GlueX Offline Meeting, September 7, 2011

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GlueX Offline Software Meeting
Wednesday, September 7, 2011
1:30 pm EDT
JLab: CEBAF Center F326


  1. Announcements
  2. Review of minutes from the last meeting: all
  3. Compressed Data Format Update (Richard or Igor)
  4. BCAL Reconstruction Update (Will)
  5. Reconstruction chi-squared/uncertainty update: Paul Mattione.
  6. Discussion of Reconstruction Tasks and Topics for Further Development
  7. Software work day at the Collaboration Meeting?
  8. Other items

Communication Information


To connect by telephone:

  1. dial:
  2. enter access code followed by the # sign: 3421244#

Video Conferencing


Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2011-3Q on the JLab CUE. This directory is accessible from the web at . You have to be a member of the "halld" Unix group to do this.



  • CMU: Will Levine, Paul Mattione, Curtis Meyer
  • IU: Ryan Mitchell, Kei Moriya, Matt Shepherd (chair)
  • JLab: Mark Ito, David Lawrence, Dmitry Romanov, Simon Taylor, Elliott Wolin, Beni Zihlmann
  • UConn: Igor Senderovich


Elliott issued a head-up for the need for creating digitized data for online testing from Monte Carlo events. He will write-up requirements for this.

Review of minutes from the last meeting

We skimmed the minutes from the August 24 meeting.

Mark reminded us that we still need a solution for putting large magnetic field maps into the CCDB.

Compressed Data Format Update

Igor reported that Richard is working on the code based on feedback received at the last meeting.

BCAL Reconstruction Update

Will reported that the BCAL seems to do well for single photon events. He is also starting to look at implementing the new 1-2-3-4 segmentation for the read-out.

Matt mentioned that the read-out change should be easy, modulo calibration. There is a header file that defines the geometry.

Reconstruction chi-squared/uncertainty update

Curtis posted a document on the DocDB from PANDA, describing the scheme for their central tracking

Simon reported a pattern with some tracks with chi-squared problems. In the forward direction problems are correlated with track finding producing candidates with the wrong charge hypothesis.

Paul presented a wiki page summarizing work to study reported errors from the FCAL, BCAL, and TOF. He decided to focus on these detectors since others are working on tracking errors. Some of his observations:

  • There an energy-dependent offset between simulated and reconstructed times in the FCAL of about 2 ns.
  • The observed FCAL energy resolution is about 50-60% greater than the value from the function that reports errors in the reconstruction.
  • The TOF also shows a small offset, about 150 ps, in reconstructed time.

See his page for details.

We agreed on a convention for reported times from reconstruction, the time when the particle crosses the inner surface of the detector. Some of the time offsets may be due to the correction used for doing this.

Brainstorming Reconstruction Issues

Other discussion items not described above.

  • Beni: many more reconstructed photons than the number generated. Details on his b1pi analysis wiki page.
  • Beni: reconstruction efficiency seems very low for protons. Again see his wiki page.
    • Will thinks that the problem was not as bad a few months ago.
  • Simon/Mark: In general, track down major causes of complete failure of track fitting and finding in both single-particle and multi-particle events.
  • Paul will present a design for how TOF information should be used. [?]
  • Beni will present HERMES particle ID scheme.
  • Mark will add new items to list on the Reconstruction Tasks and Topics for Further Development page.

Matt proposed that we have standing agenda items at the Physics and Offline meetings with conveners reporting on progress in three major areas:

  • Tracking: Simon
  • PID: Paul
  • Photons: Matt

They will get together and organize the list from the wiki page and assign priorities.

New Action Items

  • Write requirements for digitizing Monte Carlo data for online testing. -> Elliott
  • Paul will present a design for how TOF information should be used.
  • Beni will present HERMES particle ID scheme.
  • Mark will add new items to list on the Reconstruction Tasks and Topics for Further Development page.
  • Conveners with organize the list.