August 26, 2009 Software

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The meeting will be at 2:00 pm in CEBAF Center F326/327.


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

A) ESNet: 8542553
B) EVO: direct meeting link


  1. Review minutes from August 12, 2009 Software meeting
  2. Announcements
  3. Collaboration Meeting Talk: Mark
  4. Action item review


Present: Pawel Ambrozewicz, Eugene Chudakov, Mark Ito (chair), David Lawrence, Simon Taylor, Elliott Wolin, Beni Zihlmann

Review of Last Meetings Minutes

We went over items from the last meeting. Most of the issues left over from last time were addressed in the review of action items below.


  • David: A bug in Jana was been found, having to do with multiple threads setting configuration parameters at initialization. This was only discovered when running many tens of threads under a single process. It has been fixed.
  • Elliott: The halld group changeover is done.
  • Elliott: Next week's online meeting conflicts with the first staff scientist interview. Look for changes in the schedule for that meeting.

Talk at Collaboration Meeting

Mark solicited input for the offline talk at the upcoming collaboration meeting. David suggested that he target individuals and ask for slides.

Action Item Review

We went over recently completed and outstanding items on the list

Drawing Storage: We need to ask Tim Whitlatch about how we can access Document Control at JLab and further, how to navigate the terrain once we get access. We might want to extract certain key drawings and make them available on the wiki. JT2GO-accessible drawings might be nice as well.

Group Disk Usage: CLAS is using about 150 GB of space compared to our 35 GB. This ratio does not seem unreasonable at this point. Beni pointed out that 9 TB of RAID 6 storage would run about $1,200 these days.

FDC Half-Cell Stagger Studies: Simon gave a presentation at last Monday's tracking meeting. His preliminary conclusion is that we do not need the half-cell stagger. The \chi ^{2} distributions do not look much different between the two designs he studied. Eugene wondered if the results depended on the starting parameter of the fit; if the start is far away from the true parameters, then it may be more likely that incorrect left-right choices are made. Simon sketched the procedure used in track finding and fitting. He has a few more things to look at before he is done, including a geometry where a packages has six layers with all wires in all layers parallel to each other, with an alternate half-cell stagger.

Alternate B-Field Studies: David has been using Poisson. Some maps have been generated, some with a finger grid than Eugene had tried previously. There is a discreprency with Ansys for the field along the beam line. David plans to do more comprehensive comparisons of the field between Poisson and Ansys and then turn to differences in momentum resolution.

Checking the CDC Geometry: Beni reports that 1 mm of plastic has been added to the inside of the CDC for structural reasons. He will add this to the geometry specification.

Position-Dependent Position Resolution: David mentioned that Yves Van Haarlem sent him calculations of position resolution as a function of position in cell. David plans to add this effect into mcsmear.

New Action Items

  1. Talk to Tim about access to drawings. -> Mark
  2. Add inner plastic cylinder to CDC geometry. -> Beni
  3. Add position-dependent position smearing to mcsmear. -> David