuit structure in Uni-polar power supply [1]~[3]. Superconductivity is an electrical resistance of exactly zero which occurs in certain materials below a characteristic temperature [4]. It’s operation at the steady state in constant temperature area. When Rise up resistance and temperature of superconductivity will have been dissipates function. Uni-polar power supply has needed to design discharge energy circuit when superconductor reduces the current. To make use release the energy transfers to external circuit keep the constant temperature with the superconductivity. The superconducting coil wingding has a total length magnetic period of 56.56cm, total magnet length of 478.9cm and vertical (horizontal) magnetic field of 18.7T.

THPO016

Design and Implementation the LLC Resonant Transformer

impedance, power-supply, controls

3370

C.-Y. Liu, Y.S. Wong
NSRRC, Hsinchu, Taiwan

The energy and dc to dc conversion voltage waveform of the LLC resonant transformer are required to achieve optimal working condition of the resonant region frequency. To meet this requirement, a reliable and precise instrument is needed to scan the resonant cure of the LLC resonant transformer such that its output power performance can meet the required specification. In this paper, the design and model of a new LLC resonant transformer deployed in NSRRC is described. This LLC resonant transformer is capable of delivering energy conversion with high efficiency performance, which is better than traditional transformer, and the voltage transfer ratio is depended on the resonant Frequency. Using the simulation circuit model to develop a power converter of it is also included in the design of this new LLC resonant transformer. It has been tested and proven to be working well in power conversion with excellent efficiency and performance.

THPO018

N+1 Redundancy Power Supply System by Paralleling Current Converter Modules with Digital Regulation Control

controls, power-supply, feedback, storage-ring

3376

B.S. Wang, K.-B. Liu, Y.S. Wong
NSRRC, Hsinchu, Taiwan

The N+1 redundancy power supply system is fulfilled with adopting the Bira System MCOR30s as a platform, eight pieces of Bira MCOR 30 power converter boards are installed at crate 2512 and outputs are connected together, the output current of these paralleled eight Bira MCOR 30 power converters are regulated by an external homemade digital control circuit. With homemade digital control circuit, these paralleled eight Bira MCOR 30 power converter modules could deliver up to 240A/30V with ±20ppm precision and stability. The digital regulation control circuit of the N+1 redundancy power supply system is implemented by using a multi-channel DAC5868 16-bits digital-to-analog converter (DAC)、a high speed AD8382 18-bits analog-to-digital converter and a TMS320F28335 digital signal processor (DSP). The update reference voltage frequency of DAC is 83.3 kHz. A DCCT is used as the current feedback component and the output current ripple of the N+1 redundancy power supply system is lower than 20ppm which is beyond the requirement of current TLS quadruple and sextuple power supplies and qualified to be used in the future TPS facility.

THPO033

Calculation of Metallization Resistivity and Thickness for MedAustron Kicker Systems

vacuum, kicker, status, proton

3412

M.J. Barnes
CERN, Geneva, Switzerland
T. Kramer, T. Stadlbauer
EBG MedAustron, Wr. Neustadt, Austria

The MedAustron facility, to be built in Wiener Neustadt (Austria), will provide protons and ions for both cancer therapy and research. Different types of kicker magnets will be used in the facility. The kicker magnets are outside machine vacuum: each kicker magnet has a ceramic beam chamber whose inner surface is metallized. The resistivity and thickness of the metallization are chosen such that the induced eddy currents, resulting from the pulsed kicker magnetic field, do not unduly affect the rise/fall times or homogeneity of the magnetic field. A comparison of an analytical calculation and measurement is reported for the effect of metallization of the ceramic beam chamber of an existing kicker system at CERN. For a MedAustron kicker the result of an analytical calculation is compared with predictions from electromagnetic simulations: conclusions concerning the metallization of the ceramic beam chambers, for the MedAustron kicker magnets, are presented.

