Log entry time 03:09:00 on March 29, 2014

Entry number 387959

The plots of active wires and number of hits from Run 1286(1.8kV) and Run 1288(1.7kV) are displayed. The average number of hits drops with the new HV. And the R-arm Fpp plots from Run 20299(1.7kV) are also displayed, which show the average number of hits is correlated to the HV.

Mark Jones taught me this simple way to estimate the efficiency of FPP chambers.

R=Ration= (#2hits / #3hits)

e=( 1 / (1 + R/2))

According to this formula:

Run 1286 (1.8kV): U(e)=0.76, V(e)=0.73

Run 1288 (1.7kV): U(e)=0.55, V(e)=0.53

Run 20299 (1.7kV): U(e)=0.37, V(e)=0.35

I will write a code to investigate the efficiency more accurately with smaller groups, such as making sure the fires two wires and three wire are close to each other.

I think the HV 1.8kV is better and we should perhaps set the HV of R-arm to 1.8kV too. And increase the threshold of L-arm to 3V to get rid of the noises when we have access to the Hall A.

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