1 Stony Brook Update Jason Kamin… the Cleaning Machine! T.K. Hemmick

2 Cleaning Success At SB, we excellent de-ionized water: –typically 18 M  -cm, alarmed below 16 M  -cm –Delivered at “faucet pressure” –Can be sprayed forcefully like a rambunctious kid with a garden hose:

3 Cleaning success rate: 6 for 6! FIX: GEM 218 (was ok up to 350V but drew non-ohmic current higher than that) FIX: Au#206 dead short strip 15 washed once, no change. second wash + dry Ar at 500V, fixed. FIX: Cu#152: dead short, strip9. FIX: Cu#172: two SST (strips shorted together), strips 2&3 and 24&25. FIX: Au#221: two separate dead shorts. this is the gem that is part of "Test Stack 1". (Story follows…) FIX: Au#230: CsI coated GEM with no resistance.

4 Ooops on Test Stack #1. Fumble-fingers (TKH) arrived back in the lab just in time to mess up a precious GEM. While handing the GEM between people, the GEM guy moved Forward-Backward, while the pizza-box guy moved Side-Side (miscommunication). The result was that the GEM was poked TWICE by a sharp SS corner and developed TWO shorted strips (uggg…). After a single HARD-wash in the HBD Spa, both strips recovered and the GEM is back to 100%.

5 A funny thing happened on the way to… The next GEM was the CsI-coated GEM that had been delivered to BNL for the single GEM tests, but then returned unused. GEM has been in air since Thanksgiving. EVERY SINGLE STRIP(!!!!) on this GEM showed 1.2~1.6 M to ground. This would presumably be from the fact that heavily contaminated CsI is a bad insulator and made resistive path through nearly every hole. This GEM was also recovered by HARD- wash in the HBD Spa. Does this indicate a potential trouble that could happen to cathodes?

6 Summary Good news: –HARD cleaning (forceful spray) works great and every GEM tested so far has recovered. –We will continue to clean through everything we presently have. Not as Good News: –Since TKH mishandled the top GEM, we did not today get the final gain test measurement and will only begin that tomorrow after the overnight vacuum pumping is done. Suggestion: –Old: “If trouble try cleaning.” –New: “Clean all GEMs before testing as STD procedure.” –Paraphrasing Rui (via Jason): Hard Spray Washing NEVER hurts and usually helps.