GlueX Offline Meeting, April 20, 2010

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GlueX Offline Meeting
Tuesday, April 20, 2010
2:00 pm EDT
JLab: CEBAF Center F326/7


To connect by telephone:

  1. dial:
    • 800-377-8846 : US
    • 888-276-7715 : Canada
    • 302-709-8424 : International
  2. enter participant code: 77438230# (remember the "#")

Video Conferencing


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2010-04 on the JLab CUE (you have to be a member of the "halld" Unix group). This directory is accessible from the web at .


  1. Announcements
  2. Collaboration Meeting Agenda: Mark
  3. Review of minutes from the last meeting: all
  4. Information about the new FineMesh B-field option: Simon
  5. Action Item Review: all


  • IU: Ryan Mitchell, Matt Shepherd
  • JLab: Craig Bookwalter, Mark Ito (chair), David Lawrence, Sascha Somov, Simon Taylor, Elliott Wolin, Beni Zihlmann


  1. Elliott announced that the DANA-to-EVIO conversion module is 99% done. He is waiting on a new release of JANA (0.6.2) to do final tests. Some changes were necessary in EVIO to support the latest features.
    • This raised the issue of getting an official release of EVIO from the Data Acquisition group so that we can have a stable code base. No such official release seems to exist. David will talk to Graham Heyes and try to work out a solution.
  2. David announced that the mysterious factor of two he has been seeing in the energy loss correction in tracking has been found and fixed (simple typo).
  3. David identified a bug in hit generation in HDGeant in the rare case where a particle ranges out in the gas of a CDC straw. In that case the drift time is essentially indeterminate. He found this when looking at low energy protons. A fix has been implemented in HDGEANT. Protections against this case have not been introduced into the tracking code.
  4. Elliott reported that Dave Heddle has hired a CNU undergraduate to work on the GlueX event display this summer. His name is Andrew.
  5. Elliott mentioned that there will be a workshop on CLAS12 software, May 25 and 26, at the University of Richmond. He and David will be talking.
  6. Mark reminded us that the Collaboration Meeting is approaching and encouraged us to think about talks we might want to give in the offline software session.

Review of Minutes from the Last Meeting

We reviewed the minutes from the April 6 meeting.

Matt reported that new graduate student, Dan Bennett, will be joining the IU group and will start working on the general problem of "extra" cluster generation in the calorimeters.

New Fine-Mesh B-field Option

Simon described recent work in trying to speed up the tracking code. The code spends a lot of time in interpolation of the B-field and its derivatives. He tried an approach where the interpolation was done in advance and the results stored as a map with a much smaller grid spacing. Some comments:

  • Matt asked about whether profiling had been tried. He has used "sampler" on Mac with success in the past. Simon has tried gprof on the code, but the results were inconclusive.
  • David tried Simon's approach with the ALT1 fitter and had good results.
  • There are some global makefiles that need to be modified to use this approach generally.
  • Craig referred us to "cachegrind", a KDE gui-based wrapper for gprof.

Action Item Review

We reviewed the action items. There are still some items outstanding that should not be so difficult to complete. We should make an effort to address them.

Construction and Wiring Database

Beni wondered out loud about whether we should create a database to track construction and generate wiring maps, in particular for the CDC. David mentioned that he produced a simple application for PrimEx. Mark noted that Matt has done something for the FCAL in this regard and that there is also the PANSOPHY programs used the the RF group at the Lab. Beni will pursue options.

New Action Items

  1. Talk to Graham about getting a release of EVIO. -> David