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| MPPE003 | Monte Carlo Simulations of Thin Internal Target Scattering In CELSIUS | target, simulation, electron, proton | |||
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In the practical operation of the storage ring CELSIUS with the hydrogen pellet target, we simetimes observe a cooling phenomenon in the longitudinal phase space, that is, the circulating beam's phase space gets shrunk instead of blown up. This phenomenon occurs independently on the electron cooling. In this paper, we aim to investigate and interpret this phenomenon as well as the beam lifetime in the presence of hydrogen pellet target with and without rf and with and without electron cooling in CELSIUS using Monte Carlo simulations.
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| MPPE013 | High Precision Measurement of Muon Beam Emittance Reduction in MICE | emittance, factory, simulation, background | 1330 | ||
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Muon ionization cooling, an essential ingredient of a neutrino factory, will be demonstrated for the first time by the MICE experiment. The central part of MICE consists of a short section of a neutrino factory cooling channel and the emittance reduction achieved in this experiment is quite modest, 10% to 15%. In order to extrapolate the performance of a full cooling channel from these values, it is crucial for MICE to achieve an emittance measurement accuracy of 10-3 absolute. So far, beam emittance has never been measured with such a high level of precision and normailzed emittance in its present definition is not even conserved to 10-3 in the absence of dissipative forces. We present an improved definition of beam emittance and the requirements and constraints on MICE beam optics and spectrometers that are necessary to achieve the 10-3 level of accuracy.
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| MPPE028 | Non Linear Error Analysis from Orbit Measurements in SPS and RHIC | sextupole, simulation, interaction-region, resonance | 2012 | ||
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Funding: U.S. Department of Energy and Colciencias. |
Recently, an "action and phase" analysis of SPS orbits measurements proved to be sensitive to sextupole components intentionally activated at specific locations in the ring. In this paper we attempt to determine the strenght of such sextupoles from the measured orbits and compare them with the set values. Action and phase analysis of orbit trayectories generated by RHIC models with non linearities will also be presented and compare with RHIC experiments. |
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| MPPT063 | Optimized Analyzing Magnet for Measurements of Polarization of Gamma-Quants at 10 MeV | polarization, electron, target, positron | 3582 | ||
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We described here calculations and test of magnet for measurement of polarization of gammas by its helicity-dependent attenuation in magnetized iron. Magnet is a compact device which size is ~ten times smaller, than world wide analogues.
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| MPPT077 | Radiation of Electron in the Field of Plane Light Wave | electron, radiation, laser, photon | 3997 | ||
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In the work the process of electron interaction with field of oncoming light wave (Compton scattering) has been considered with methods of classical electrodynamics. As results of Lorenz equation integration the trajectories of electron motion in the wave field were derived. On the base of obtained results the expressions for electron radiation spectrum were produced.In the work dependences of spectrum shape on electron and photon beams parameters are analyzed.
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| TPAE027 | Calculations for Tera-Hertz (THz) Radiation Sources | radiation, electron, simulation, laser | 1994 | ||
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Funding: This work was supported by the U.S. Department of Energy under contract DE-2-76SF00515. |
We explore possibilities for THz sources from 0.3 - 30 THz. While still inaccessible, this broad gap is even wider for advanced acceleration schemes extending from X or, at most, W band RF at the low end up to CO2 lasers. While the physical implementations of these two approaches are quite different, both are proving difficult to develop so that even lower frequency, superconducting RF seems to be the currently preferred means. Similarly, the validity of modelling techniques varies greatly over this range of frequencies but generally mandates coupling Maxwell’s equations to the appropriate device transport physics for which there are many options. Here we calculate radiation from shaped transmission lines using finite-difference, time-domain (FDTD) simulations of Maxwell’s equations coupled to Monte-Carlo techniques for both the production and transport physics of short electron pulses. Examples of THz sources that demonstrate coherent interference effects will be discussed with the goal of optimizing on-chip THz radiators for different applications - ultimately including improved electron sources and accelerators. |
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| TPAE064 | Externally Controlled Injection of Electrons by a Laser Pulse in a Laser Wakefield Electron Accelerator | electron, injection, plasma, laser | 3644 | ||
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Funding: National Science Council, Taiwan |
Spatially and temporally localized injection of electrons is a key element for development of plasma-wave electron accelerator. Here we report the demonstration of two different schemes for electron injection in a self-modulated laser wakefield accelerator (SM-LWFA) by using a laser pulse. In the first scheme, by implementing a copropagating laser prepulse with proper timing, we are able to control the growth of Raman forward scattering and the production of accelerated electrons. We found that the stimulated Raman backward scattering of the prepulse plays the essential role of injecting hot electrons into the fast plasma wave driven by the pump pulse. In the second scheme, by using a transient density ramp we achieve self-injection of electrons in a SM-LWFA with spatial localization. The transient density ramp is produced by a prepulse propagating transversely to drill a density depression channel via ionization and expansion. The same mechanism of injection with comparable efficiency is also demonstrated with a transverse plasma waveguide driven by Coulomb explosion. |
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| TPAP020 | Tests of a Roman Pot Prototype for the TOTEM Experiment | impedance, insertion, coupling, vacuum | 1701 | ||
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The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC.* TOTEM Roman Pots contain stacks of 10 silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10 σ + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are used both for precise track reconstruction and for triggering. The first full-sized prototypes of both detector technologies as well as their read-out electronics have been developed, built and operated. The tests took place first in a fixed-target muon beam at CERN's SPS, and then in the proton beam-line of the SPS accelerator ring. We present the test beam results demonstrating the successful functionality of the system despite slight technical shortcomings to be improved in the near future.
