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scattering

Paper Title Other Keywords Page
MOZAC03 The LANSCE Accelerator: A Powerful Tool for Science and Applications proton, isotope-production, linac, storage-ring 120
 
  • K. Schoenberg
  The Los Alamos Neutron Science Center (LANSCE) accelerator was built over 30 years ago. It consists of a 800-MeV proton linac, a proton storage ring, and facilities for isotope production, proton radiography, ultra-cold neutrons, weapons neutron research and for various sciences such as materials, biological and nanotechnology using neutron scattering. For national security, it plays a vital role in stockpile stewardship by providing important data on dynamic events during weapons detonation using proton radiography. The aging components of LANSCE will be refurbished and modernized in the next few years and the LANSCE will continue serving as a prominent facility for both science and national security in the years ahead. After SNS comes on line, it will play a complementary role and will also serve as a staging facility for some experiments to be carried out at SNS. Interesting science being conducted at LANSCE and the plans for the refurbishment and future enhancement of the facility will be presented.  
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MOOAC02 A Short-Pulse Hard X-ray Source with Compact Electron LINAC Via Laser-Compton Scattering for Medical and Industrial Radiography laser, electron, photon, cathode 121
 
  • H. Toyokawa
  • H. Ikeura-Sekiguchi, M. K. Koike, R. Kuroda, H. Ogawa, N. Sei, M. Tanaka, K. Y. Yamada, M. Y. Yasumoto
    AIST, Tsukuba, Ibaraki
  • T. Nakajyo, F. Sakai, T. Y. Yanagida
    SHI, Tokyo
  An intense, quasi-monochromatic hard X-ray beam has been generated via the laser-Compton scattering of a picosecond electron bunch with an intense femtosecond TW laser. A s-band linear accelerator of 40 MeV and Ti:Sa femtosecond TW laser were used to generate X-rays. We plan to increase the X-ray yield up to two-orders than the current one until FY2008. Our recent R&D for that purpose are generation of multi-pulse electron beam using a photo-cathode rf-gun, and multi-pulse laser cavity for Compton scattering. We briefly describe the specifications of the electron accelerator and the laser systems, together with the developments and modifications being undergone.  
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MOPAN069 Ultrasound Diagnostics of the Superconducting Cable Connections Between the Main Ring Magnets of LHC diagnostics, controls, superconducting-magnet, quadrupole 311
 
  • F. Caspers
  • T. Kroyer, J.-P. G. Tock, L. R. Williams
    CERN, Geneva
  • J. Kulka
    AGH, Cracow
  As part of the LHC assembly program, the super-conducting magnets are interconnected after installation. Electrical continuity between the magnets is ensured via a specifically designed cable splice box which allows the cables to be electrically joined by an automated low temperature brazing technique. The electrical resistance and mechanical strength of the cable junctions depend on the quality of the brazed joint. An ultrasound diagnostic of the brazed joint has been developed to accompany the visual inspection and reinforce the quality control process. Non-standard ultrasound diagnostic techniques, without using matching liquids or gel in the harsh and congested working environment, applied to the sandwich structure of the cable splice box, which presents high ultra-sonic losses due to multiple scattering, have been developed. The equipment and methods implemented are described in detail, together with results of quality control tests made in the production environment.  
 
MOPAS045 Fiber-Based, Spatially and Temporally Shaped Picosecond UV Laser for Advanced RF Gun Applications laser, electron, gun, simulation 533
 
  • M. Shverdin
  • S. G. Anderson, C. P.J. Barty, M. Betts, D. J. Gibson, F. V. Hartemann, J. Hernandez, M. Johnson, I. Jovanovic, D. P. McNabb, M. J. Messerly, J. A. Pruet, C. Siders, A. M. Tremaine
    LLNL, Livermore, California
  Funding: This work was performed under auspices of the U. S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7504-Eng-48.

The fiber-based, spatially and temporally shaped, picosecond UV laser system described here has been specifically designed for advanced rf gun applications, with a special emphasis on the production of high-brightness electron beams for free-electron lasers and Compton scattering light sources. The laser pulse can be shaped to a flat-top in both space and time with a duration of 10 ps FWHM and rise and fall times under 1 ps. The pulse energy is 100 micro-joules at 261.75 nm and the spot size diameter of the beam at the photocathode measures 2 mm. A fiber oscillator and amplifier system generates a chirped pump pulse at 1047 nm; stretching is achieved in a chirped fiber Bragg grating. A single multi-layer dielectric grating based compressor recompresses the input pulse to 250 fs FWHM and a two stage harmonic converter frequency quadruples the beam. A custom-designed diffractive optic reshapes the input pulse to a flat-top. Temporal shaping is achieved with a Michelson-based ultrafast pulse stacking device with nearly 100% throughput. The integration of the system, as well as preliminary electron beam measurements will be discussed.

 
 
MOPAS046 LANSCE Radiation Resistant Water Manifold Retrofit for DC Magnets radiation, injection, proton, storage-ring 536
 
  • M. J. Borden
  • J. F. O'Hara, E. M. Perez, B. J. Roller, V. P. Vigil, L. S. Walker
    LANL, Los Alamos, New Mexico
  Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396

Large maintenance dose burdens have necessitated the development of radiation resistant water manifolds for use on DC magnets in the Proton Storage Ring, at the Los Alamos Neutron Science Center (LANSCE) accelerator. This paper will describe dose measurements and the mechanical design of radiation resistant water manifolds used in PSR.

 
 
MOPAS069 Analysis of a Compact Circular TE 01-Rectangular TE 02 Waveguide Mode Converter simulation, coupling, linear-collider, collider 587
 
  • M. Yeddulla
  • S. G. Tantawi
    SLAC, Menlo Park, California
  An analysis method for a three section mode transformer that converts a TE 01 circular waveguide mode to a TE 02 rectangular waveguide mode will be presented. Experimental results for this taper were earlier published in*. The middle section is a cylinder with a wall radius defined by rw = a(1 + d cos(2Θ)), where a is the radius of the circular guide and d is a design parameter. This cylinder is connected on either side to a circular waveguide and a rectangular waveguide section respectively, through tapered waveguide sections. In this analysis we used a perturbation technique where the rectangular waveguide section's wall radius is treated as a Fourier series expansion with a, the fundamental radius and d the perturbation parameter. By applying the proper boundary conditions we optimize the taper dimensions to minimize conversion into spurious modes.

*S. G. Tantawi et al., Physical Review Special Topics – Accelerator and Beams. 8, 042002 (2005)

 
 
TUODKI06 Observation of Proton Reflection on Bent Silicon Crystals at the CERN SPS proton, collider, hadron, collimation 751
 
  • W. Scandale
  Funding: INTAS-CERN, contract number 05-96-7525 and CARE, contract number RII3-CT-2003-506395.

We report observations, performed by the H8-RD22 Collaboration*, of the so-called volume reflection effect with 400 GeV/c protons interacting with bent Silicon crystals in the H8 beam line at the CERN SPS. The volume reflection is closely related with particle channeling. This phenomenon occurs at the tangency point of a particle trajectory with the bent crystalline planes and consists in the reversal of the transverse component of the particle momentum. The measurements were collected with a high spatial resolution detector mainly based on Silicon strips. The proton beam was deviated in the direction opposite to that of channeling by ~12μrad, which is ~1.3 times the critical angle, with an efficiency larger than 97% in a range of the proton-to-crystal incident angle as large as the bending angle of crystallographic planes. This evidence opens new perspectives for manipulation of high-energy beams, e.g., for collimation and extraction in the new-generation of hadron colliders or as a method for high-energy experiments in the region near to the circulating beam.