THPO035

Computer Investigation of Efficiency Enhancement in Coaxial Gyrotron Backward Wave Oscillators

electron, plasma, injection, bunching

3418

V.M. Khoruzhiy
NSC/KIPT, Kharkov, Ukraine

The gyrotron backward wave oscillator (gyro-BWO) is a high frequency (HF) powerful oscillator for cm and mm wavelengths*,**,***.Gyro-oscillators are possible devices for accelerators techniques. For efficiency enhancement in gyro-devices we suggest profiling of guiding magnetic field Hg(z) at longitudinal direction z by special law, namely Hg(z)=Hg0*(1+alfa*(z/L)*f(z/L))**0.5 where Hg0 is amplitude of homogenous guiding magnetic field, alfa is non-homogeneity amplitude, L is waveguide length and function f(z/L))is similarly to the shape (envelope) of longitudinal distribution of HF electrical field E(z) in gyro-device along longitudinal coordinate z. For investigated gyro-BWO f(z/L)=(cos(pi*z/2L))**m, f(0)=1, f(L)=0, L=60cm, m=6 and pi=3.14. We obtained enhancing of gyro-BWO’s efficiency from 11% (homogenous distribution of guiding magnetic field) up to 32% (non-homogenous one) due to profiling of magnetic field under conditions above.
* A.V.Gaponov et al., Izv. VUZov(USSR), Radiofizika 10(9), 10, 1967.
** V.Khoruzhiy et al., Phys. J.of Ukraine 49(2), 126, 2004.
*** V.Khoruzhiy et al., Phys. J.of Ukraine 50(11), 1230, 2005.

THPS004

Beam Dynamics Simulation on Simultaneous use of Stochastic Cooling and Electron Cooling with Internal Target

electron, emittance, target, proton

3433

T. Kikuchi, N. Harada, T. Sasaki, H. Tamukai
Nagaoka University of Technology, Nagaoka, Niigata, Japan
T. Katayama
GSI, Darmstadt, Germany

The small momentum spread of proton beam has to be realized and kept in the storage ring during the experiment with a dense internal target. The stochastic cooling alone does not compensate the momentum spread increases due to the scattering at the internal target. The dense proton beam in the six dimensional phase space includes intra-beam scattering as one of emittance growth mechanisms. The numerical simulation is carried out using Fokker-Planck equation solver, and the results on the simultaneous use of stochastic cooling and electron cooling at COSY are indicated.

THPS012

Simulation of the Generation and Transport of Laser-Accelerated Ion Beams

electron, ion, target, laser

3445

O. Boine-Frankenheim, V. Kornilov
GSI, Darmstadt, Germany
L. Zsolt
TEMF, TU Darmstadt, Darmstadt, Germany

In the framework of the LIGHT project a dedicated test stand is under preparation at GSI for the transport and focusing of laser accelerated ion beams. The relevant acceleration mechanism for the parameters achievable at the GSI PHELIX laser is the TNSA (Target Normal Sheath Acceleration). The subsequent evolution of the ion beam can be described rather well by the isothermal plasma expansion model. This model assumes an initial dense plasma layer with a 'hot' electron component and 'cold' ions. We will present 1D and 2D simulation results obtained with the VORPAL code on the expansion of the beam and on the cooling down of the neutralizing electrons. The electrons and their temperature can play an important role for the focusing of the beam in a solenoid magnet, as foreseen in the GSI test stand. We will discuss possible controlled de-neutralization schemes using external magnet fields.

THPS017

Simulation of Hollow Beam Formation at the Initial Part of RIB Transport Channel of SPIRAL2

ion, solenoid, emittance, focusing

3457

N.Yu. Kazarinov
JINR, Dubna, Moscow Region, Russia
F.R. Osswald
IPHC, Strasbourg Cedex 2, France

The initial part of Radioactive Ion Beam (RIB) transport channel of SPIRAL2 consists of 2.45 GHz ECR Ion Source, focusing solenoid, triplet of quadrupole lenses and 90-degrees analyzing bending magnet. The supporting gas (Nitrogen) current of ECRIS used in RIB production has a value about 1 mA. The influence of the Nitrogen beam self-fields may leads to hollow beam formation in the transported ion species at the part of beam line placed after the focusing solenoid. This effect increases the RIB emittance and therefore complicates the RIB transport. In this report the numerical simulation of hollow beam formation is fulfilled. The threshold current of ECRIS supporting gas which gives a hollow beam formation of transported ions is defined. The influence of the beam neutralization is taking into account. The possible neutralization factor is found from results of simulation of GANIL Test Bench. The simulation of a variant of quadrupoles focusing system of the initial part of RIB transport channel is performed. The influence of the Nitrogen beam space charge on transport of 120+ ions with energy of 60 keV is studied.

