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This update from Stony Brook Gang discusses the recent QE test results, equipment updates, pump issues, and the problem with the Gain Test Chamber hole. It also outlines the plan to address the inconsistent performance of the cryo pump and upcoming modifications to the Evap chamber.
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Update from Stony Brook Stony Brook Gang
Two More Shots • Seem to show Good QE in local tests: • https://www.phenix.bnl.gov/WWW/p/draft/jkamin/browse1_qe.html • Chicklet mystery: • Expect 150 pA current. • Saw 0.7 pA??? • Mishandling cause factor of 200 QE drop?? • Still have another Chicklet, same shot.
Pump Woes • Main Scroll pump suffered failure. • Rebuilt one on order. • Local fix to existing one as well. • Used “little guy” as main pump. • Revealed additional troubles: • Cryo gate valve leaks! • Too large gas load during cool-down. • Burden on turbo during pumpdown. • Rich L and Bill will service it this week.
Bad hole on Gain Test Chamber. • One LEMO hole is bigger than others! • LEMO does not engage. • Will weld plug over the hole to seal.
No shot this week. • Concentrate on curing the inconsistent performance of the cryo pump: • Cryo Gate Valve CERTAINLY leaks. • ALL observations could be consistent with a single failure: Cryo Main Gate Valve. • Time for minor mods to Evap chamber. • Next “weekly shot” next week.