Speaker
Description
The generation of polarized positron beams for the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab is based on bremsstrahlung radiation and electron-positron pair production by a 90% longitudinally polarized electron beam in a rotating tungsten target. The required electron beam energy and target thickness for generating a 100 nA positron beam with 60% polarization and a normalized emittance of 100 mm·mrad are calculated. To prevent target overheating and damage, the peak energy deposition density (PEDD) is also calculated. The electron beam current, beam spot size on the target, and target rotation speed are determined for a PEDD limit of 35 J/g for the tungsten target. The objective of this study is to work backward from the CEBAF 6D acceptance to determine the required parameters of the primary electron beam and tungsten target for positron production.