3.4.1. Error on Peak Counts

The count rate in microprobe analysis, R, is a function of the weight fraction of the element analyzed. Let T be the total counting time, and let "bgk" and "pk" refer to background and peak, respectively. Now,

So for the count rate:

Thus, for the corrected count rate, R_c:

Now if the times are equal for peak and background,

Typically for microprobe analysis, we measure peaks and backgrounds for the standard and the unknown. Data reduction uses the ratio of the corrected counts in the unknown to the corrected counts in the standard. The combined uncertainty due solely to X-ray counting statistics is:

When the element of interest is present in low concentrations in the unknown, the term for the standard in the above equation becomes insignificant.

Copyright 1997-2003, James H. Wittke

Last update: 01/18/2006 01:47 PM.