05/09/2011

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I did some counts test like:

The powers were:

PS1 and PS2:  -1000 V
n's: -1100 V

The PMT for n's detectors is PMT HAMAMATSU R580 with supply voltage 1250/1500 V. But I have used the value above, because I though the counts rate was reasonable. See my table below.

The thresholds were:

PS1 and PS2:  -80 mV
n's: -60 mV

Let see what we have. First he CF-243 source is far far away (sealed in the safe):

	counts/min	counts/min
PS1	153 counts/min	170 counts/min
PS2	150 counts/min	173 counts/min
PS1+PS2	3.8	5.8
n's	358 counts/min

Second the CF-243 source is somewhere aside (on the table 40 - 60 cm away from detectors. That test supposed to be initially as test without CF243 source and I just put the isotope away from detectors somewhere on the table, but as happened the PS detectors was able to see the source):

	counts/min	counts/min
PS1	373 counts/min	362 counts/min
PS2	654 counts/min	656 counts/min
PS1+PS2	2.0	6.0
n's	358 counts/min	368 counts/min

Third the CF-243 source is on the top of PS1:

	counts/min	counts/min
PS1	364,570 counts/min	363,477 counts/min
PS2	19,832 counts/min	19.980 counts/min
PS1+PS2	993	959
n's	369 counts/min	352 counts/min