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SB Summary. 4 March 2008. Update. 9 stacks have been installed. One more was tested which shows lower gain has not yet been installed. The scintillation cube has been evaporated onto. The trip recovery procedure was altered to increase wait time before ramp up.
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SB Summary 4 March 2008
Update • 9 stacks have been installed. • One more was tested which shows lower gain has not yet been installed. • The scintillation cube has been evaporated onto. • The trip recovery procedure was altered to increase wait time before ramp up. • The GEMs from the east have been washed. • Drift field studies are in progress.
GEM Failures • Last week we presented the hypothesis that the increase in GEM failures inside the test box was due to the old feed-through to power the light cube. • This has been confirmed. • Not just luck.
Do We Understand The Gain? • We’ve become accustomed to gains > 20,000 with CsI and > 10,000 without at dV = 511 • We got worried about WN4 with a post-CsI gain of <9000 and now we’ve tested a stack with gain of 11,000 (not installed yet) • Is water the mystery variable? • Is there an evaporation dependence to the post-CsI gain increase?
Not very conclusive in my opinion. • The next GEM of Shot #310 seems to have high gain. • What variable does any possible correlation reflect?
What’s Next? • We plan to complete instrumentation of the HBD west soon. A possible plan: • Power each module and make sure it holds voltage • Heat the glove box in an effort to remove water. • Close the vessel and use Bob’s gas system, to gauge the water content in N. • When we’ve reached an acceptable water level use Bob’s or the LEGS gas system to flow CF4 and power the whole detector for a long test (maybe only 7/10 at a time depending on the availability of HV feed-throughs). • HV from LeCroy - we need more modules!
8107 Installed in WN4
8108 Installed in WN4
8110 Not installed
8114 Installed in WS1
8115 Installed in WS2
8116 Installed in WS5