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TOTEM, Technical Design Report, CERN-LHCC-2004-002. |
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| TPAT010 | Practical Definitions of Beam Lifetimes in an Electron Storage Ring | electron, polarization, storage-ring, beam-losses | 1216 | ||
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Derived are simple definitions of beam lifetimes in an electron storage ring. They are defined in terms of measured beam lifetime and its time derivative. They are practical rather than theoretical. The only condition required is suppression or saturation of the radiative polarization.
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| TPAT027 | Measurement of Transverse Echoes in RHIC | quadrupole, dipole, lattice, octupole | 1955 | ||
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Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886. |
Beam echoes are a very sensitive method to measure diffusion, and longitudinal echo measurements were performed in a number of machines. In RHIC, for the first time, a transverse beam echo was observed after applying a dipole kick followed by a quadrupole kick. After application of the dipole kick, the dipole moment decohered completely due to lattice nonlinearities. When a quadrupole kick is applied at time T after the dipole kick, the beam re-cohered at time 2T thus showing an echo response. We describe the experimental setup and measurement results. In the measurements the dipole and quadrupole kick amplitudes, amplitude dependent tune shift, and the time between dipole and quadrupole kick were varied. In addition, measurements were taken with gold bunches of different intensities. These should exhibit different transverse diffusion rates due to intra-beam scattering. |
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| TOPC005 | Transverse Emittance Blow-Up Due to the Operation of Wire Scanners, Analytical Predictions and Measurements | emittance, simulation, proton, betatron | 437 | ||
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Wire Scanner monitors are used in the CERN accelerators to measure the transverse beam size. In the SPS and the LHC they will serve as calibration devices for other emittance monitors. The PSB, PS and SPS are equipped with scanners which move through the beam a 30 um wire, with a speed that can vary between 0.4 to 20 m/s. During each scan, the beam suffers an emittance blow up, due to multiple Coulomb scattering of the beam protons on the lattice nuclei of the wire material. The effect depends on the particles' energy, the betatron function at the monitor location and on the wire characteristics (material, diameter and speed). In this paper we will present a comparison of the analytically predicted emittance increase caused by the instruments and a number of experimental measurements. For the small LHC beams the relative emittance blow-up can exceed a few 10e-2.
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| TPPE042 | Study of Secondary Emission Enhanced Photoinjector | electron, cathode, gun, space-charge | 2711 | ||
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The secondary emission enhanced photoinjector (SEEP) is a very promising new approach to the generation of high-current, high-brightness electron beams. Primary electrons with a few thousand electron-volts of energy strike a specially prepared diamond window. The large Secondary Electron Yield (SEY) provides a multiplication of the number of electrons by about two orders of magnitude. The secondary electrons drift through the diamond under an electric field and emerge into the accelerating proper of the “gun” through a Negative Electron Affinity (NEA) surface of the diamond (Hydrogen terminated). We present the calculation of heating power sources and the temperature distribution in details. Some properties of the secondary electron beam related to beam dynamics are also reported. The results show feasibility of this kind of cathode.
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| TPPP018 | Progress on the MICE Liquid Absorber Cooling and Cryogenic Distribution System | vacuum, emittance, factory, focusing | 1601 | ||
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Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC03-76SF00098. |
This report describes the progress made on the design of the liquid hydrogen absorber for the international Muon Ionization Cooling Experiment (MICE). The absorber consists of a 21-liter vessel that contains liquid hydrogen (1.5 kg) or liquid helium (2.63 kg). The cryogen vessel is within the warm bore of the superconducting focusing magnet for the MICE. The purpose of the magnet is to provide a low beam beta region within the absorber. For safety reasons, the vacuum vessel for the hydrogen absorber is separated from the vacuum vessel for the superconducting magnet and the vacuum that surrounds the RF cavities or the detector. The absorber has two 300 mm-diameter thin aluminum windows. The vacuum vessel around the absorber has a pair of thin aluminum windows that separate the absorber vacuum space from adjacent vacuum spaces. Because the muon beam in MICE is of low intensity, there is no beam heating in the absorber. As a result, the absorber can be cooled using a single 4 K cooler. This report describes progress on the MICE liquid absorber and its cryogenic cooling system. |
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| TPPP023 | Simulation of PEP-II Accelerator Backgrounds Using TURTLE | background, collimation, betatron, electron | 1835 | ||
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We present studies of accelerator-induced backgrounds in the BaBar detector at the SLAC B-Factory, carried out using a modified version ofthe DECAY TURTLE simulation package. Lost-particle backgrounds in PEP-II are dominated by a combination of beam-gas bremstrahlung, beam-gas Coulomb scattering, radiative-Bhabha events and beam-beam blow-up. The radiation damage and detector occupancy caused by the associated electromagnetic shower debris can limit the usable luminosity. In order to understand and mitigate such backgrounds, we have performed a full programme of beam-gas and luminosity-background simulations, that include the effects of the detector solenoidal field, detailed modelling of limiting apertures in both collider rings, and optimization of the betatron collimation scheme in the presence of large transverse tails.
