2011 Particle Accelerator Conference - List of Keywords (scattering)

Paper	Title	Other Keywords	Page
MOP022	The Expected Performance of MICE Step IV	emittance, optics, solenoid, lattice	151
	T. Carlisle, J.H. Cobb JAI, Oxford, United Kingdom
	Funding: STFC The international Muon Ionization Cooling Experiment (MICE), under construction at the Rutherford Appleton Laboratory in Oxfordshire (UK), is a test of a prototype cooling channel for a future Neutrino Factory. The experiment aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance, measured to an accuracy of 1% by two scintillating fibre trackers within 4 T solenoid fields. Step IV of MICE will begin in 2012, producing the experiment's first cooling measurements. Step IV uses an absorber focus coil module, placed between the two trackers, to house liquid hydrogen or solid absorbers. The performance of Step IV using various absorber materials was simulated. Multiple scattering in high Z absorbers was found to mismatch the beam with the lattice optics, which was largely corrected by re-tuning the MICE lattice accordingly.

MOP038	Non-Magnetic Momentum Spectrometer Based on Fast Time-of-Flight System	electron, factory, simulation, cathode	169
	R.J. Abrams, C.M. Ankenbrandt, G. Flanagan, S.A. Kahn, M. Notani, T.J. Roberts Muons, Inc, Batavia, USA H.J. Frisch Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
	Funding: Supported in part by SBIR Grant DE-SC0005445 A new generation of large-area, low cost time-of-flight detectors with time resolutions ≤ 10 ps and space resolutions ≤ 1 mm is being developed for use in nuclear and particle physics experiments, as well as for medical and industrial applications. Such detectors can serve as the basis for measuring momenta without requiring measurement of curvature in magnetic fields. Factors affecting measurement accuracy and simulation results are presented.

MOP040	Fast Time-of-Flight System for Muon Cooling Experiments	simulation, cathode, emittance, collider	172
	R.J. Abrams, C.M. Ankenbrandt, G. Flanagan, S.A. Kahn, M. Notani, T.J. Roberts Muons, Inc, Batavia, USA H.J. Frisch Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
	Funding: Supported in part by SBIR Grant DE-SC0005445. A new generation of large-area, low cost time-of-flight detectors with time resolutions ≤ 10 ps and space resolutions ≤ 1 mm is being developed for use in nuclear and particle physics experiments, as well as for medical and industrial applications. Such detectors are being considered for use in muon cooling channel tests. Designs and fabrication of prototype planes and associated readout electronics are described. Results of simulations of time and space resolutions are presented.

MOP060	Wedge Absorber Design and Simulation for MICE Step IV	emittance, simulation, lattice, controls	220
	C.T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom L. Coney, G.G. Hanson UCR, Riverside, California, USA P. Snopok IIT, Chicago, Illinois, USA
	Funding: Work is supported by the Science and Technology Facilities Council, the U.S. Department of Energy and the U.S. National Science Foundation. In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material, then through RF cavities to compensate for the energy loss; which reduces the transverse emittance. It is planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge absorber in Step IV. Based on the outcome of previous studies, the shape and material of the wedge were chosen. We address here further simulation efforts for the absorber of choice as well as engineering considerations in connection with the absorber support design.

MOP182	Measurement of the Energy Dependence of Touschek Electron Counting Rate	electron, background, wiggler, polarization	426
	I.B. Nikolaev, V.E. Blinov, V.A. Kiselev, S.A. Nikitin, V.V. Smaluk BINP SB RAS, Novosibirsk, Russia
	We have measured a dependence of the intra-beam scattering rate on the VEPP-4M beam energy and compared it with our theoretical estimates. Measurements have been performed at several energy points in a wide range: from 1.85 up to 4.0 GeV.

MOP190	Precision, Absolute Proton Beam Polarization Measurements at 200 MeV Beam	proton, polarization, target, monitoring	444
	G. Atoian, A. Zelenski BNL, Upton, Long Island, New York, USA A. Bogdanov, M.F. Runtso MEPhI, Moscow, Russia E.J. Stephenson IUCF, Bloomington, Indiana, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. A new polarimeter for absolute proton beam polarization measurements at 200 MeV to accuracy better than ±0.5% has been developed as a part of the RHIC polarized source upgrade. The polarimeter is based on the elastic proton-carbon scattering at 16.2 degree angle, where the analyzing power is close to 100% and was measured with high accuracy. The elastically and in-elastically scattered protons are clearly identified by the difference in the propagation through variable copper absorber and energy deposition of the protons in the detectors. The 16.2 degree elastic scattering polarimeter was used for calibration of a high rate inclusive 12 degree polarimeter for the on-line polarization tuning and monitoring. This technique can be used for accurate polarization measurements in energy range of at least 160-250 MeV.

MOP209	Proposed Scattered Electron Detector System as One of the Beam Overlap Diagnostic Tools for the New RHIC Electron Lens	electron, proton, solenoid, diagnostics	489
	P. Thieberger, E.N. Beebe, C. Chasman, W. Fischer, D.M. Gassner, X. Gu, R.C. Gupta, J. Hock, R.F. Lambiase, Y. Luo, M.G. Minty, C. Montag, M. Okamura, A.I. Pikin, Y. Tan, J.E. Tuozzolo, W. Zhang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. An electron lens for head-on beam-beam compensation planned for RHIC requires precise overlap of the electron and proton beams which both can have down to 0.3 mm rms transverse radial widths along the 2m long interaction region. Here we describe a new diagnostic tool that is being considered to aid in the tuning and verification of this overlap. Some of ultra relativistic protons (100 or 250 GeV) colliding with low energy electrons (2 to 10 keV) will transfer sufficient transverse momentum to cause the electrons to spiral around the magnetic guiding field in a way that will make them detectable outside of the main solenoid. Time-of-flight of the halo electron signals will provide position-sensitive information along the overlap region. Scattering cross sections are calculated and counting rate estimates are presented as function of electron energy and detector position.

