New Results From The Mainz Polarized Electron Facilities

The polarized electron source at the Mainz microtron has improved it's performance in every parameter during the last year. Run times have been performed with simultaneously 20 Mikroamps of beam current and more than 80% of polarization. We demonstrate that the limited beam-current lifetime product is due to a transmission loss of about several 10(-4). The loss can be minimized by the usage of photocathodes with only partially photosensitive surface, thus resulting in a nearly one order of magnitude higher beam-current lifetime product.