CH He3 Attenuation Measurements

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  • Build poly box to house source and help thermalize neutron flux
  • Get Cf source
  • Measure rates in He3 tube with differing amounts of poly (and different types) -> get to background levels
    • Thermalize neutron flux from Cf with virgin poly for all measurements
    • Build virgin poly box around Cf source
      • Pretty quick and dirty measurement to figure out which poly is best


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



He3 tube is mounted on 2" of virgin poly to put it at rough center of californium source

Cf252 source is enclosed in thermalizing virgin poly box

He3 tube is 8.5" from outside face of thermalizer

Cf252 is mounted approximately .5" behind thermalizing poly plate

Thermalizing poly plate is 1" thick

Will upload pictures and attached comments to each picture

Measurements

Background Measurements

1250V Source Out Data
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 No 32 300 0.107 0.019
2 Detector on poly at +1250V 255 No 44 300 0.147 0.022
3 Detector on poly at +1250V 255 No 55 300 0.183 0.025
4 Detector on poly at +1250V 255 No 34 300 0.113 0.019
5 Detector on poly at +1250V 255 No 20 300 0.067 0.015

Source In

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 11255 300
2 Detector on poly at +1250V 255 Yes 10996 300
3 Detector on poly at +1250V 255 Yes 10750 300
4 Detector on poly at +1250V 255 Yes 10815 300
5 Detector on poly at +1250V 255 Yes 10696 300

Purple Poly without Thermalizer

For some reason, the purple poly bricks are 1 1/8" thick

1" Purple poly, no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 2816 300 9.39 0.177
2 Detector on poly at +1250V 255 Yes 2809 300 9.36 0.177
3 Detector on poly at +1250V 255 Yes 2774 300 9.25 0.176
4 Detector on poly at +1250V 255 Yes 2790 300 9.30 0.176
5 Detector on poly at +1250V 255 Yes 2875 300 9.58 0.179

2 1/8" Purple poly (one brick) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 2118 300 7.06 0.153
2 Detector on poly at +1250V 255 Yes 2012 300 6.71 0.150
3 Detector on poly at +1250V 255 Yes 2092 300 6.97 0.152
4 Detector on poly at +1250V 255 Yes 2025 300 6.75 0.150
5 Detector on poly at +1250V 255 Yes 2092 300 6.97 0.152

3 1/8" Purple poly (one brick & sheet) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 1434 300 4.78 0.126
2 Detector on poly at +1250V 255 Yes 1348 300 4.49 0.122
3 Detector on poly at +1250V 255 Yes 1489 300 4.96 0.129
4 Detector on poly at +1250V 255 Yes 1393 300 4.64 0.124
5 Detector on poly at +1250V 255 Yes 1372 300 4.57 0.124

4 1/4" Purple poly (two bricks) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 1093 300 3.64 0.110
2 Detector on poly at +1250V 255 Yes 1068 300 3.56 0.109
3 Detector on poly at +1250V 255 Yes 1116 300 3.72 0.111
4 Detector on poly at +1250V 255 Yes 1031 300 3.44 0.107
5 Detector on poly at +1250V 255 Yes 1142 300 3.81 0.113

6 3/8" Purple poly (two bricks) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 743 300 2.48 0.091
2 Detector on poly at +1250V 255 Yes 694 300 2.31 0.088
3 Detector on poly at +1250V 255 Yes 756 300 2.52 0.092
4 Detector on poly at +1250V 255 Yes 735 300 2.45 0.090
5 Detector on poly at +1250V 255 Yes 745 300 2.48 0.091

8 1/2" Purple poly (two bricks) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 662 300 2.21 0.086
2 Detector on poly at +1250V 255 Yes 586 300 1.95 0.081
3 Detector on poly at +1250V 255 Yes 613 300 2.04 0.083
4 Detector on poly at +1250V 255 Yes 560 300 1.87 0.079
5 Detector on poly at +1250V 255 Yes 622 300 2.07 0.083

Purple poly with Thermalizer

2 1/8" Purple poly (one brick) with thermalizer

1250V Thermalized source
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes, thermalized 2117 300 7.06 0.153
2 Detector on poly at +1250V 255 Yes, thermalized 1869 300 6.23 0.144
3 Detector on poly at +1250V 255 Yes, thermalized 1836 300 6.12 0.143
4 Detector on poly at +1250V 255 Yes, thermalized 1893 300 6.31 0.145
5 Detector on poly at +1250V 255 Yes, thermalized 1886 300 6.29 0.145

Green Poly without Thermalizer

1" Green poly, no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 2566 300 8.55 0.169
2 Detector on poly at +1250V 255 Yes 2627 300 8.76 0.171
3 Detector on poly at +1250V 255 Yes 2559 300 8.53 0.169
4 Detector on poly at +1250V 255 Yes 2562 300 8.54 0.169
5 Detector on poly at +1250V 255 Yes 2660 300 8.87 0.172

