IPAC2011 - List of Keywords (scattering)

Paper	Title	Other Keywords	Page
MOPO011	The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC	alignment, controls, HOM, beam-losses	502
	M. Deile, G.H. Antchev, R.W. Assmann, I. Atanassov, V. Avati, J. Baechler, R. Bruce, M. Dupont, K. Eggert, B. Farnham, J. Kaspar, F. Lucas Rodríguez, J. Morant, H. Niewiadomski, X. Pons, E. Radermacher, S. Ravat, F. Ravotti, S. Redaelli, G. Ruggiero, H. Sabba, M. Sapinski, W. Snoeys, G. Valentino, D. Wollmann CERN, Geneva, Switzerland R. Appleby UMAN, Manchester, United Kingdom
	Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed.

MOPS050	Electron Beam Dynamics in the 50 MeV ThomX Compact Storage Ring	electron, emittance, photon, collective-effects	715
	C. Bruni, J. Haissinski LAL, Orsay, France A. Loulergue, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	ThomX is a high flux compact X-ray source based on Compton back scattering between a relativistic electron beam and an intense laser pulse. To increase the repetition rate, the electron beam is stored in a ring. The main drawback of such a scheme is the low energy of the electrons regarding collective effects and intrabeam scattering. These effects tend to enlarge or even disrupt the stored bunch and they limit its charge, especially in a system where damping plays a negligible role. Thus such collective effects reduce the maximum X-ray flux and it is important to investigate them to predict the performance of this type of X-ray source. In addition, the Compton back scattering acts on the electron beam by increasing its energy spread. This presentation will show firstly the impact of collective effects on the electron beam, essentially during the first turns when they are the most harmful. Then, the reduction of the X-ray flux due to Compton back scattering and intrabeam scattering will be investigated on a longer time scale.

MOPZ036	Ionization Cooling in MICE Step IV	emittance, simulation, 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.

TUPC062	Electron Beam Energy Measurement at the Australian Synchrotron Storage Ring	storage-ring, electron, synchrotron, resonance	1138
	M.J. Boland ASCo, Clayton, Victoria, Australia H. Panopoulos, R.P. Rassool, K.P. Wootton The University of Melbourne, Melbourne, Australia
	The technique of resonant spin depolarization was used to precisely measure the electron beam energy in the storage ring at the Australian Synchrotron. A detector and data acquisition system dedicated to the measurement were developed. Using the system, the long term energy stability of the storage ring was monitored and a mechanical realignment of the ring was clearly seen in the energy data. Details of the parameters used to optimize the measurement are also discussed.

TUPC074	A New Counting Silicon Strip Detector System for Precise Compton Polarimetry	electron, polarization, photon, laser	1171
	R. Zimmermann, W. Hillert, J.C. Wittschen ELSA, Bonn, Germany
	Funding: Supported by the German Research Foundation within the SFB/TR16 A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. Above all, as a result of ELSA's beam energies, it is necessary to measure the shift of the center of the photon spatial distribution which is obtained when the polarization of the laser is switched from left-hand to right-hand circular polarization with an accuracy of a few microns. In order to meet the required specifications, a new counting silicon strip detector system has been developed in cooperation with the SiLab/ATLAS group of the Physics Institute of the University of Bonn. In this contribution, the design of the system will be presented and first results will be shown.

TUPC091	Operational Results of the Diamond-based Halo Monitor during Commissioning of SPring-8 XFEL (SACLA)	electron, undulator, laser, wakefield	1218
	H. Aoyagi JASRI/SPring-8, Hyogo-ken, Japan Y. Asano, H. Kitamura, T. Tanaka RIKEN/SPring-8, Hyogo, Japan
	Funding: This work is partly supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (c) 21604017. Measurement of electron beam halo is very important issue for X-ray free electron laser and synchrotron radiation facilities, because the beam halo may cause radiation damage of undulator magnets. Furthermore, it may cause degradation in quality of electron beam, and radio activation of beam ducts and components. In order to prevent these situations, a diamond-based halo monitor (HM) has been developed for the SPring-8 Angstrom Compact free electron LAser (SACLA). We have achieved excellent detection limit of 0.3 fC/pulse for single-shot measurement, which corresponds to the ratio of 10^-6 to the beam core. The commissioning of the HM, which was installed at the upstream of 90m undulator, has been carried out, and it has been figured out that the intensity of the beam halo can be measured very nicely since secondary electrons and bremsstrahlung that are emitted in the accelerator components have not been observed. We also describe systematic profile measurements of the beam halo and operational results of the HM during the commissioning of SACLA.

TUPO013	Development of Pulse Width Measurement Techniques in a Picosecond Range of Ultra-short Gamma Ray Pulses	laser, photon, electron, storage-ring	1473
	Y. Taira, M. Hosaka, K. Soda, N. Yamamoto Nagoya University, Nagoya, Japan M. Adachi, M. Katoh, H. Zen Sokendai - Okazaki, Okazaki, Aichi, Japan T. Tanikawa UVSOR, Okazaki, Japan
	Funding: This work was supported by Grants-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS). We are developing the ultra-short gamma ray pulse source with the energy of MeV region based on laser Compton scattering at the 750 MeV electron storage ring, UVSOR-II. Gamma rays with pulse width of sub-picosecond range can be generated by injecting femtosecond laser pulses into the electron beam from the vertical 90-degree direction* because the electron beam circulating in the storage ring is focused more tightly in the vertical direction than in the longitudinal direction. The energy, intensity, and pulse width of the gamma rays can be tuned by changing the collision angle between the electron beam and the laser. We are developing pulse width measurement techniques of ultra-short gamma ray pulses at present. As the first step of the pulse width measurement, we used a fast response photodetector, Geiger-mode APD, the time resolution of which is few hundreds picoseconds. Although we cannot measure the pulse width of the gamma rays with sub-picosecond range using this detector, we could measure the pulse width of the gamma rays as 430 ps or less by measuring the timing of Cherenkov radiations generated from the gamma rays. * Y. Taira et al., Nucl. Instrum. Meth. A, in press, 2010.

TUPO023	Narrow Spectral Bandwidth Optimization of Compton Scattering Sources	electron, laser, simulation, 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.

TUPO024	Precision X-band Linac Technologies for Nuclear Photonics Gamma-ray Sources	gun, electron, laser, photon	1491
	F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, M. J. Messerly, S.S.Q. Wu LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, M.V. Fazio, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA D. Cutoiu Horia Hulubei National Institute for Physics and Nuclear Engineering, Bucharest, Romania D. Ighigeanu, M. Toma INFLPR, Bucharest - Magurele, Romania V.A. Semenov UCB, Berkeley, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies.

TUPS033	Foil Scattering Loss Mitigation by the Additional Collimation System of J-PARC RCS	injection, collimation, vacuum, septum	1605
	K. Yamamoto, H. Harada, J. Kamiya, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We presents a overview of this new collimation system.