MOP238	Laser Compton Proton Polarimetry Revisited	photon, proton, laser, electron	560
	A.N. Stillman Private Address, Huntington, USA
	Compton polarimetry of polarized proton beams is more feasible now than it was in 1995, when I first estimated the laser requirements of a polarimeter using the available laser technology. New methods of high energy photon generation make the technique of Compton proton polarimetry a viable option for polarized proton beams. Since the analyzing power of a Compton polarimeter increases with photon energy and the count rate of the polarimeter increases with the laser intensity, the new laser technologies available today imply the construction of a working device with reasonable effort. I estimate the device parameters necessary for a working Compton polarimeter at RHIC using several methods of high energy photon generation. Arnold Stillman, in Proceedings of the 1995 Particle Accelerator Conference, 1995, p.2560

TUP005	Comparison of Back-scattering Properties of Electron Emission Materials	electron, simulation, target, feedback	817
	Z. Insepov, V. Ivanov, S.J. Jokela, M. Wetstein ANL, Argonne, USA
	We use “microscopic” Monte Carlo (MC) simulations, empirical theories, and comparison with experiments to identify the influence of back-scattered electrons and the saturation effect on the emissive properties of materials and to study the gain and transit times for various microchannel plates (MCPs). We have applied this method to Al2O3 and MgO emissive materials of various thickness and surface quality. The experimental secondary emission yield (SEY) data were obtained at normal electron impacts and were used as the reference data for adjusting our MC simulations. The SEY data were calculated at oblique angles of the primary electrons in the interval of 0-80 degrees. The energy dependence of backscattered electron coefficients (BSCs) for various primary electron incidence angles was calculated by MC for both materials, and the results were compared with experimental “average” values obtained in the literature. Both SEY and BSC data were used as input files to our “macroscopic” trajectory simulation, which models MCP amplifiers as whole devices and is capable of gain and transit time calculations.

TUP009	A Computational Model for Muons Passing Gas and Plasma Targets: Beam Emittance.	target, simulation, emittance, collective-effects	823
	A. Samolov, A.L. Godunov ODU, Norfolk, Virginia, USA
	A good understanding of interaction of muon beams with gas targets is crucial for attaining high acceleration gradients in gas pressured RF cavities. This physics includes a number of challenging problems. Our objective has been to develop a computational model for studying the most important effects within the same level of accuracy. The computational model simulates scattering of a bunch of charged particles on multiple atomic, molecular and ionic centers. The interaction potentials have been calculated using Hartree-Fock method for atomic targets, and Molecular Orbital method for molecular targets. Target particles are populated randomly to simulate either a gas in a pressured RF cavity with a particular material density, or liquid hydrogen. In the present work the following effects on beam emittance have been studied: effect of multiple scattering (comparing to single particle tracking models), effect of various degree of target ionization (beam-plasma interaction), space charge screening in plasma, effect of strong magnetic fields. Our preliminary results demonstrate that the degree of plasma ionization has a strong effect of the beam emittance.

TUP013	A Concept Design of a Compton Scattering Light Source based on the HLS Electron Storage Ring	electron, laser, photon, storage-ring	835
	X.C. Lai, H. Hao, H.Q. Huang, W.W. Li, X.Q. Wang, D.R. Xu USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: National Natural Science Foundation of China (Contract NO. 11045003) Hefei Light Source (HLS) is a 2nd generation light source lasering high flux ultraviolet and soft x-ray with 200 MeV to 800 MeV electron beam. To explorer other applications of the electron storage ring of HLS, a concept design of Hefei Compton Scattering Light Source (HCSLS) is proposed. In this paper, Compton Scattring Simulation Code(CSSC), a parallel code based on the analytical method to simulate the Compton scattering between the laser beam and the electron beam, is presented. Using the CSSC, it is computed that HCSLS will produce photons with a total flux of 10⁹ s^-1 to 10¹1 s^-1, and energy of 0.07 MeV to 1.15 MeV at the maximum spectral flux density with the 200 MeV to 800 MeV electron beam scattering with a kilo-watts CO2 laser. With a much shorter wave laser beam from an Nd:YVO4 laser, the scattered photons energy at the maximum spectral flux density is improved by a factor of 10, while its flux is reduce by a factor of 100 due to the lower peak laser power.

TUP124	Phase Contrast Imaging Using a Single Picosecond X-ray Pulse of the Inverse Compton Source at the BNL Accelerator Test Facility	photon, brightness, electron, laser	1062
	M. Carpinelli Università di Sassari and INFN, Sassari, Italy P. Delogu, M. Endrizzi INFN-Pisa, Pisa, Italy B. Golosio, P. Oliva INFN-Cagliari, Monserrato (Cagliari), Italy I. Pogorelsky, V. Yakimenko BNL, Upton, Long Island, New York, USA
	Inverse Compton scattering (ICS) X-ray sources are of current interest due to their novel features that enable new methods in medical and biological imaging. As a compelling example of such a possibility, we present an experimental demonstration of single shot inline phase contrast imaging using the ICS source located at the BNL Accelerator Test Facility. The phase contrast effect is clearly observed in the images obtained. Further, its qualities are shown to be in agreement with the predictions of theoretical models through comparison of experimental and simulated images of a set of plastic wires of differing composition and size. We also display an example of application of the technique to single shot phase contrast imaging of a biological sample.

TUP242	Electron Cloud Issues for the APS Superconducting Undulator	photon, electron, undulator, ion	1283
	K.C. Harkay, Y. Ivanyushenkov, R. Kustom, E.R. Moog, E. Trakhtenberg ANL, Argonne, USA L.E. Boon, A.F. Garfinkel Purdue University, West Lafayette, Indiana, USA
	Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. The APS Upgrade calls for the development and commissioning of a superconducting undulator (SCU) at the Advanced Photon Source (APS), a 7-GeV electron synchrotron. Operation of an SCU at Angstromquelle Karlsruhe (ANKA), also an electron ring, suggests that electron multipacting is consistent with the observed heat load and pressure rise, but this effect is not predicted by an electron cloud generation code. At APS it was found that while the cloud code POSINST agreed fairly well with retarding field analyzer (RFA) data for a positron beam (operated 1996-98), the agreement was less satisfactory for the electron beam. The APS data suggest that the photoelectron model is not complete. Given that the heat load is a critical parameter in designing the cryosystem for the SCU and given the experience at ANKA, a study is underway to minimize the possible contribution to the heat load by the electron cloud at the APS, the photoelectrons in particular. In this talk, the results from POSINST are presented. Preliminary tracking of the photon flux using SYNRAD3D for the APS SCU chamber is presented, and possible ways to mitigate the photoelectrons are discussed.

