About ATLAS Groups Files 

The ATLAS suite uses a groups file to specify which spectra from the .RAW file should be combined together by the NORM program. 

Ordinarily, the groups file will be provided by the instrument scientists.

The first record in the file indicates the number of output groups. After that, the other records in the file specify which spectra are included in each group. 

The first number in a record indicates how many more numbers there are in the record. If the first number in the record is negative, then the subsequent numbers in the record are individual spectrum numbers. If the first number in the record is positive, then the subsequent numbers in the record specify the start and end of ranges. Note that it is permitted for a record to occupy more than one line of the file.

For example:

3
-5 11 13 14 16 19
-9 1 2 3 4 5
6 7 8 9
4 21 30 41 60

In this example the groups file specifies three groups. The first group contains 5 spectra, with various spectrum numbers. The second group contains 9 spectra, numbered from 1 to 9. The third group contains 30 spectra, numbered from 21 to 30, and from 41 to 60. 

Last updated on 12 Sep 2003 by Alex Hannon (a.c.hannon@rl.ac.uk)