Note that the singles rates in BB and LHRS were 10% lower after the new 3He cell installation and beam tune yesterday. If I normalize to the T1 rate then we get (roughly):
Thresh Delta(Rate) vs. Pb-only config
-100 +10 %
-300 +10 %
-500 -33 %
-700 -36 %
-900 -38 %
Started 3:19pm, Thursday Nov 27, run 3977
Beam current: 11.8 uA
93.6 kHz T1 rate (about 10% lower than with previous 3He cell + beam
tune)
1.3 kHz T3 rate (about 10% lower than with previous 3He cell + beam
tune)
0.046 kHz T5 rate
19.4 kHz T6 rate
(T1) Threshold for 'BB_Sh_2' is -0.080 V (1925)
(T6) Threshold for 'BB_Sh' is -0.120 V (1833)
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.
### Target side has 2+" of Pb.
### 1" thick Al plates on bottom, 1" Pb plate on top
### All sides covered with 2--4" of borated plastic. There are some gaps
### though, particularly at the front (unfortunately).
T7 rates w/ HV on 19 on (witness PMT @ 2100V); 11.8 uA beam
Thresh Rate (kHz)
-100 124.
-300 23.5
-500 5.6
-700 3.6
-900 2.4
Done 3:27pm, Thursday, run 3978
---------------------------------------------------------------------
### This is with the 1" of Pb on all sides but that facing the target.
## Side facing target is unshielded.
### 1" thick Al plates are on top and bottom.
### Done on Tuesday, run 3654
Beam current: 11.8 uA
103. kHz T1 rate
1.4 kHz T3 rate
0.051 kHz T5 rate
22.5 kHz T6 rate
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
### This is the first (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