WEP090	Simulation Study of Intrabeam Scattering in Low Emittance Ring	emittance, simulation, lattice, storage-ring	1639
	W. Fan, G. Feng, D.H. He, W. Li, L. Wang, S.C. Zhang, T. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	HALS(Hefei Advanced Light Source) is under designing dedicated to good coherence and high brightness at 1.5GeV. Low emittance is required to reach the design request. Due to the low energy and emittance with relative high bunch charge, intrabeam scattering effect will be very strong. It is worth accurately calculating to check if the design goal can be reached. Theoretic calculation based on Gaussian beam distribution doesn't warrant in strong IBS regime. In this paper we present the results of particle simulation study of intrabeam scattering effect on a temporary design lattice of HALS ring.

WEP138	Developing Software Packages for Electromagnetic Simulations	simulation, vacuum, electromagnetic-fields, radio-frequency	1740
	J. Xu, M. Min, B. Mustapha ANL, Argonne, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. In addition to previous developments on parallel beam dynamics software packages, our efforts have been extended to electromagnetic simulations. These efforts include developing new software packages solving the Maxwell equations in 2D and 3D. Scalable algorithms have been used for use of ALCF supercomputers. These new solvers are based on high order numerical methods. Comparative studies of structured and unstructured grids, continuous and discontinuous Galerkin methods will be discussed. The effects of bases will also be presented. Efficiency and challenges of new software packages will be presented. Some benchmarking and simulation results will be shown.

WEP161	Modeling and Simulations of Electron Emission from Diamond-Amplified Cathodes	electron, simulation, vacuum, cathode	1791
	D.A. Dimitrov, R. Busby, J.R. Cary, D.N. Smithe Tech-X, Boulder, Colorado, USA I. Ben-Zvi, X. Chang, T. Rao, J. Smedley, E. Wang, Q. Wu BNL, Upton, Long Island, New York, USA
	Funding: This work is supported by the U. S. Department of Energy under the DE-SC0004431 grant. Emission of electrons from a diamond-amplified cathode was recently demonstrated. This experiment was based on a promising new concept* for generation of high-current, high-brightness, and low thermal emittance electron beams. The measurements from transmission and emission experiments have shown the potential to realize the diamond-amplified cathode concept. However, the results indicate that the involved physical properties should be understood in greater detail to build diamond cathodes with optical properties. We have already made progress in understanding the secondary electron generation and charge transport in diamond with the models we implemented in the VORPAL computational framework. We have been implementing models for electron emission from diamond and will present results from 3D VORPAL simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, propagation of the charge clouds, and then the emission of electrons into diamond. We will discuss simulation results on the dependence of the electron emission on diamond surface properties. * X. Chang et al., Electron Beam Emission from a Diamond-Amplified Cathodes, to appear in Phys. Rev. Lett. (2010). ** I. Ben-Zvi et al., Secondary emission enhanced photoinjector, Rep. C-A/AP/149, BNL (2004).

WEP162	Modeling of Diamond Based Devices for Beam Diagnostics	electron, photon, simulation, diagnostics	1794
	D.A. Dimitrov, R. Busby Tech-X, Boulder, Colorado, USA I. Ben-Zvi, J.W. Keister, T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA E.M. Muller Stony Brook University, Stony Brook, USA
	Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grants DE-SC0004584 (Tech-X Corp.) and DE-FG02-08ER41547 (BNL). Beamlines at new light sources, such as the National Synchrotron Light Source II will operate at flux levels beyond the saturation level of existing diagnostics, necessitating the development of new devices. Currently, there is no detector which can span the entire flux range that is possible even in a second generation light source and will become crucial for next generation light sources. One new approach* is a diamond-based detector that will be able to monitor beam position, flux and timing to much better resolution. Furthermore, this detector also has linear response to flux over 11 orders of magnitude. However, the successful development of the detector requires thorough understanding and optimization of the physical processes involved. We will discuss the new modeling capabilities we have been implementing in the VORPAL 3D code to investigate the effects of charge generation due to absorption of x-ray photons, transport, and charge trapping. We will report results from VORPAL simulations on charge collection and how it depends on applied field, charge trapping, and the energy of absorbed photons. *J. W. Keister, J. Smedley, D. A. Dimitrov, and R. Busby, Charge Collection and Propagation in Diamond X-ray Detectors, IEEE Transactions on Nuclear Science, 57, 2400 (2010).

WEP224	Operational Status and Life Extension Plans for the Los Alamos Neutron Science Center (LANSCE)	neutron, proton, linac, target	1906
	J.L. Erickson, D. Rees LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the U. S. Department of Energy, National Nuclear Security Administration, Contract No. DE-AC52-06NA25396 – Publication Release LA-UR- 10-06556 The Los Alamos Neutron Science Center (LANSCE) accelerator and beam delivery complex generates the proton beams that serve three neutron production sources, a proton radiography facility and a medical and research isotope production facility. The recent operating history of the facility, including both achievements and challenges, will be reviewed. Plans for performance improvement will be discussed, together with the underlying drivers for the ongoing LANSCE Linac Risk Mitigation project. The details of this latter project will be discussed. The status of accelerator-related plans for the MaRIE Project (Matter-Radiation Interactions in Extremes Experimental Project) will also be discussed. Taken together, the LANSCE Linac Risk Mitigation Project and the MaRIE initiative demonstrate a commitment to investment in the ongoing operation and improvement of the facility, and a resurgent interest in the spectrum of science accessible at LANSCE. These plans will assure continued facility operational and scientific vitality well beyond 2020.

THP010	Optimization of Dual Scattering Foil for 6 to 20 MeV Electron Beam Radiotherapy	electron, simulation, radiation, target	2157
	B.J. Patil, V.N. Bhoraskar, S.D. Dhole University of Pune, Pune, India S.T. Chavan, R. Krishnan, S.N. Pethe SAMEER, Mumbai, India
	From last 50 years, electron beam therapy has an important radiation therapy modality. The electron beam from the LINAC is of size ~ 2 mm, whereas the size required for actual treatment is usually larger than 2 X 2 cm² up to 30 X 30 cm² at the isocenter. In the present work, it is proposed to use dual scattering foil system for production of clinical electron beam. The foils for 6 to 20 MeV electrons were optimized using the Monte Carlo based FLUKA code. The material composition, thickness of primary foil, Gaussian width and thickness of secondary foil were optimized such that it should meet the design parameters such as Dose at iso-center, beam uniformity, admixture of bremsstrahlung, etc. A pencil beam of electrons passing through primary foil converted into Gaussian shape and falling at the centroid of secondary foil which experienced maximum scattering, whereas falling at the edge experienced the minimum scattering. This results into flat profile of electron at isocenter. In conclusion, the primary scattering foil has been optimized with high Z element (Ta) having uniform thickness, whereas the secondary foil has been optimized with low Z element (Al) having Gaussian shape.