TUPS086	Ultra-high Resolution Observation Device for Carbon Stripper Foil	radiation, monitoring, vacuum, proton	1740
	Y. Takeda, Y. Irie, I. Sugai KEK, Ibaraki, Japan
	To observe a growth process of a pinhole on a HBC-foil due to beam irradiation, an up to 10 um of device for ultra-high resolution observation is needed. For the environment where we use the device for observation is so severe as under high radiation and in vacuum, there is no device available for long-time observation. Then, we designed and created a wholly new method based system which enables constant observation by ultra-high resolution even under high radiation environment. We attempted several experiments, compared materials usable under radiation environment, checked up various optical systems which enables high resolution, and finally developed the best method. As a result, we successfully invented an ultra-high resolution observation device available for monitoring an object about 8 meters distant by 8.3um resolution.

TUPZ001	90 m Optics Commissioning	optics, proton, coupling, injection	1795
	S. Cavalier LAL, Orsay, France H. Burkhardt, M. Fitterer, G.J. Müller, S. Redaelli, R. Tomás, G. Vanbavinckhove, J. Wenninger CERN, Geneva, Switzerland
	Special β* = 90 m optics have been developed for the two very high luminosity insertions of the LHC, as a first step towards to allow for very low angle precision measurements of the proton-proton collisions in the LHC. These optics were developed to be compatible with the standard LHC injection and ramp optics. The target value of β* = 90 m is reached by an un-squeeze from the injection β* = 11 m. We describe the implementation of this optics in the LHC and the first experience in the commissioning of these optics.

TUPZ002	90 m β* Optics for ATLAS/ALFA	optics, emittance, luminosity, quadrupole	1798
	S. Cavalier, P.M. Puzo LAL, Orsay, France H. Burkhardt CERN, Geneva, Switzerland A. Peskov NNGU, Nizhny Novgorod, Russia
	We describe a high β* optics developed for the ATLAS detector at the LHC interaction regions (IR1), Roman Pots have been installed 240 m left and right of IR1 to allow to measure the absolute luminosity and the total elastic cross section for ATLAS with ALFA (Absolute Luminosity for ATLAS). Ultimately, it is planned to preform these measurements at a very high β* of 2625 m. Here we describe a new, intermediate β* = 90 m optics, which has been optimized for compatibility with the present LHC running conditions. We described the main features and expected performance of this optics for ALFA.

TUPZ011	LHC Collimation with a Reduced Beam Pipe Radius in ATLAS	simulation, optics, collimation, 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.

WEIB01	Chasing Femtoseconds – How Accelerators Can Benefit from Economies of Scale in Other Industries	laser, optics, polarization, controls	1973
	M. Vidmar, J. Tratnik University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia P.L. Lemut COBIK, Solkan, Slovenia
	Building accelerators we frequently push the limits of what is possible in terms of performance. When trying to solve a very challenging engineering problem, we normally resort to specialization; we narrow our focus. This talk suggests a possible alternative path. Huge benefits and great results can be achieved by combining creative ideas and approaches with ideas and solutions borrowed from the economies of scale like telecommunications. The aim of the talk is to show possibilities for combining ideas, technologies and components from different industries into innovative products.
	Slides WEIB01 [0.799 MB]

WEPC045	Transverse Emittance Reduction with Tapered Foil	emittance, electron, target, simulation	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.

WEPC051	Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring	electron, laser, damping, cavity	2127
	I. Chaikovska, C. Bruni, N. Delerue, A. Variola, Z.F. Zomer LAL, Orsay, France K. Kubo, T. Naito, T. Omori, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of e⁺e⁻ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-Perot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and will be used to produce an intense flux of polarized gamma rays by Compton scattering. For electrons at the energy of the ATF (1.28GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed.

WEPC064	Long Term Beam Dynamics in Ultra-Low Energy Storage Rings	ion, storage-ring, antiproton, target	2166
	A.V. Smirnov MPI-K, Heidelberg, Germany A.I. Papash, A.V. Smirnov JINR, Dubna, Moscow Region, Russia M.R.F. Siggel-King, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: "Work supported by STFC, the Helmholtz Association and GSI under contract VH-NG-328." Electrostatic storage rings operate at very low energies in the tens of keV range and have proven to be invaluable tools for atomic and molecular physics experiments. However, earlier measurements showed strong limitations in beam intensity, a fast reduction in the stored ion current, as well as significantly reduced beam life time at higher beam intensities and as a function of the ion optical elements used in the respective storage ring. In this contribution, the results from studies with the computer code BETACOOL into the long term beam dynamics in such storage rings, based on the examples of ELISA, the AD Recycler and the USR are presented.

WEPC098	Automatic Pole and Q-Value Extraction for RF Structures	resonance, cavity, RF-structure, cryomodule	2241
	C. Potratz, H.-W. Glock, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany F. Marhauser JLAB, Newport News, Virginia, USA
	The experimental characterization of RF structures like accelerating cavities often demands for measuring resonant frequencies of Eigenmodes and corresponding (loaded) Q-values over a wide spectral range. A common procedure to determine the Q-values is the -3dB method, which works well for isolated poles, but may not be applicable directly in case of multiple poles residing in close proximity (e.g. for adjacent transverse modes differing by polarization). Although alternative methods may be used in such cases, this often comes at the expense of inherent systematic errors. We have developed an automation algorithm, which not only speeds up the measurement time significantly, but is also able to extract Eigenfrequencies and Q-values both for well isolated and overlapping poles. At the same time the measurement accuracy may be improved as a major benefit. To utilize this procedure merely complex scattering parameters have to be recorded for the spectral range of interest. In this paper we present the proposed algorithm applied to experimental data recorded for superconducting higher-order-mode damped multi-cell cavities as an application of high importance.

WEPC099	Coupler Design and Optimization by GPU-Accelerated DG-FEM	HOM, simulation, 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.

WEPC105	Multiparticle Simulation of Intrabeam Scattering for SuperB	emittance, simulation, damping, 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, simulation, vacuum, 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.

WEPC116	A Matrix Presentation for a Beam Propagator including Particles Spin	collider, storage-ring, controls, heavy-ion	2283
	M. Kosovtsov, S.N. Andrianov, A.N. Ivanov St. Petersburg State University, St. Petersburg, Russia
	Particles beam dynamics in magnetic and electrical fields with spin is discussed. This approach provides a constructive method of matrix presentation derivation for a beam propagator in magnetic and electrical fields. The beam propagator is evaluated in according to the well-known Lie algebraic tools. But in contrast to traditional approaches matrix presentation for Lie propagators bases on two-indexes matrices. This approach permit to apply all of matrix algebra opportunities and advantages in contrast with the tenzor presentation based on multi-indexes description. The necessary computation can be realized in symbolic (using computer algebra codes as Mathematica, Maple, Maxima and so on). The corresponding symbolic objects itself can be stored in special databases and used then in numerical computing. Parallel and distributed conception is well acceptable with the suggested matrix formalism. Some symbolic and numerical results are discussed for problems of long term evolution of particles with spin.

WEPC132	Simulations of Surface Effects and Electron Emission from Diamond-Amplifier Cathodes	electron, simulation, vacuum, 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).

WEPC141	Application of the SYNRAD3D Photon-Tracking Model to Shielded Pickup Measurements of Electron Cloud Buildup at CesrTA	photon, electron, simulation, 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.

