NSLS vacuum system operating experience conditioning and desorption yields

All straight sections in both the VUV and the X-Ray rings have been filled with various insertion devices, most of them fully operational. Beam lifetime in the VUV ring is limited by the Touschek effect to ∼100 minutes at 800 mA due to the small vertical beam size required by users. With no experiments running, X-Ray beam lifetime is >35 hours at 220 mA and is limited by beam gas scattering. During the past several years the U10 beam line was used to measure PSD yields from various metals to study their relative merits for light sources. These yields were also compared to those measured in X-Ray ring dipoles during initial commissioning when desorption was high. Despite the large differences in critical photon energies, agreement was quite good. Both rings are now fully conditioned and their pressures and lifetimes have reached equilibrium. Well established conditioning procedures are followed after every intervention into their vacuum systems