THP030	GEANT4 Studies of the Thorium Fuel Cycle	proton, simulation, neutron, target	2178
	C. Bungau Manchester University, Manchester, United Kingdom R.J. Barlow UMAN, Manchester, United Kingdom A. Bungau, R. Cywinski University of Huddersfield, Huddersfield, United Kingdom
	Thorium “fuel” has been proposed as an alternative to uranium fuel in nuclear reactors. New GEANT4 developments allow the Monte Carlo code to be used for the first time in order to simulate the time evolution of the concentration of isotopes present in the Thorium fuel cycle. A full study is performed in order to optimise the production of Uranium-233 starting with "pure" Thorium fuels, leading to levels of Uranium-233 which ensure the operation of the nuclear reactor in a regime close to criticality.

THP038	Development of Laser Compton Scattering X-ray Source on the Basis of Compact Electron Linac	laser, electron, cavity, gun	2187
	R. Kuroda, E. Miura, H. Toyokawa, K. Yamada, E. Yamaguchi AIST, Tsukuba, Ibaraki, Japan M. Kumaki RISE, Tokyo, Japan
	A compact hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yields, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch beam will be generated from a Cs-Te photocathode rf gun sytem using a multi-pulse UV laser. The laser optical cavity will be built like the regenerative amplification including the collision point between the electron pulse and the laser pulse to enhance the laser peak power per 1 collision on laser Compton scattering. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans.

THP101	The MERLIN Simulation Program: New Features used in Studies of the LHC Collimation System using MERLIN	simulation, proton, collimation, target	2312
	R.J. Barlow, R. Appleby, J. Molson, H.L. Owen, A.M. Toader UMAN, Manchester, United Kingdom
	We present recent developments in the MERLIN particle tracking simulation code, originally developed at DESY. Their use is illustrated by studies of the LHC collimation system. We make detailed comparisons of our results with those of other codes, and also, where possible, with the data. Different beam optics designs are studied, and the effect of new collimator materials for different upgrade scenarios is predicted.

THP181	Low Intensity Nonlinear Effects in Compton Scattering Sources	electron, laser, photon, radiation	2453
	F. Albert, S.G. Anderson, C.P.J. Barty, M. Betts, R.R. Cross, 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
	The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. 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. In particular, while it is 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, 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.

THP182	Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source	laser, electron, gun, photon	2456
	F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders LLNL, Livermore, California, USA C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang SLAC, Menlo Park, 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 A new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linear accelerator designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable gamma-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.

THP204	Corrections to Quantum Efficiency Predictions for Low Work Function Electron Sources	electron, simulation, target, vacuum	2504
	K. L. Jensen NRL, Washington, DC, USA D.W. Feldman, E.J. Montgomery, P.G. O'Shea UMD, College Park, Maryland, USA J.J. Petillo SAIC, Billerica, Massachusetts, USA
	Funding: Funding by the Joint Technology Office and the Office of Naval Research. The Three-Step Model of Spicer, or the analogous Moments-based models, can be used to predict photoemission from metals and cesiated metals. In either, it is a convenient approximation to neglect electrons that have undergone scattering. Using Monte Carlo to follow scattered electrons, we assess the utility of the approximation particularly for low work function (cesiated) surfaces.

THP205	Modeling the Performance of a Diamond Current Amplifier for FELs	electron, FEL, simulation, background	2507
	K. L. Jensen, B. Pate, J.L. Shaw, J.E. Yater NRL, Washington, DC, USA J.J. Petillo SAIC, Billerica, Massachusetts, USA
	Funding: We gratefully acknowledge funding by the Joint Technology Office and the Office of Naval Research. A diamond current amplifier concept can reduce demands made of photocathodes under development for high performance Free Electron Lasers (FELs) by augmenting the charge per bunch (i.e., increasing the apparent QE of the photocathode) by employing secondary emission amplification in a diamond flake. The characteristics of the bunch that emerges from the diamond flake is dependent on properties of the diamond (e.g., impurity concentrations) and the conditions under which it is operated (e.g., voltage drop, space charge, temperature). A study of the electron bunches produced by an incident 3-5 keV beam striking a very thin diamond and its transport under bias subject to scattering and space charge forces is considered. The quantities of greatest interest are then the yield, the transit time, emittance, and the rise/fall characteristics of the emerging bunch. These are simulated using Monte Carlo techniques, the application of which shall be described as it applies to the initial generation of the secondary electrons followed by their scattering and transport in the presence of band bending and space charge. J.E. Yater, et al., IEEE IVNC (2009); J. L. Shaw, et al., ibid. **K.L. Jensen, et al. J. Appl. Phys. 108, 044509 (2010).

THP223	Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source	laser, electron, photon, emittance	2540
	D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly LLNL, Livermore, 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. A Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.

FROCB1	Understanding Nuclear Physics with Accelerators	hadron, collider, electron, ion	2592
	A. Deshpande Stony Brook University, Stony Brook, USA
	There is substantial international interest in construction of an Electron Ion Collider. Such a collider could explore physics ranging from discovery of a new state of matter in QCD to probing physics beyond the standard model. The speaker will review the physics goals for a proposed Electron Ion Collider, and review relevant performance of existing proposals for such a facility.
	Slides FROCB1 [15.321 MB]

FROCB2	Science with Light and Neutron Sources	neutron, synchrotron, electron, photon	2596
	S.K. Sinha UCSD, La Jolla, California, USA
	In recent years there has been great progress in the development of accelerator-based light and neutron sources. The speaker will give an overview of the exciting new opportunities provided by the enhanced source capabilities available at present and future facilities. Speaker Sunhil Sinha, a professor in the Physics Department of the University of California at San Diego
	Slides FROCB2 [26.588 MB]

Paper

Title

Other Keywords

Page

MOP022

The Expected Performance of MICE Step IV

emittance, optics, solenoid, lattice

151

T. Carlisle, J.H. Cobb
JAI, Oxford, United Kingdom

Funding: STFC
The international Muon Ionization Cooling Experiment (MICE), under construction at the Rutherford Appleton Laboratory in Oxfordshire (UK), is a test of a prototype cooling channel for a future Neutrino Factory. The experiment aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance, measured to an accuracy of 1% by two scintillating fibre trackers within 4 T solenoid fields. Step IV of MICE will begin in 2012, producing the experiment's first cooling measurements. Step IV uses an absorber focus coil module, placed between the two trackers, to house liquid hydrogen or solid absorbers. The performance of Step IV using various absorber materials was simulated. Multiple scattering in high Z absorbers was found to mismatch the beam with the lattice optics, which was largely corrected by re-tuning the MICE lattice accordingly.

