Poly box to contain Cf-252 source for attenuation measurements
He3 tube mounting for attenuation measurements
He3 tube mounted on 2" of virgin poly for attenuation measurements
Full poly box with lid pulled back for easy insertion of Cf-252 source
Top down view of Cf-252 source in place, ready to be covered by top sheet of virgin poly
Full setup with 8.5" of purple borated poly in place
The He3 detector is shrouded in BorAl, in a triangular configuration with +1250V to the pre-amp (this voltage is based on previous work by Jeff Burggraf and David Friant).
The thermalizing box is designed as regular poly surrounding the Cf-252 source on all sides except the side in the direction of the He3 tube.
The thermalizer is considered a regular poly sheet that can be slid in and out of the experimental setup.
The detector is ~30cm from the Cf-252 source. This allows for enough distance to insert 8" (20.32cm) of green borated poly, a 1" (2.54cm) thermalizing sheet, and still have the BorAl in the correct position.
No lead was included in the setup as it was not necessary.
The discriminator threshold was not changed during this experiment as it is in the center of the plateau work done by David Friant. See plot below.
Credit: David Friant. This plot is source in and source out He3 tube plateau measurements which were used to base discriminator and bias voltages for attenuation measurements.
Measurements
Background Measurements
I will be performing background runs overnight due to the low amount of background counts. This is necessary to get an acceptable level of uncertainty in the measurements as the count rate looks to be on the order of .5Hz.
The first run background run is taking place the evening of 6/25/21 and will end the following day.
Background run lasted for 60000 seconds and took place overnight. Run ended at approximately 11:45am 6/26/21
1250V Source Out Data
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Button Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector surrounded by BorAl at +1250V
255
No
722
60000
0.0120
0.000448
Source In
No borated poly, just BorAl shielding around detector
1250V Source In Data
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on BorAl at +1250V
255
Yes
236
300
0.787
0.0512
2
Detector on BorAl at +1250V
255
Yes
263
300
0.877
0.0541
3
Detector on BorAl at +1250V
255
Yes
251
300
0.837
0.0528
4
Detector on BorAl at +1250V
255
Yes
203
300
0.677
0.0475
5
Detector on BorAl at +1250V
255
Yes
218
300
0.727
0.0492
Green Poly
1" Green poly (one sheet)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
165
300
0.55
0.0428
2
Detector on poly at +1250V
255
Yes
219
300
0.73
0.0493
3
Detector on poly at +1250V
255
Yes
197
300
0.657
0.0468
4
Detector on poly at +1250V
255
Yes
220
300
0.733
0.0494
5
Detector on poly at +1250V
255
Yes
199
300
0.663
0.0470
2" Green poly (one brick)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
154
300
0.513
0.0414
2
Detector on poly at +1250V
255
Yes
163
300
0.543
0.0426
3
Detector on poly at +1250V
255
Yes
150
300
0.5
0.0408
4
Detector on poly at +1250V
255
Yes
125
300
0.417
0.0373
5
Detector on poly at +1250V
255
Yes
154
300
0.513
0.0414
3" Green poly (one brick & sheet)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
220
600
2
Detector on poly at +1250V
255
Yes
177
600
3
Detector on poly at +1250V
255
Yes
195
600
4
Detector on poly at +1250V
255
Yes
215
600
5
Detector on poly at +1250V
255
Yes
188
600
4" Green poly (two bricks)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
153
600
0.255
0.0412
2
Detector on poly at +1250V
255
Yes
134
600
0.223
0.0386
3
Detector on poly at +1250V
255
Yes
124
600
0.207
0.0371
4
Detector on poly at +1250V
255
Yes
145
600
0.242
0.0401
5
Detector on poly at +1250V
255
Yes
133
600
0.222
0.0384
6" Green poly (three bricks)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
115
900
0.128
0.0119
2
Detector on poly at +1250V
255
Yes
137
900
0.152
0.0130
3
Detector on poly at +1250V
255
Yes
149
900
0.166
0.0136
4
Detector on poly at +1250V
255
Yes
151
900
0.168
0.0137
5
Detector on poly at +1250V
255
Yes
116
900
0.129
0.0120
8" Green poly (four bricks)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
143
1200
0.119
0.00997
2
Detector on poly at +1250V
255
Yes
133
1200
0.111
0.00961
3
Detector on poly at +1250V
255
Yes
152
1200
0.127
0.0102
4
Detector on poly at +1250V
255
Yes
154
1200
0.128
0.0103
5
Detector on poly at +1250V
255
Yes
149
1200
0.124
0.0102
Regular Poly
1" Regular Poly
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
247
300
0.823
0.0524
2
Detector on poly at +1250V
255
Yes
189
300
0.63
0.0458
3
Detector on poly at +1250V
255
Yes
218
300
0.727
0.0492
4
Detector on poly at +1250V
255
Yes
220
300
0.733
0.0494
5
Detector on poly at +1250V
255
Yes
243
300
0.81
0.0520
2" Regular Poly (one brick)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
192
300
0.64
0.0462
2
Detector on poly at +1250V
255
Yes
158
300
0.527
0.0419
3
Detector on poly at +1250V
255
Yes
189
300
0.63
0.0458
4
Detector on poly at +1250V
255
Yes
174
300
0.58
0.0440
5
Detector on poly at +1250V
255
Yes
177
300
0.59
0.0443
3" Regular Poly (one brick & sheet)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
125
300
0.417
0.0373
2
Detector on poly at +1250V
255
Yes
142
300
0.473
0.0397
3
Detector on poly at +1250V
255
Yes
96
300
0.32
0.0327
4
Detector on poly at +1250V
255
Yes
117
300
0.39
0.0361
5
Detector on poly at +1250V
255
Yes
143
300
0.477
0.0399
4" Regular Poly (two bricks)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
142
600
0.237
0.0199
2
Detector on poly at +1250V
255
Yes
150
600
0.25
0.0204
3
Detector on poly at +1250V
255
Yes
165
600
0.275
0.0214
4
Detector on poly at +1250V
255
Yes
194
600
5
Detector on poly at +1250V
255
Yes
160
600
6" Regular Poly (three bricks)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
131
900
2
Detector on poly at +1250V
255
Yes
139
900
3
Detector on poly at +1250V
255
Yes
129
900
4
Detector on poly at +1250V
255
Yes
140
900
5
Detector on poly at +1250V
255
Yes
145
900
8" Regular Poly (four bricks)
1250V source in
Run Number
Configuration
Discriminator Threshold (mV)
Cf-252 Source
Counts
Run Time (Sec)
Count Rate (Hz)
Uncertainty
1
Detector on poly at +1250V
255
Yes
162
1200
2
Detector on poly at +1250V
255
Yes
142
1200
3
Detector on poly at +1250V
255
Yes
183
1200
4
Detector on poly at +1250V
255
Yes
165
1200
5
Detector on poly at +1250V
255
Yes
152
1200
Results
Completed attenuation measurements with differing thicknesses of Borated Poly vs unborated poly with the He3 detector shielded by BorAl.