* H8-RD22 collaboration: CERN, FNAL, INFN (Ferrara, Legnaro, Perugia, Roma, Milano, Trieste), IHEP, PNPI, JINR

 
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TUZAAB01 Equilibrium Beam Distribution in Electron Storage Rings near Synchrobetatron Coupling Resonances resonance, coupling, damping, emittance 789
 
  • B. Nash
  Linear dynamics in a storage ring can be described by the one-turn map matrix. In the case of a resonance where two of the eigenvalues of this matrix are degenerate, a coupling perturbation causes a mixing of the uncoupled eigenvectors. A perturbation formalism is developed to find eigenvalues and eigenvectors of the one-turn map near such a linear resonance. Damping and diffusion due to synchrotron radiation can be obtained by integrating their effects over one turn, and the coupled eigenvectors can be used to find the coupled damping and diffusion coefficients. Expressions for the coupled equilibrium emittances and beam distribution moments are then derived. In addition to the conventional instabilities at the sum, integer, and half-integer resonances, it is found that the coupling can cause an instability through antidamping near a sum resonance even when the symplectic dynamics are stable. E. G., the case of linear synchrobetatron coupling is analyzed where the coupling is caused by dispersion in the rf cavity, or by a crab cavity. Explicit closed-form expressions for the sum/difference resonances are given along with the integer/half-integer resonances.  
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TUPMN003 Lifetime Contribution Measurements at the Australian Synchrotron vacuum, electron, coupling, synchrotron 914
 
  • M. J. Spencer
  • M. J. Boland, R. T. Dowd, G. LeBlanc, Y. E. Tan
    ASP, Clayton, Victoria
  There are always a number of factors that contribute to the lifetime of a stored particle beam. Measurements presented here show the relative importance of these effects during the commissioning of the Australian Synchrotron storage ring.  
 
TUPMN041 Three Dimensional Analysis of the X-Radiation Produced by a Collective Thomson Source laser, radiation, electron, emittance 1007
 
  • V. Petrillo
  • A. Bacci, C. Maroli, A. R. Rossi, L. Serafini, P. Tomassini
    INFN-Milano, Milano
  • A. Colzato
    Universita degli Studi di Milano, Milano
  A set of 3-D equations that describes the collective head to head interaction between a laser pulse and a relativistic electron beam is presented and solved. The relevant dispersion relation is studied, as well as the gain properties of the system. The FEL instability dominates the radiation process. The radiation emitted is characterized by short wavelength, thin spectrum and high coherence. The most important three-dimensional effects are the emittance of the beam and the transverse distribution of the laser energy. The production of radiation wavelengths of 12 nm, 1nm, and 1 Angstron are presented.  
 
TUPMN049 Improvement of Soft X-ray Generation System Based on Laser Compton Scattering laser, photon, electron, cathode 1031
 
  • T. Gowa
  • H. Hayano, J. Urakawa
    KEK, Ibaraki
  • Y. Kamiya, A. Masuda, R. Moriyama, K. Sakaue, M. Washio
    RISE, Tokyo
  • S. Kashiwagi
    ISIR, Osaka
  • R. Kuroda
    AIST, Tsukuba, Ibaraki
  • K. U. Ushida
    RIKEN, Saitama
  Funding: This work is supported by MECSST High Tech Research Center Project No. 707 and JSPS (B) (2) 18340079.

At Waseda University, we have succeeded in generating soft X-rays based on laser Compton scattering. The energies are within "Water Window" part (250~500eV) where the X-ray absorption coefficient of water is much less than that of constituent elements of living body such as carbon, hydrogen and nitrogen. For this reason, it is expected to apply to a bio-microscope with which we can observe living cells without dehydration. To improve the generation system, we remodeled our collision chamber and adopted 3-pass flash lamp amplifier system. With these modifications, we achieved high S/N ratio. The photon number detected by MCP was 278/pulse, tenfold increase of that in last year. Moreover, we succeeded in generating soft X-rays stably for more than 10 hours. Now we are planning to measure two-dimensional distribution of the X-rays by CCD. In this conference, experimental results and future plans will be reported.

 
 
TUPMN051 Development of Photocathode RF Gun and Laser System for Multi-collision Laser Compton Scattering laser, electron, photon, gun 1037
 
  • R. Kuroda
  • T. Gowa, Y. Kamiya, A. Masuda, R. Moriyama, K. Sakaue, M. Washio
    RISE, Tokyo
  • S. Kashiwagi
    ISIR, Osaka
  • M. K. Koike, H. Ogawa, N. Sei, H. Toyokawa, K. Y. Yamada, M. Y. Yasumoto
    AIST, Tsukuba, Ibaraki
  • T. Nakajyo, F. Sakai, T. Y. Yanagida
    SHI, Tokyo
  A compact soft and 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 yield, 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 a 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.  
 
TUPMN054 Design of a Source to Supply Ultra-fast Electron and X-Ray Pulses electron, laser, gun, linac 1046
 
  • W.-H. Huang
  • H. Chen, Y.-C. Du, Hua, J. F. Hua, R. K. Li, Y. Lin, J. Shi, C.-X. Tang, D. Xiang, L. X. Yan, P.-CH. Yu
    TUB, Beijing
  In this paper we report the preliminary design and considerations on a multi-discipline ultra-fast source, which is capable of providing the user community with femtosecond electron bunch and light pulses with the wavelength ranging from IR to X-ray. The facility is based on photocathode RF gun driven by a Ti:Sapphire laser system. The low emittance subpicosecond electron bunch at the gun exit can be used in femtosecond electron diffraction setup to visualize the ultrafast structural dynamics. After acceleration and compression, the electron beam with the energy of 50 MeV is further used to provide high peak brightness X-ray by inverse Compton scattering with TW laser. We also consider the possibility and reliability of storing the electron beam in a compact storage ring and the laser pulse in a super-cavity. Operating in this scheme may increase the average flux of the X-ray photons by orders of magnitude.  
 
TUPMN056 MEASUREMENTS OF LASER TEMPORAL PROFILE AND POLARIZATION-DEPENDENT QUANTUM EFFICIENCY laser, polarization, electron, emittance 1052
 
  • L. X. Yan
  • J. P. Cheng, Y.-C. Du, W.-H. Huang, Y. Lin, C.-X. Tang
    TUB, Beijing
  Funding: The work was supported by the Program for New Century Excellent Talents in University and the National Natural Science Foundation of China (No.10645002）

The ultrashort ultraviolet (UV) laser system and the optical transport line for driving the photocathode RF gun at Accelerator Laboratory of Tsinghua University are introduced in the article. Temporal profile of the UV pulse was measured by non-colinear difference frequency generation (DFG) between the UV pulse itself and the jitter-free residual IR laser pulse after third harmonic generation (THG) process. Experiments to measure the dependence of quantum efficiency (QE) on laser polarization state are also performed. Results show that in our case the ratio of QE between p- and s- polarization is more than 2.6.

