Hi All,

Geary asked me to take a look at the HV currents when TOF is in standby mode (i.e. HV = 5000 instead of 7000V).

I looked at the daily HV log files for 1/10/2010 to 1/17/2010 (including). Each log file contains a voltage and current value for each channel every ten seconds. This means for 1 hour = 3600s I have 360 entries for each measurement (i.e. HV and I of a channel).

So when I read in the file I required the HV to be greater than 4990 but less than 5010 and then entered the current for each channel into the histogram

In the above histogram I required all channels to be at standby HV for the current of each channel to be entered. In pseudocode this means

if( 4990 < West_1_HV_pos < 5010 && 4990 < West_1_HV_neg < 5050 && 4990 < West_2_HV_pos < 5050 && .... 4990 < East_5_HV_neg < 5010)

{

Hist->Fill(West_1_I_pos)

Hist->Fill(West_1_I_neg)

Hist->Fill(West_2_I_pos)

...

Hist->Fill(East_5_I_neg)

}

So, the average current per channel is 0.07uA which multiplied by 20 channels (10 sectors * 2 polarities) means the average standby current for the entire system is less than 2uA.

One thing to note though is the large RMS (0.05uA) per channel, which means for the entire system it is +/- 1uA.

Bertrand