WEPO022	Tightening the Tolerance Budget of Core Fabrication to Achieve Higher Magnet Performance	sextupole, vacuum, dipole, quadrupole	2448
	N. Li, A. Madur LBNL, Berkeley, California, USA J. Jin SINAP, Shanghai, People's Republic of China
	Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231. Traditionally, laminated cores of AC magnets have been always built by the laminations that are produced by a punching die. There are 5 links in the tolerance chain when a magnet core is built by this procedure: 1. Error of punching die; 2. Error of lamination punching; 3. Error of half core stacking; 4. Error of core assembly; and 5. Error of magnet re-assembling during the installation in the accelerator. As time goes on, the Lattice physicists call for more and more ever higher magnet performance, which makes the required magnet field quality almost impossible achieve by traditional core fabrication procedures. It is the goal of this paper to describe a relatively new procedure that was first used by Buckley System Ltd, NZ and is being used at SINAP, China for ALS combined function sextupole core fabrication. The advantage of this new procedure and the fabrication issues related to this procedure will be described in this paper.

WEPS005	Investigation of Intrabeam Scattering in the Heavy Ion Storage Ring TSR	ion, bunching, electron, storage-ring	2490
	S.T. Artikova, M. Grieser, J. Ullrich MPI-K, Heidelberg, Germany
	Intrabeam scattering (IBS) is a multiple scattering effect between stored beam particles. It leads to diffusion in all three spatial dimensions and thus, causes an expansion of the whole beam. IBS plays an important role in the equilibrium diameter of a low-velocity, electron-cooled ion beam. IBS effects for coasting and bunched 12C⁶⁺ ion beams at an energy of 73.3 MeV were studied using the TSR heavy ion cooler storage ring. Experimental results of the IBS rates are presented.

WEPS047	Beamloss Study at J-PARC Linac by using Geant4 Simulation	beam-losses, simulation, 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.

WEPS098	Combined Momentum Collimation Method in High-intensity Rapid Cycling Proton Synchrotrons	collimation, synchrotron, simulation, 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”.

WEPZ011	Fast Cooling of Bunches in Compton Storage Rings	laser, electron, emittance, photon	2790
	E.V. Bulyak NSC/KIPT, Kharkov, Ukraine J. Urakawa KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling', the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.

WEPZ027	Stabilization of the LWFA and its Application to the Single-shot K-edge Densitometry	electron, laser, emittance, wakefield	2823
	K. Koyama, H. Madokoro, Y. Matsumura University of Tokyo, Tokyo, Japan R. Kuroda, K. Yamada AIST, Tsukuba, Ibaraki, Japan H. Masuda, M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan S. Masuda Osaka University, Suita, Osaka, Japan
	Funding: This work was supported in part by Global COE Program “Nuclear Education and Research Initiative,” MEXT, Japan Injection of electrons into a laser wakefield accelerator (LWFA) via a wavebreaking process was investigated in order to obtain stable output of electron bunches. A density down ramp for occurring the wavebreaking was formed by an oblique shockwave, which was excited by setting a little flow-deflector on an edge of the supersonic nozzle of high-Mach number (M=5). Parameters of the jet were examined by using PIC code and evaluated by using an interferometer, the density was 10¹⁹cm^-3, density ratio was 2, and the characteristic length was 70 microns. Injection experiments using 7-TW laser pulses suggested that electrons were injected in the density ramp. Since the all-optical Compton X-ray is attractive source for an accurate densitometry, a preliminary experiment of a single-shot K-edge densitometry was performed by using X-ray pulses generated by the laser-Compton scattering (LCS) device based on a compact S-band 40 MeV linac at AIST. The single-shot K-edge densitometry was also applicable to evaluate the transverse emittance of electron bunches.

THPPA02	EPS-AG Budker Prize Presentation: Retrospective of 24 years of RIBF Life	cyclotron, factory, ion, electron	2899
	Y. Yano RIKEN Nishina Center, Wako, Japan
	The speaker will look back on 24 years (from 1987 to now) devoted to the RIBF project.
	Slides THPPA02 [10.303 MB]

THPC008	Touschek Lifetime and Momentum Acceptance Measurements for ESRF	vacuum, emittance, synchrotron, electron	2921
	B. Nash, F. Ewald, L. Farvacque, J. Jacob, E. Plouviez, J.-L. Revol, K.B. Scheidt ESRF, Grenoble, France
	The Touschek lifetime of a synchrotron results from electrons scattering off one another within the bunch and subsequently being lost. We have measured the Touschek lifetime for the major operating modes of the ESRF as a function of RF voltages. This includes multibunch and few bunch filling patterns with correspondingly different chromaticity values. Through calibration of the RF voltage and measurement of the other beam parameters such as bunch length and vertical emittance, we may understand the momentum acceptance in the regime where this is determined by non-linear dynamics effects.

THPC045	Design of a Compact Storage Ring for the TTX	cavity, injection, kicker, emittance	3005
	H.S. Xu, W.-H. Huang, C.-X. Tang TUB, Beijing, People's Republic of China S.-Y. Lee IUCEEM, Bloomington, Indiana, USA
	We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented.

THPC102	Production of Coherent Optical \vCerenkov Radiation in Silica Aerogel	radiation, electron, photon, emittance	3125
	F.H. O'Shea, J.B. Rosenzweig UCLA, Los Angeles, California, USA
	As a demonstration of the apposite properties of silica aerogel as an electron beam diagnostic we intend to use it to produce coherent optical Cˇ erenkov radation (COCR). In this paper we propose an experiment and provide details of the challenges to be overcome in producing COCR.

THPC133	Pre-Conceptual Design Requirements For The MaRIE Facility At LANL And The Resulting X-Ray Free Electron Laser Baseline Design	photon, linac, electron, emittance	3197
	R.L. Sheffield, B.E. Carlsten LANL, Los Alamos, New Mexico, USA
	The MaRIE (Matter-Radiation Interactions in Extremes) facility is being proposed to advance materials science by the concurrent utilization of a diverse set of highly penetrating probes. These probes will provide the basis for developing materials that will perform predictably and on demand with currently unattainable lifetimes in extreme environments. The MaRIE facilities, the Multi-Probe Diagnostic Hall (MPDH), the Fission and Fusion Materials Facility (F³), and the Making, Measuring, and Modeling Materials (M4) Facility will each have experimental needs for one or more high-energy x-ray beam probes, but all require a 50-keV coherent source of greater than 10¹0 photons in less than 1 ps. Because of space considerations at the facility, a high-gradient design is being investigated that will use a X-band RF systems to drive a 20-GeV normal-conducting linac. Experimental requirements drive a need for multiple photon bunches over time durations greater than 1 microsecond, as well as interleaving 0.1 nC very-low-emittance bunches with 2-nC electron bunches. This paper will cover an overview of the scientific requirements for the MaRIE XFEL and the baseline XFEL design.

