Measurements and Calculations (Introduction to Radiochemistry)

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Which detector did you use?

Background

Note down the values from the background counting you started the day before.
Counting number Nbck=              counts
Counting time tbck=              sec
Counting speed [math]\frac{N_{bck}}{t_{bck}}[/math] =                cps
Standard deviation [math]\frac{\sqrt{N_{bck}}}{t_{bck}}[/math]=                       cps

Counting Efficiency

Do a one minute count on every shelf. Use these measurements to calculate the counting-efficiency of the GM-detector in %, for 234mPa. The activity of the sample can be calculated from the amount of UO3 used.

Counting number for each shelf (CPM) Counting Efficency
1
2
3
4

Twenty Measurements with Constant Distance from the Source

Do twenty measurements on 1 minute with the source in the same position. Calculate the standard deviation and complete the table:

Nr Np [math]N_{P}-\overline{N}[/math] [math]\left(N_{P}-\overline{N}\right)^{2}[/math]
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
SUM: SUM:



Mean value of the counting numbers
[math]\overline{N}=\frac{\sum N_{P}}{20}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\mbox{counts}[/math]
The squere of the mean value [math]sqrt{\overline{N}}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\mbox{counts}/maht\gt Standard deviation \lt math\gt S_{N}=\sqrt{\frac{\left(N_{P}-\overline{N}\right)^{2}}{19}}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}[/math]