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| TPPP025 | Modeling Lost-Particle Accelerator Backgrounds in PEP-II Using LPTURTLE | background, vacuum, electron, optics | 1889 | ||
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Funding: Department of Energy Contract DE-AC02-76SF00515. |
Background studies during the design, construction, commissioning, operation and improvement of BaBar and PEP-II have been greatly influenced by results from a program referred to as LPTURTLE (Lost Particle TURTLE a modified version of Decay TURTLE) which was originally conceived for the purpose of studying gas background for SLC. This venerable program is still in use today. We describe its use, capabilities and improvements and refer to current results now being applied to BaBar. |
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| TPPP031 | A Proposal for a New HOM Absorber in a Straight Section of the PEP-II Low Energy Ring | impedance, quadrupole, dipole, damping | 2173 | ||
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Funding: Work supported by the U.S. Department of Energy under contract number DE-AC03-76SF00515. |
Attainment of high luminosity in storage ring colliders necessitates increasing stored currents and reducing bunch lengths. Consequently, intense beam fields will scatter more power into higher order modes from beam line sources such as collimators, masks and tapers. This power penetrates into sensitive components such as a bellows, causing undesirable heating and limits machine performance. To overcome this limitation we propose incorporating ceramic absorbers in the vicinity of the bellows to damp beam induced modes while preserving a matched impedance to the beam. This is accomplished with an absorber configuration which damps TE dipole and quadrupole traveling waves while preserving TM monopole propagation. A scattering parameter analysis is presented utilizing properties of commercial grade ceramics and indicates a feasible solution. |
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| TPPP049 | eRHIC Detector Design Studies - Implications and Constraints on the ep(A) Interaction-Region Design | electron, interaction-region, proton, luminosity | 3043 | ||
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An electron-proton/ion collider facility (eRHIC) is under consideration at Brookhaven National Laboratory. This high energy, high intensity polarized electron/positron beam facility to collide with the existing RHIC heavy ion and polarized proton beam would significantly enhance the exploration of fundamental aspects of Quantum Chromodynamics (QCD), the underlying quantum field theory of strong interactions. The design of a new optimized detector is closely coupled to the design of the interaction region and thus to the machine development work in general. A GEANT-based detector simulation framework has been developed to study various processes at eRHIC taking into consideration the impact of machine elements inside the detector volume and the synchrotron radiation fan generated by the electron/positron beam. The GEANT-based detector simulation framework called ELECTRA will be presented followed by a discussion of constraints and implications on the interaction region design.
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| TPPP051 | A Muon Cooling Ring with Curved Lithium Lenses | emittance, simulation, factory, collider | 3167 | ||
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We design a muon cooling ring with curved Lithium lenses for the 6 dimensional muon phase space cooling. The cooling ring can be the final muon phase space cooling ring for a Higgs Factory, a low energy muon collider.Tracking simulation shows promising muon cooling with simplified magneti element models.
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| TPPP053 | Thin RF Windows for High-Pressure Gas-Filled Cavities | vacuum, beam-cooling, collider, linac | 3224 | ||
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Funding: This work was supported in part by DOE STTR grant DE-FG02-02ER86145. |
RF cavities for muon ionization cooling channels can have RF windows over their ends to create better internal voltage profiles and to make them independent of each other. To be effective, the conducting window material must be sufficiently transparent to the muons to not affect the beam cooling, which means low mass and low Z. In the case of pressurized RF cavities, as to opposed to those that operate in vacuum, the RF window design is simplified because the heat deposited in the windows from the RF and the beam is carried off by the hydrogen gas. In this report we analyze the thermal, mechanical, and electrical properties of a simple beryllium grid structure to improve the performance of pressurized RF cavities that are to be used for muon beam cooling. |
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| WPAE022 | Progress on the Liquid Hydrogen Absorber for the MICE Cooling Channel | vacuum, focusing, acceleration, target | 1772 | ||
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This report describes the progress made on the design of the liquid hydrogen absorber for the international Muon Ionization Cooling Experiment (MICE). The absorber consists of a 21-liter vessel that contains liquid hydrogen (1.5 kg) or liquid helium (2.63 kg). The cryogen vessel is within the warm bore of the superconducting focusing magnet for the MICE. The purpose of the magnet is to provide a low beam beta region within the absorber. For safety reasons, the vacuum vessel for the hydrogen absorber is separated from the vacuum vessel for the superconducting magnet and the vacuum that surrounds the RF cavities or the detector. The absorber has two 300 mm-diameter thin aluminum windows. The vacuum vessel around the absorber has a pair of thin aluminum windows that separate the absorber vacuum space from adjacent vacuum spaces. The absorber will be cooled down using a heat exchanger that is built into the absorber walls. Liquid nitrogen is used to cool the absorber to 80 K. Liquid helium completes the absorber cool down and condenses hydrogen in the absorber. The absorber may also be filled with liquid helium to measure muon cooling in helium.