THPS038

Possibility of longitudinal painting injection with debuncher system in J-PARC linac

injection, linac, cavity, controls

3505

G.H. Wei
KEK/JAEA, Ibaraki-Ken, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

J-PARC linac is presently operating with the output energy of 181 MeV and providing a negative hydrogen beam to the succeeding 3-GeV synchrotron. To achieve the design beam power of 1 MW from the synchrotron, we plan to upgrade the linac beam energy to 400 MeV. In the energy upgrade, we replace the debuncher system installed between the linac and synchrotron. The main roles of the debuncher system are to correct the momentum jitter and to control the momentum spread at the ring injection. Usually, we don’t assume acceleration or deceleration with the debuncher cavities except for passive momentum jitter correction. However, we are studying the possibility of actively controlling the center momentum with debuncher cavities to enable longitudinal painting injection into the succeeding ring as a potential new feature. If it finds feasible, it would provide an additional tuning knob to mitigate the beam loss in the synchrotron. In this paper, we show a beam dynamics design of the new debuncher system with emphasis on the possibility of its application for the longitudinal painting injection.

THPS039

Diffusion of a Circulating Beam by the RF-Knockout with a Spectrum including Many Bands

synchrotron, resonance, extraction, controls

3508

M. Tashiro, T. Nakanishi
Nihon University, Narashino, Chiba, Japan

The fast control of beam spill extracted from a synchrotron is a key function for the spot scanning irradiation in cancer therapy application. The authors have proposed the extraction method for the application which uses the control of a quadruple field of fast response as well as the RFKO (QAR method). The RF signal for the RFKO should cover a frequency band corresponding to a tune spread. A simulation with continuous RFKO operation, however, showed a spill intensity changes with time largely with only this band. The large change of spill is due to not uniform diffusion of circulating beam and it makes a constant spill difficult in the QAR method. A wider band gives a uniform spill, but it requires a larger Amp power. We proposed a spectrum including many bands around the resonances to reduce the power, since the bands outside around the resonances do not contribute to the diffusion. Such a spectrum has also an advantage to increase spill intensity for the QAR method, using a band so that the RFKO diffuses more inside particles of the separatrix but also it affects little them near the boundary. We can extract several times particles with a same shrink ratio of the separatrix.

THPS041

Design of Beam Transport Line from RCS to Target for CSNS

target, kicker, proton, octupole

3514

W.B. Liu, N. Huang, J. Qiu, J. Tang, S. Wang, G. Xu
IHEP Beijing, Beijing, People's Republic of China

China Spallation Neutron Source (CSNS) uses the high energy proton beam to strike the Tungsten target to generate neutrons through spallation reaction. The proton beam is extracted from the Rapid Cycling Synchrotron (RCS), whose beam power reaches 100 kW. For the sake of target lifetime, beam distribution at the target surface is required as uniform as possible. Nonlinear beam density redistribution method with two octupole magnets has been studied. Also some simulation and theoretical calculation have been done. According to the simulation result, the beam density at the target is optimized and the beam loss is under control.

THPS042

Feasibility Studies of the Foil Scattering Extraction in CSNS/RCS

extraction, scattering, beam-losses, proton

3517

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

A slow extraction based on foil scattering was suggested in the rapid cycling synchrotron of China Spallation Neutron Source for particle calibration. Protons with large scattering angle will be extracted during 2 ms at the end of each beam cycle, via a carbon foil. The feasibility of the extraction scheme is investigated. The extraction efficiency is studied by both single turn and multi-turn simulations with FLUKA and ORBIT, respectively. Beam losses due to multiple scattering to the downstream components are predicted.

