LB DetLimits Thesis

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50% Excluded

For this analysis, begin by using the first measurement of the Se-75 line and using the standard exponential decay equation to correct it and its error back to the time of beam off. Below is a table of the Se-75 (120d) corrected measurements as well as the front nickel foils and the Mn-54 data for each measurement. Note the Mn-54 analysis was weighted by the mass of the soil.

Sample Activated (total beam time) Counted Fully Thesis Corrected Rate @ 1st Measurement (Hz) [math] A_{Beam Off} [/math]
10% Se/Soil Mixture 5/23/17 and 5/24/17 (83 min) 07/18/17 (16:25:44) 3109.68 [math] \pm [/math] 95.39 4280.08 [math] \pm [/math] 131.29
10% Se/Soil Pure Witness selenium 5/23/17 and 5/24/17 (83 min) 8/1/17 (16:05:51) 4161.29 [math] \pm [/math] 127.63 6210.50 [math] \pm [/math] 190.48
10% Se/Soil Front Inner Ni Foil 5/23/17 (1h) 5/23/17 (15:52:21) 385955 [math] \pm [/math] 23488.8 425064.36 [math] \pm [/math] 25868.95
10% Se/Soil Mixture Mn-54 5/23/17 (1h) 07/18/17 (16:25:44) 15.63 [math] \pm [/math] 0.56 17.67 [math] \pm [/math] 0.63
1% Sample Se/Soil Mixture 5/23/17 (1h) 6/23/17 (16:39:03) 2233.33 [math] \pm [/math] 68.52 2675.24 [math] \pm [/math] 82.08
1% Sample Se/Soil Pure Witness selenium 5/23/17 (1h) 7/20/17 (16:39:46) 3840.86 [math] \pm [/math] 117.81 5379.43 [math] \pm [/math] 165.00
1% Sample Se/Soil Front Inner Ni Foil 5/23/17 (1h) 5/23/17 (17:59:39) 261461 [math] \pm [/math] 16045.7 293170.78 [math] \pm [/math] 17991.71
1% Sample Se/Soil Mixture Mn-54 5/23/17 (1h) 6/23/17 (16:39:03) 9.38 [math] \pm [/math] 0.39 10.05 [math] \pm [/math] 0.42
0.1% Sample Se/Soil Mixture 5/23/17 (30 min) 6/19/17 (18:25:18) 849.46 [math] \pm [/math] 26.07 993.59 [math] \pm [/math] 30.49
0.1% Sample Se/Soil Pure Witness Selenium 5/23/17 (30 min) 07/25/17 (16:32:52) 834.41 [math] \pm [/math] 25.61 1201.58 [math] \pm [/math] 36.88
0.1% Sample Se/Soil Front Inner Ni Foil 5/23/17 (30 min) 5/24/17 (14:25:39 118412 [math] \pm [/math] 7280.06 197670.18 [math] \pm [/math] 12152.98
0.1% Sample Se/Soil Mn-54 5/23/17 (30 min) 6/19/17 (18:25:18) 9.38 [math] \pm [/math] 0.33 9.96 [math] \pm [/math] 0.35

Mn-54 Efficiency

A calibrated Mn-54 source was used to find the efficiency of an 834 keV line. The source was serial #J4-348, which had an activity of 9.882 [math] \mu Ci [/math] on 8/01/12, so the activity on 4/18/17 was

[math] A(4/18/17) = 9.882 \times e^{-2.57 \times 10^{-8} * 148694400} = 0.22 \mu Ci [/math]

Now converting to Hz gives

[math]\left (0.999760 \right )\left ( 0.22 \times 10^{-6} \mbox{Ci} \right) \left (\frac{ (3.7 \times 10^{10} \mbox{Hz}}{\mbox{Ci}} \right)= (8138.05 \pm 3\%) Hz [/math]

Source Energy (keV) Position Expected Rate (Hz) ROOT Window (keV) HpGe Rate (Hz) HpGe Detector A Efficiency (%)
Mn-54 (J4-348) 834 10cm (Det A) 8138.05 [math] \pm [/math] 3\% [829,839] 25.87 [math] \pm [/math] 0.28 0.32 [math] \pm [/math] 0.01


Below are plots of the activity ratio of the Se/Soil mixture and specific activity of the pure selenium pellet as a reference material

A Mix Div a Pure NormCorrected Se75 NoFitRestrict.png