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| MOPCH099 | Performance and Capabilities of the NASA Space Radiation Laboratory at BNL | ion, booster, extraction, RHIC | 270 | ||
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The NASA Space Radiation Laboratory (NSRL) at BNL has been in operation since 2003. The first commissioning of the facility took place beginning in October 2002 and the facility became operational in July 2003. The facility was constructed in collaboration with NASA for the purpose of performing radiation effect studies for the NASA space program. The NSRL is capable of making use of protons and heavy ions in the range of 0.05 to 3 GeV/n slow extracted from BNL's AGS Booster. It is also capable of making use of protons and heavy ions fast extracted from the AGS Booster. Many different beam conditions have been produced for experiments at NSRL, including very low intensity In this report we will describe the facility and its' performance over the eight experimental run periods that have taken place since it became operational. We will also describe the current and future capabilities of the NSRL.
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| MOPCH134 | Electron-impact Desorption at the RHIC Beam Pipes | electron, RHIC, injection, vacuum | 360 | ||
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The electron induced molecular desorption coefficient of a material provides the number of molecules released when an electron hits its surface. This coefficient changes as a function of the material, energy of the electrons, surface status, etc. In this paper, this coefficient is inferred analyzing electron detector and pressure gauge signals during electron clouds at the Relativistic Heavy Ion Collider (RHIC) beam pipes. The evolution of the electron-impact desorption coefficient after weeks of electron bombardment is followed for both baked and unbaked stainless steel chambers, evaluating the feasibility of the scrubbing effect. Measurements of an energy spectrum during multipacting conditions are shown, and the final results are compared with laboratory simulations.
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| MOPCH135 | Benchmarking Electron Cloud Data with Computer Simulation Codes | electron, simulation, LEFT, RHIC | 363 | ||
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Saturated electron flux and time decay of the electron cloud are experimentally inferred using many electron detector datasets at the Relativistic Heavy Ion Collider (RHIC). These results are compared with simulation results using two independent electron cloud computer codes, CSEC and ECLOUD. Simulation results are obtained over a range of different values for 1) the maximum Secondary Electron Yield (SEY), and 2) the electron reflection probability at zero energy. These results are used to validate parameterization models of the SEY as a function of the electron energy.
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| TUPLS133 | Material Irradiation Damage Studies for High Power Accelerators | target, proton, AGS, controls | 1816 | ||
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High-performance targets intercepting multi MW proton beams are the key toward intense muon or neutrino beams. To achieve this goal one must push the envelope of the current knowledge on material science and material endurance and survivability to both short and long proton beam exposure. The demand imposed on the targets of high power accelerators and the limitations of most materials in playing such pivotal roles have led to an extensive search and experimentation with new alloys and composites. These new high-performance materials and composites, which at first glance, appear to possess the right combination of properties satisfying target requirements, are explored under accelerator target conditions where both shock and irradiation damage are at play. Results of the on-going, multi-phased experimental effort under way at BNL involving heavy irradiation of candidate materials using 200 MeV protons at the end of the BNL Linac as well as results on post-irradiation analysis assessing irradiation damage are presented.
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| TUPLS140 | An Overview of the SNS Accelerator Mechanical Engineering | SNS, target, vacuum, RTBT | 1831 | ||
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The Spallation Neutron Source (SNS) is an accelerator-based neutron source currently nearing completion at Oak Ridge National Laboratory. When completed in 2006, the SNS will provide a 1GeV, 1.44MW proton beam to a liquid mercury target for neutron production. SNS is a collaborative effort between six U.S. Department of Energy national laboratories and offered a unique opportunity for the mechanical engineers to work with their peers from across the country. This paper presents an overview of the overall success of the collaboration concentrating on the accelerator ring mechanical engineering along with some discussion regarding the relative merits of such a collaborative approach. Also presented are a status of the mechanical engineering installation and a review of the associated installation costs.
