1. Status of CsBr Photocathodes Juan R. Maldonado, David Dowell, Jeff Corbett, Sam Park, John Schmerge, Alan Fisher, Piero Pianetta, Ann Trautwein SLAC, National Accelerator Laboratory Menlo Park, CA 94025 and William Clay Stanford University 94305

2. Outline CW Performance of CsBr photocathodes Energy Spread/Emittance Measurements Pulsed Behavior

3. Behavior of CsBr coated Cu

4. ENERGY SPREAD/EMITTANCE MEASUREMENTS

5. ENERGY SPREAD ANALYZER

6. Energy Spread Measurements

7. Emittance calculation from 3 step model agrees with experimental value

8. Pulsed Behavior of CsBr Photocathodes

10. Apparent QE of CsBr on Cu

11. Jedi Laser 7 nsec

16. Summary The 3 step model predicts the observed emittance and QE in CsBr/Cu. The small increase in emittance observed in CsBr/Cu over Cu is a small price to pay relative to the large QE gain observed. The observed QE behavior of CsBr/Cu is limited by space charge due to the relatively low extraction voltage utilized in the experiments. CsBr/Cu survived short pulse operation without ablation. Future experiment: Operation in a microwave cavity