 
 
TUPMN075 BEAM LIFETIME ESTIMATION FOR TAIWAN 3GEV SYNCHROTRON LIGHT SOURCE lattice, emittance, synchrotron, electron 1094
 
  • W. T. Liu
  • H.-P. Chang, H. C. Chao, P. J. Chou, C.-C. Kuo, G.-H. Luo, H.-J. Tsai, M.-H. Wang
    NSRRC, Hsinchu
  The demanding design features of Taiwan Photon Source (TPS), low emittance and small gap undulator vacuum vessels, cause Touschek scattering and gas scattering to play a major limitation role for beam lifetime. We calculate the Touschek lifetime based on the tracking procedure determining energy acceptance. The nonlinear synchrotron oscillation due to large second-order momentum compaction factor is included in the energy acceptance calculations. Small vertical ID gaps are imposed in the tracking procedure. Besides, the gas scattering lifetime is estimated with varying gas pressure. The possible improvement solutions for lifetime will be addressed.  
 
TUPMN116 Numerical Study of Coulomb Scattering Effects on Electron Beam from a Nano-tip emittance, electron, simulation, space-charge 1185
 
  • J. Qiang
  • A. Adelmann
    PSI, Villigen
  • J. N. Corlett, S. M. Lidia, H. A. Padmore, W. Wan, A. Zholents, M. S. Zolotorev
    LBNL, Berkeley, California
  Funding: This work was supported by the U. S. Department of Energy under Contract no. DE-AC02-05CH11231.

Nano-tips with high acceleration gradient around the emission surface have been proposed to generate high brightness beams. However, due to the small size of the tip, the charge density near the tip is very high even for a small number of electrons. The Coulomb scattering near the tip can significantly degrade the beam quality and cause extra emittance growth and energy spread. In the paper, we present a numerical study of these effects using a direct relativistic N-body model. We found that emittance growth and energy spread, due to Coulomb scattering, can be significantly enhanced with respect to mean-field space-charge calculations in different parameter regimes.

 
 
TUPMS007 NSLS VUV Ring Lifetime Study septum, simulation, closed-orbit, injection 1203
 
  • L. Yang
  • S. L. Kramer, B. Podobedov
    BNL, Upton, Long Island, New York
  • S.-Y. Lee
    IUCF, Bloomington, Indiana
  Beam lifetime at VUV ring of National Synchrotron Light Source(NSLS) at BNL is limited by Touschek effect. This effect is affected by momentum acceptance and beam density. The geometry near injection septum, dynamic aperture and the RF acceptance all can limit the over all momentum acceptance. Extensive experiments including coupling, gas scattering, RF acceptance, have been done for understanding the lifetime, and the result is confirmed with theoretical predictions.  
 
TUPMS029 Gamma-Ray Compton Light Source Development at LLNL laser, electron, brightness, gun 1245
 
  • F. V. Hartemann
  • S. G. Anderson, C. P.J. Barty, D. J. Gibson, C. Hagmann, M. Johnson, I. Jovanovic, D. P. McNabb, M. J. Messerly, J. A. Pruet, M. Shverdin, C. Siders, A. M. Tremaine
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U. S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

A new class of tunable, monochromatic gamma-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photo-science and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. Key technologies, basic scaling laws, and recent experimental results will be presented, along with an overview of future research and development directions.

 
 
TUPMS030 Optimal Design of a Tunable Thomson-Scattering Based Gamma-Ray Source electron, laser, photon, emittance 1248
 
  • D. J. Gibson
  • S. G. Anderson, C. P.J. Barty, S. M. Betts, F. V. Hartemann, I. Jovanovic, D. P. McNabb, M. J. Messerly, J. A. Pruet, M. Shverdin, C. Siders, A. M. Tremaine
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U. S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Thomson-Scattering based systems offer a path to high-brightness high-energy (> 1 MeV) x-ray & gamma-ray sources due to their favorable scaling with electron energy. LLNL is currently engaged in an effort to optimize such a device, dubbed the "Thomson-Radiated Extreme X-Ray" (T-REX) source, targeting up to 680 keV photon energy. Such a system requires precise design of the interaction between a high-intensity laser pulse and a high-brightness electron beam. Presented here are the optimal design parameters for such an interaction, including factors such as the collision angle, focal spot size, optimal bunch charge and laser intensity, pulse duration, and laser beam path. These parameters were chosen based on extensive modelling using PARMELA and in-house, well-benchmarked scattering simulation codes. Also discussed are early experimental results from the newly commissioned system.

 
 
TUPMS031 High-energy Picosecond Laser Pulse Recirculation for Compton Scattering laser, recirculation, electron, accumulation 1251
 
  • I. Jovanovic
  • S. G. Anderson, C. P.J. Barty, C. G. Brown, D. J. Gibson, F. V. Hartemann, J. Hernandez, M. Johnson, D. P. McNabb, M. J. Messerly, J. A. Pruet, M. Shverdin, C. Siders, A. M. Tremaine
    LLNL, Livermore, California
  Funding: This work was performed under the auspices of the U. S Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-Eng-48.

Frequency upconversion of laser-generated photons by inverse Compton scattering for applications such as nuclear spectroscopy and gamma-gamma collider concepts on the future ILC would benefit from an increase of average source brightness. The primary obstacle to higher average brightness is the relatively small Thomson scattering cross section. It has been proposed that this limitation can be partially overcome by use of laser pulse recirculation. The traditional approach to laser recirculation entails resonant coupling of low-energy pulse train to a cavity through a partially reflective mirror.* Here we present an alternative, passive approach that is akin to "burst-mode" operation and does not require interferometeric alignment accuracy. Injection of a short and energetic laser pulse is achieved by placing a thin frequency converter, such as a nonlinear optical crystal, into the cavity in the path of the incident laser pulse. This method leads to the increase of x-ray/gamma-ray energy proportional to the increase in photon energy in frequency conversion. Furthermore, frequency tunability can be achieved by utilizing parametric amplifier in place of the frequency converter.

* G. Klemz, K. Monig, and I. Will, "Design study of an optical cavity for a future photon-collider at ILC", Nucl. Instrum. Meth. A 564, 212-224 (2006).

 
 
TUPMS041 The Wisconsin VUV/Soft X-ray Free Electron Laser Project laser, electron, linac, photon 1278
 
  • J. Bisognano
  • R. A. Bosch, M. A. Green, H. Hoechst, K. Jacobs, K. J. Kleman, R. A. Legg, R. Reininger, R. Wehlitz
    UW-Madison/SRC, Madison, Wisconsin
  • J. Chen, W. Graves, F. X. Kaertner, J. Kim, D. E. Moncton
    MIT, Cambridge, Massachusetts
  Funding: Work supported by the University of Wisconsin - Madison. SRC is supported by the U. S. National Science Foundation under Award No. DMR-0537588.

The University of Wisconsin-Madison and its partners are developing a design for an FEL operating in the UV to soft x-ray range that will be proposed as a new multidisciplinary user facility. Key features of this facility include seeded, fully coherent output with tunable photon energy and polarization over the range 5 eV to 1240 eV, and simultaneous, independent operation of multiple beamlines. The different beamlines will support a wide range of science from femto-chemistry requiring ultrashort pulses with kHz repetition rates to photoemission and spectroscopy requiring high average flux and narrow bandwidth at MHz rates. The facility will take advantage of the flexibility, stability, and high average pulse rates available from a CW superconducting linac driven by a photoinjector. This unique facility is expected to enable new science through ultra-high resolution in the time and frequency domains, as well as coherent imaging and nano-fabrication. This project is being developed through collaboration between the UW Synchrotron Radiation Center and MIT. We present an overview of the facility, including the motivating science, and its laser, accelerator, and experimental systems.