THPS036	Development of Thin NCS-foils by N+ Ion Beam Sputtering and Their Characteristics	ion, target, heavy-ion	3499
	I. Sugai, H. Kawakami, M. Oyaizu, Y. Takeda KEK, Ibaraki, Japan T. Hattori, K.K. Kawasaki RLNR, Tokyo, Japan
	We have developed thin Nitride Carbon Stripper foils (NCS-foil) with a higher nitrogen content by ion beam sputtering　method with reactive nitrogen gas. Such NCS-foils have been demonstrated that the foils in range of 10^-25 ug/m2 have shown long-lifetime as stripper foil against high intensity heavy ion beam bombardment. From the results, we found that the nitrogen element in the carbon foils plays very important role of the foil lifetime. Therefore, in order to investigate further influence of the lifetime on the nitrogen amount in the NCS-foils, we measured the sputtering yield at the different sputtering angles and carbon source materials. We also measured the ratio of nitrogen in carbon foil made at the different sputtering angles, target materials and the sputtering voltages of 4-15 kV by means of RBS method. The foil-lifetime made in above different conditions was measured with a 3.2 MeV Ne⁺ ion beam. The lifetime does not essentially depend on the sputtering angles and the target materials, and the maximum and average lifetimes showed 240 and 40 times longer than that of the CM-best foils.

THPS040	Measurement of the Stripping Efficiency for HBC Stripper Foil in the 3-GeV RCS of J-PARC	injection, extraction, proton, beam-losses	3511
	P.K. Saha, H. Harada, S. Hatakeyama, H. Hotchi, M. Kinsho, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan Y. Irie, I. Sugai KEK, Ibaraki, Japan
	We have carried out experimental measurement of the stripping efficiency for the newly developed HBC (Hybrid type Boron doped Carbon) stripper foils. The HBC foil is used for charge-exchange injection in the RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) and plays an important role for the RCS operation. We have developed a rather simple but very precise method using which stripping efficiencies for several HBC foils were determined accurately. Importance of knowing an accurate stripping efficiency so as to determine a realistic stripper foil for the RCS operation will be discussed.

THPS042	Feasibility Studies of the Foil Scattering Extraction in CSNS/RCS	extraction, beam-losses, simulation, 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, simulation, proton, synchrotron	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.

THPS073	Dosimetric Impact of Multiple Energy Operation in Carbon-ion Radiotherapy	target, ion, synchrotron, simulation	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.

THPS081	Design Choices of the MedAustron Nozzles and Proton Gantry based on Modeling of Particle Scattering	proton, vacuum, dipole, optics	3621
	M. Palm CERN, Geneva, Switzerland M. Benedikt, A. Fabich EBG MedAustron, Wr. Neustadt, Austria M. Palm ATI, Wien, Austria
	MedAustron, the Austrian hadron therapy center is currently under construction. Irradiations will be performed using active scanning with a proton or carbon ion pencil beam which is subject to scattering in vacuum windows, beam monitors and air gap. For applications where sharp lateral beam penumbras are required in order to spare critical organs from unwanted dose, scattering should be minimal. A semi-empirical scattering model has been established to evaluate beam size growth at the patient due to upstream scattering. Major design choices for proton gantry and nozzle based on the scattering calculations are presented.

THPS082	Dose-homogeneity Driven Beam Delivery System Performance Requirements for MedAustron	proton, ion, target, extraction	3624
	M. Palm, F. Moser CERN, Geneva, Switzerland M. Benedikt, A. Fabich EBG MedAustron, Wr. Neustadt, Austria M. Palm ATI, Wien, Austria
	MedAustron, the Austrian hadron therapy center is currently under construction. Irradiation will be performed using active scanning with proton or carbon ion pencil beams. Major beam delivery system contributors to dose heterogeneities during active scanning are evaluated: beam position, beam size and spot weight errors. Their individual and combined effect on the dose distribution is quantified, using semi-analytical models of lateral beam spread in the nozzle and target and depth-dose curves for protons and carbon ions. Deduced requirements on critical parts of the beam delivery system are presented. Preventive and active methods to suppress the impact of beam delivery inaccuracies are proposed.

THPS095	Q-factor of an Open Resonator for a Compact Soft X-ray Source based on Thomson Scattering of Stimulated Coherent Diffraction Radiation	cavity, radiation, electron, vacuum	3657
	A.S. Aryshev, S. Araki, M.K. Fukuda, J. Urakawa KEK, Ibaraki, Japan V. Karataev JAI, Egham, Surrey, United Kingdom G.A. Naumenko Tomsk Polytechnic University, Nuclear Physics Institute, Tomsk, Russia A. Potylitsyn, L.G. Sukhikh, D. Verigin TPU, Tomsk, Russia K. Sakaue RISE, Tokyo, Japan
	High-brightness and reliable sources in the VUV and the soft X-ray region may be used for numerous applications in such areas as medicine, biology, biochemistry, material science, etc. We have proposed a new approach to produce the intense beams of X-rays in the range of eV based on Thomson scattering of Coherent Diffraction Radiation (CDR) on a 43 MeV electron beam. CDR is generated when a charged particle moves in the vicinity of an obstacle. The radiation is coherent when its wavelength is comparable to or longer than the bunch length. The CDR waves are generated in an opened resonator formed by two mirrors. In this report the status of the experiment, the first CDR measurements at the multibunch beam of the LUCX facility and general hardware design will be reported.

THPS099	Design Study of a Nuclear Material Detection System Based on a Quasi Monochromatic Gamma Ray Generator and a Nuclear Resonance Fluorescence Gamma Ray Detection System	neutron, laser, background, photon	3666
	T. Kii, T. Hori, K. Masuda, H. Ohgaki, M. Omer Kyoto IAE, Kyoto, Japan R. Hajima, T. Hayakawa, M. Kando, T. Shizuma JAEA, Ibaraki-ken, Japan T. Misawa, C.H. Pyeon KURRI, Osaka, Japan H. Toyokawa AIST, Ibaraki, Japan
	Funding: This work was partially supported by Special Coordination Funds for romoting Science and Technology in Japan, Nuclear Resonance Fluorescence (NRF) measurement is a powerful tool for isotope detection for the homeland security such as a nondestructive measurement of containers at airports or harbors and detection or identification of special nuclear materials. In this paper, we will discuss on basic design of a quasi-monochromatic gamma-ray generator based on the backward Compton scattering of laser light on high-energy electrons and an NRF gamma ray detection system using a high-speed scintillation detector.

THPZ009	Beam Background Simulation for SuperKEKB/Belle-II	background, simulation, 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.

THPZ010	Beam Background and MDI Design for SuperKEKB/Belle-II	background, luminosity, radiation, positron	3702
	H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama KEK, Tsukuba, Japan H. Nakano Tohoku University, Graduate School of Science, Sendai, Japan
	The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at^-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x10³5 cm^-2s^-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.

