KILLRAWSPIKE: Remove electronics spikes

Previously the recommended way of dealing with electronics spikes was to run the FINDSPIKE program for each run, and hence generate a mask file which excludes all spectra which exhibit a spike.

A new way of dealing with spikes which actively removes them from a .RAW file is now available. This method should be a better way to deal with the problem. The steps involved are as follows...

1. Run FINDSPIKE for the .RAW file concerned. This generates two files named GEM*****.SPIKE1 and GEM*****.SPIKE2 which indicate the locations of the spikes.
2. Run KILLRAWSPIKE by typing run g_f:killrawspike (NOT in GENIE). This creates a modified version of the .RAW file from which spikes have been removed.
3. The modified .RAW file produced by KILLRAWSPIKE is very large (about 260,000 blocks). It can be compressed by typing run g_f:compress2byte (NOT in GENIE).
4. Then get rid of the uncompressed .RAW file, e.g. by typing purge gem*.raw .

The KILLRAWSPIKE program produces a very large output file. Hence you will almost certainly not be able to run these programs in your own area. Instead use the GEM instrument account.

Please note that at the time of writing this is new software. Although it should remove most electronics spikes from the data, it will not remove every single spike that might possibly occur.

You should run KILLRAWSPIKE on each .RAW file before running NORM. It is then not necessary to create a new masked version of the groups file.

Thanks to Kevin Knowles, without whom I could not have written this software.

Algorithm

This software seeks to identify both single spikes (1 channel wide) and double spikes (2 channels wide). As well as removing large spikes, it also removes their smaller shadows in the other spectra in the same detector module. Each spike time-of-flight histogram is replaced by the average of the two adjacent good histograms.

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