MOP038

Non-Magnetic Momentum Spectrometer Based on Fast Time-of-Flight System

electron, factory, simulation, cathode

169

R.J. Abrams, C.M. Ankenbrandt, G. Flanagan, S.A. Kahn, M. Notani, T.J. Roberts
Muons, Inc, Batavia, USA
H.J. Frisch
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA

Funding: Supported in part by SBIR Grant DE-SC0005445
A new generation of large-area, low cost time-of-flight detectors with time resolutions ≤ 10 ps and space resolutions ≤ 1 mm is being developed for use in nuclear and particle physics experiments, as well as for medical and industrial applications. Such detectors can serve as the basis for measuring momenta without requiring measurement of curvature in magnetic fields. Factors affecting measurement accuracy and simulation results are presented.

MOP040

Fast Time-of-Flight System for Muon Cooling Experiments

simulation, cathode, emittance, collider

172

R.J. Abrams, C.M. Ankenbrandt, G. Flanagan, S.A. Kahn, M. Notani, T.J. Roberts
Muons, Inc, Batavia, USA
H.J. Frisch
Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA

Funding: Supported in part by SBIR Grant DE-SC0005445.
A new generation of large-area, low cost time-of-flight detectors with time resolutions ≤ 10 ps and space resolutions ≤ 1 mm is being developed for use in nuclear and particle physics experiments, as well as for medical and industrial applications. Such detectors are being considered for use in muon cooling channel tests. Designs and fabrication of prototype planes and associated readout electronics are described. Results of simulations of time and space resolutions are presented.

MOP060

Wedge Absorber Design and Simulation for MICE Step IV

emittance, simulation, lattice, controls

220

C.T. Rogers
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
L. Coney, G.G. Hanson
UCR, Riverside, California, USA
P. Snopok
IIT, Chicago, Illinois, USA

Funding: Work is supported by the Science and Technology Facilities Council, the U.S. Department of Energy and the U.S. National Science Foundation.
In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material, then through RF cavities to compensate for the energy loss; which reduces the transverse emittance. It is planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge absorber in Step IV. Based on the outcome of previous studies, the shape and material of the wedge were chosen. We address here further simulation efforts for the absorber of choice as well as engineering considerations in connection with the absorber support design.

MOP182

Measurement of the Energy Dependence of Touschek Electron Counting Rate

electron, background, wiggler, polarization

426

I.B. Nikolaev, V.E. Blinov, V.A. Kiselev, S.A. Nikitin, V.V. Smaluk
BINP SB RAS, Novosibirsk, Russia

We have measured a dependence of the intra-beam scattering rate on the VEPP-4M beam energy and compared it with our theoretical estimates. Measurements have been performed at several energy points in a wide range: from 1.85 up to 4.0 GeV.

MOP190

Precision, Absolute Proton Beam Polarization Measurements at 200 MeV Beam

proton, polarization, target, monitoring

444

G. Atoian, A. Zelenski
BNL, Upton, Long Island, New York, USA
A. Bogdanov, M.F. Runtso
MEPhI, Moscow, Russia
E.J. Stephenson
IUCF, Bloomington, Indiana, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
A new polarimeter for absolute proton beam polarization measurements at 200 MeV to accuracy better than ±0.5% has been developed as a part of the RHIC polarized source upgrade. The polarimeter is based on the elastic proton-carbon scattering at 16.2 degree angle, where the analyzing power is close to 100% and was measured with high accuracy. The elastically and in-elastically scattered protons are clearly identified by the difference in the propagation through variable copper absorber and energy deposition of the protons in the detectors. The 16.2 degree elastic scattering polarimeter was used for calibration of a high rate inclusive 12 degree polarimeter for the on-line polarization tuning and monitoring. This technique can be used for accurate polarization measurements in energy range of at least 160-250 MeV.

MOP209

Proposed Scattered Electron Detector System as One of the Beam Overlap Diagnostic Tools for the New RHIC Electron Lens

electron, proton, solenoid, diagnostics

489

P. Thieberger, E.N. Beebe, C. Chasman, W. Fischer, D.M. Gassner, X. Gu, R.C. Gupta, J. Hock, R.F. Lambiase, Y. Luo, M.G. Minty, C. Montag, M. Okamura, A.I. Pikin, Y. Tan, J.E. Tuozzolo, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An electron lens for head-on beam-beam compensation planned for RHIC requires precise overlap of the electron and proton beams which both can have down to 0.3 mm rms transverse radial widths along the 2m long interaction region. Here we describe a new diagnostic tool that is being considered to aid in the tuning and verification of this overlap. Some of ultra relativistic protons (100 or 250 GeV) colliding with low energy electrons (2 to 10 keV) will transfer sufficient transverse momentum to cause the electrons to spiral around the magnetic guiding field in a way that will make them detectable outside of the main solenoid. Time-of-flight of the halo electron signals will provide position-sensitive information along the overlap region. Scattering cross sections are calculated and counting rate estimates are presented as function of electron energy and detector position.

