August 1, 2008 Software

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  1. Review minutes from July 18, 2008 Software meeting
  2. BCAL Reconstruction Status (Blake L.)
  3. Discussion Items:
    • TOF reconstruction
    • Hall-D share on JLab Batch farm
    • gxtwist location and build scheme
  4. Action Items



The meeting will be at 1:00pm in Cebaf Center F326.


To connect by telephone: 1.) dial:

800-377-8846 : US
888-276-7715 : Canada
302-709-8424 : International

2.) enter participant code: 39527048# (remember the "#")

Video Conferencing

We will attempt an EVO connection for this meeting. We have a reasonable expectation that this will work.


Attendees: David L. (chair), Simon T., Beni Z., Elke A., Sascha S., Mark I., Herun Y., Elton S., Jim S., Eugene C.

Phone: Blake L. (Univ. Regina), Alexander O.(FSU), Matt S.(IU)

BCAL Reconstruction Status

Blake gave a brief status report on some of the recent work done on the BCAL reconstruction and simulation. Much of this was started during a recent trip Blake made to IU to work with Matt and Mihajlo. The main changes to the code were:

  • Time smearing of the BCAL hits
  • Low energy threshold recalculated and set

Results of a study comparing resolutions of a BCAL design with the nominal 6x4 and the alternate 3x3 inner region readout segmentation were presented. The 6x4 segmentation corresponds to a readout design using SiPMs and the 3x3 using Planacon PMTs. The studies indicated very little difference in the energy or angular resolutions of the 2 schemes. It was noted, however, that the same low energy threshold (4.8MeV) was used for both cases even though the Planacon design is expected to have a lower threshold. The resolution has a dependence on the low energy threshold.

Discussion items

TOF Reconstruction

Alexander O. of FSU has started looking into the TOF reconstruction since FSU is now responsible for that detector system. Since some code is already in place for the TOF, Alex was thinking of looking into the PID aspects a bit more and the integration of the TOF into the tracking code.

David noted that the TOF is currently not used anywhere in the tracking code. The particle TOF is calculated assuming it is e.g. a pion and knowing that the drift time is measured (essentially) from the start time.

It was suggested that since the time-of-flight problem must be solved in both the TOF and BCAL detectors as far as tracking is concerned that Alex broaden the scope of his project to include the BCAL time-of-flight as well. He was going to think about it.

Hall-D Batch Farm Priority

As a follow up to last week's meeting when Sascha noted that Hall-D had essentially no priority on the JLab batch farm Dave went and talked to Sandy Philpott, head of Scientific Computing for the IT division. They arranged to add Hall-D into the priority with about a 5% guaranteed share. Of course, if no one else is using the farm, then we get 100%. The 5% only comes into play when there is competition.

There was some debate as to whether we should ask for more. It was decided (with dissension) that we should keep it at this level until we see it hindering our work flow. It was noted that several of our collaborators (IU, FSU, CMU, UConn) all have farms of their own that can be made available to others. The JLab farm is primarily used by JLab staff at this point.

gxtwist location in repository

There was a brief discussion on moving the gxtwist package (simulation of the tagger building) from the topmost directory of the repository down into a directory parallel to HDGeant. It was quickly and unanimously agreed that this should be done and David volunteered to do it.

Action items

Next Meeting

Charged particle tracking.