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| WPAE056 | Geant4-Based Simulation Study of PEP-II Beam Backgrounds in the BaBar Detector at the SLAC B-Factory | vacuum, simulation, luminosity, background | 3351 | ||
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To improve the understanding of accelerator-induced backgrounds at the SLAC B-Factory and validate the proposed PEP-II luminosity upgrade, we simulate lost-particle backgrounds in the BaBar detector originating from beam-gas interactions and radiative-Bhabha scatters. To perform this study, we have extended the GEANT4-based BaBar detector simulation to include PEP-II beam-line components and magnetic fields up to 10m away from the interaction point. We first describe the simulation model and then compare predicted background levels with measurements from dedicated single-and colliding-beam experiments. Finally, we compare the simulated background levels in the current and the proposed luminosity-upgrade configurations.
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| WPAP019 | X-Band Thermionic Cathode RF Gun at UTNL | gun, cathode, linac, emittance | 1646 | ||
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The X-band (11.424 GHz) linac for compact Compton scattering hard X-ray source are under construction at Nuclear Engineering Research Laboratory, University of Tokyo. This linac designed to accelerate up to 35 MeV, and this electron beam will be used to produce hard X-ray by colliding with laser. It consists of a thermionic cathode RF gun, an alpha magnet, and a traveling wave tube. The gun has 3.5 cells (unloaded Q is 8250) and will be operated at pi-mode. A dispenser cathode is introduced. Since the energy spread of the beam from the gun is predicted to be broad due to the continuous emission from the thermionic cathode, a slit is placed in the alpha magnet to eliminate low energy electrons. The simulation on the injector shows the beam energy 2.9 MeV, the charge 23 pC/bunch, and the emittance less than 10 mm.mrad. The experiment on the gun is planed in the beginning of 2005, and the details will be discussed on the spot.
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| WPAT016 | Stable Low Noise RF Source for Main Ring | storage-ring, feedback, electron, synchrotron | 1494 | ||
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The Duke Storage ring is a 1 Gev electron ring, which is designed for driving UV-VUV FEL. It also provides variable energy high intensive gamma rays by Compton back scattering. It requires an RF master oscillator with very low phase noise. We built a Surface Acoustic Wave (SAW) Oscillator. However, the long-term stability does not meet requirements for FEL ring. Previously we used a commercial signal generator HP 4400B as the master oscillator. It has excellent long-term stability, but the phase noise is not acceptable. A phase feedback loop has been added between the SAW oscillator and the HP source, which provides us an excellent RF source. The design details and the test results are presented in this paper.
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| WPAT067 | High Power Disk Loaded Guide Load | impedance | 3715 | ||
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Funding: Department of Energy, contract DE-AC03-76SF00515. |
A method to design a matching section from a smooth guide to a disk loaded guide, using a variation of broadband matching* is described. Using this method, we show how to design high power loads, filters and attenuators. The load consists of a disk loaded coaxial guide, operating in the T·1001 mode. This mode has no electric field terminating on a conductor, has no axial currents. Therefore, it is expected that it will carry the 600 MW peak output power of the pulse compression network. We use coaxial geometry and stainless steel material to increase the attenuation per cell. *S. B. Cohn, Optimum Design of Stepped Transmission Line Transformers. IRE Trans., Vol. MTT-3 pp16-21, April, 1995. |
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| WOAC008 | Measuring and Understanding the Momentum Aperture in a Storage Ring | resonance, coupling, synchrotron, storage-ring | 645 | ||
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Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-AC03-76SF00098. |
The momentum aperture of a storage ring is a very important parameter that strongly influences the performance, especially the beam lifetime. For the special case of synchrotron light sources with small emittance like the Advanced Light Source (ALS), the momentum aperture depends strongly on the transverse dynamics. It is very sensitive to machine conditions such as the tunes, chromaticities, lattice symmetry, and spurious coupling, since depending on those conditions the Touschek scattered particles explore different resonance regions in the phase space. In light sources, the momentum aperture usually also depends strongly on the vertical physical aperture. Applying frequency analysis techniques in simulations and for turn-by-turn orbit measurement data provides a very powerful tool to measure and understand limitations of the dynamic momentum aperture. The techniques presented are applicable to other light sources, as well as damping rings and many types of colliders. |
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| RPAE013 | Laser System for Photoelectron and X-Ray Production in the PLEIADES Compton Light Source | laser, electron, photon, linac | 1347 | ||
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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. |
The PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility provides tunable short x-ray pulses with energies of 30-140 keV and pulse durations of 0.3 – 5 ps by scattering an intense, ultrashort laser pulse off a 35-75 MeV electron beam. Synchronization of the laser and electron beam is obtained by using a photoinjector gun, and using the same laser system to generate the electrons and the scattering laser. The Ti:Sapphire, chirped pulse amplification based 500 mJ, 50 fs, 810 nm scattering laser and the similar 300 μJ, 5 ps, 266 nm photoinjector laser systems are detailed. Additionally, an optical parametric chirped pulse amplification (OPCPA) system is studied as a replacement for part of the scattering laser front end. Such a change would significantly simplify the set-up the laser system by removing the need for active switching optics, as well as increase the pre-pulse contrast ratio which will be important when part of the scattering laser is used as a pump beam in pump-probe diffraction experiments using the ultrashort tunable x-rays generated as the probe. |
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| RPAE018 | Calculation of Reflection Matrix Elements of a Grating for Growing Evanescent Waves | electron, radiation, electromagnetic-fields | 1616 | ||