 
 
TUPAN031 Touschek Background and Beam Lifetime Studies for the DAFNE Upgrade simulation, background, optics, insertion 1454
 
  • M. Boscolo
  • M. E. Biagini, S. Guiducci, P. Raimondi
    INFN/LNF, Frascati (Roma)
  For the low energy collider DAFNE the machine induced backgrounds into the experiments as well as the beam lifetime are dominated by the Touschek effect. Many efforts have been put in its reduction: by adjusting optical parameters, by inserting additional collimators, as well as by simulating and tracking scattered particles in order to find the proper actions that allow reducing these effects. Studies on the distribution and trajectories of the Touschek particles along the ring are discussed here for the Siddarta run configuration with the crabbed waist scheme, together with an evaluation of the beam lifetime. Effectiveness of the scrapers installed in the two rings has been investigated with the new machine configuration and new optimized positions along the beam pipe have been found.  
 
TUPAN039 Profile Measurement and Transverse Matching in J-PARC Linac beam-losses, linac, electron, simulation 1472
 
  • H. Akikawa
  • Z. Igarashi, M. Ikegami, S. Lee
    KEK, Ibaraki
  • S. Sato, T. Tomisawa, A. Ueno
    JAEA/LINAC, Ibaraki-ken
  • G. B. Shen
    JAEA, Ibaraki-ken
  Beam commissioning of J-PARC linac has been performed since November 2006. In the beam commissioning, transverse matching has been performed by measurement of beam profiles and emittance with wire scanners. In this presentation, detail of wire scanners and the method of matching are described.  
 
TUPAN061 Updated Simulation for the Nuclear Scattering Loss Estimation at the RCS Injection Area injection, beam-losses, simulation, space-charge 1526
 
  • P. K. Saha
  • H. Hotchi, Y. Irie, F. Noda
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  We have updated the simulation for the realistic beam loss estimation at the RCS (Rapid Cycling Synchrotron) injection area of J-PARC(Japan Proton Accelerator Research Complex). At the injection area, beam loss caused by the nuclear scattering together with the multiple coulomb scattering at the charge-exchange foil is the dominant one and is an important issue for designing mainly the foil thickness and other beam elements like, the falling time of bump magnets after the injection is finished and so on. The simulation tool GEANT for the scattering effect and the real injection process have been employed together in order to estimate the beam loss turn by turn including identification of loss points too.  
 
TUPAN089 The LHC Beampipe Waveguide Mode Reflectometer cryogenics, quadrupole, pick-up, controls 1583
 
  • F. Caspers
  • P. Borowiec, T. Kroyer, Z. Sulek, L. R. Williams
    CERN, Geneva
  Several specially developed waveguide-mode reflectometers for obstacle detection in the LHC magnet beampipes have been intensively used for more than 18 months. This "Assembly" version is based on the synthetic pulse method using a modern vector network analyzer. It has mode selective excitation couplers and uses a specially developed waveguide mode dispersion compensation algorithm with external software. In addition there is a similar "in situ" version of the reflectometer which uses permanently installed microwave couplers at the end of each of the nearly 3 km long LHC arcs. A considerable number of unexpected objects have been found in the beampipes and subsequently removed. Operational statistics and lessons learned are presented and the overall performance is discussed.  
 
WEOAKI01 Optical Stochastic Cooling Proof-of-Principle Experiment electron, radiation, undulator, damping 1904
 
  • W. A. Franklin
  Cooling of charged particle beams plays a key role in achieving peak luminosity in high-energy colliders. The presently undemonstrated technique of optical stochastic cooling (OSC)* holds promise for fast cooling of high energy protons and heavy ions. A proof-of-principle experiment with electrons is proposed at relatively modest cost using the MIT-Bates South Hall Ring, which is well suited for such a test due to its energy range, layout, and RF system, as well as its present availability. An overview of the experiment will be presented. The design of key systems for the achievement of OSC will be disucussed along with beam requirements and cooling projections.

*M. Zolotorev and A. Zholents, Phys Rev. E 50 (1994) 3087.

 
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WEOBKI02 Evolution of Relativistic Plasma Wave-Front in LWFA plasma, electron, laser, diagnostics 1919
 
  • C. E. Clayton
  • F. Fang, C. Joshi, K. A. Marsh, A. E. Pak, J. E. Ralph
    UCLA, Los Angeles, California
  • N. C. Lopes
    Instituto Superior Tecnico, Lisbon
  Funding: Work supported by DOE Grant Nos. DE-FG52-03NA00138 and DE-FG02-92ER40727, and Grant POCI/FIS/58776/2004 (FCT-Portugal)

In a laser wakefield accelerator experiment where the length of the pump laser pulse is several plasma period long, the leading edge of the laser pulse undergoes frequency downshifting as the laser energy is transferred to the wake. Therefore, after some propagation distance, the group velocity of the leading edge of of the pump pulse–and therefore of the driven electron plasma wave–will slow down. This can have implications for the dephasing length of the accelerated electrons and therefore needs to be understood experimentally. We have carried out an experimental investigation where we have measured the velocity vf of the 'wave-front' of the plasma wave driven by a nominally 50fs (FWHM), intense (a0~1), 0.8 micron laser pulse. To determine the speed of the wave front, time- and space-resolved shadowgraphy, interferometry, and Thomson scattering were used. Although low density data (ne ~ 1018 cm-3) showed no significant changes in vf over 1.5mm (and no accelerated electrons), high-density data shows accelerated electrons and an approximately 5% drop in vf after a propagation distance of about 800 microns.

 
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WEOCC03 Halo Estimates and Simulations for Linear Colliders simulation, linac, electron, photon 2041
 
  • H. Burkhardt
  • I. V. Agapov, G. A. Blair
    Royal Holloway, University of London, Surrey
  • F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • A. Latina, L. Neukermans, D. Schulte
    CERN, Geneva
  Funding: This work is supported by the Commission of the European Communities under the 6th Framework Programme "Structuring the European Research Area", contract number RIDS-011899.

Halo simulations and estimates are important for the design of future linear accelerators. We present simulations performed for the ILC and CLIC and compare these with semi-analytical estimates and other simulations.

 
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WEPMN082 Global Scattering Matrix Technique Applied to the Calculation of Higher Order Modes for ILC Superconducting Cavities simulation, dipole, linac, electromagnetic-fields 2218
 
  • I. R.R. Shinton
  • R. M. Jones
    Cockcroft Institute, Warrington, Cheshire
  A cascaded scattering matrix approach is used to determine the electromagnetic (e.m.) field in the main ILC cavities. This approach is used to compute higher order e.m. modes in the baseline configuration, and high gradient alternative configurations. We present results on three designs: TESLA, Cornell University's re-entrant and, KEK's "Ichiro". This approach allows realistic experimental errors to be incorporated in the studies in an efficient manner and allows several cavities to be modelled en masse. Simulations are presented on the wake-fields in super-structures and segments of entire modules. Details on trapped eigen-modes and means to avoid them are delineated. The influence of cell misalignments and cavity perturbations on the modes are also presented.  
 
WEPMS051 One Channel, Multi-Mode Active Pulse Compressor plasma, linear-collider, collider, coupling 2460
 
  • S. V. Kuzikov
  • J. L. Hirshfield, V. P. Yakovlev
    Omega-P, Inc., New Haven, Connecticut
  • M. E. Plotkin, D. Yu. Shegolkov, A. A. Vikharev
    IAP/RAS, Nizhny Novgorod
  Funding: Research sponsored in part by US DoE.