Paper

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Other Keywords

Page

MOPO011

The First 1 1/2 Years of TOTEM Roman Pot Operation at LHC

alignment, controls, HOM, beam-losses

502

M. Deile, G.H. Antchev, R.W. Assmann, I. Atanassov, V. Avati, J. Baechler, R. Bruce, M. Dupont, K. Eggert, B. Farnham, J. Kaspar, F. Lucas Rodríguez, J. Morant, H. Niewiadomski, X. Pons, E. Radermacher, S. Ravat, F. Ravotti, S. Redaelli, G. Ruggiero, H. Sabba, M. Sapinski, W. Snoeys, G. Valentino, D. Wollmann
CERN, Geneva, Switzerland
R. Appleby
UMAN, Manchester, United Kingdom

Since the LHC running season 2010, the TOTEM Roman Pots (RPs) are fully operational and serve for collecting elastic and diffractive proton-proton scattering data. Like for other moveable devices approaching the high intensity LHC beams, a reliable and precise control of the RP position is critical to machine protection. After a review of the RP movement control and position interlock system, the crucial task of alignment will be discussed.

MOPS050

Electron Beam Dynamics in the 50 MeV ThomX Compact Storage Ring

electron, emittance, photon, collective-effects

715

C. Bruni, J. Haissinski
LAL, Orsay, France
A. Loulergue, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

ThomX is a high flux compact X-ray source based on Compton back scattering between a relativistic electron beam and an intense laser pulse. To increase the repetition rate, the electron beam is stored in a ring. The main drawback of such a scheme is the low energy of the electrons regarding collective effects and intrabeam scattering. These effects tend to enlarge or even disrupt the stored bunch and they limit its charge, especially in a system where damping plays a negligible role. Thus such collective effects reduce the maximum X-ray flux and it is important to investigate them to predict the performance of this type of X-ray source. In addition, the Compton back scattering acts on the electron beam by increasing its energy spread. This presentation will show firstly the impact of collective effects on the electron beam, essentially during the first turns when they are the most harmful. Then, the reduction of the X-ray flux due to Compton back scattering and intrabeam scattering will be investigated on a longer time scale.

MOPZ036

Ionization Cooling in MICE Step IV

emittance, simulation, 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.

TUPC062

Electron Beam Energy Measurement at the Australian Synchrotron Storage Ring

storage-ring, electron, synchrotron, resonance

1138

M.J. Boland
ASCo, Clayton, Victoria, Australia
H. Panopoulos, R.P. Rassool, K.P. Wootton
The University of Melbourne, Melbourne, Australia

The technique of resonant spin depolarization was used to precisely measure the electron beam energy in the storage ring at the Australian Synchrotron. A detector and data acquisition system dedicated to the measurement were developed. Using the system, the long term energy stability of the storage ring was monitored and a mechanical realignment of the ring was clearly seen in the energy data. Details of the parameters used to optimize the measurement are also discussed.

TUPC074

A New Counting Silicon Strip Detector System for Precise Compton Polarimetry

electron, polarization, photon, laser

1171

R. Zimmermann, W. Hillert, J.C. Wittschen
ELSA, Bonn, Germany

Funding: Supported by the German Research Foundation within the SFB/TR16
A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. Above all, as a result of ELSA's beam energies, it is necessary to measure the shift of the center of the photon spatial distribution which is obtained when the polarization of the laser is switched from left-hand to right-hand circular polarization with an accuracy of a few microns. In order to meet the required specifications, a new counting silicon strip detector system has been developed in cooperation with the SiLab/ATLAS group of the Physics Institute of the University of Bonn. In this contribution, the design of the system will be presented and first results will be shown.

TUPC091

Operational Results of the Diamond-based Halo Monitor during Commissioning of SPring-8 XFEL (SACLA)

electron, undulator, laser, wakefield

1218

H. Aoyagi
JASRI/SPring-8, Hyogo-ken, Japan
Y. Asano, H. Kitamura, T. Tanaka
RIKEN/SPring-8, Hyogo, Japan

Funding: This work is partly supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (c) 21604017.
Measurement of electron beam halo is very important issue for X-ray free electron laser and synchrotron radiation facilities, because the beam halo may cause radiation damage of undulator magnets. Furthermore, it may cause degradation in quality of electron beam, and radio activation of beam ducts and components. In order to prevent these situations, a diamond-based halo monitor (HM) has been developed for the SPring-8 Angstrom Compact free electron LAser (SACLA). We have achieved excellent detection limit of 0.3 fC/pulse for single-shot measurement, which corresponds to the ratio of 10^-6 to the beam core. The commissioning of the HM, which was installed at the upstream of 90m undulator, has been carried out, and it has been figured out that the intensity of the beam halo can be measured very nicely since secondary electrons and bremsstrahlung that are emitted in the accelerator components have not been observed. We also describe systematic profile measurements of the beam halo and operational results of the HM during the commissioning of SACLA.

TUPO013

Development of Pulse Width Measurement Techniques in a Picosecond Range of Ultra-short Gamma Ray Pulses

laser, photon, electron, storage-ring

1473

Y. Taira, M. Hosaka, K. Soda, N. Yamamoto
Nagoya University, Nagoya, Japan
M. Adachi, M. Katoh, H. Zen
Sokendai - Okazaki, Okazaki, Aichi, Japan
T. Tanikawa
UVSOR, Okazaki, Japan

Funding: This work was supported by Grants-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS).
We are developing the ultra-short gamma ray pulse source with the energy of MeV region based on laser Compton scattering at the 750 MeV electron storage ring, UVSOR-II. Gamma rays with pulse width of sub-picosecond range can be generated by injecting femtosecond laser pulses into the electron beam from the vertical 90-degree direction* because the electron beam circulating in the storage ring is focused more tightly in the vertical direction than in the longitudinal direction. The energy, intensity, and pulse width of the gamma rays can be tuned by changing the collision angle between the electron beam and the laser. We are developing pulse width measurement techniques of ultra-short gamma ray pulses at present. As the first step of the pulse width measurement, we used a fast response photodetector, Geiger-mode APD, the time resolution of which is few hundreds picoseconds. Although we cannot measure the pulse width of the gamma rays with sub-picosecond range using this detector, we could measure the pulse width of the gamma rays as 430 ps or less by measuring the timing of Cherenkov radiations generated from the gamma rays.
* Y. Taira et al., Nucl. Instrum. Meth. A, in press, 2010.

TUPO023

Narrow Spectral Bandwidth Optimization of Compton Scattering Sources

electron, laser, simulation, 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.

TUPO024

Precision X-band Linac Technologies for Nuclear Photonics Gamma-ray Sources

gun, electron, laser, photon

1491

F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, M. J. Messerly, S.S.Q. Wu
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, M.V. Fazio, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA
D. Cutoiu
Horia Hulubei National Institute for Physics and Nuclear Engineering, Bucharest, Romania
D. Ighigeanu, M. Toma
INFLPR, Bucharest - Magurele, Romania
V.A. Semenov
UCB, Berkeley, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies.

TUPS033

Foil Scattering Loss Mitigation by the Additional Collimation System of J-PARC RCS

injection, collimation, vacuum, septum

1605

K. Yamamoto, H. Harada, J. Kamiya, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the RCS, the significant losses were observed at the branch of H0 dump line and the Beam Position Monitor which was put at the downstream of the H0 dump branch duct. From the beam study, we were certain that these losses were caused by the scattering of the injection and circulating beam at the charge exchange injection foil. In order to mitigate these losses, we started to develop a new collimation system in the H0 branch duct. We presents a overview of this new collimation system.