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| WEPCH132 | Design Study of Dedicated Computer System for Wake Field Analysis with Time Domain Boundary Element Method | simulation, CSR, electron, controls | 2233 | ||
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Time domain boundary element method (TDBEM) has advantages of dispersion free calculations and modeling of curved beam trajectories in wake field analysis compared to conventional methods. These advantages give us powerful possibilities for analysis of beam dynamics due to CSR in bunch compressors of next-generation accelerators. On the other hand, the TDBEM also has a serious difficulty of large computational costs. In this paper, a dedicated computer system for wake field analysis with the TDBEM is proposed as one of solutions for high performance computing (HPC) technologies. Recent remarkable progress of LSI hardware design environments such as HDL compiler tools and large scale FPGAs enables us to make up computer hardware systems with very low cost in a short development period. The authors have been working in design studies of the TDBEM dedicated computer system on such LSI design environments. This paper presents a system design and VHDL simulations of a wake field analysis machine based on the TDBEM.
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| WEPCH152 | Comment on Healy's Symplectification Algorithm | AGS, CERN, dipole | 2281 | ||
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For long-term tracking, it is important to have symplectic maps for the various electromagnetic elements in an accelerator ring. While many standard elements are handled well by modern tracking programs, new magnet configurations (e.g., a helical dipole with a superimposed solenoid) are being used in real accelerators. Transport matrices and higher terms may be calculated by numerical integration through model-generated or measured field maps. The resulting matrices are most likely not quite symplectic due to numerical errors in the integrators as well as the field maps. In his thesis*, Healy presented a simple algorithm to symplectify a matrix. This paper presents a discussion of limitations of this method.
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*L. M. Healy, "Lie Algebraic Methods for Treating Parameter Errors in Particle Accelerators", Doctoral Thesis. University of Maryland, unpublished (1986). |
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| WEPCH153 | Symplectic Interpolation | coupling, AGS, resonance, dipole | 2284 | ||
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It is important to have symplectic maps for the various electromagnetic elements in an accelerator ring. For some tracking problems we must consider elements which evolve during a ramp. Rather than performing a complicated numerical integration for every turn, it should be possible to integrate the trajectory for a few sets of parameters, and then interpolate the transport map as a function of one or more parameters, such as energy. We present two methods for interpolation of symplectic matrices as a function of parameters: one method is based on the logarithm of the matrix, and the other is based on the related but simpler Healy symplectification method.
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| THPCH081 | Transverse Impedance of Elliptical Cross-section Tapers | impedance, vacuum, damping, synchrotron | 2973 | ||
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We investigate the transverse impedance of elliptical cross-section tapers. Analytical estimates for the dipole and quadrupolar components of the impedance at low frequency are obtained by extending a perturbation approach introduced by Stupakov. The perturbation theory results are compared to EM code GdfidL and are found to be in excellent agreement.
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| THPCH196 | A Proof-of-Principle Experiment for a High-Power Target System | target, proton, CERN, factory | 3254 | ||
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The MERIT experiment, to be run at CERN in 2007, is a proof-of-principle test for a target system that converts a 4-MW proton beam into a high-intensity muon beam for either a neutrino factory complex or a muon collider. The target system is based on a free mercury jet that intercepts an intense proton beam inside a 15-T solenoidal magnetic field.
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| THPLS093 | Status of the Photocathode RF Gun System at Tsinghua University | gun, laser, cathode, scattering | 3496 | ||
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An S-band high gradient photocathode RF gun test stand is in construction process at Tsinghua University. The photocathode RF gun test stand is a primary step of a femtosecond hard x-ray source based on Thomson scattering. The photocathode RF gun system adopts Ti:Sap laser, BNL IV type 1.6 cell RF gun, compact compensation solenoid. We foresee to conduct investigations on the thermal emittance contribution of surface roughness, the emittance compensation technique under various laser shape and its application to Thomson scattering x-ray source. Except for the transportation of laser, correction of laser front for glazing incidence and laser pulse shaping system, other parts of the photocathode RF gun test stand have been constructed, and we can start very primary experiment on the RF gun test stand, such as measurements of dark current, QE and energy of the beam. The experimental results are reported.
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