Log entry time 14:06:59 on November 17, 2008

Entry number 249394

This entry is a followup to: 248212

I adjusted the HV for the paddles until the average peak amplitudes for coincident events were similar and then measured singles rates and coincidence rates.

The theory was that we were to measure electrons with sufficient energy to punch through both paddles and the sandwiched 1" thick steel plate. The high energy charged flux from the target would be swept away by BB and effectively blocked by the shower+preshower. Whatever punched through from the target side to trigger the paddles would be very high energy (and a negligible rate contribution).

These measurements were taken after the Pb block beamline shielding was added, so the paddles were reasonably well shielded from the upstream beamline.

P1: downstream paddle (horizontal in photo), unshielded against the dump.
P2: upstream paddle (vertical in photo), right next to the Shower.

The data were taken around 11pm--midnight, Oct. 12. Pol. 3He target, 8uA.

Thresh      P1        P2        Coin.
[mV]       [kHz]     [kHz]      [kHz]
----------------------------------------
 30         22        36        1.350
 40         16        21
 50         12        12
 60         10         8        0.200
 70         8          6
 80         7          4
 90         6          3
100         5          3
120         4          2
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No beam rates, during a trip:
 30 mV      20 Hz     30 Hz       0 Hz
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Figure 1