Online Analysis of the Clusters-at-GSI experiments at GSI

The functionality of the code has been discussed and finalised at a meeting held at GSI on 9 February. We will provide

raw and calibrated energy and time spectra for all NaI and Ge detectors
energy and time OR spectra, an energy sum spectrum for the Crystal Ball
raw spectra for all mounted particle counters, calculated positions and angles for detected particles
raw and calibrated spectra for the silicon ball
Doppler corrected Ge energy OR spectra under a variety of one dimensional conditions on various multiplicities, trigger patterns and scattering angles.
two independent Doppler corrections may be active at the same time, you may choose from four possible combinations of detected/excited projectil/target.
As none of the BGO VXI cards are available today, BGO spectra cannot be provided neither for online nor offline analysis.

During your experiment at GSI you should be able to control the data acquisition system - this is basically starting and stopping of the data acquisition itself as well as tape handling - and to monitor your experiment via the online analysis - this is basically displaying spectra to check if all detectors are still alive and if you get the peaks you are looking for. We provide an X-terminal to keep some windows to control the data acquisition system and a DEC AXP workstation running Open VMS for the GOOSY online analysis. To give you an idea what the commands will look like, we created a small manual in postscript describing all those commands as well as further details of the online analysis you may be interested in. Please note that some postscript viewers may be unable to correctly display this file.

Offline Analysis of the Clusters-at-GSI experiments

All experiment data is currently written to DLT2000 tapes by a drive connected to the VME hardware. If you need to copy to exabyte, you may use public drives at GSI.

On tape you will find binary files containing GOOSY buffers. GSIs data acquisition group has created a postscript manual about these buffers and their structure. The buffers themselves contain buffer headers and events. Events consist of event headers and sub events, sub events consist of sub event headers and the data itself. Depending whether your system is a Big/Little Endian system, you may have to swap all longwords read from tape before you process the buffer.

If you are using GOOSY for offline analysis, talk to Matthias so you can taylor the exisiting PLI GOOSY unpacking routine to your needs. If you are not using GOOSY but some other software unable to process GOOSY buffers, you may take a look at a small c program scanning the binary files written during your experiment to decode the data itself. Please note that this program is just intended to serve as a guide to establish your own unpacking routine; it has not been optimized in any way. Even if your software is able to process GOOSY buffers, I'm afraid you need to take a look at the sub event format as it differs from what GOOSY expects as we use some non-standard sub event formats.

Finally, you may need the positions of the NaI and Ge crystals for your analysis. The reference frame we suggest to use is defined via:

X axis is left, looking in beam direction
Y axis is up
Z axis is defined by the beam itself
theta from 0 to 180 deg, theta = 0 deg is in beam, theta = 180 deg is opposite to the beam direction
phi from 0 to 360 deg, for theta = 90 deg: phi = 0 is along positive X, phi = 90 is along positive Y, phi = 180 is along negative X, phi = 270 is along negative Y

For your code, you may need a list of theta and phi for all NaI detectors and for all Ge detectors. Additionaly, we provide a drawing of the Cluster-ring so you can check which crystal is sitting where.

last update April 17th, 1996 / Euroball at GSI / MK