TUPS086

Ultra-high Resolution Observation Device for Carbon Stripper Foil

radiation, monitoring, vacuum, proton

1740

Y. Takeda, Y. Irie, I. Sugai
KEK, Ibaraki, Japan

To observe a growth process of a pinhole on a HBC-foil due to beam irradiation, an up to 10 um of device for ultra-high resolution observation is needed. For the environment where we use the device for observation is so severe as under high radiation and in vacuum, there is no device available for long-time observation. Then, we designed and created a wholly new method based system which enables constant observation by ultra-high resolution even under high radiation environment. We attempted several experiments, compared materials usable under radiation environment, checked up various optical systems which enables high resolution, and finally developed the best method. As a result, we successfully invented an ultra-high resolution observation device available for monitoring an object about 8 meters distant by 8.3um resolution.

TUPZ001

90 m Optics Commissioning

optics, proton, coupling, injection

1795

S. Cavalier
LAL, Orsay, France
H. Burkhardt, M. Fitterer, G.J. Müller, S. Redaelli, R. Tomás, G. Vanbavinckhove, J. Wenninger
CERN, Geneva, Switzerland

Special β* = 90 m optics have been developed for the two very high luminosity insertions of the LHC, as a first step towards to allow for very low angle precision measurements of the proton-proton collisions in the LHC. These optics were developed to be compatible with the standard LHC injection and ramp optics. The target value of β* = 90 m is reached by an un-squeeze from the injection β* = 11 m. We describe the implementation of this optics in the LHC and the first experience in the commissioning of these optics.

TUPZ002

90 m β* Optics for ATLAS/ALFA

optics, emittance, luminosity, quadrupole

1798

S. Cavalier, P.M. Puzo
LAL, Orsay, France
H. Burkhardt
CERN, Geneva, Switzerland
A. Peskov
NNGU, Nizhny Novgorod, Russia

We describe a high β* optics developed for the ATLAS detector at the LHC interaction regions (IR1), Roman Pots have been installed 240 m left and right of IR1 to allow to measure the absolute luminosity and the total elastic cross section for ATLAS with ALFA (Absolute Luminosity for ATLAS). Ultimately, it is planned to preform these measurements at a very high β* of 2625 m. Here we describe a new, intermediate β* = 90 m optics, which has been optimized for compatibility with the present LHC running conditions. We described the main features and expected performance of this optics for ALFA.

TUPZ011

LHC Collimation with a Reduced Beam Pipe Radius in ATLAS

simulation, optics, collimation, 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.

WEIB01

Chasing Femtoseconds – How Accelerators Can Benefit from Economies of Scale in Other Industries

laser, optics, polarization, controls

1973

M. Vidmar, J. Tratnik
University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia
P.L. Lemut
COBIK, Solkan, Slovenia

Building accelerators we frequently push the limits of what is possible in terms of performance. When trying to solve a very challenging engineering problem, we normally resort to specialization; we narrow our focus. This talk suggests a possible alternative path. Huge benefits and great results can be achieved by combining creative ideas and approaches with ideas and solutions borrowed from the economies of scale like telecommunications. The aim of the talk is to show possibilities for combining ideas, technologies and components from different industries into innovative products.

Slides WEIB01 [0.799 MB]

WEPC045

Transverse Emittance Reduction with Tapered Foil

emittance, electron, target, simulation

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.

WEPC051

Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring

electron, laser, damping, cavity

2127

I. Chaikovska, C. Bruni, N. Delerue, A. Variola, Z.F. Zomer
LAL, Orsay, France
K. Kubo, T. Naito, T. Omori, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of e⁺e⁻ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-Perot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and will be used to produce an intense flux of polarized gamma rays by Compton scattering. For electrons at the energy of the ATF (1.28GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed.

WEPC064

Long Term Beam Dynamics in Ultra-Low Energy Storage Rings

ion, storage-ring, antiproton, target

2166

A.V. Smirnov
MPI-K, Heidelberg, Germany
A.I. Papash, A.V. Smirnov
JINR, Dubna, Moscow Region, Russia
M.R.F. Siggel-King, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: "Work supported by STFC, the Helmholtz Association and GSI under contract VH-NG-328."
Electrostatic storage rings operate at very low energies in the tens of keV range and have proven to be invaluable tools for atomic and molecular physics experiments. However, earlier measurements showed strong limitations in beam intensity, a fast reduction in the stored ion current, as well as significantly reduced beam life time at higher beam intensities and as a function of the ion optical elements used in the respective storage ring. In this contribution, the results from studies with the computer code BETACOOL into the long term beam dynamics in such storage rings, based on the examples of ELISA, the AD Recycler and the USR are presented.

WEPC098

Automatic Pole and Q-Value Extraction for RF Structures

resonance, cavity, RF-structure, cryomodule

2241

C. Potratz, H.-W. Glock, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
F. Marhauser
JLAB, Newport News, Virginia, USA

The experimental characterization of RF structures like accelerating cavities often demands for measuring resonant frequencies of Eigenmodes and corresponding (loaded) Q-values over a wide spectral range. A common procedure to determine the Q-values is the -3dB method, which works well for isolated poles, but may not be applicable directly in case of multiple poles residing in close proximity (e.g. for adjacent transverse modes differing by polarization). Although alternative methods may be used in such cases, this often comes at the expense of inherent systematic errors. We have developed an automation algorithm, which not only speeds up the measurement time significantly, but is also able to extract Eigenfrequencies and Q-values both for well isolated and overlapping poles. At the same time the measurement accuracy may be improved as a major benefit. To utilize this procedure merely complex scattering parameters have to be recorded for the spectral range of interest. In this paper we present the proposed algorithm applied to experimental data recorded for superconducting higher-order-mode damped multi-cell cavities as an application of high importance.

WEPC099

Coupler Design and Optimization by GPU-Accelerated DG-FEM

HOM, simulation, 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.

WEPC105

Multiparticle Simulation of Intrabeam Scattering for SuperB

emittance, simulation, damping, 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, simulation, vacuum, 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.

WEPC116

A Matrix Presentation for a Beam Propagator including Particles Spin

collider, storage-ring, controls, heavy-ion

2283

M. Kosovtsov, S.N. Andrianov, A.N. Ivanov
St. Petersburg State University, St. Petersburg, Russia

Particles beam dynamics in magnetic and electrical fields with spin is discussed. This approach provides a constructive method of matrix presentation derivation for a beam propagator in magnetic and electrical fields. The beam propagator is evaluated in according to the well-known Lie algebraic tools. But in contrast to traditional approaches matrix presentation for Lie propagators bases on two-indexes matrices. This approach permit to apply all of matrix algebra opportunities and advantages in contrast with the tenzor presentation based on multi-indexes description. The necessary computation can be realized in symbolic (using computer algebra codes as Mathematica, Maple, Maxima and so on). The corresponding symbolic objects itself can be stored in special databases and used then in numerical computing. Parallel and distributed conception is well acceptable with the suggested matrix formalism. Some symbolic and numerical results are discussed for problems of long term evolution of particles with spin.

WEPC132

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

electron, simulation, vacuum, 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).

WEPC141

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

photon, electron, simulation, 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.

