User name R. Michaels
Log entry time 11:26:39 on July17,2005
Entry number 148320
keyword=counting mode with Helium4
Initial alignment and checkout
HV det3 (R-arm) 1700 V
HV det1 (L-arm) 1850 V
Rates for I = 0.5 uA
L-arm HAPPEX detector 6 kHz
S0 PMT1 2 x 10^5 Hz
S0 PMT2 2.8 x 10^5 Hz
R-arm HAPPEX detector 3460 Hz
S0 PMT1 4.6 x 10^5 Hz
S0 PMT2 5.2 x 10^5 Hz
T1 = 4.5 x 10^5 Hz
T2 = 3400 Hz
T3 = 1.4 x 10^5 Hz
T4 = 6300
T5 = T6 = 0
T7 = 5.8 x 10^5 Hz
T8 = 6.0 x 10^5 Hz
Run 2098 - At the "nominal" momentum setting, to check detectors, etc
Ooops ! VDC HV was off. Well, that's why we have checklists...
Run 2099 Repeat, with VDCs on. Noticed one S2m was off. Turned
Fig 1 shows the ADC spectra for the 2 HAPPEX detectors
using the above-written HV settings.
There is a peak seperated from pedestal; this was filled for
triggers 2 & 4 respectively (the pedestal is identified for
other triggers). We could bump up the HV some more ...
Increasing HV on HAPPEX Dets
Det1 (L-arm) 1850 -> 1900 Volts. Rate went from 6 kHz to 36 kHz
Det3 (R-arm) 1700 -> 1800 Volts. Rate went from 3.3 kHz to 38 kHz
(oops, this was done at about event#400K of run 2099, we forgot
to stop the run).
Run 2100 -- Another detector check.
Fig 2 shows detectors (different X axis now).
Now decreasing magnetic field to 2.653 (2 % low).