05/13/2011 coincidence test

Set up like that:

The voltages, thresholds and widths are as below. Note: I increased my thresholds for PS1 and PS2 from 80 mV up to 100 mV according to my previous calibration threshold line.

	PMT voltage, V	threshold, mV	discr. width, ns
PS1	-1000	-100	50
PS1	-1000	-100	50
n's	-1500	-200	10

First let's do the PS1+PS2 coincidence test. The distance between PS and n's PMT is about 80 cm

	counts	time	counts/sec
PS1	$2823\pm53.1$	20 min	$2.35\pm0.04$
PS2	$3091\pm55.6$	20 min	$2.58\pm0.05$
PS1+PS2	$93\pm9.6$	20 min	$(7.7\pm0.8)\cdot 10^{-2}$

The distance between PS and n's PMT is about 50 cm

	counts	time	counts/sec
PS1	$7513\pm86.5$	60 min	$2.09\pm0.02$
PS2	$9036\pm95.1$	60 min	$2.51\pm0.03$
PS1+PS2	$251\pm15.8$	60 min	$(6.9\pm0.4)\cdot 10^{-2}$

The scope picture of PS1+PS2 coincidence event like:

Second tet's do the PS1+PS2+n's coincidence test

	counts	time	counts/sec
PS1	$3229\pm56.8$	20 min	$2.69\pm0.05$
PS2	$3192\pm56.5$	20 min	$2.66\pm0.05$
PS1+PS2+n's	$59\pm7.7$	20 min	$(4.9\pm0.6)\cdot 10^{-2}$

The scope picture of PS1+PS2 coincidence event like:

The ratio of (PS+PS2) rate to (PS+PS2+n's) rate is

[math]\frac{7.7}{4.9} = 1.6[/math]