2" Green poly (one brick) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 2176 300 7.25 0.155
2 Detector on poly at +1250V 255 Yes 2070 300 6.90 0.152
3 Detector on poly at +1250V 255 Yes 2055 300 6.85 0.151
4 Detector on poly at +1250V 255 Yes 2131 300 7.10 0.154
5 Detector on poly at +1250V 255 Yes 1957 300 6.52 0.147

3" Green poly (one brick & sheet) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 1345 300 4.48 0.122
2 Detector on poly at +1250V 255 Yes 1335 300 4.45 0.122
3 Detector on poly at +1250V 255 Yes 1295 300 4.32 0.120
4 Detector on poly at +1250V 255 Yes 1384 300 4.61 0.124
5 Detector on poly at +1250V 255 Yes 1297 300 4.32 0.120

4" Green poly (two bricks) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 1056 300 3.52 0.108
2 Detector on poly at +1250V 255 Yes 1085 300 3.62 0.110
3 Detector on poly at +1250V 255 Yes 1151 300 3.84 0.113
4 Detector on poly at +1250V 255 Yes 1064 300 3.55 0.109
5 Detector on poly at +1250V 255 Yes 1059 300 3.53 0.108

6" Green poly (three bricks) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 728 300 2.43 0.090
2 Detector on poly at +1250V 255 Yes 737 300 2.46 0.090
3 Detector on poly at +1250V 255 Yes 759 300 2.53 0.092
4 Detector on poly at +1250V 255 Yes 717 300 2.39 0.089
5 Detector on poly at +1250V 255 Yes 764 300 2.55 0.092

8" Green poly (four bricks) no thermalizer

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 612 300 2.04 0.082
2 Detector on poly at +1250V 255 Yes 606 300 2.02 0.082
3 Detector on poly at +1250V 255 Yes 582 300 1.94 0.080
4 Detector on poly at +1250V 255 Yes 606 300 2.04 0.082
5 Detector on poly at +1250V 255 Yes 597 300 1.99 0.081

Green Poly with Thermalizer

2 1/8" Green poly (one brick) with thermalizer

1250V Thermalized source
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes, thermalized 1904 300 6.35 0.145
2 Detector on poly at +1250V 255 Yes, thermalized 1829 300 6.10 0.143
3 Detector on poly at +1250V 255 Yes, thermalized 1851 300 6.17 0.143
4 Detector on poly at +1250V 255 Yes, thermalized 1887 300 6.29 0.145
5 Detector on poly at +1250V 255 Yes, thermalized 1914 300 6.38 0.146

Virgin Poly

1" Virgin Poly (one sheet)

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 12743 300 42.47 0.376
2 Detector on poly at +1250V 255 Yes 13109 300 43.69 0.382
3 Detector on poly at +1250V 255 Yes 13052 300 43.51 0.381
4 Detector on poly at +1250V 255 Yes 13136 300 43.79 0.382
5 Detector on poly at +1250V 255 Yes 13064 300 43.55 0.381

2" Virgin Poly (one brick)

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 11950 300
2 Detector on poly at +1250V 255 Yes 12088 300
3 Detector on poly at +1250V 255 Yes 12068 300
4 Detector on poly at +1250V 255 Yes 12163 300
5 Detector on poly at +1250V 255 Yes 12183 300

3" Virgin Poly (one sheet & one brick)

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 9185 300
2 Detector on poly at +1250V 255 Yes 9091 300
3 Detector on poly at +1250V 255 Yes 9040 300
4 Detector on poly at +1250V 255 Yes 9211 300
5 Detector on poly at +1250V 255 Yes 9035 300

4" Virgin Poly (two bricks)

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 5924 300
2 Detector on poly at +1250V 255 Yes 6232 300
3 Detector on poly at +1250V 255 Yes 6006 300
4 Detector on poly at +1250V 255 Yes 5978 300
5 Detector on poly at +1250V 255 Yes 6222 300

6" Virgin Poly (3 bricks)

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 2837 300
2 Detector on poly at +1250V 255 Yes 2985 300
3 Detector on poly at +1250V 255 Yes 3019 300
4 Detector on poly at +1250V 255 Yes 2912 300
5 Detector on poly at +1250V 255 Yes 3009 300

8" Virgin Poly (four bricks)

1250V Source In
Run Number Configuration Discriminator Threshold (mV) Cf-252 Button Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on poly at +1250V 255 Yes 1974 300
2 Detector on poly at +1250V 255 Yes 2006 300
3 Detector on poly at +1250V 255 Yes 1975 300
4 Detector on poly at +1250V 255 Yes 2069 300
5 Detector on poly at +1250V 255 Yes 1990 300

Results

Posted 6/22/21

Completed attenuation measurements with differing thicknesses of Borated Poly vs unborated poly.

The purple and green poly definitely have some boron concentration in them. The fitted curves are the same within uncertainty, so it should not matter which type of borated poly is used in our experimental setup.

Go Back

PAS Experiment Attenuation Measurements

PAS_He3_Detector

PAS_Experiment

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