Warning: prior to Monday 18th June 2002, there was an error on this webpage with the generation of the new ESDs, please review if you have been using this page prior to this date
Advice on summing multiple powder diffraction files, normalizing the data to look like a fixed count time datafile, and re-generating the resulting ESDs on each data point.
If you sum up and normalize 2 points - each having 100 counts - using the above - . Sum a point on 2 scans: Scan one: Counts = 100 Sigma Y = 10 Monitor = 1 Scan two: Counts = 100 Sigma Y = 10 Monitor = 1 Summed Counts = 200, Summed Sigma^2 = 200, Summed Monitor = 2 Square root the Summed Sigma^2 = 14.14 Summed Counts = 200, New Sigma = 14.14, Summed Monitor = 2 Now divide Y and (new) sigma by the monitor value to give the merged and normalised value, Merged/Normalized Counts = 100 , New ESD = 7.1
In the above case, the ESD has improved by root (2), in this instance by counting twice (as to be expected).