WEPO022

Tightening the Tolerance Budget of Core Fabrication to Achieve Higher Magnet Performance

sextupole, vacuum, dipole, quadrupole

2448

N. Li, A. Madur
LBNL, Berkeley, California, USA
J. Jin
SINAP, Shanghai, People's Republic of China

Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231.
Traditionally, laminated cores of AC magnets have been always built by the laminations that are produced by a punching die. There are 5 links in the tolerance chain when a magnet core is built by this procedure: 1. Error of punching die; 2. Error of lamination punching; 3. Error of half core stacking; 4. Error of core assembly; and 5. Error of magnet re-assembling during the installation in the accelerator. As time goes on, the Lattice physicists call for more and more ever higher magnet performance, which makes the required magnet field quality almost impossible achieve by traditional core fabrication procedures. It is the goal of this paper to describe a relatively new procedure that was first used by Buckley System Ltd, NZ and is being used at SINAP, China for ALS combined function sextupole core fabrication. The advantage of this new procedure and the fabrication issues related to this procedure will be described in this paper.

WEPS005

Investigation of Intrabeam Scattering in the Heavy Ion Storage Ring TSR

ion, bunching, electron, storage-ring

2490

S.T. Artikova, M. Grieser, J. Ullrich
MPI-K, Heidelberg, Germany

Intrabeam scattering (IBS) is a multiple scattering effect between stored beam particles. It leads to diffusion in all three spatial dimensions and thus, causes an expansion of the whole beam. IBS plays an important role in the equilibrium diameter of a low-velocity, electron-cooled ion beam. IBS effects for coasting and bunched 12C⁶⁺ ion beams at an energy of 73.3 MeV were studied using the TSR heavy ion cooler storage ring. Experimental results of the IBS rates are presented.

WEPS047

Beamloss Study at J-PARC Linac by using Geant4 Simulation

beam-losses, simulation, 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.

WEPS098

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

collimation, synchrotron, simulation, 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”.

WEPZ011

Fast Cooling of Bunches in Compton Storage Rings

laser, electron, emittance, photon

2790

E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
J. Urakawa
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling', the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.

WEPZ027

Stabilization of the LWFA and its Application to the Single-shot K-edge Densitometry

electron, laser, emittance, wakefield

2823

K. Koyama, H. Madokoro, Y. Matsumura
University of Tokyo, Tokyo, Japan
R. Kuroda, K. Yamada
AIST, Tsukuba, Ibaraki, Japan
H. Masuda, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
S. Masuda
Osaka University, Suita, Osaka, Japan

Funding: This work was supported in part by Global COE Program “Nuclear Education and Research Initiative,” MEXT, Japan
Injection of electrons into a laser wakefield accelerator (LWFA) via a wavebreaking process was investigated in order to obtain stable output of electron bunches. A density down ramp for occurring the wavebreaking was formed by an oblique shockwave, which was excited by setting a little flow-deflector on an edge of the supersonic nozzle of high-Mach number (M=5). Parameters of the jet were examined by using PIC code and evaluated by using an interferometer, the density was 10¹⁹cm^-3, density ratio was 2, and the characteristic length was 70 microns. Injection experiments using 7-TW laser pulses suggested that electrons were injected in the density ramp. Since the all-optical Compton X-ray is attractive source for an accurate densitometry, a preliminary experiment of a single-shot K-edge densitometry was performed by using X-ray pulses generated by the laser-Compton scattering (LCS) device based on a compact S-band 40 MeV linac at AIST. The single-shot K-edge densitometry was also applicable to evaluate the transverse emittance of electron bunches.

THPPA02

EPS-AG Budker Prize Presentation: Retrospective of 24 years of RIBF Life

cyclotron, factory, ion, electron

2899

Y. Yano
RIKEN Nishina Center, Wako, Japan

The speaker will look back on 24 years (from 1987 to now) devoted to the RIBF project.

Slides THPPA02 [10.303 MB]

THPC008

Touschek Lifetime and Momentum Acceptance Measurements for ESRF

vacuum, emittance, synchrotron, electron

2921

B. Nash, F. Ewald, L. Farvacque, J. Jacob, E. Plouviez, J.-L. Revol, K.B. Scheidt
ESRF, Grenoble, France

The Touschek lifetime of a synchrotron results from electrons scattering off one another within the bunch and subsequently being lost. We have measured the Touschek lifetime for the major operating modes of the ESRF as a function of RF voltages. This includes multibunch and few bunch filling patterns with correspondingly different chromaticity values. Through calibration of the RF voltage and measurement of the other beam parameters such as bunch length and vertical emittance, we may understand the momentum acceptance in the regime where this is determined by non-linear dynamics effects.

THPC045

Design of a Compact Storage Ring for the TTX

cavity, injection, kicker, emittance

3005

H.S. Xu, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented.

THPC102

Production of Coherent Optical \vCerenkov Radiation in Silica Aerogel

radiation, electron, photon, emittance

3125

F.H. O'Shea, J.B. Rosenzweig
UCLA, Los Angeles, California, USA

As a demonstration of the apposite properties of silica aerogel as an electron beam diagnostic we intend to use it to produce coherent optical Cˇ erenkov radation (COCR). In this paper we propose an experiment and provide details of the challenges to be overcome in producing COCR.

THPC133

Pre-Conceptual Design Requirements For The MaRIE Facility At LANL And The Resulting X-Ray Free Electron Laser Baseline Design

photon, linac, electron, emittance

3197

R.L. Sheffield, B.E. Carlsten
LANL, Los Alamos, New Mexico, USA

The MaRIE (Matter-Radiation Interactions in Extremes) facility is being proposed to advance materials science by the concurrent utilization of a diverse set of highly penetrating probes. These probes will provide the basis for developing materials that will perform predictably and on demand with currently unattainable lifetimes in extreme environments. The MaRIE facilities, the Multi-Probe Diagnostic Hall (MPDH), the Fission and Fusion Materials Facility (F³), and the Making, Measuring, and Modeling Materials (M4) Facility will each have experimental needs for one or more high-energy x-ray beam probes, but all require a 50-keV coherent source of greater than 10¹0 photons in less than 1 ps. Because of space considerations at the facility, a high-gradient design is being investigated that will use a X-band RF systems to drive a 20-GeV normal-conducting linac. Experimental requirements drive a need for multiple photon bunches over time durations greater than 1 microsecond, as well as interleaving 0.1 nC very-low-emittance bunches with 2-nC electron bunches. This paper will cover an overview of the scientific requirements for the MaRIE XFEL and the baseline XFEL design.