Basic studies of factors that limit RF fields in warm accelerator structures require experiments at RF power that can be produced using pulse compression. This approach is being implemented to compress output pulses from the Yale/Omega-P 34-GHz magnicon to produce ~100-200 MW, 100 ns pulses. A new approach for passive pulse compression is a SLED-II type circuit operating with axisymmetrical modes of the TE0n type that requires only a single channel instead of the usual double channel scheme. This allows avoidance of a 3-dB coupler and need for simultaneous fine tuning of two channels. A 30 GHz passive prototype was tested at low power level in order to demonstrate key principles. The prototype showed a power gain 3,8 at a compression ratio 6:1 for an efficiency 63%. An active version of the one-channel pulse compressor is also suggested. It is attractive due to a possibility to achieve higher power gain. The mentioned active version naturally requires an electrically controlled coupler. In particular, as active elements of the coupler we suggest to use gas filled discharge tubes or ferroelectrics which have well recommended itself at 11.4 GHz experiments.

 
 
THOAAB02 Upgrade of the LENS Proton Linac: Commissioning and Results target, proton, klystron, rfq 2611
 
  • A. Bogdanov
  • V. Anferov, M. Ball, D. V. Baxter, V. P. Derenchuk, A. V. Klyachko, T. Rinckel, P. E. Sokol, K. A. Solberg
    IUCF, Bloomington, Indiana
  Funding: The LENS project is supported by the NSF (grants DMR-0220560, DMR-0242300), the 21st Century Science and Technology fund of Indiana, Indiana University, and the Department of Defense

A Low Energy Neutron Source at Indiana University provides cold neutrons for material research and neutron physics as well as neutrons in the MeV energy range for the neutron radiation effects studies. Neutrons are being produced by a 7 MeV proton beam incident on a Beryllium target. Presently, the Proton Delivery System has been routinely running at 7 MeV, 8 mA and with up to 0.5% duty factor. The RF system of the accelerator is currently being upgraded by replacing 350 kW 425 MHz 12 tube amplifiers with two Litton 5773 klystron RF tubes capable of running at 425 MHz and 1 MW. A new DTL section will be added to increase proton beam energy from 7 to 13 MeV. A 3 MeV RFQ and 13 MeV DTL will be powered by the klystrons. The expected output is 20 mA and 13 MeV of proton current at more than 1% duty factor. Other upgrades include construction of the 2nd beamline, which copies the 1st line, and a new target station for the production of cold neutrons. In this contribution we discuss the results of the commissioning of the new DTL accelerator, new RF system and 2nd beamline. The future plans will also be outlined.

 
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THYC01 RHIC Hydrogen Jet Luminesence Monitor optics, photon, proton, polarization 2648
 
  • T. Russo
  • S. Bellavia, D. M. Gassner, P. Thieberger, D. Trbojevic, T. Tsang
    BNL, Upton, Long Island, New York
  Funding: US Department of Energy

A hydrogen jet polarimeter was developed for the RHIC accelerator to improve the process of measuring polarization. Particle beams intersecting with gas molecules can produce light by the process known as luminescence. This light can then be focused, collected, and processed giving important information such as size, position, emittance, motion, and other parameters. The RHIC hydrogen jet polarimeter was modified in 2005 with specialized optics, vacuum windows, light transport, and camera system making it possible to monitor the luminescence produced by polarized protons intersecting the hydrogen beam. This paper will describe the configuration and preliminary measurements taken using the RHIC hydrogen jet polarimeter as a luminescence monitor.

 
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THPMN019 Morphological Changes of Electron-beam Irradiated PMMA Surface electron, ion, vacuum, plasma 2745
 
  • R. Nathawat
  • A. K. Kumar, Y. K. Vijay
    UOR, Jaipur
  Funding: Author are thankful to DAE-BRNS, India for financial support for research work

Atomic force microscopy (AFM) study of low energy (10 keV) electron beam irradiated Polymethylmethacrylate (PMMA)20 micron thick surface was performed. PMMA film has been used in lithography applicatiion by this technique. AFM in tapping mode has been utilized to investigate the morphological changes on the samples surface as a function of fluence. TM-AFM showed the hills of the nano size surrounded by the craters type features in all the irradiated samples. The shape and size of these features varied with fluence. The root-mean-square (rms) surface roughness of the samples changed from 2.666 nm to 5.617 nm with fluence from 2x1014 electrons/cm2 to 1x1016 electrons/cm2. It shows that roughness increases as increasing fluence.

 
 
THPMN032 Beam Generation and Acceleration Experiments of X-Band Linac and Monochromatic keV X-Ray Source of the University of Tokyo laser, electron, gun, cathode 2784
 
  • F. Sakamoto
  • M. Akemoto, T. Higo, J. Urakawa
    KEK, Ibaraki
  • D. Ishida, N. Kaneko, H. Nose, H. Sakae, Y. Sakai
    IHI/Yokohama, Kanagawa
  • T. Natsui, Y. Taniguchi, M. Uesaka, T. Yamamoto
    UTNL, Ibaraki
  • M. Yamamoto
    Akita National College of Technology, Akita
  In the Nuclear Professional School, the University of Tokyo, we are constructing an X-band linear accelerator that consists of an X-band thermionic cathode RF gun and X-band accelerating structure. This system is considered for a compact inverse Compton scattering monochromatic X-ray source for the medical application. The injector of this system consists of the 3.5-cell coaxial RF feed coupler type X-band thermionic cathode RF gun and an alpha-magnet. The X-band accelerating structure is round detuned structure (RDS) type that developed for the future linear collider are fully adopted. So far, we have constructed the whole RF system and beam line for the X-band linac and achieved 2 MeV electron beam generation from the X-band thermionic cathode RF gun. In addition, we achieved 40 MW RF feeding to the accelerating structure. The laser system for the X-ray generation via Compton scattering was also constructed and evaluated its properties. In this presentation, we will present the details of our system and progress of beam acceleration experiment and the performance of the laser system for the Compton scattering experiment.  
 
THPMN035 Pinpoint keV/MeV X-ray Sources for X-ray Drug Delivery System linac, radiation, electron, laser 2793
 
  • M. Uesaka
  • F. Sakamoto, A. Sakumi
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken
  X-ray Drug Delivery System (DDS) is the most advanced radiation therapy coming after IMRT (Intensity Modulated Radiation Therapy) and IGRT (Image Guided). DDS uses advanced nano-scaled polymers which contain and deliver drug or contrast agent to cancers without side effects. Several X-ray DDS poses high-Z atoms like Pt and Au to absorb X-rays effectively and used as contrast agent for inspection. Moreover, they have radiation enhancement effect by emission of Auger electron and successive characteristic X-rays. The enhancement factor off Pt and Au is more than five. This can be used for therapy. This new modality must be very important for inspection and therapy of deep cancers. We are making use of our Compton scattering monochromatic keV X-ray source and MeV linac aspinpoint keV/MeV X-ray sources for the purpose. Physical analysis and evaluation of the contrast efficiency and radiation enhancement of the X-ray DDS are under way. Furthermore, a new compact X-band linac with a multi-beam klystron for a pinpoint X-ray source is proposed and designed. Updated research status and result are presented.  
 