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Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
Reflection matrix elements of a grating play an important role in the study of Smith-Purcell (SP) free-electron lasers (FELs). Especially, the matrix element e00, which couples the incident co-propagating evanescent wave to the outgoing co-propagating evanescent wave, is important for the evaluation of the gain of an SP FEL system.* We use the modal expansion method as well as the integral method and extend them to the case of growing evanescent waves. We present the results of numerical calculations for rectangular and sinusoidal gratings. We study the singularity of e00 and find that it is possible to get a simple formula for the location of singularity for the case of rectangular grating if we chose the eigenmodes of the groove as the basis set as done by Andrews et. al.** *K.-J. Kim and S. B. Song, Nucl. Instrum. Methods Phys. Res. A 475, 158 (2001). **H. L. Andrews and C. A. Brau, Phys. Rev. ST Accel. Beams 7, 07070 (2004). |
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| RPAE020 | Production of High Harmonic X-Ray Radiation from Non-linear Thomson at LLNL PLEIADES | laser, electron, radiation, focusing | 1673 | ||
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Funding: US-DOE under contract no. DE-FG-98ER45693 and DE-FG03-92ER40693, and by LLNL under contract no. W-7405-Eng-48 and the LLNL ILSA program under contract LS04-001-B. |
We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a “figure-8” motion under the influence of the high-intensity laser field, where the constant characterizing the field strength is expected to exceed unity: $aL=e*EL/m*c*ωL ≥ 1$. With large $aL$ this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals. |
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| RPAE071 | Touschek Lifetime and Undulator Damage in the Advanced Photon Source | injection, simulation, radiation, lattice | 3835 | ||
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Funding: Work supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38. |
The Advanced Photon Source (APS) has two insertion devices (IDs) with small-aperture vacuum chambers. The full vertical aperture in these chambers is 5 mm, while the inboard horizontal aperture is 15 mm. These devices suffer significant radiation damage, requiring frequent retuning. We recently hypothesized that the damage resulted from loss of Touschek-scattered particles on the horizontal aperture of the chambers. This results partly from the smallness of the aperture and partly from the pattern of the dispersion and beta functions in the low-emittance APS lattice. The horizontal scrapers were originally at a high-dispersion location, but, in the low-emittance lattice, they are at a fairly low-dispersion location. Similarly, the dispersion at the IDs was originally zero but is now close to the maximum for the lattice. In this paper, we summarize simulations and experiments that support our hypothesis and discuss plans to remedy the problem. |
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| RPAP006 | X-Band Linac Beam-Line for Medical Compton Scattering X-Ray Source | laser, photon, electron, linac | 994 | ||
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Compton scattering hard X-ray source for 10~80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U. Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard ( 10-80 keV) X-rays with the intensities of 108-10 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at the beam dump by adopting the deceleration of electrons after the Compton scattering. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2.5 J/10 ns is 107 photons/RF-pulse (108 photons/sec in 10 pps). X-band beam line for the demonstration is under commissioning. We also design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). The construction of the whole system starts. X-ray generation and medical application will be performed in this year.
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| RPAP011 | Technical Development of Profile Measurement for the Soft X-Ray Via Compton Backward Scattering | electron, laser, background, quadrupole | 1260 | ||
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A compact X-ray source is called for such various fields as material development, biological science, and medical treatment. At Waseda University, we have already succeeded to generate the soft X-ray of the wavelength within so-called water window region (250-500eV) via Compton backward scattering between 1047nm Nd:YLF laser and 4.2MeV high quality electron beam. Although this method equips some useful characters, e.g. high intensity, short pulse, energy variableness, etc, the X-ray generating system is compact enough to fit in tabletop size. In the next step, there rises two principal tasks, that is, to make the soft X-ray intensity higher, and to progress X-ray profile measurement techniques as preliminary experiments for biomicroscopy. Specifically, we utilize two-pass amp for the former, and irradiate X-ray to a resist film which is previously exposed by UV lamp or get images with X-ray CCD for the latter. In this conference, we will show the experimental results and some future plans.
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| RPAP012 | Dual Energy X-Ray CT by Compton Scattering Hard X-Ray Source | electron, simulation, linac, photon | 1291 | ||
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We have developed a compact Compton scattering hard X-ray source at Nuclear Engineering Research Laboratory, University of Tokyo. The compact hard X-ray source can produce tunable monochromatic hard X-rays. The monochromatic hard X-rays are required in large field of medical and biological applications. We are planning to perform dual-energy X-ray CT, which enables us to measure atomic number Z distribution and electron density re distribution in a material. The hard X-ray source has an advantage to perform dual-energy X-ray CT. The X-ray energy can be changed quickly by introducing a fundamental frequency and a second harmonic frequency lasers. This quick energy change is indispensable to medical imaging and very difficult in a large SR light source and others. The information on the atomic number and electron density will be used for treatment plan in radiotherapy as well as for identification of materials in a nondestructive test. We examined applicability of the dual-energy X-ray CT for atomic number measurement for low to medium Z elements (Z=30) by considering the X-ray profile generated by Compton scattering. Details of the numerical simulations and plans of the dual-energy X-ray CT will be reported in the conference.
