biodex ATOMLAB 960 - Appendix F: Formulas; FWHM and Chi-Square Formulas

ATOMLAB 960 MEDICAL SPECTROMETER APPENDIX F F-1
F. APPENDIX F –
FORMULAS
FWHM =
Right ch # - Left ch #
Peak channel #
x 100
a) Divide Peak channel count by 2
b) Right channel is 1
st
channel # that has counts less than ½ Peak channel counts
c) Left channel is 2st channel # that has counts less than ½ Peak channel counts
Chi-Square
Chi-Square (χ
2
) test is a means for testing whether random variations in a set of measurements
are consistent with what should be expected for a POISSON DISTRIBUTION.
1. Obtain a set of 10 counting measurements, 10 seconds each.
2. Compute the mean 𝑁
4. The probability is that it should fail 20% of the time: 10% high and 10% low.
This Chi-Square result should be between 4.168 and 14.684.
𝑁 =
!𝑁i
𝑛
!
!!!
n = number of samples
Ni = each measurement from 1 to 10
3. χ
2
=
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!!!!!!!! !!!!!!!!!!!
!
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