THPMN037 Development of Compact EUV Source based on Laser Compton Scattering laser, electron, undulator, radiation 2799
 
  • S. Kashiwagi
  • R. Kato, J. Yang
    ISIR, Osaka
  • R. Kuroda
    AIST, Tsukuba, Ibaraki
  • K. Sakaue, M. Washio
    RISE, Tokyo
  • J. Urakawa
    KEK, Ibaraki
  High-power extreme ultraviolet (EUV) source is required for next generation semiconductor lithography. We start to develop a compact EUV source in the spectral range of 13-14 nm, which is based on laser Compton scattering between a 7 MeV electron beam and a high intensity CO2 laser pulse. Electron beam is pre-bunched using two different wavelengths of laser pulses with a dispersion section of beam transport line*,**. In this conference, we describe the results of numerical study for the EUV source and a plan of test experiment generating micro-bunched electron beam.

*M. Goldstein et al., Proc. of the 27th Int. FEL conference, Stanford, California, USA (2005) pp.422-425**A. Endo, Sematic EUV source workshop, Barcelona, Spain (2006)

 
 
THPMN081 Measuring Single Particle Amplitudes with MICE emittance, factory, insertion, coupling 2895
 
  • M. Apollonio
  The cooling of muons will be an essential element of a future neutrino factory. The Muon Ionization Cooling Experiment, MICE, to be built at RAL (UK) will be the first apparatus to demonstrate the feasibility of the ionisation cooling of muons. MICE will be unique in being able to make single-particle measurements. It will be possible to measure the amplitude of each muon in 6D phase space. We show how amplitude measurements can be used to quantify the transmission of the cooling channel and the increase in central phase space density due to cooling.  
 
THPMS022 6 Dimensional Muon Phase Space Cooling by Using Curved Lithium Lenses emittance, simulation, target, vacuum 3047
 
  • Y. Fukui
  • D. B. Cline, A. A. Garren
    UCLA, Los Angeles, California
  • H. G. Kirk
    BNL, Upton, Long Island, New York
  A curved Lithium lens ring model can provide the emittance exchange mechanism in obtaining the muon 6 dimensional phase space cooling. With straight Lithium lenses in a muon cooling ring, only transverse phase space cooling has been demonstrated. We demonstrate the 6 dimensional phase space cooling with various parameters of a muon cooling ring in tracking simulation.  
 
THPMS047 Emittance Growth from Multiple Coulomb Scattering in a Plasma Wakefield Accelerator emittance, ion, electron, plasma 3097
 
  • N. A. Kirby
  • M. K. Berry, I. Blumenfeld, M. J. Hogan, R. Ischebeck, R. Siemann
    SLAC, Menlo Park, California
  Funding: This work was supported by the Department of Energy contracts DE- AC02-76SF00515

Emittance growth is an important issue for plasma wakefield accelerators (PWFAs). Multiple Coulomb scattering (MCS) is one factor that contributes to this growth. Here, the MCS emittance growth of an electron beam traveling through a PWFA in the blow out regime is calculated. The calculation uses well established formulas for angular scatter in a neutral vapor and then extends the range of Coulomb interaction to include the effects of traveling through an ion column. Emittance growth is negligible for low Z materials; however, becomes important for high Z materials.

 
 
THPMS095 Experimental Demonstration of Feasibility of a Polarized Gamma-source for ILC Based on Compton Backscattering Inside a CO2 Laser Cavity laser, electron, positron, photon 3208
 
  • I. Pogorelsky
  • V. Yakimenko
    BNL, Upton, Long Island, New York
  Funding: Work supported by US Department of Energy contract DE-AC02-98CH10886

Compton interaction point incorporated into a high-average-power laser cavity is the key element of the Polarized Positron Source (PPS) concept proposed for ILC [1]. According to this proposal, circularly polarized gamma rays are produced in Compton backscattering from a 6 GeV linac e-beam inside a CO2 laser amplifier cavity. Intra-cavity positioning of the interaction point allows multiple laser recycling to match the electron bunch train format. We conducted experimental tests of multi-pulse operation of such active Compton cavity upon injection of a picosecond CO2 laser beam. Together with earlier demonstration of a high x-ray yield via the e-beam/CO2-laser backscattering, these new results show a viability of the entire PPS concept and closely prototype the laser source requirements for ILC.

[1] V. Yakimenko and I. V. Pogorelsky, Phys. Rev. ST Accel. Beams 9, 091001 (2006)

 
 
THPAN008 TRIUMF Extraction and 500 MeV Beamline Optics optics, cyclotron, emittance, extraction 3238
 
  • Y.-N. Rao
  • A. Baartman
    TRIUMF, Vancouver
  The beamline 2A, one of TRIUMF cyclotron primary extraction beamlines, is 60m in length. It is now routinely operating up to 70uA (proton beam) at 500MeV for ISAC. ISAC requires a diffuse spot of specific size on the radioactive beam production target at the end of 2A. To help achieve this, we developed a program aimed at obtaining a better understanding and more accurate description of 2A optics and the extracted beam from the cyclotron. The beam envelopes along 2A were measured with profile monitors and compared with theoretical predictions. During the course of this work, we discovered that the transfer matrix, involved in the optics calclations, between the stripping foil and the beamline entrance was incorrect. After correcting this error, we obtained good agreement between the measured and calculated envelopes. We report on the details of this work as well as on a measurement of the beam characteristics as a function of stripper foil thickness.  
 
THPAN031 Optimization of the Beam Line Characteristics by Means of a Genetic Algorithm electron, laser, photon, emittance 3295
 
  • A. Bacci
  • V. Petrillo
    Universita' degli Studi di Milano, Milano
  • A. R. Rossi, L. Serafini
    INFN-Milano, Milano
  The optimization of the optics in a LINAC requires a very demanding tuning of the involved parameters, particularly in the case of high brightness electron beams applied to the production of X-ray in a Thomson back-scattering source. The relationship between the parameters is non-linear and it is not possible to treat them as independent variables, causing the impossibility of setting them handily. A genetic algorithm is a powerful tool able to circumvent this difficulty. We have applied the genetic algorithm to the case of the SPARC beam line.  
 
THPAN045 Explicit Time Domain Boundary Element Scheme for Dispersion-free Wake Field Calculation of Long Accelerator Structures simulation, linac, electromagnetic-fields, electron 3330
 
  • K. Fujita
  • T. Enoto, S. Tomioka
    Hokkaido University, Sapporo
  • R. Hampel, W. F.O. Muller, T. Weiland
    TEMF, Darmstadt
  • H. Kawaguchi
    Muroran Institute of Technology, Department of Electrical and Electronic Engineering, Muroran
  This paper introduces a new explicit scheme with a moving window option for wake field calculation of long accelerator structures. This scheme is based on a time domain boundary element method (TDBEM) which uses a retarded Kirchhoff boundary integral equation on interior region problems. As a corollary of this boundary integral equation, our approach allows a conformal modeling of a structure and time domain wake field simulation without numerical grid dispersion errors in all spatial directions. The implementation of a moving window technique in the framework of TDBEM is presented and it is shown that this moving window technique allows to significantly reduce memory requirement of the TDBEM scheme in the short range wake field calculation. Several numerical examples are demonstrated for the TESLA 9-cell cavity and tapered collimators. The results of the new TDBEM scheme are compared with that of finite difference codes.  
 
THPAN098 Touschek Effect Calculation and Its Application to a Transport Line beam-losses, emittance, storage-ring, coupling 3453
 
  • A. Xiao
  • M. Borland
    ANL, Argonne, Illinois
  Funding: Work supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.

The Touschek effect is a major concern for lepton storage rings of low emittance (i.e., high bunch density) and low or moderate beam energy, such as third-generation synchrotron light sources. Piwinski's formula, which includes beam shape variation along the beamline and which is suitable for any beam energy, has been incorporated into a program that interoperates with elegant for use in lifetime calculations. The difference between using Piwinski's method and other simplified methods for the APS is shown in this paper. Furthermore, because of the generality of this formula, we also applied it to transport lines to predict beam loss rates and beam loss locations for the first time. An example related to a possible energy recovery linac upgrade of the APS (APS-ERL) is also given in this paper.