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| RPAP033 | Investigation of X-Ray Harmonics of the Polarized Inverse Compton Scattering Experiment at UCLA | electron, laser, photon, permanent-magnet | 2303 | ||
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Funding: U.S. Dept. of Energy grant DE-FG03-92ER40693. |
An Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of scattering utilizing a terawatt CO2 laser system with various polarizations, is ongoing at the UCLA Neptune Laboratory. When the normalized amplitude of the incident laser’s vector potential a0 is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. ICS can be used, e.g., for a polarized positron source by striking a thin target (such as tungsten) with the polarized X-rays. As such, it is critical to demonstrate the production of polarized scattered photons and to investigate the ICS process as it enters the nonlinear regime. We present the description of the experimental set up and equipment utilized, including diagnostics for electron and photon beam detection. We present the current status of the experiment. |
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| RPAT006 | Design and Initial Tests of a Gas Scattering Energy Monitor in the PEFP RFQ and DTL | proton, energy-calibration, rfq, linac | 997 | ||
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Funding: This work is supported by the 21C Frontier R&D program in the Ministry of Science and Technology of the Korean government. |
We have developed a gas scattering energy monitor to measure the energy spectrum of the proton beam at the end of 3MeV RFQ and 20MeV DTL for the low energy part of the PEFP(Proton Engineering Frontier Project). The energy monitor is comprised of a Xe scattering chamber, two collimators to reduce the beam intensity, and a surface barrier detector for measuring the proton energy. In order to measure the beam current simultaneously, a faraday cup is incorporated into the energy monitor. The calculated flux attenuation through the 0.2 mm diameter collimator is 3·10-4 and the energy loss is 28 keV. We report on design details and multiple gas scattering of proton beams in Xe gas by using a SRIM code. |
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| RPAT031 | Beam Profile Measurement with Flying Wires at the Fermilab Recycler Ring | emittance, antiproton, lattice, vacuum | 2182 | ||
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The Fermilab Recycler Ring is a high vacuum fixed energy antiproton storage ring with stochastic and electron cooling systems. Flying wires were installed at the Fermilab Recycler Ring for transverse beam profile measurement. The following note describes the system configuration, calibration and resolution of the flying wire system, as well as analysis of the transverse beam profile in the presence of both cooling systems.
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| RPAT042 | Emittance Scanner Optimization for Low Energy Ion Beams | emittance, ion, SNS, proton | 2705 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
Ion beam emittances are normally measured as two-dimensional distributions of the beam current fraction within a window dx centered at position coordinate x and a window dx’ centered at trajectory angle x’. Unthresholded rms emittances evaluated from experimental data are very sensitive to noise, bias, and other undesired signals. Undesired signals occur when particles from outside the measured window dx*dx’ contribute to the signal from the particles within the measured window. Increasing the window size increases the desired signal while most undesired contributions remain unchanged. However, the decreasing resolution causes an error in the emittance results, especially in the rms emittance. Using theoretical distributions we will present the tradeoff between resolution and accuracy. |
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| RPAT067 | Beam Angle Measurement Using Cherenkov Radiation | electron, radiation, optics, photon | 3742 | ||
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A simple beam angle monitor utilizing observation of far-field Cherenkov radiation is being developed. The monitor is independent of beam energy as well as position and requires only modest camera sensitivity. Since the wavefront of Cherenkov radiation is not spherical but planar, the far-field image is supposed to be infinetesimally small in one-dimensional geometrical optics, which may result in high angular resolution. In a practical experiment, however, beam scattering in a radiator and diffraction from a finite size radiation source determine the resolution. Numerical analysis shows that the angular resolution with a 100-um thickness fused silica radiator is 0.8 mrad. The experimental results with 2-mm and 100-um thickness fused silica are shown. The possibility of non-destructive measurement is also discussed.