THPS057

Stripping Foil Simulations for ISIS Injection Upgrades

injection, proton, synchrotron, scattering

3556

H. V. Smith, D.J. Adams, B. Jones, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

ISIS, the pulsed neutron and muon spallation source located at the Rutherford Appleton Laboratory (UK), currently delivers a mean beam power of 0.2 MW to target. A 70 MeV H⁻ linear accelerator feeds into a 50 Hz, 800 MeV proton synchrotron (through a 0.3·10^-6 m Aluminium Oxide stripping foil), accelerating up to 3·10¹³ protons per pulse. Potential injection scheme upgrades, aiming to raise average beam power towards 0.5 MW with a new 180 MeV linear accelerator, are being studied. Detailed consideration of the injection stripping foil forms a key element of this study: scattering, stripping efficiency and foil lifetime are significant factors in determining loss levels, which consequently limit operational intensity. This paper describes the identification of a suitable stripping foil specification for successful 180 MeV H⁻ charge exchange injection into the ISIS synchrotron. Simulation code was developed to investigate electron stripping, scattering events and temperature rises, in order to witness their subsequent effect on foil lifetime. ANSYS models were also used to investigate the heat transfer and temperature distribution within thin foils.

THPS059

Thermo-mechanical Design of Particle-stopping Devices at the High Energy Beamline Sections of the IFMIF/EVEDA Accelerator

ion, linac, rfq, focusing

3562

D. Iglesias, F. Arranz, B. Brañas, J.M. Carmona, N. Casal, A. Ibarra, C. Oliver, M. Parro, I. Podadera, D. Rapisarda
CIEMAT, Madrid, Spain

Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230.
The IFMIF/EVEDA linear accelerator is a 9 MeV, D⁺ prototype for the validation of the 40 MeV final IFMIF design. The high intensity, 125 mA CW, high power beam (1.125 MW) produces an extremely high thermal load in all the elements intercepting the ions. Independently of the final purpose of each device, if its working conditions imply stopping a non-negligible amount of particles, the associated thermal solicitation greatly determines the design constraints. The present work will summarize a thermo-mechanical design workflow that can be applied to any beam facing element of high current accelerators and its application in beam dump, scrappers and slits design. This approach is based on analysis experiences at the IFMIF/EVEDA project and, while taking into account the particularities of each device, uses the same tools and parameter evaluation criteria for all of them. It has been applied successfully to recent designs, effectively reducing the number of iterations before achieving a valid thermo-mechanical behavior. Results of each design and the concrete advantages of this approach will be detailed.

THPS068

A Proton Therapy Test Facility: The Radiation Protection Design

proton, shielding, radiation, neutron

3583

S. Sandri, M.C. Carpanese, G. Ottaviano, L. Picardi, C. Poggi, C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

A proton therapy test facility is planned to be sited in the Frascati ENEA Research Center, in Italy. A 30 m long, 3 m wide bunker has to be designed to host a proton linear accelerator with a low beam current, lower than 10 nA in average, and an energy up to 150 MeV. The accelerator will be part of the TOP-IMPLART project for deep tumors treatment. The design of the 150 MeV accelerator is under study and the radiation protection solutions are considered in this phase. The linear accelerator has some safety advantages if compared to cyclotrons and synchrotrons. It can be easily housed in the long, narrow tunnel. The main radiation losses during the acceleration process occur below 20 MeV, with a low neutron production. As a consequence the barriers needed should be substantially lighter than the one used for other types of machines. In the paper the simulation models and the calculation performed with Monte Carlo codes are described. The related results are presented together with those assessed by using published experimental data. Considerations about workers and population protection are issued in the conclusions.