 
 
THPAN106 6D Ionization Cooling Channel with Resonant Dispersion Generation emittance, damping, focusing, resonance 3477
 
  • Y. Alexahin
  • R. B. Palmer
    BNL, Upton, Long Island, New York
  • K. Yonehara
    Fermilab, Batavia, Illinois
  Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy

For muons with preferable for ionization cooling momentum <300MeV/c the longitudinal motion is naturally undamped. In order to provide the longitudinal damping a correlation between muon momentum and transverse position - described in terms of the dispersion function - should be introduced. In the present report we consider the possibility of dispersion generation in a periodic sequence of alternating solenoids (FOFO channel) by choosing the tune in the second passband (i.e. above half-integer per cell) and tilting the solenoids in adjacent cells in the opposite direction. Analytical estimates as well as simulation results for equilibrium emittances and cooling rates are presented.

 
 
THPAS020 3D Simulations of Secondary Electron Generation and Transport in a Diamond Amplifier for Photocathodes electron, simulation, lattice, acceleration 3555
 
  • D. A. Dimitrov
  • I. Ben-Zvi, X. Chang, T. Rao, J. Smedley, Q. Wu
    BNL, Upton, Long Island, New York
  • D. L. Bruhwiler, R. Busby, J. R. Cary
    Tech-X, Boulder, Colorado
  The Relativistic Heavy Ion Collider (RHIC) contributes fundamental advances to nuclear physics by colliding a wide range of ions. A novel electron cooling section, which is a key component of the proposed luminosity upgrade for RHIC, requires the acceleration of high-charge electron bunches with low emittance and energy spread. A promising candidate for the electron source is the recently developed concept of a high quantum efficiency photoinjector with a diamond amplifier. We have started to implement algorithms, within the VORPAL particle-in-cell framework, for modeling of secondary electron and hole generation, and for charge transport in diamond. The algorithms include elastic and various inelastic scattering processes over a wide range of charge carrier energies. Initial results from the implemented capabilities will be presented and discussed.

The work at Tech-X Corp. is supported by the U. S. Department of Energy under a Phase I SBIR grant.

 
 
THPAS076 ORBIT Injection Dump Simulations of the H0 and H- Beams injection, septum, dipole, beam-losses 3657
 
  • J. A. Holmes
  • M. R. Perkett
    Denison University, Granville, Ohio
  • M. A. Plum, J.-G. Wang, Y. Zhang
    ORNL, Oak Ridge, Tennessee
  Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U. S. Department of Energy under contract DE-AC05-00OR22725.

Simulations of the transport of H0 and H- beams to the SNS ring injection dump are carried out using the ORBIT code. During commissioning and early operations, beam losses in this region have been the highest in the accelerator and presented the most obvious hurdle to cross in achieving high intensity operation. Two tracking models are employed:

  1. a piecewise continuous symplectic representation of the lattice elements in the injection chicane and dump line, and
  2. particle tracking in full 3D magnetic fields, as obtained from OPERA code evaluations.
The physics models also include estimations of scattering from both the primary and secondary stripper foils, and beam losses due to apertures throughout the beam line. 		 
 
FRZKI01 Physics from Tevatron to LHC and ILC coupling, luminosity, collider, lepton 3830
 
  • M. Mangano
  The physics reach of LHC and the need of ILC beams in the investigation of the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics.  
slides icon Slides  
 
FRPMN012 Bias on Absolute Luminosity Measurements at the ILC from Beam-Beam Space Charge Effects luminosity, space-charge, linear-collider, simulation 3907
 
  • C. Rimbault
  • P. Bambade
    LAL, Orsay
  • K. Moenig
    DESY Zeuthen, Zeuthen
  • D. Schulte
    CERN, Geneva
  A way to determine luminosity at the International Linear Collider (ILC) is to measure the Bhabha event rate in a finely segmented calorimeter (LumiCal) at very low polar angles in the very forward region of the detector. An absolute precision between 10-4 and 10-3 is needed for a number of key physics measurements. Besides theoretical uncertainties on the Bhabha cross section and experimental errors when identifying Bhabha events in the LumiCal, the very strong beam-beam space charge effects which characterise the ILC e+e- collisions lead to a major bias in the counting rate, which drastically limits the luminosity measurement if uncorrected. In this paper, Bhabha event samples produced with the BHLUMI generator are used in the context of the GUINEA-PIG beam-beam simulation to study how beamstrahlung radiation and electromagnetic deflections affect the proposed experimental selections. A corrective method based on determining the luminosity spectrum within the LumiCal is suggested to minimise the resulting errors. The expected residual uncertainty after correction is estimated based on simulations with realistic beam conditions.  
 
FRPMN030 RF measurements results of the final brazed SPARC RF Deflector coupling, controls, dipole, emittance 3994
 
  • L. Ficcadenti
  • D. Alesini, G. Di Pirro, C. Vaccarezza
    INFN/LNF, Frascati (Roma)
  • A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma
  • J. B. Rosenzweig
    UCLA, Los Angeles, California
  The longitudinal phase space and the horizontal beam slice emittance measurements of the SPARC 150MeV-1nC electron beam, foresee the use of a RF deflector. The device is a five cells standing wave structure operating on the TM110-like dipole mode at 2.856GHz and allows reaching a longitudinal resolution of 12μm with 2MW of peak input power. In the paper we illustrate the RF measurements on the final copper device.

This work has been partially supported by the EU in the sixth framework program, Contract no. 011935 EUROFEL-DS1.

 
 
FRPMN062 OTR Interferometry Diagnostic for the A0 Photoinjector electron, radiation, simulation, diagnostics 4144
 
  • G. M. Kazakevich
  • H. Edwards, R. P. Fliller, V. A. Lebedev, S. Nagaitsev, R. Thurman-Keup
    Fermilab, Batavia, Illinois
  Funding: Operated by Universities Research Association, Inc. for the U. S. Department of Energy under contract DE-AC02-76CH03000.

OTR interferometry (OTRI) is an attractive diagnostic for investigation of relativistic electron beam parameters. The diagnostic is currently under development at the A0 Photoinjector. This diagnostic is applicable for NML accelerator test facility that will be built at Fermilab. The experimental setups of the OTR interferometers for the Photoinjector prototype are described in the report. Results of simulations and measurements are presented and discussed.

 
 
FRPMS002 Parametric Modeling of Electron Beam Loss in Synchrotron Light Sources electron, beam-losses, synchrotron, simulation 3853
 
  • B. Sayyar-Rodsari
  • W. J. Corbett, M. J. Lee, P. Lui, J. M. Paterson
    SLAC, Menlo Park, California
  • E. Hartman, C. A. Schweiger
    Pavilion Technologies, Inc, Austin, Texas
  Funding: DOE Phase II STTR: DE-FG02-04ER86225

Synchrotron light is used for a wide variety of scientific disciplines ranging from physical chemistry to molecular biology and industrial applications. As the electron beam circulates, random single-particle collisional processes lead to decay of the beam current in time. We report a simulation study in which a combined neural network (NN) and first-principles (FP) model is used to capture the decay in beam current due to Touschek, Bremsstralung, and Coulomb effects. The FP block in the combined model is a parametric description of the beam current decay where model parameters vary as a function of beam operating conditions (e.g. vertical scraper position, RF voltage, number of the bunches, and total beam current). The NN block provides the parameters of the FP model and is trained (through constrained nonlinear optimization) to capture the variation in model parameters as operating condition of the beam changes. Simulation results will be presented to demonstrate that the proposed combined framework accurately models beam decay as well as variation to model parameters without direct access to parameter values in the model.

