FINDSPIKE : Deal with electronics spikes

The program FINDSPIKE may be used to search for electronics spikes in the data stored in a .RAW file. 

FINDSPIKE is run by typing @g_f:findspike (NOT in GENIE). Usually it is best to run the program using the default parameter values which it offers. The program takes quite a long time to run. When it has finished searching for spikes, it offers the chance to create a mask file for excluding the spiky spectra. The mask file will be called findspike.mask, but you are advised to rename it.

The user should copy the standard groups file to their area, and then the mask file can be used to remove the affected spectra from this groups file by running the program MASKGROUP. For a particular set of data (e.g. sample, vanadium, can and background) it is necessary to use the same groups file for all of the runs of NORM. Hence it is necessary to produce mask files for each of the runs concerned and then to combine them all to produce one final groups file that is used for all the runs of NORM.

There is a new improved way of dealing with spikes, where they are removed from the spectra in the .RAW file - click here for details.

Algorithm

The FINDSPIKE program compares the i^th count, y_i, in a time-of-flight spectrum with the previous and next counts, y_i-1 and y_i+1. If yi differs from both y_i-1 and y_i+1 by more than a tolerance times its standard deviation, e_i, then FINDSPIKE identifies y_i as a spike. Usually the default value for the tolerance will not require changing, but it may need to be adjusted for the occasional dataset.

Last updated on 20 May 2003 by Alex Hannon (a.c.hannon@rl.ac.uk)