MVD Calibrations

Here is the 2005 two-button calibration procedure

This page is intended to summarize what I know about MVD calibrations as well as collect relevant links.

The fact that there is little information on this page is not without meaning.

Allan Hansen's documentation page has some relevant links.

Here is Allan's document describing the online calibration procedure.

This document from Allan describes the offline calibration.

A list of calibration runs in run 3.

Online calibration uses the following scripts (all in the ~phnxmvd/calib directory, which is visible from both phoncsb and va002). The purpose of these calibrations is to set up the zero-suppression thresholds. One of the files created in the process (/home/phnxmvd/calib/run/mvdsummary.txt) is read by the online monitoring code to define the "standard" pedestals, from which pedestal shifts are measured. Some of the scripts are run from phoncs0 and others from va002. The scripts are described in documents by David Silvermyr (click here for threshold procedure and here for pedestal (aka AMU cell dependence) procedure).

Log in as phnxrc on phoncsb, and cd ~phnxmvd/calib/

For AMU cell dependence calibration type: ped_super_calib.sh
which calls:

  1. ped_process_calib.csh (run from va002)
  2. install_ped_files.csh (run from phoncs0)
The files produced are copied to the directory: $DCM_PEDESTALS/mvd, the original files are stored in /home/phnxmvd/ped_files/ped$RUN.tar, where $RUN is the run number. The "pedestal" files are ascii files which look like this.
You can get a quick look at all the files by going to ~phnxmvd/calib/run/ and running check_pedestals.pl

For thresholds calibration type: super_calib.sh (run from phoncs0)
which calls:

  1. process_calib.csh (run from va002)
  2. install_thresh_files (run from phoncs0)
The files produced are copied to the directory $DCM_PEDESTALS/mvd, the original files are stored in /home/phnxmvd/threshold_files/thresh$RUN.tar, where $RUN is the run number. The "threshold" files are ascii files which look like this.

A key macro used by process_calib.csh is calcthr.C. We normally leave some fraction of the channels not zero suppressed. In the past, this fraction has be 1/8 for Au+Au and 1/16 for p+p and d+Au. This allows us to track pedestal shifts in the online monitoring. To change the fraction of channels which are not zero suppressed, you need to edit /home/phnxmvd/calib/run/calcthr.C and change the variable called chansave to the number you want (8 or 16 normally).

In the past, there was one major problem which occured in both the AMU cell dependence calibrations and in the threshold calibration. The problem was that the scripts tried to automatically figure out the run number so that you do not need to type it. This usually worked, but the method had a flaw. The scripts picked up the next run number before calling runcontrol. The next run number sat in a file which runcontrol reads. However, after this number was saved (it is in a file called /home/phnxmvd/calib/runnumber) runcontrol was started. Runcontrol needs to download the DCMs and do a few other things before starting the run. This takes ~60 seconds. If someone else started a run in this time period, then the run number in /home/phnxmvd/calib/runnumber was wrong (too low). This was fixed by a perl script called run_find.pl which Hubert wrote.

Sangsu has a new procedure for calibrations for run 3. He does not do the event-by-event correction. The following email messages describe part of the procedure, including the locations of some key files.

Two emails from Matt (3-Sept-2003) which describe the locations of some of his files for calibration.

An email from Sangsu (3-Sept-2003) which answers some questions about the procedures.

An email from Sangsu (14-Aug-2003) which gives the locations of some of his key files for analysis.

updated 13 Apr 2004
John Sullivan