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| RPAT075 | Optical Synchronization Systems for Femtosecond X-Ray Sources | laser, polarization, linac, synchrotron | 3958 | ||
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Funding: This work was supported by the Laboratory Directed Research and Development Program of Lawrence Berkeley National Laboratory under the Department of Energy Contract No. DE-AC03-76SF00098. |
In femtosecond pump/probe experiments using short x-ray and optical pulses, precise synchronization must be maintained between widely separated lasers in a synchrotron or FEL facility. We are developing synchronization systems using optical signals for applications requiring different ranges of timing error. For the sub-100fs range we use an amplitude modulated CW laser at 1GHz to transmit RF phase information, and control the delay through a 100m fiber by observing the retroreflected signal. Initial results show 40fs peak-to-peak error above 10Hz, and 200fs long term drift, mainly due to amplitude sensitivity in the analog mixers. For the sub-10fs range we will lock two single-frequency lasers separated by several teraHertz to a master modelocked fiber laser, transmit the two frequencies over fiber, and lock two comb lines of a slave laser to these frequencies, thus synchronizing the two modelocked laser envelopes. For attosecond synchronization we propose a stabilized, free space link using bulk lens waveguides and high peak power ultrashort pulses. |
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| RPPE027 | High Intensity High Energy E-Beam Interacting with a Thin Solid State Target: First Results at AIRIX | electron, focusing, target, emittance | 1982 | ||
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Funding: CEA, Polygone d’Expérimentation de Morronvilliers, LEXA F-51 475 Pontfaverger (France). |
AIRIX is a 2 kA, 20 MeV, 60 ns linear accelerator dedicated to X-ray flash radiography. During a regular running phase, the primary electron beam is accelerated to and focused on a high atomic number target in order to generate X-rays by brembtrahlung mainly. The huge energy density deposited into the material is such that temperature rises up to 15000°K and that clusters and particles are violently ejected from the surface. In that mechanism, the backward emission speed can reach 5 km.s-1 and the debris can gradually accumulate and subsequently contaminate some sensitive parts of the machine. In order to protect the whole accelerating line from the detrimental effect of back-ejected particles, we have investigated the technical feasibility of a thin foil implementation upstream the X-ray converter. |
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| RPPP008 | The Short Circumference Damping Ring Design for the ILC | wiggler, damping, emittance, dynamic-aperture | 1126 | ||
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The ILC damping ring tentative design is driven by the operational scenario of the main linac, the beam-dynamics demand of producing a stable and high-quality beam, the injection/extraction scheme and the kicker performance. In this paper, a short circumference damping ring design based on TME cells is described. The ring accommodates injection kickers which provide a flat top of 280 nsec and a 60 nsec rise and fall time and very fast strip-line kickers for beam extraction with a 2 nsec rise and fall time for 3-MHz operation. The potential impact of collective effects and the possible degradation of the dynamic aperture by nonlinear-wiggler fields are estimated.
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| RPPT014 | Design and Measurements of an X-Band Accelerating Cavity for SPARC | coupling, resonance, linac, higher-order-mode | 1407 | ||
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The paper presents the design of an X-band accelerating section for linearizing the longitudinal phase space in the Frascati Linac Coherent Light Source (SPARC). The structure, operating on the pi standing wave mode, is a 9 cells structure feeded by a central waveguide coupler and has been designed to obtain a 5 MV accelerating voltage. The 2D profile has been obtained using the e.m. codes SUPERFISH and OSCARD2D while the coupler has been designed using HFSS. Bead-pull measurement made on a copper prototype are illustrated and compared with the numerical results. Mechanical details of the realized prototype and RF properties of the structure as a function of the assembly characteristics are also discussed.
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| ROPC008 | Experimental Progress in Fast Cooling in the ESR | ion, electron, emittance, injection | 615 | ||
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The ESR storage ring at GSI is operated with highly charged heavy ions. Due to the high electric charge the ions interact much stronger with electromagnetic fields. Therefore both cooling methods which are applied to stored ions in the ESR, stochastic cooling and electron cooling, are more powerful than for singly charged particles. The experimental results exhibit cooling times for stochastic cooling of a few seconds. For cold ion beams, electron cooling provides cooling times which are one to two orders of magnitude smaller. The beams are cooled to beam parameters which are limited by intrabeam scattering. At small ion numbers, however, intrabeam scattering is suppressed by electron cooling, clear evidence was found that the ion beam forms a one-dimensional ordered structure, a linear chain of ions. The strengths of stochastic cooling and electron cooling are complementary and can be combined favorably. Stochastic cooling is employed for pre-cooling of hot secondary beams followed by electron cooling to provide ultimate beam quality. In a similar manner, first experiments with carbon ions have been performed to use electron cooling as a pre-cooling method in combination with laser cooling.
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| FPAE009 | Bunched Beam Cooling in the Fermilab Recycler | emittance, synchrotron, collider, bunching | 1153 | ||
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Stochastic cooling with bunched beam in a linear bucket has been obtained and implemented operationally in the fermilab recycler. In this implementation the particle bunch length is much greater than the cooling system wavelengths. The simultaneous longitudinal bunching enables cooling to much smaller longitudinal emittances than the coasting beam or barrier bucket system. Characteristics and limitations of bunched beam stochastic cooling are discussed.
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| FPAE017 | Observation of Longitudinal Diffusion and Cooling Due to Intrabeam Scattering at the Fermilab Recycler Ring | emittance, antiproton, proton, luminosity | 1560 | ||
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The Fermilab Recycler Ring is a high vacuum fixed energy antiproton storage ring with both stochastic and electron cooling systems. In this note the technique for diffusion rate measurement, beam parameters and the analysis of data are presented, as well as the effect of intrabeam scattering on the operational considerations for the storage and cooling of the antiproton beam in the Recycler.
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| FPAE036 | Lattice Modification of a 1.2 GeV STB Ring for Generation of High Energy Gamma-Rays Using Internal Target Wire | electron, target, lattice, simulation | 2458 | ||
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A 1.2 GeV Stretcher-Booster Ring (STB ring) has been routinely operated at Laboratory of Nuclear Science (LNS), Tohoku University. The STB ring has functions of a pulse-beam stretcher and a booster-storage ring. In the booster-storage operation, high energy gamma-ray beam generated via bremsstrahlung from internal target wire is utilized for experiments of nuclear physics. Some fractions of circulating electrons are also deflected in the target wire due to Coulomb scattering without significant loss of the energy. The scattered electrons that are not getting out of the dynamic aperture once can circulate in the ring. Such electrons, however, would hit the chamber walls and supports of the target wire during further turns, because they have very large betatron amplitude. Consequently the Coulomb scattered electrons must be a source of significant background and may cause a degradation of gamma-ray beam quality. The quality of the gamma-ray beam has been improved by modifying the lattice functions of the ring, and we report the improvement in this conference.
