CH He3 Attenuation Measurements: 3 Different Cf252 Sources

Results

• 

  Red: Log plot of scalar measurements using the high activity source with [math]Ae^Bx+C[/math] fit. Blue: Log plot of scalar measurements using the undetermined activity source with [math]Ae^Bx+C[/math]

• 

  Energy spectrum of He3 tube using peak sensing ADC for the varying thicknesses of borated polyethylene. Note that the 0" of poly (open source) is scaled by [math]\frac{1}{3}[/math].

• 

  Simulated energy spectrum of He3 tube in borated poly box.

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

Background Measurements

1250V Background Measurements
Run Number	Configuration	Discriminator Threshold (mV)	Cf-252 Source	Counts	Run Time (Sec)
1	Detector on 3D printed stands at +1250V	255	No	33	100
2	Detector on 3D printed stands at +1250V	255	No	24	100
3	Detector on 3D printed stands at +1250V	255	No	30	100
4	Detector on 3D printed stands at +1250V	255	No	26	100
5	Detector on 3D printed stands at +1250V	255	No	19	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

Undetermined Activity Source Poly Box Attenuation Measurements

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	3873	100
2	Detector on poly at +1250V	80	Yes	3909	100
3	Detector on poly at +1250V	80	Yes	3859	100
4	Detector on poly at +1250V	80	Yes	3944	100
5	Detector on poly at +1250V	80	Yes	3812	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	764	100
2	Detector on poly at +1250V	80	Yes	819	100
3	Detector on poly at +1250V	80	Yes	818	100
4	Detector on poly at +1250V	80	Yes	815	100
5	Detector on poly at +1250V	80	Yes	913	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	486	100
2	Detector on poly at +1250V	80	Yes	509	100
3	Detector on poly at +1250V	80	Yes	531	100
4	Detector on poly at +1250V	80	Yes	544	100
5	Detector on poly at +1250V	80	Yes	530	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	415	100
2	Detector on poly at +1250V	80	Yes	373	100
3	Detector on poly at +1250V	80	Yes	380	100
4	Detector on poly at +1250V	80	Yes	397	100
5	Detector on poly at +1250V	80	Yes	419	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	371	100
2	Detector on poly at +1250V	80	Yes	396	100
3	Detector on poly at +1250V	80	Yes	351	100
4	Detector on poly at +1250V	80	Yes	366	100
5	Detector on poly at +1250V	80	Yes	394	100

Lead Attenuation Measurements

The purpose of these measurements was to determine if photon build up in the He3 tube was a significant effect to consider when trying to determine the activity of the Unknown Source 

4/5/22

Lead 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	3873	100
2	Detector on poly at +1250V	80	Yes	3909	100
3	Detector on poly at +1250V	80	Yes	3859	100
4	Detector on poly at +1250V	80	Yes	3944	100
5	Detector on poly at +1250V	80	Yes	3812	100

1" Lead

1250V source in
Run Number	Configuration	Discriminator Threshold (mV)	Cf-252 Source	Counts	Run Time (Sec)
1	Detector on poly at +1250V	80	Yes	4152	100
2	Detector on poly at +1250V	80	Yes	3945	100
3	Detector on poly at +1250V	80	Yes	4141	100
4	Detector on poly at +1250V	80	Yes	3974	100
5	Detector on poly at +1250V	80	Yes	4154	100

2" Lead

1250V source in
Run Number	Configuration	Discriminator Threshold (mV)	Cf-252 Source	Counts	Run Time (Sec)
1	Detector on poly at +1250V	80	Yes	3509	100
2	Detector on poly at +1250V	80	Yes	3472	100
3	Detector on poly at +1250V	80	Yes	3387	100
4	Detector on poly at +1250V	80	Yes	3488	100
5	Detector on poly at +1250V	80	Yes	3463	100

3" Lead

1250V source in
Run Number	Configuration	Discriminator Threshold (mV)	Cf-252 Source	Counts	Run Time (Sec)
1	Detector on poly at +1250V	80	Yes	2995	100
2	Detector on poly at +1250V	80	Yes	2921	100
3	Detector on poly at +1250V	80	Yes	2956	100
4	Detector on poly at +1250V	80	Yes	2916	100
5	Detector on poly at +1250V	80	Yes	3015	100

4" Lead

1250V source in
Run Number	Configuration	Discriminator Threshold (mV)	Cf-252 Source	Counts	Run Time (Sec)
1	Detector on poly at +1250V	80	Yes	2630	100
2	Detector on poly at +1250V	80	Yes	2601	100
3	Detector on poly at +1250V	80	Yes	2558	100
4	Detector on poly at +1250V	80	Yes	2629	100
5	Detector on poly at +1250V	80	Yes	2650	100

Lowest Activity Source 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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