Start the Genie 2000 software and turn on the high voltage to the system to the recommended setting.
Set the boundary markers to the extremes of the graphic display window. If needed set the system to Intergral
Set the acquire time for 60 seconds using real time. Take a measurement and verify your reading with the Instructor
Procedure
Taking a sample of data
Record 20 background readings, for 60 seconds each.
Place a source in front of the detector and record 20 more one minute counts.
For steps a) and b) calculate Experimental Mean and Sample Varianc
Analysis of Data Set
If we believe the data are subject to Poisson fluctuations, the expected standard deviation for one typical measurement should be
(Since X is approximately the same as any typical value). If the data fits the Poisson model, then your experimentally measured S should be approximately the same as the calculated s. Comment on the significance of s in this application
Apply the c2 test to the sets of data obtained in steps “1” and “2”. What is your p value in each case? (You should use figure 3.11 from Knoll)
Using this information, calculate the expected standard deviation of the mean value X determined in step “1”. Write down your interpretation of the significance of this value in comparison to the sample standard deviation.
ALARA in Action
To see the effects of detector-source geometry (and one of the ALARA principles), take several counts at various measured distances from the detector. How does the net count rate change with respect to the distance from the detector? Use this data to plot a trendline of the count rate vs. distance from the source. How would you use error propagation techniques for this trendline?