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| FPAT012 | Tevatron Beam Lifetimes at Injection Using the Shot Data Analysis System | proton, antiproton, injection, beam-beam-effects | 1279 | ||
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The purpose of the Shot Data Acquisition and Analysis (SDA) system is to provide summary data on the Fermilab RunII accelerator complex and provide related software for detailed analyses. In this paper, we discuss such a specific analysis on Tevatron beam lifetimes at injection. These results are based on SDA data, tools and methodology. Beam lifetime is one of our most important diagnostics. An analysis of it can give information on intra beam scattering, aperture limitations, instabilities and most importantly beam-beam effects. Such an analysis gives us a better understanding of our machine, and will lead to an improved performance in the future.
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| FPAT017 | SNS Diagnostics Tools for Data Acquisition and Display | diagnostics, SNS, target, beam-losses | 1544 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S Department of Energy. |
The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of a 1.0 GeV linear accelerator, an accumulator ring and associated transport lines. The SNS diagnostics platform is PC-based and will run Windows for its OS and LabVIEW as its programming language. The diagnostics platform as well as other control systems and operator consoles use the Channel Access (CA) protocol of the Experimental Physics and Industrial Control System (EPICS) to communicate. This paper describes the tools created to evaluate the diagnostic instrument using our standard programming environment, LabVIEW. The tools are based on the LabVIEW Channel Access library and can run on Windows, Linux, and Mac OS X. The data-acquisition tool uses drop and drag to select process variables organized by instrument, accelerator component, or beam parameters. The data can be viewed on-line and logged to disk for later use. A drag and drop display creation tool supports the quick creation of graphical displays to visualize the data produced by the instruments without the need for programming. |
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| FPAT053 | LabVIEW Library to EPICS Channel Access | SNS, Spallation-Neutron-Source, diagnostics, target | 3233 | ||
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. |
The Spallation Neutron Source (SNS) accelerator systems will deliver a 1.0 GeV, 1.4 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of a 1 GeV linear accelerator, an accumulator ring and associated transport lines. The SNS diagnostics platform is PC-based and will run Windows for its OS and LabVIEW as its programming language. Data acquisition hardware will be based on PCI cards. There will be about 300 rack-mounted computers. The Channel Access (CA) protocol of the Experimental Physics and Industrial Control System (EPICS) is the SNS control system communication standard. This paper describes the approaches, implementation, and features of LabVIEW library to CA for Windows, Linux, and Mac OS X. We also discuss how the library implements the asynchronous CA monitor routine using LabVIEW’s occurrence mechanism instead of a callback function (which is not available in LabVIEW). The library is used to acquire accelerator data and applications have been built on this library for console display and data-logging. |
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| FPAT081 | A New Version of SixTrack with Collimation and Aperture Interface | collimation, simulation, proton, betatron | 4084 | ||
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Simulations of collimation and beam cleaning were so far often performed with simplified computer models. However, the increase in available CPU power has opened the possibility for far more realistic simulations. For large accelerators like LHC it is now possible to track millions of particles, element by element over hundreds of turns. The well established SixTrack code treats the full six-dimensional phase space and considers the non-linear magnet components up to very high order. This code is being used for all LHC tracking simulations and has well developed linear and non-linear error models. SixTrack was extended for tracking of large ensembles of halo particles, taking into account halo interaction with arbitrarily placed collimators. An interface to a program for aperture analysis allows obtaining beam loss maps in the machine aperture. A standardized and portable SixTrack version is now available, providing all functionality of the old SixTrack, as well as the newly added support for halo tracking, collimation and aperture loss maps.
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| FOAA001 | New Technology in Hydrogen Absorbers for Muon Cooling Channels | emittance, simulation, linac, proton | 84 | ||
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Funding: National Science Foundation. |
Ionization cooling is the only technique fast enough to cool and focus muons for neutrino factories and muon colliders, and hydrogen is the optimal material for maximum cooling and minimal multiple scattering. Liquid hydrogen absorber R & D for the Muon Colloboration has proceeded on parallel and complementary fronts. The continuing LH2 absorber engineering and technical developments by the MuCool group conducted by ICAR* institutions (NIU, IIT and UIUC), the University of Mississippi and Oxford University, in cooperation with Fermilab, will be summarized, including results from the first hydrogen absorber tests at the newly constructed FNAL Mucool Test Area (MTA). The program includes designs for the high-powered test of an absorber prototype (external heat exchange) at the MTA which are nearing completion to be installed by summer 2005, an alternative absorber design (internal heat exchange) being finalized for the approved cooling experiment (MICE) at Rutherford-Appleton Laboratory, and a novel idea for gaseous hydrogen absorbers being developed at Fermilab for a high powered test at the MTA in 2006. *Illinois Consortium for Accelerator Research. |
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