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| MOP38 | Background from Undulator in the Proposed Experiment with Polarized Positrons | undulator, electron, photon, positron | 123 | ||||
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E-166 is a proposed experiment for verification of polarized positron production for linear collider. According to polarized positron source design, high energy electrons pass through helical undulator and produce circularly polarized photons, which interact with tungsten target and produce longitudinally polarized positrons. In the proposed E-166 experiment, 50 GeV beam propagates inside 1m long undulator followed by a drift space of 35 m before interaction with target. Polarized positrons are analyzed by Si-W calorimeter, which is placed along the axis. Polarized positrons are analyzed by CsI calorimeter after reconversion of positrons to photons at the second target. Background is an issue for a considered experiment. GEANT3 simulations were performed to model production of secondary particles from primary electrons hitting undulator. Energy density distribution of background particles at the target and effect of background collimation are discussed.
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| MOP67 | TESLA RF Power Coupler Thermal Calculations | linac, simulation | 174 | ||||
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The main RF power coupler is one of the key elements of the accelerating module for the superconducting linac. It provides RF power to the cavity and interconnect different temperature layers in the module. Therefore statistical and dynamical thermal losses have to be optimized. Different operating modes as well as geometries were investigated. Coupler design optimization studies are carried out for TESLA and for the XFEL case. Especially long pulse operation for the X-FEL is being investigated.
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| TU204 | Effect of High Solenoidal Magnetic Fields on Breakdown Voltages of High Vacuum 805 MHz Cavities | vacuum, collider, linac, factory | 271 | ||||
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The demonstration of muon ionization cooling by a large factor is necessary to demonstrate the feasilibility of a collider or neutrino factory. An important cooling experiment, MICE [1], has been proposed to demonstrate 10 % cooling which will validate the technology. Ionization cooling is accomplished by passing a high-emittance beam in a multi-Tesla solenoidal channel alternately through regions of low Z material and very high accelerating RF Cavities. To determine the effect of very large solenoidal magnetic fields on the generations of Dark current, X-Rays and breakdown Voltage gradients of vacuum RF cavities, a test facility has been established at Fermilab in Lab G. This facility consists of a 12 MW 805 MHz RF station, and a large bore 5 T solenoidal superconducting magnet containing a pill box type Cavity with thin removable window apertures allowing dark current studies and breakdown studies of different materials. The results of this study will be presented. The study has shown that the peak achievable accelerating gradient is reduced by almost a factor two in a 4 T field.
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[1] http://mice.iit.edu/. |
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Transparencies
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| TUP63 | The First Results of Bunch Shape Measurements in SNS Linac | electron, emittance, target, linac | 408 | ||||
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Three Bunch Shape Monitors with transverse scanning of low energy secondary electrons for the SNS Linac have been developed and fabricated. The peculiarity of the detectors is using of energy separation of the electrons. The separation enables to minimize influence of detached electrons originated from dissociation of H-minus ions in the detector wire target. The first detector was used at the exit of the first DTL tank during its commissioning. The results of Bunch Shape measurements are presented and discussed. These results were used to verify beam quality, to set parameters of the accelerating field, to estimate a longitudinal beam halo and to restore a longitudinal beam emittance.
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Transparencies
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