MOP238

Laser Compton Proton Polarimetry Revisited

photon, proton, laser, electron

560

A.N. Stillman
Private Address, Huntington, USA

Compton polarimetry of polarized proton beams is more feasible now than it was in 1995*, when I first estimated the laser requirements of a polarimeter using the available laser technology. New methods of high energy photon generation make the technique of Compton proton polarimetry a viable option for polarized proton beams. Since the analyzing power of a Compton polarimeter increases with photon energy and the count rate of the polarimeter increases with the laser intensity, the new laser technologies available today imply the construction of a working device with reasonable effort. I estimate the device parameters necessary for a working Compton polarimeter at RHIC using several methods of high energy photon generation.
* Arnold Stillman, in Proceedings of the 1995 Particle Accelerator Conference, 1995, p.2560

TUP005

Comparison of Back-scattering Properties of Electron Emission Materials

electron, simulation, target, feedback

817

Z. Insepov, V. Ivanov, S.J. Jokela, M. Wetstein
ANL, Argonne, USA

We use “microscopic” Monte Carlo (MC) simulations, empirical theories, and comparison with experiments to identify the influence of back-scattered electrons and the saturation effect on the emissive properties of materials and to study the gain and transit times for various microchannel plates (MCPs). We have applied this method to Al2O3 and MgO emissive materials of various thickness and surface quality. The experimental secondary emission yield (SEY) data were obtained at normal electron impacts and were used as the reference data for adjusting our MC simulations. The SEY data were calculated at oblique angles of the primary electrons in the interval of 0-80 degrees. The energy dependence of backscattered electron coefficients (BSCs) for various primary electron incidence angles was calculated by MC for both materials, and the results were compared with experimental “average” values obtained in the literature. Both SEY and BSC data were used as input files to our “macroscopic” trajectory simulation, which models MCP amplifiers as whole devices and is capable of gain and transit time calculations.

TUP009

A Computational Model for Muons Passing Gas and Plasma Targets: Beam Emittance.

target, simulation, emittance, collective-effects

823

A. Samolov, A.L. Godunov
ODU, Norfolk, Virginia, USA

A good understanding of interaction of muon beams with gas targets is crucial for attaining high acceleration gradients in gas pressured RF cavities. This physics includes a number of challenging problems. Our objective has been to develop a computational model for studying the most important effects within the same level of accuracy. The computational model simulates scattering of a bunch of charged particles on multiple atomic, molecular and ionic centers. The interaction potentials have been calculated using Hartree-Fock method for atomic targets, and Molecular Orbital method for molecular targets. Target particles are populated randomly to simulate either a gas in a pressured RF cavity with a particular material density, or liquid hydrogen. In the present work the following effects on beam emittance have been studied: effect of multiple scattering (comparing to single particle tracking models), effect of various degree of target ionization (beam-plasma interaction), space charge screening in plasma, effect of strong magnetic fields. Our preliminary results demonstrate that the degree of plasma ionization has a strong effect of the beam emittance.

TUP013

A Concept Design of a Compton Scattering Light Source based on the HLS Electron Storage Ring

electron, laser, photon, storage-ring

835

X.C. Lai, H. Hao, H.Q. Huang, W.W. Li, X.Q. Wang, D.R. Xu
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: National Natural Science Foundation of China (Contract NO. 11045003)
Hefei Light Source (HLS) is a 2nd generation light source lasering high flux ultraviolet and soft x-ray with 200 MeV to 800 MeV electron beam. To explorer other applications of the electron storage ring of HLS, a concept design of Hefei Compton Scattering Light Source (HCSLS) is proposed. In this paper, Compton Scattring Simulation Code(CSSC), a parallel code based on the analytical method to simulate the Compton scattering between the laser beam and the electron beam, is presented. Using the CSSC, it is computed that HCSLS will produce photons with a total flux of 10⁹ s^-1 to 10¹1 s^-1, and energy of 0.07 MeV to 1.15 MeV at the maximum spectral flux density with the 200 MeV to 800 MeV electron beam scattering with a kilo-watts CO2 laser. With a much shorter wave laser beam from an Nd:YVO4 laser, the scattered photons energy at the maximum spectral flux density is improved by a factor of 10, while its flux is reduce by a factor of 100 due to the lower peak laser power.

TUP124

Phase Contrast Imaging Using a Single Picosecond X-ray Pulse of the Inverse Compton Source at the BNL Accelerator Test Facility

photon, brightness, electron, laser

1062

M. Carpinelli
Università di Sassari and INFN, Sassari, Italy
P. Delogu, M. Endrizzi
INFN-Pisa, Pisa, Italy
B. Golosio, P. Oliva
INFN-Cagliari, Monserrato (Cagliari), Italy
I. Pogorelsky, V. Yakimenko
BNL, Upton, Long Island, New York, USA

Inverse Compton scattering (ICS) X-ray sources are of current interest due to their novel features that enable new methods in medical and biological imaging. As a compelling example of such a possibility, we present an experimental demonstration of single shot inline phase contrast imaging using the ICS source located at the BNL Accelerator Test Facility. The phase contrast effect is clearly observed in the images obtained. Further, its qualities are shown to be in agreement with the predictions of theoretical models through comparison of experimental and simulated images of a set of plastic wires of differing composition and size. We also display an example of application of the technique to single shot phase contrast imaging of a biological sample.

TUP242

Electron Cloud Issues for the APS Superconducting Undulator

photon, electron, undulator, ion

1283

K.C. Harkay, Y. Ivanyushenkov, R. Kustom, E.R. Moog, E. Trakhtenberg
ANL, Argonne, USA
L.E. Boon, A.F. Garfinkel
Purdue University, West Lafayette, Indiana, USA

Funding: Work supported by U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
The APS Upgrade calls for the development and commissioning of a superconducting undulator (SCU) at the Advanced Photon Source (APS), a 7-GeV electron synchrotron. Operation of an SCU at Angstromquelle Karlsruhe (ANKA), also an electron ring, suggests that electron multipacting is consistent with the observed heat load and pressure rise, but this effect is not predicted by an electron cloud generation code. At APS it was found that while the cloud code POSINST agreed fairly well with retarding field analyzer (RFA) data for a positron beam (operated 1996-98), the agreement was less satisfactory for the electron beam. The APS data suggest that the photoelectron model is not complete. Given that the heat load is a critical parameter in designing the cryosystem for the SCU and given the experience at ANKA, a study is underway to minimize the possible contribution to the heat load by the electron cloud at the APS, the photoelectrons in particular. In this talk, the results from POSINST are presented. Preliminary tracking of the photon flux using SYNRAD3D for the APS SCU chamber is presented, and possible ways to mitigate the photoelectrons are discussed.

WEP090

Simulation Study of Intrabeam Scattering in Low Emittance Ring

emittance, simulation, lattice, storage-ring

1639

W. Fan, G. Feng, D.H. He, W. Li, L. Wang, S.C. Zhang, T. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

HALS(Hefei Advanced Light Source) is under designing dedicated to good coherence and high brightness at 1.5GeV. Low emittance is required to reach the design request. Due to the low energy and emittance with relative high bunch charge, intrabeam scattering effect will be very strong. It is worth accurately calculating to check if the design goal can be reached. Theoretic calculation based on Gaussian beam distribution doesn't warrant in strong IBS regime. In this paper we present the results of particle simulation study of intrabeam scattering effect on a temporary design lattice of HALS ring.