THPS069

Particle Beam Characteristics Verification for Patient Treatment at CNAO

synchrotron, controls, proton, monitoring

3586

M. Donetti, M. Ciocca, M.A. Garella, A. Mirandola, S. Molinelli, M. Pullia, G. Vilches Freixas
CNAO Foundation, Milan, Italy
S. Giordanengo
INFN-Torino, Torino, Italy
M. Lavagno
DE.TEC. TOR. S.r.l., Torino, Italy
R. Sacchi
Torino University, ., Torino, Italy

At Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia, Italy, a synchrotron has been designed to treat tumor with protons and ions delivered with a full active delivery system. Several pencil beams with appropriate energy are steered in sequence to the right positions inside the tumor volume covering it totally. Several beam characteristics have to be deeply known in order to be able to deliver a safe patient treatment. CNAO is now able to send beam in the treatment room and the Dose Delivery system is in the commissioning phase. Dose Delivery system, composed by beam monitoring and scanning magnets, manages the treatment with high precision in real time. The dose delivery system functions and components will be presented. Beam characteristic are studied by means of several detectors and verification systems in the treatment room to guarantee the quality of the treatment. Quality is checked in terms of pencil beam characteristics and characteristic of the overall dose in the treatment fields. The detector used and the results of the measurements will be shown.

THPS073

Dosimetric Impact of Multiple Energy Operation in Carbon-ion Radiotherapy

target, ion, synchrotron, scattering

3598

T. Inaniwa, T. Furukawa, N. Kanematsu, S. Mori, K. Noda, S. Sato, T. Shirai
NIRS, Chiba-shi, Japan

In radiotherapy with a scanned carbon beam, its Bragg peak is placed within the target volume either by inserting the range shifter plates or by changing the beam energy extracted from the synchrotron. The former method (range shifter scanning: RS) is adopted in NIRS while the latter method (active energy scanning: ES) has been used in GSI and HIT. In NIRS, an intermediate method, a combination scanning (CS), is now under consideration where eleven beam energies having the ranges with 30 mm intervals are prepared and used in conjunction with the range shifter plates for slighter range shift. The disadvantages of the RS are the beam spread due to the multiple scattering within the range shifter plates and the production of fragment particles through the nuclear reactions within them. On the other hand, for the ES, severely time-consuming beam commissioning and the expensive devices are required. In this study, we compare these three methods from the viewpoint of dose distributions and the impacts for clinical cases will be discussed.

THPS083

Two-channel Mode of Mo-99 Production at an Electron Accelerator

target, neutron, electron, photon

3627

V.L. Uvarov, A.N. Dovbnya, V.V. Mytrochenko, V.I. Nikiforov, S.A. Perezhogin, V.A. Shevchenko, B.I. Shramenko, A.Eh. Tenishev, A.V. Torgovkin
NSC/KIPT, Kharkov, Ukraine

High-energy bremsstrahlung is the main source of isotopic target activation at an electron accelerator. The photoneutrons concurrently generated are generally considered as a background radiation. At the same time, the natural materials entering into photonuclear targets sometimes comprise a mixture of stable isotopes, the atomic-number difference of which equals 2. Thus, if the desired isotope has an intermediate mass, then at certain conditions, it can be produced on two target nuclei at once, via (γ,n) and (n,γ) channels. As an example, we investigate the possibility of increasing the yield of 99Mo by means of its simultaneous production from 100Mo(γ,n)99Mo and 98Mo(n,γ)99Mo reactions. The method and the device have been developed to provide measurements of the 99Mo yield from the natural molybdenum target as it is placed inside the neutron moderator and without the latter. Experiments were performed at the NSC KIPT accelerator LU-40m at electron energies ranging from 30 to 60 MeV. It is demonstrated that the use of the moderator gives nearly a 30% increase in the 99Mo yield. The experimental results are in good agreement with the computer simulation data.

THPS084

Modification of the PENELOPE Transport System for HS Simulation of Isotope Production Mode

target, electron, photon, radiation

3630

V.L. Uvarov, V.I. Nikiforov
NSC/KIPT, Kharkov, Ukraine

A method has been developed for high-speed computing the photonuclear isotope yield along with the absorbed radiation power in exit devices of electron accelerator. The technique involves a step-by-step calculation of isotope microyield along the photon trajectories. The approach has been realized in the computer programs based on the PENELOPE system of -2001, -2006 and -2008 versions. For their benchmarking, use has been made of the experimental data on activity distributions of the 67Cu produced from 68Zn(γ,p)67Cu reaction in thick zinc targets. The results of simulation using the PENELOPE-2006 and -2008 codes are in excellent agreement with all experimental data. At the same time, the PENELOPE-2001 computations give good agreement with the experimental results for target activation by the electron beam, but systematically underestimate (~15%) in case of the target exposed to bremsstrahlung. The proposed technique provides a ~ 10⁴ times higher computation speed as compared with the direct Monte Carlo simulation of photonuclear events and that speed is independent of the reaction cross section.

