CH He3 Attenuation Measurements: 3 Different Cf252 Sources

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Attenuation Experiment using New Modules in Electronics Chain and Inside Borated Poly Box

Electronics Chain (Poly Box)

Include schematic of electronics chain

Components

Each component of electronics chain with make/model, function, and brief description of why it's present

Ortec 142PC Pre-amp

Pre-amp for the He3 tube

CAEN Quad Linear Fan In - Fan Out Model N25 Tag #15687

  • The fan in/out is used to duplicate the pulse to run the spec amp and watch the signal on the scope for any anomalies.
  • The fan in/out is also used to invert the signal from the spec amp to send a negative pulse to the discriminator to trigger the scalar.

Ortec Spec Amp Model 672

  • 10x Course Gain
  • 1x Fine Gain
  • 0.5us Shaping Time
  • Uni Shaping: Gaussian
  • Input: Norm (+)
  • Output: Unipolar
  • Manual Pole Zero adjustment

LeCroy Discriminator Model 821 Serial #B16303

  • Variable threshold
  • Pulse width as measured on scope: ~43ns

Scope Images

Background Measurements

1250V Background Measurements
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec) Count Rate (Hz) Uncertainty
1 Detector on 3D printed stands at +1250V 255 No 100
2 Detector on 3D printed stands at +1250V 255 No 100
3 Detector on 3D printed stands at +1250V 255 No 100
4 Detector on 3D printed stands at +1250V 255 No 100
5 Detector on 3D printed stands at +1250V 255 No 100

High Activity Source Poly Box Attenuation Measurements

472[math]\mu[/math]Ci at time of measurement.

Open Source

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 34456 10
2 Detector on poly at +1250V 80 Yes 34920 10
3 Detector on poly at +1250V 80 Yes 34422 10
4 Detector on poly at +1250V 80 Yes 34007 10
5 Detector on poly at +1250V 80 Yes 34420 10

2" Green poly (one brick) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 7538 10
2 Detector on poly at +1250V 80 Yes 7515 10
3 Detector on poly at +1250V 80 Yes 7613 10
4 Detector on poly at +1250V 80 Yes 7566 10
5 Detector on poly at +1250V 80 Yes 7510 10

4" Green poly (two bricks) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 4758 10
2 Detector on poly at +1250V 80 Yes 4798 10
3 Detector on poly at +1250V 80 Yes 4722 10
4 Detector on poly at +1250V 80 Yes 4859 10
5 Detector on poly at +1250V 80 Yes 4672 10

6" Green poly (three bricks) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 3664 10
2 Detector on poly at +1250V 80 Yes 3627 10
3 Detector on poly at +1250V 80 Yes 3699 10
4 Detector on poly at +1250V 80 Yes 3688 10
5 Detector on poly at +1250V 80 Yes 3500 10

8" Green poly (four bricks) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 3140 10
2 Detector on poly at +1250V 80 Yes 3064 10
3 Detector on poly at +1250V 80 Yes 3030 10
4 Detector on poly at +1250V 80 Yes 3095 10
5 Detector on poly at +1250V 80 Yes 3113 10

Lowest Activity Poly Box Attenuation Measurements

Approximately 1.15[math]\mu[/math]Ci at time of measurement, according to ISU Radiation Safety

Open Source

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 31 100
2 Detector on poly at +1250V 80 Yes 32 100
3 Detector on poly at +1250V 80 Yes 26 100
4 Detector on poly at +1250V 80 Yes 23 100
5 Detector on poly at +1250V 80 Yes 29 100

2" Green poly (one brick) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 18 100
2 Detector on poly at +1250V 80 Yes 27 100
3 Detector on poly at +1250V 80 Yes 21 100
4 Detector on poly at +1250V 80 Yes 21 100
5 Detector on poly at +1250V 80 Yes 22 100

4" Green poly (two bricks) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 31 100
2 Detector on poly at +1250V 80 Yes 18 100
3 Detector on poly at +1250V 80 Yes 19 100
4 Detector on poly at +1250V 80 Yes 31 100
5 Detector on poly at +1250V 80 Yes 30 100

6" Green poly (three bricks) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 35 100
2 Detector on poly at +1250V 80 Yes 24 100
3 Detector on poly at +1250V 80 Yes 23 100
4 Detector on poly at +1250V 80 Yes 21 100
5 Detector on poly at +1250V 80 Yes 22 100

8" Green poly (four bricks) in Box

1250V source in
Run Number Configuration Discriminator Threshold (mV) Cf-252 Source Counts Run Time (Sec)
1 Detector on poly at +1250V 80 Yes 20 100
2 Detector on poly at +1250V 80 Yes 28 100
3 Detector on poly at +1250V 80 Yes 29 100
4 Detector on poly at +1250V 80 Yes 16 100
5 Detector on poly at +1250V 80 Yes 22 100





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