WEP138

Developing Software Packages for Electromagnetic Simulations

simulation, vacuum, electromagnetic-fields, radio-frequency

1740

J. Xu, M. Min, B. Mustapha
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
In addition to previous developments on parallel beam dynamics software packages, our efforts have been extended to electromagnetic simulations. These efforts include developing new software packages solving the Maxwell equations in 2D and 3D. Scalable algorithms have been used for use of ALCF supercomputers. These new solvers are based on high order numerical methods. Comparative studies of structured and unstructured grids, continuous and discontinuous Galerkin methods will be discussed. The effects of bases will also be presented. Efficiency and challenges of new software packages will be presented. Some benchmarking and simulation results will be shown.

WEP161

Modeling and Simulations of Electron Emission from Diamond-Amplified Cathodes

electron, simulation, vacuum, cathode

1791

D.A. Dimitrov, R. Busby, J.R. Cary, D.N. Smithe
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, X. Chang, T. Rao, J. Smedley, E. Wang, Q. Wu
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by the U. S. Department of Energy under the DE-SC0004431 grant.
Emission of electrons from a diamond-amplified cathode was recently demonstrated*. This experiment was based on a promising new concept** for generation of high-current, high-brightness, and low thermal emittance electron beams. The measurements from transmission and emission experiments have shown the potential to realize the diamond-amplified cathode concept. However, the results indicate that the involved physical properties should be understood in greater detail to build diamond cathodes with optical properties. We have already made progress in understanding the secondary electron generation and charge transport in diamond with the models we implemented in the VORPAL computational framework. We have been implementing models for electron emission from diamond and will present results from 3D VORPAL simulations with the integrated capabilities on generating electrons and holes, initiated by energetic primary electrons, propagation of the charge clouds, and then the emission of electrons into diamond. We will discuss simulation results on the dependence of the electron emission on diamond surface properties.
* X. Chang et al., Electron Beam Emission from a Diamond-Amplified Cathodes, to appear in Phys. Rev. Lett. (2010).
** I. Ben-Zvi et al., Secondary emission enhanced photoinjector, Rep. C-A/AP/149, BNL (2004).

WEP162

Modeling of Diamond Based Devices for Beam Diagnostics

electron, photon, simulation, diagnostics

1794

D.A. Dimitrov, R. Busby
Tech-X, Boulder, Colorado, USA
I. Ben-Zvi, J.W. Keister, T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA
E.M. Muller
Stony Brook University, Stony Brook, USA

Funding: The authors wish to acknowledge the support of the U.S. Department of Energy (DOE) under grants DE-SC0004584 (Tech-X Corp.) and DE-FG02-08ER41547 (BNL).
Beamlines at new light sources, such as the National Synchrotron Light Source II will operate at flux levels beyond the saturation level of existing diagnostics, necessitating the development of new devices. Currently, there is no detector which can span the entire flux range that is possible even in a second generation light source and will become crucial for next generation light sources. One new approach* is a diamond-based detector that will be able to monitor beam position, flux and timing to much better resolution. Furthermore, this detector also has linear response to flux over 11 orders of magnitude. However, the successful development of the detector requires thorough understanding and optimization of the physical processes involved. We will discuss the new modeling capabilities we have been implementing in the VORPAL 3D code to investigate the effects of charge generation due to absorption of x-ray photons, transport, and charge trapping. We will report results from VORPAL simulations on charge collection and how it depends on applied field, charge trapping, and the energy of absorbed photons.
*J. W. Keister, J. Smedley, D. A. Dimitrov, and R. Busby, Charge Collection and Propagation in Diamond X-ray Detectors, IEEE Transactions on Nuclear Science, 57, 2400 (2010).

WEP224

Operational Status and Life Extension Plans for the Los Alamos Neutron Science Center (LANSCE)

neutron, proton, linac, target

1906

J.L. Erickson, D. Rees
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the U. S. Department of Energy, National Nuclear Security Administration, Contract No. DE-AC52-06NA25396 – Publication Release LA-UR- 10-06556
The Los Alamos Neutron Science Center (LANSCE) accelerator and beam delivery complex generates the proton beams that serve three neutron production sources, a proton radiography facility and a medical and research isotope production facility. The recent operating history of the facility, including both achievements and challenges, will be reviewed. Plans for performance improvement will be discussed, together with the underlying drivers for the ongoing LANSCE Linac Risk Mitigation project. The details of this latter project will be discussed. The status of accelerator-related plans for the MaRIE Project (Matter-Radiation Interactions in Extremes Experimental Project) will also be discussed. Taken together, the LANSCE Linac Risk Mitigation Project and the MaRIE initiative demonstrate a commitment to investment in the ongoing operation and improvement of the facility, and a resurgent interest in the spectrum of science accessible at LANSCE. These plans will assure continued facility operational and scientific vitality well beyond 2020.

THP010

Optimization of Dual Scattering Foil for 6 to 20 MeV Electron Beam Radiotherapy

electron, simulation, radiation, target

2157

B.J. Patil, V.N. Bhoraskar, S.D. Dhole
University of Pune, Pune, India
S.T. Chavan, R. Krishnan, S.N. Pethe
SAMEER, Mumbai, India

From last 50 years, electron beam therapy has an important radiation therapy modality. The electron beam from the LINAC is of size ~ 2 mm, whereas the size required for actual treatment is usually larger than 2 X 2 cm² up to 30 X 30 cm² at the isocenter. In the present work, it is proposed to use dual scattering foil system for production of clinical electron beam. The foils for 6 to 20 MeV electrons were optimized using the Monte Carlo based FLUKA code. The material composition, thickness of primary foil, Gaussian width and thickness of secondary foil were optimized such that it should meet the design parameters such as Dose at iso-center, beam uniformity, admixture of bremsstrahlung, etc. A pencil beam of electrons passing through primary foil converted into Gaussian shape and falling at the centroid of secondary foil which experienced maximum scattering, whereas falling at the edge experienced the minimum scattering. This results into flat profile of electron at isocenter. In conclusion, the primary scattering foil has been optimized with high Z element (Ta) having uniform thickness, whereas the secondary foil has been optimized with low Z element (Al) having Gaussian shape.