THPS036

Development of Thin NCS-foils by N+ Ion Beam Sputtering and Their Characteristics

ion, target, heavy-ion

3499

I. Sugai, H. Kawakami, M. Oyaizu, Y. Takeda
KEK, Ibaraki, Japan
T. Hattori, K.K. Kawasaki
RLNR, Tokyo, Japan

We have developed thin Nitride Carbon Stripper foils (NCS-foil) with a higher nitrogen content by ion beam sputtering　method with reactive nitrogen gas. Such NCS-foils have been demonstrated that the foils in range of 10^-25 ug/m2 have shown long-lifetime as stripper foil against high intensity heavy ion beam bombardment. From the results, we found that the nitrogen element in the carbon foils plays very important role of the foil lifetime. Therefore, in order to investigate further influence of the lifetime on the nitrogen amount in the NCS-foils, we measured the sputtering yield at the different sputtering angles and carbon source materials. We also measured the ratio of nitrogen in carbon foil made at the different sputtering angles, target materials and the sputtering voltages of 4-15 kV by means of RBS method. The foil-lifetime made in above different conditions was measured with a 3.2 MeV Ne⁺ ion beam. The lifetime does not essentially depend on the sputtering angles and the target materials, and the maximum and average lifetimes showed 240 and 40 times longer than that of the CM-best foils.

THPS040

Measurement of the Stripping Efficiency for HBC Stripper Foil in the 3-GeV RCS of J-PARC

injection, extraction, proton, beam-losses

3511

P.K. Saha, H. Harada, S. Hatakeyama, H. Hotchi, M. Kinsho, Y. Yamazaki, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
Y. Irie, I. Sugai
KEK, Ibaraki, Japan

We have carried out experimental measurement of the stripping efficiency for the newly developed HBC (Hybrid type Boron doped Carbon) stripper foils. The HBC foil is used for charge-exchange injection in the RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex) and plays an important role for the RCS operation. We have developed a rather simple but very precise method using which stripping efficiencies for several HBC foils were determined accurately. Importance of knowing an accurate stripping efficiency so as to determine a realistic stripper foil for the RCS operation will be discussed.

THPS042

Feasibility Studies of the Foil Scattering Extraction in CSNS/RCS

extraction, beam-losses, simulation, 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, simulation, proton, synchrotron

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.

THPS073

Dosimetric Impact of Multiple Energy Operation in Carbon-ion Radiotherapy

target, ion, synchrotron, simulation

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.

THPS081

Design Choices of the MedAustron Nozzles and Proton Gantry based on Modeling of Particle Scattering

proton, vacuum, dipole, optics

3621

M. Palm
CERN, Geneva, Switzerland
M. Benedikt, A. Fabich
EBG MedAustron, Wr. Neustadt, Austria
M. Palm
ATI, Wien, Austria

MedAustron, the Austrian hadron therapy center is currently under construction. Irradiations will be performed using active scanning with a proton or carbon ion pencil beam which is subject to scattering in vacuum windows, beam monitors and air gap. For applications where sharp lateral beam penumbras are required in order to spare critical organs from unwanted dose, scattering should be minimal. A semi-empirical scattering model has been established to evaluate beam size growth at the patient due to upstream scattering. Major design choices for proton gantry and nozzle based on the scattering calculations are presented.

THPS082

Dose-homogeneity Driven Beam Delivery System Performance Requirements for MedAustron

proton, ion, target, extraction

3624

M. Palm, F. Moser
CERN, Geneva, Switzerland
M. Benedikt, A. Fabich
EBG MedAustron, Wr. Neustadt, Austria
M. Palm
ATI, Wien, Austria

MedAustron, the Austrian hadron therapy center is currently under construction. Irradiation will be performed using active scanning with proton or carbon ion pencil beams. Major beam delivery system contributors to dose heterogeneities during active scanning are evaluated: beam position, beam size and spot weight errors. Their individual and combined effect on the dose distribution is quantified, using semi-analytical models of lateral beam spread in the nozzle and target and depth-dose curves for protons and carbon ions. Deduced requirements on critical parts of the beam delivery system are presented. Preventive and active methods to suppress the impact of beam delivery inaccuracies are proposed.

THPS095

Q-factor of an Open Resonator for a Compact Soft X-ray Source based on Thomson Scattering of Stimulated Coherent Diffraction Radiation

cavity, radiation, electron, vacuum

3657

A.S. Aryshev, S. Araki, M.K. Fukuda, J. Urakawa
KEK, Ibaraki, Japan
V. Karataev
JAI, Egham, Surrey, United Kingdom
G.A. Naumenko
Tomsk Polytechnic University, Nuclear Physics Institute, Tomsk, Russia
A. Potylitsyn, L.G. Sukhikh, D. Verigin
TPU, Tomsk, Russia
K. Sakaue
RISE, Tokyo, Japan

High-brightness and reliable sources in the VUV and the soft X-ray region may be used for numerous applications in such areas as medicine, biology, biochemistry, material science, etc. We have proposed a new approach to produce the intense beams of X-rays in the range of eV based on Thomson scattering of Coherent Diffraction Radiation (CDR) on a 43 MeV electron beam. CDR is generated when a charged particle moves in the vicinity of an obstacle. The radiation is coherent when its wavelength is comparable to or longer than the bunch length. The CDR waves are generated in an opened resonator formed by two mirrors. In this report the status of the experiment, the first CDR measurements at the multibunch beam of the LUCX facility and general hardware design will be reported.

THPS099

Design Study of a Nuclear Material Detection System Based on a Quasi Monochromatic Gamma Ray Generator and a Nuclear Resonance Fluorescence Gamma Ray Detection System

neutron, laser, background, photon

3666

T. Kii, T. Hori, K. Masuda, H. Ohgaki, M. Omer
Kyoto IAE, Kyoto, Japan
R. Hajima, T. Hayakawa, M. Kando, T. Shizuma
JAEA, Ibaraki-ken, Japan
T. Misawa, C.H. Pyeon
KURRI, Osaka, Japan
H. Toyokawa
AIST, Ibaraki, Japan

Funding: This work was partially supported by Special Coordination Funds for romoting Science and Technology in Japan,
Nuclear Resonance Fluorescence (NRF) measurement is a powerful tool for isotope detection for the homeland security such as a nondestructive measurement of containers at airports or harbors and detection or identification of special nuclear materials. In this paper, we will discuss on basic design of a quasi-monochromatic gamma-ray generator based on the backward Compton scattering of laser light on high-energy electrons and an NRF gamma ray detection system using a high-speed scintillation detector.

THPZ009

Beam Background Simulation for SuperKEKB/Belle-II

background, simulation, 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.

THPZ010

Beam Background and MDI Design for SuperKEKB/Belle-II

background, luminosity, radiation, positron

3702

H. Nakayama, M. Iwasaki, K. Kanazawa, Y. Ohnishi, S. Tanaka, T. Tsuboyama
KEK, Tsukuba, Japan
H. Nakano
Tohoku University, Graduate School of Science, Sendai, Japan

The Belle experiment, operated at the asymmetric electron-positron collider KEKB, had accumulated a data sample with an integrated luminosity of more than 1 at^-1before the shutdown in June 2010. We have started upgrading both the accelerator and detector, SuperKEKB and Belle-II, to achieve the target luminosity of 8x10³5 cm^-2s^-1. With the increased luminosity, the beam background will also increase. The development of Machine-Detector Interface (MDI) design is very important to cope with the increased background and protect Belle-II detector. We will present the estimation of impact from each beam background sources at SuperKEKB and our countermeasures for them, such as collimators to stop Touschek-scattered beam particles, Tungsten shield to protect inner detectors from shower particles, dedicated beam pipe design around interaction point to stop synchrotron radiation, etc.