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Nuclear Safeguards Education Portal

Introduction to Counting Statistics

Frequency Plot.  Click on Image to view larger.
Frequency Plot. Click on Image to view larger. 

To understand detectors, we must first have a basic understanding of the statistics associated with measuring purely random events. The radioactive decay of a nucleus is a purely random event. There is no way to determine when a particular nucleus will decay. If two identical counts are taken in sequence on a sample of a long-lived radioisotope, the counts will almost always differ even though the activity of the sample is essentially unchanged. If a large number of these individual counts are taken, then the average Χe  of these counts can be determined.



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