SLAC E-158 is an experiment designed to make the first measurement of parity violation in Møller scattering. E-158 will measure the right-left cross-section asymmetry, A M øller LR , in the elastic scattering of a 45-GeV polarized electron beam off unpolarized electrons in a liquid hydrogen target. E-158 plans to measure the expected Standard Model asymmetry of ∼ 10 −7 to an accuracy of better than 10 −8 . To make this measurement, the polarized electron source requires for operation an intense circularly polarized laser beam and the ability to quickly switch between right-and left-helicity polarization states with minimal right-left helicity-correlated asymmetries in the resulting beam parameters (intensity, position, angle, spot size, and energy), beam A LR 's. This laser beam is produced by a unique SLAC-designed flashlamp-pumped Ti:Sapphire laser and is propagated through a carefully designed set of polarization optics. We analyze the transport of nearly circularly polarized light through the optical system and identify several mechanisms that generate beam A LR 's. We show that the dominant effects depend linearly on particular polarization phase shifts in the optical system. We present the laser system design and a discussion of the suppression and control of beam A LR 's. We also present results on beam performance from engineering and physics runs for E-158.
The SLAC PES, developed in the early 1990s for the SLC, has been in continuous use since 1992, during which time it has undergone numerous upgrades. The upgrades include improved cathodes with their matching laser systems, modified activation techniques and better diagnostics. The source itself and its performance with these upgrades will be described with special attention given to recent high-intensity long-pulse operation for the E-158 fixed-target parity-violating experiment. (PESP 2002), September 4-6, 2002 Abstract. The SLAC PES, developed in the early 1990s for the SLC, has been in continuous use since 1992, during which time it has undergone numerous upgrades. The upgrades include improved cathodes with their matching laser systems, modified activation techniques and better diagnostics. The source itself and its performance with these upgrades will be described with special attention given to recent high-intensity long-pulse operation for the E-158 fixedtarget parity-violating experiment.
Presented at the Workshop on Polarized Electron Sources and Polarimeters
Abstracttwren the buncher and the accelerator since space charge forces would cause the bunch to debunch rapidly in the absence of a comprrssing longitudinal electric field. The buncher is phased so that the bunch enters the accelerator centered on the phase focusing longitudinal electric Geld null. This causes the bunch to undergo an additional factor of 3 phase compression as it drifts back to the accelerating crest in the first meter of the 3 meter section. A cut-off iris between the buncher and accclcrator section permits independent adjustment of phase and RF power level for each.
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