EVS - Event Sorter Program

An event data file starts with a header block of 80 Bytes and the character sequence 'evt/', more in event format. The header contains all information for evs to histogram or sort the data, although the length of the sorted spectra can be changed. Modifications in the setup window (length of spectra) are kept for new event data files until changed or evs is newly started.
The program shflhd with an event file name as input prints out the header information. An event file can be sampled using the procedure shevnt filename | more.

General Use.

Evs is a Xwindow application and built to be self explanatory.
Once an event file is opened data can be histogram-med and sorted. Depending on the selection in the sort setup window one can create

Gated gamma spectra
Sorting with conditions require one particle window and two time windows. This applies for all gamma spectra including up/down separation. Windows are set conveniently in xsa as .win or mask file. The order of the windows is important. First particle mask and than the two time masks for each tac. As of now, gain matched clover data need the particle and a set of tac windows for each detector, since the tac spectra do not match well enough generally.

Gated particle spectra
Sorted particle spectra can be obtained applying one time and many gamma cuts. The setup requires one time gate for each detector and one or more gamma gates (e.g. peaks = 1 and bkgd = 2). For each gamma cut a separate particle spectrum is produced. Gain matched spectra (tacs sufficiently well aligned) require only one generic tac window and one gamma window.

Gated time spectra
Conditions are set on particle and gammas. Use same procedure as for creating particle spectra, one particle gate followed by one or more gamma gates in each detector. All gamma gates set contribute to the same TAC spectrum. Gain matched clover data require only two windows.

Mask File

A mask file is an empty histogram file where only the gate regions have a content. The content is a number which is an index for the histogram data pointers. So the value is very important.

There are two ways to create gate information using xsa.

.win file
As example lets start with gating information for gamma spectra.
In xsa create a sequence of the particle and all tac spectra. This can be done using the transfer command or if less than 16k all spectra fit into the work space e.g:
> sel 1 7 8 9 10
> ds 0
Set appropriate windows: One in the particle spectrum and two for each tac spectrum (true and randoms).
> ww name
A file name.win is written to the disk. evs takes this as mask input and creates the sorting masks. The file menu option "Save Mask" writes a file ckmask.his out which can be viewed with xsa.

mask file
The mask file can be created by hand. All steps outlined for the .win file, except ww (write win file) have to be followed. The data in the area with all the marker has to be cleared (> zero all). The data space between two marks can be set to a number.
Here is an example for creating gated particle spectra. Put the cursor in the first tac window type q1 and so on for each tac, then for each gamma set in the first window q1 in the second q2 if you selected more windows per gamma continue with q3 q4 ... Again for each gamma the same. When done type r (refresh display) and
> w name
which writes the so called mask file out. This file becomes input to evs.

Gerfried Kumbartzki
Last modified: Mon Apr 15 16:02:45 EDT 2002