 
 
FRPMS034 Optical Diffraction-Dielectric Foil Radiation Interferometry Diagnostic for Low Energy Electron Beams radiation, electron, simulation, optics 4012
 
  • A. G. Shkvarunets
  • M. E. Conde, W. Gai, J. G. Power
    ANL, Argonne, Illinois
  • R. B. Fiorito, P. G. O'Shea
    UMD, College Park, Maryland
  Funding: ONR and the DOD/Joint Technology Office

We have developed a new optical diffraction radiation (ODR) - dielectric foil radiation interferometer to measure the divergence of the low energy (8 - 14 MeV) ANL - Advanced Wakefield Accelerator electron beam. The interferometer employs an electro-formed micromesh first foil, which overcomes the inherent scattering limitation in the solid first foil of a conventional OTR interferometer, and an optically transparent second foil. The interference of forward directed ODR from the mesh and optical radiation from the dielectric foil is observed in transmission. This geometry allows a small gap between the foils (1 - 2 mm), which is required to observe fringes from two foils at low beam energies. Our measurements indicate that a single Gaussian distribution is sufficient to fit the data.

correspondance email: shkvar@umd.edu

 
 
FRPMS043 The Feasibility Study of Measuring the Polarization of a Relativistic Electron Beam using a Compton Scattering Gamma-Ray Source electron, photon, polarization, laser 4057
 
  • C. Sun
  • Y. K. Wu
    FEL/Duke University, Durham, North Carolina
  The Compton scattering of a circularly polarized photon beam and a polarized electron beam leads to an asymmetric distribution of the gamma rays. This asymmetry has been calculated for the High Intensity Gamma-ray Source (HIGS) beam at Duke University. Owing to the high intensity of the HIGS beam, this asymmetry is determined to be measurable with a small statistic error using a simple gamma-ray beam imaging system. We propose to set up this system to measure the polarization of the electron beam in the Duke storage ring.  
 
FRPMS064 Electron Beam Lifeime in SPEAR3: Measurement and Simulation optics, electron, beam-losses, coupling 4153
 
  • W. J. Corbett
  • X. Huang, M. J. Lee, P. Lui
    SLAC, Menlo Park, California
  • B. Sayyar-Rodsari
    Pavilion Technologies, Inc, Austin, Texas
  Funding: Work supported by US Department of Energy Contract DE-AC03-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.

The primary contributing factors to electron beam lifetime in a storage ring are elastic and inelastic gas scattering, and intrabeam scattering. In order to further quantify the relative contributions of each mechanism, a series of measurements using vertical scraper position and rf-voltage sweeps were performed in SPEAR3 with fill patterns featuring different single-bunch and total beam currents. In parallel, an analytic beam-lifetime simulator was developed taking scattering cross-sections, rf-bucket height and bunch lengthening effects into account. In this paper, we compare measured results with the simulated results in an effort to develop a comprehensive model for electron beam lifetime under a variety of operating conditions.

 
 
FRPMS069 Simulations of Stretched Wire Measurements of 3.9GHz Cavities for the ILC impedance, simulation, dipole, coupling 4177
 
  • R. M. Jones
  • G. Burt
    Cockcroft Institute, Lancaster University, Lancaster
  • N. Chanlek, B. Spencer
    UMAN, Manchester
  • P. Goudket
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  We present wake-field simulations on both the main superconducting cavities and on the beam delivery system crab cavities of the ILC. We utilize both finite difference and finite element computer codes to simulate the electromagnetic fields in these cavities in the presence of a stretched wire. This study is intended to both predict the wake-field in experiments on the modal characterisation of 3.9 GHz cavities in progress at the Cockcroft Institute and, to explore practical issues concerning the feasibility of using this stretched wire method to investigate modes in the ILC main cavities. Multi-cell scattering matrices and the modes in infinite periodic structures are calculated with a view to aiding the interpretation of experimental results. A modal convergence study is also included  
 
FRPMS070 Emittance Measurement of Trapped Electrons from a Plasma Wakefield Accelerator electron, plasma, emittance, focusing 4183
 
  • N. A. Kirby
  • M. K. Berry, I. Blumenfeld, F.-J. Decker, M. J. Hogan, R. Ischebeck, R. H. Iverson, R. Siemann, D. R. Walz
    SLAC, Menlo Park, California
  • C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
    UCLA, Los Angeles, California
  • T. C. Katsouleas, P. Muggli, E. Oz
    USC, Los Angeles, California
  Funding: This work was supported by the Department of Energy contracts DE- AC02-76SF00515, DE-FG02-92ER40727, DE-FG02-92-ER40745. DE- FG02-03ER54721, DE-FC02-01ER41179 and NSF grant Phy-0321345

Recent electron beam driven plasma wakefield accelerator experiments carried out at SLAC showed trapping of plasma electrons. These trapped electrons appeared on an energy spectrometer with smaller transverse size than the beam driving the wake. A connection is made between transverse size and emittance; due to the spectrometer?s resolution, this connection allows for placing an upper limit on the trapped electron emittance. The upper limit for the lowest normalized emittance measured in the experiment is 1 mm∙mrad.

 
 
FRPMS112 Absolute Measurement of the Polarization of High Energy Proton Beams at RHIC polarization, proton, target, background 4369
 
  • Y. Makdisi
  • I. G. Alekseev, D. Svirida
    ITEP, Moscow
  • A. Bravar, G. Bunce, R. L. Gill, H. Huang, A. Khodinov, A. Kponou, Z. Li, W. Meng, A. N. Nass, S. Rescia, A. Zelenski
    BNL, Upton, Long Island, New York
  • M. Chapman, W. Haeberli, T. Wise
    UW-Madison/PD, Madison, Wisconsin
  • S. Dhawan
    Yale University, Physics Department, New Haven, CT
  • O. Eyser
    UCR, Riverside, California
  • O. Jinnouchi, I. Nakagawa
    RBRC, Upton, Long Island, New York
  • H. Okada, N. Saito
    Kyoto University, Kyoto
  • E. J. Stephenson
    IUCF, Bloomington, Indiana
  Funding: Work supported by the Department of Energy Contract no. DE-AC02-98CH10886 and the RIKEN BNL Research Center.

The spin physics program at the Relativistic Heavy Ion Collider (RHIC) requires knowledge of the proton beam polarization to better than 5%. To achieve this goal, a polarized hydrogen jet target was installed in RHIC where it intersects both beams. The premise is to utilize the precise knowledge of the jet proton polarization to measure the analyzing power in the proton - proton elastic scattering process in the Coulomb Nuclear Interference (CNI) region at the prescribed RHIC proton beam energy, then use the reverse reaction to measure the degree of the beam polarization, and finally confront the results with simultaneous measurements by the fast high statistics polarimeter that measure the p-Carbon elastic scattering process in the CNI region to calibrate the latter. In this presentation, the polarized jet target mechanics, operation, detector systems and the p-Carbon polarimeter are described. The statistical accuracy attained as well as the systematic uncertainties will be discussed. Such techniques may well become the standard for high energy polarized proton beams planned elsewhere in Russia and Japan.