Exploration of Long-Life Polarized Electron Sources

75592-A radio frequency (RF) photoemission source that delivers polarized electrons at low emittance would be an attractive electron source for a linear collider. Moreover, if such a source were used in conjunction with nearby injection system optics, a beam with a high ratio of transverse emittances could be delivered, thereby simplifying the linear collider¿s damping system. However, present electron source technology has not developed sufficiently to assure that such a source is feasible. This project will fabricate a long-life, low emittance photocathode source for producing polarized electrons. The development of this source will require a substantial improvement in the vacuum inside an RF source, or in a booster in close proximity to a DC source, as well as an understanding and reduction of the effects of ion back bombardment. Phase I will study three configurations for beam dynamics and ion back bombardment and choose a configuration and operating temperature, so that the source for polarized electrons can be designed and fabricated in Phase II. Commercial Applications and Other Benefits as described by the awardee: All linear collider designs should benefit from long-life, low-emittance polarized sources, which would significantly ease the requirements on the damping rings. As an additional benefit, sources with a solenoid field on the cathode followed by a flat beam transformer could provide large aspect ratio beam emittance.