Detector HVs and thresholds were unchanged for these tests. NA threshold: -50 mV BB threshold: 700 MeV No beam (halog entry: 163984), Run 2311, T1: 360 kHz T2: 1 Hz T3: 0 Hz 1 uA on EMPTY target (halog entry: 163992), Runs 2313, 2309, 2314* T1: 3.3 MHz T2: 110 Hz T3: 56 Hz 1 uA on OPTICS target (halog entry: 163985), Runs 2312, 2315* T1: 5.7 MHz T2: 955 Hz T3: 682 Hz
The (*)'ed runs were taken after the beam was initially steered through the Compton chicane. (No extra tuning was done based on the Compton polarimeter detector rates yet). The associated trigger rates did not change.
T2 rates are very reasonable with the empty target and a threshold at 700 MeV. That suggests that there isn't too much unwanted material in the way of the beam.
The T2 and T3 rates both go up by a factor of 10 when the optics foils are inserted.
T1 only goes up by a factor of 2... The T1 beam-off rate is pretty high
though -- could be something is unstable and oscillating? Thresholds
aren't what we think they are? Not sure yet...