THPS086

Compact Beam Delivery Systems for Ion Beam Therapy

ion, beam-transport, quadrupole, focusing

3633

C. Sun, D. Arbelaez, S. Caspi, D. Robin, A. Sessler, W. Wan
LBNL, Berkeley, California, USA
M. Yoon
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: Work supported by the United States Department of Energy under Contract No. DE-AC02-05CH11231
In this paper we present a coil winding concept for a large aperture, combined-function 90 degree magnet that allows for a significantly more compact carbon ion gantry. The winding concept enables the reduction in the size and weight of the magnet without compromising the important beam transport properties. Alternatively, a small aperture gantry requires a post-gantry scanner. We present a compact design for a post-gantry point-to-parallel scanning system.

THPS088

LHC Beam Impact on Materials Considering the Time Structure of the Beam

target, proton, kicker, extraction

3639

N.A. Tahir
GSI, Darmstadt, Germany
J. Blanco, R. Schmidt
CERN, Geneva, Switzerland
R. Piriz
Universidad de Castilla-La Mancha, Ciudad Real, Spain
A. Shutov
IPCP, Chernogolovka, Moscow region, Russia

The LHC is the world's largest and highest energy accelerator. Two counter-rotating beams can be accelerated up to 7 TeV and kept colliding for several hours. The energy stored in each beam is up to 362MJ, enough to melt 500 kg of copper. A fast loss of a small fraction of the beam can cause damage to a superconducting coil in a magnet. Primary beam collimators, one of the most robust parts of the machine protection, can be damaged with about 5% of the beam. An accident involving the entire beam is very unlikely but cannot be fully excluded. Understanding the consequences of such accidents is fundamental for the machine protection. Detailed numerical simulations have been carried out to assess the damage caused by full LHC beam impact on solid Cu and C cylinders. The energy loss of the protons is calculated with the FLUKA code and this data is used as input to a 2D hydrodynamic code BIG2, to study the thermodynamic and hydrodynamic response of the material. Since the target parameters change substantially during the time of impact, a new approach of running the two codes iteratively, has been developed. In this paper the results are presented and compared with the previous studies.

THPS089

Application of Particle Accelerators to Study High Energy Density Physics in the Laboratory

ion, target, heavy-ion, plasma

3642

N.A. Tahir, T. Stöhlker
GSI, Darmstadt, Germany
R. Piriz
Universidad de Castilla-La Mancha, Ciudad Real, Spain
A. Shutov
IPCP, Chernogolovka, Moscow region, Russia
A.A. Zharikov
BINP SB RAS, Novosibirsk, Russia

High Energy Density (HED) Physics spans over wide areas of basic and applied physics. Strongly bunched high quality intense particle beams are an excellent tool to generate HED matter in the laboratory. Over the past decade, we have carried out extensive theoretical work to design HED physics experiments for the future FAIR facility at Darmstadt. These experiments will be carried out to study the equation-of-state properties of HED matter*, interiors of the Giant planets**, growth of hydrodynamic instabilities in solids and ideal fluids in the linear and the non-linear regimes*** as well as the solid constitutive properties of materials of interest under dynamic conditions.
* N.A. Tahir et al., PRL 95 (2005) 135004.
** N.A. Tahir et al., New J. Phys. 12 (2010) 073022.
*** N.A. Tahir et al., Phys. Plasmas 18 (2011) 032704.

