Today we are continuing our plateauing of the scintillators. For this next test, we are replateauing the bottom scintillator but with its threshold at 225 mV instead of 275 like before while keeping the top scintillator at 275 mV. We are decreasing the threshold because we are still not seeing the count rate that we expect, which is about 8 coincidence counts per minute. Since the count rate in our past experiments is too low, it can be deduced that the threshold is too high and therefore we are not reading some of the cosmic rays that pass through.
| Plateau of Bottom Scintillator
|
| Time
|
HV on top scint.
|
HV on bottom scint.
|
Singles Count (on top)
|
Coinc. Counts
|
Coinc. per minute
|
| 30 min
|
1300
|
1450
|
2831
|
111
|
3.7
|
| 30 min
|
1300
|
1400
|
2880
|
104
|
3.47
|
| 30 min
|
1300
|
1350
|
3000
|
101
|
3.37
|
| 30 min
|
1300
|
1300
|
3164
|
68
|
2.27
|
| 30 min
|
1300
|
1250
|
3121
|
77
|
2.57
|
| 30 min
|
1300
|
1200
|
3182
|
47
|
1.57
|
| 30 min
|
1300
|
1150
|
3100
|
16
|
0.533
|
| 30 min
|
1300
|
1100
|
3141
|
3
|
0.1
|
This next data set is from the replateau of the top scintillator with both scinitillators thresholds set at 225 mV.
| Plateau of Top Scintillator
|
| Time
|
HV on top scint.
|
HV on bottom scint.
|
Singles Count (on top)
|
Coinc. Counts
|
Coinc. per minute
|
| 90 min
|
1300
|
1450
|
|
|
|
| 30 min
|
1300
|
1400
|
3924
|
90
|
3
|
| 30 min
|
1300
|
1350
|
4088
|
87
|
2.9
|
| 30 min
|
1300
|
1300
|
4397
|
93
|
3.1
|
| 30 min
|
1300
|
1250
|
2120
|
75
|
2.5
|
| 30 min
|
1300
|
1200
|
1737
|
81
|
2.67
|
| 30 min
|
1300
|
1150
|
893
|
70
|
2.33
|
| 30 min
|
1300
|
1100
|
347
|
40
|
1.33
|