Difference between revisions of "Measurements and Calculations (Introduction to Radiochemistry)"

Revision as of 09:02, 3 July 2012

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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:
[math]N_{bck}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\mbox{counts}[/math] Counting time:

[math]t{bck}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\mbox{sec}[/math]

Counting speed:
[math]\frac{N_{bck}}{t_{bck}}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\mbox{cps}[/math] Standard deviation:
[math]\frac{\sqrt{N_{bck}}}{t_{bck}}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}\mbox{cps}[/math]

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.

Twenty Measurements with Constant Distance from the Source

Do twenty measurements lasting for one minute with the source in the same position. Calculate the standard deviation and complete the table:

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}[/math]
Standard deviation [math]S_{N}=\sqrt{\frac{\left(N_{P}-\overline{N}\right)^{2}}{19}}=\underline{\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,}[/math]
Discuss the results from [math]S_{N}\,[/math]and [math] \sqrt{\overline{N}}[/math]?

Assessment of the Results

Write down the given measurements and calculate how many % of the countings that are outside of the intervals <N-S_N,N+S_N and <N-2S_N,N+2S_N>:

Is there, in your opinion, to many single measurements outside of the given areas? Give a answer based on statistical normal distribution.