THPS092

Conceptual Design of the ESS-Bilbao Materials Irradiation Laboratory

proton, neutron, target, radiation

3651

R. Martinez, E. Abad
ESS Bilbao, Bilbao, Spain
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
I. Garcia-Cortes, A. Ibarra, R. Vila
CIEMAT, Madrid, Spain

Funding: ESS-Bilbao
The baseline design for the first stage of the ESS-Bilbao proton linear accelerator up to 50 MeV is almost concluded and the linac is at present under construction. Three main application laboratories have been envisaged in this first stage: two proton irradiation laboratories and a low intensity neutron source. In particular, the high intensity proton beam of 50 MeV will be used to test structural materials for fusion reactors* under project named “Protons for Materials” (P4M), described in this contribution. The P4M irradiation room will be an underground facility located at the accelerator's tunnel depth. High levels of activation are expected in this irradiation room and its design presents challenges in both remote handling and independent operation from the other two surface laboratories. Thermal analysis of the beam power deposition over the target will be presented.
K. Konashyetal, Sci. Rep. RITU, A45(1997), pp.111-114.

THPS104

Radio-activation Effect of Target Rooms for PEFP's 20~100 MeV Linear Accelerator

proton, target, radiation, neutron

3678

S.J. Ra, M.H. Jung, K. R. Kim
KAERI, Daejon, Republic of Korea

Funding: This work was conducted as a part of the Proton Engineering Frontier Project supported by the Ministry of Education Science & Technology of Korea Government.
PEFP (Proton Engineering Frontier Project) has developed a 20~100 MeV/20 mA proton linear accelerator, proton beam utilization technology and accelerator applications, in order to acquire core technologies which are essential to develop future science and secure the industrial competitiveness. In the experimental hall, 10 target rooms will be constructed for the research of radioisotopes, material, medical, neutron source, etc. In the irradiation experiments using proton beam of more than a few MeV energy, radio-activation of targets and equipments can be essentially caused by the proton induced nuclear reactions. Highly radioactive samples occasionally makesome problems or inconveniences concerning with sample handling and post-treatment because we have to wait for the samples to be cooled down under the safe value for radiation protection. So we estimated proton beam irradiation condition of each target room and used samples including equipments, then we calculated radio-activation of each target room by using Monte Carlo N-particle Transport Code.

THPZ001

Spin Dynamic Tool Developments and Study Regarding the Super-B Project

closed-orbit, lattice, polarization, collider

3681

N. Monseu, J.-M. De Conto
LPSC, Grenoble Cedex, France
F. Méot
BNL, Upton, Long Island, New York, USA
U. Wienands
SLAC, Menlo Park, California, USA

The study of polarization is essential for e+/e^- colliders like the SuperB machine. The ZGOUBI integrator is a good and universal tool for particle tracking as well as spin tracking, and takes into account all machine realistic aspects, like real fields, non-linearities, fringing fields or misalignments. We present ZGOUBI implementation and the methods carried out to estimate invariant spin field and beam polarization evolution on some simple models (for validation) and on SuperB, and we investigate for some specific polarization behavior.

THPZ008

Strong-strong Simulations for Super B Factories II

luminosity, resonance, factory, positron

3696

K. Ohmi
KEK, Ibaraki, Japan

Trials for the strong-strong simulation for study of beam-beam effect in large Piwinski angle (LPA) collision adopted in Super B factories. So far a combination method of particle in cell method and soft-Gaussian model has been used. We now show complete strong-strong simulation for LPA collision scheme. Collisions between many slices of two bunches are evaluated by particle in cell method with shifted Green function.

THPZ009

Beam Background Simulation for SuperKEKB/Belle-II

background, scattering, luminosity, interaction-region

3699

H. Nakano, H. Yamamoto
Tohoku University, Graduate School of Science, Sendai, Japan
K. Kanazawa, H. Nakayama, Y. Ohnishi
KEK, Ibaraki, Japan
C. Kiesling, S. Koblitz, A. Moll, M. Ritter
MPI-P, München, Germany

The Belle experiment is now being upgraded to the Belle II experiment designed for a 40 times higher luminosity. Such a high luminosity is realized by the SuperKEKB collider where beam-induced background rates are expected to be much higher than those of KEKB. This poses a serious challenge for the design of the machine-detector interface. We have thus carried out a GEANT4-based beam background simulation for Touschek effect. We describe the method of generating background particles and present the result of simulation.