CH PAS He3 BorAl Attenuation Study

Experimental Setup

Attenuation Measurements Setup
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.

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CH He3 Attenuation Measurements

PAS Experiment Attenuation Measurements

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