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User name brads
Log entry time 01:36:47 on November 19, 2008
Entry number 249662
This entry is a followup to: 249625
Followups:
keyword=BB Cerenkov witness PMT rates with Pb surround shield
Bottom line: Rates dropped by a factor of 0.5--0.6 vs. the unshielded box.
Beam current: 12 uA
107. kHz T1 rate
1.4 kHz T3 rate
0.054 kHz T5 rate
23.6 kHz T6 rate
Started 1:20am, Wednesday, run 3654
T7 rates w/ all HVs off (ie. EDTM pulser only, same as T2 rate)
Thresh Rate (Hz)
-100 12.48
-300 12.48
-500 12.48
-700 12.48
-750 12.48
-800 0
-900 0
### This is with the 1" of Pb on all sides but that facing the target.
### 1" thick Al plates are on top and bottom.
T7 rates w/ HV on 19 on (witness PMT @ 2100V); 11.8 uA beam
Thresh Rate (kHz)
-100 104.
-300 27.5 (~300 Hz during trip)
-500 9.3
-700 6.3
-900 4.3
Done 1:30am, Tuesday, run 3654
### This is the old (unshielded) run
T7 rates w/ HV on 19 on (witness PMT @ 2100V); 11.8 uA beam
Thresh Rate (kHz)
-100 168.
-300 48.6
-500 17.6
-700 11.8
-900 8.8
A copy of this log entry has been emailed to: meziani