THP030

GEANT4 Studies of the Thorium Fuel Cycle

proton, simulation, neutron, target

2178

C. Bungau
Manchester University, Manchester, United Kingdom
R.J. Barlow
UMAN, Manchester, United Kingdom
A. Bungau, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom

Thorium “fuel” has been proposed as an alternative to uranium fuel in nuclear reactors. New GEANT4 developments allow the Monte Carlo code to be used for the first time in order to simulate the time evolution of the concentration of isotopes present in the Thorium fuel cycle. A full study is performed in order to optimise the production of Uranium-233 starting with "pure" Thorium fuels, leading to levels of Uranium-233 which ensure the operation of the nuclear reactor in a regime close to criticality.

THP038

Development of Laser Compton Scattering X-ray Source on the Basis of Compact Electron Linac

laser, electron, cavity, gun

2187

R. Kuroda, E. Miura, H. Toyokawa, K. Yamada, E. Yamaguchi
AIST, Tsukuba, Ibaraki, Japan
M. Kumaki
RISE, Tokyo, Japan

A compact hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yields, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch beam will be generated from a Cs-Te photocathode rf gun sytem using a multi-pulse UV laser. The laser optical cavity will be built like the regenerative amplification including the collision point between the electron pulse and the laser pulse to enhance the laser peak power per 1 collision on laser Compton scattering. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans.

THP101

The MERLIN Simulation Program: New Features used in Studies of the LHC Collimation System using MERLIN

simulation, proton, collimation, target

2312

R.J. Barlow, R. Appleby, J. Molson, H.L. Owen, A.M. Toader
UMAN, Manchester, United Kingdom

We present recent developments in the MERLIN particle tracking simulation code, originally developed at DESY. Their use is illustrated by studies of the LHC collimation system. We make detailed comparisons of our results with those of other codes, and also, where possible, with the data. Different beam optics designs are studied, and the effect of new collimator materials for different upgrade scenarios is predicted.

THP181

Low Intensity Nonlinear Effects in Compton Scattering Sources

electron, laser, photon, radiation

2453

F. Albert, S.G. Anderson, C.P.J. Barty, M. Betts, R.R. Cross, 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

The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. 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. In particular, while it is 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, 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.

THP182

Overview of Current Progress on the LLNL Nuclear Photonics Facility and Mono-energetic Gamma-ray Source

laser, electron, gun, photon

2456

F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, D.P. McNabb, M. J. Messerly, C. Siders
LLNL, Livermore, California, USA
C. Adolphsen, T.S. Chu, E.N. Jongewaard, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang
SLAC, Menlo Park, 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
A new class of gamma-ray light source based on Compton scattering is made possible by recent progress in accelerator physics and laser technology. Mono-energetic gamma-rays are produced from collisions between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linear accelerator designed in collaboration with SLAC will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable gamma-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to conduct nuclear resonance fluorescence experiments and address a broad range of current and emerging applications in nuclear photoscience. Users include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented, along with important applications.

THP204

Corrections to Quantum Efficiency Predictions for Low Work Function Electron Sources

electron, simulation, target, vacuum

2504

K. L. Jensen
NRL, Washington, DC, USA
D.W. Feldman, E.J. Montgomery, P.G. O'Shea
UMD, College Park, Maryland, USA
J.J. Petillo
SAIC, Billerica, Massachusetts, USA

Funding: Funding by the Joint Technology Office and the Office of Naval Research.
The Three-Step Model of Spicer, or the analogous Moments-based models, can be used to predict photoemission from metals and cesiated metals. In either, it is a convenient approximation to neglect electrons that have undergone scattering. Using Monte Carlo to follow scattered electrons, we assess the utility of the approximation particularly for low work function (cesiated) surfaces.

THP205

Modeling the Performance of a Diamond Current Amplifier for FELs

electron, FEL, simulation, background

2507

K. L. Jensen, B. Pate, J.L. Shaw, J.E. Yater
NRL, Washington, DC, USA
J.J. Petillo
SAIC, Billerica, Massachusetts, USA

Funding: We gratefully acknowledge funding by the Joint Technology Office and the Office of Naval Research.
A diamond current amplifier concept can reduce demands made of photocathodes under development for high performance Free Electron Lasers (FELs) by augmenting the charge per bunch (i.e., increasing the apparent QE of the photocathode) by employing secondary emission amplification in a diamond flake*. The characteristics of the bunch that emerges from the diamond flake is dependent on properties of the diamond (e.g., impurity concentrations) and the conditions under which it is operated (e.g., voltage drop, space charge, temperature)**. A study of the electron bunches produced by an incident 3-5 keV beam striking a very thin diamond and its transport under bias subject to scattering and space charge forces is considered. The quantities of greatest interest are then the yield, the transit time, emittance, and the rise/fall characteristics of the emerging bunch. These are simulated using Monte Carlo techniques, the application of which shall be described as it applies to the initial generation of the secondary electrons followed by their scattering and transport in the presence of band bending and space charge.
*J.E. Yater, et al., IEEE IVNC (2009); J. L. Shaw, et al., ibid.
**K.L. Jensen, et al. J. Appl. Phys. 108, 044509 (2010).

THP223

Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source

laser, electron, photon, emittance

2540

D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly
LLNL, Livermore, 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.
A Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.

FROCB1

Understanding Nuclear Physics with Accelerators

hadron, collider, electron, ion

2592

A. Deshpande
Stony Brook University, Stony Brook, USA

There is substantial international interest in construction of an Electron Ion Collider. Such a collider could explore physics ranging from discovery of a new state of matter in QCD to probing physics beyond the standard model. The speaker will review the physics goals for a proposed Electron Ion Collider, and review relevant performance of existing proposals for such a facility.

Slides FROCB1 [15.321 MB]

FROCB2

Science with Light and Neutron Sources

neutron, synchrotron, electron, photon

2596

S.K. Sinha
UCSD, La Jolla, California, USA

In recent years there has been great progress in the development of accelerator-based light and neutron sources. The speaker will give an overview of the exciting new opportunities provided by the enhanced source capabilities available at present and future facilities.
Speaker Sunhil Sinha, a professor in the Physics Department of the University of California at San Diego

Slides FROCB2 [26.588 MB]