April 22, 2009 Software

From GlueXWiki
Jump to: navigation, search


  1. Review minutes from April 8, 2009 Software meeting
  2. Announcements
  3. Collaboration Meeting Agenda (abridged version)
  4. Kalman filter highlights from tracking meeting: Simon
  5. Software priorities brainstorming: all
  6. Action Items
  7. Rotating secretary proposal: Mark
    • Each bi-week we have a different secretary? Yeah? Nay?



The meeting will be at 14:00pm 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. Find the direct meeting link here


Present: Beni, Simon, Mark I. (chair), Elliott, Elton, Sascha S., David L., Eugene


Mark will take over for Dave as the GlueX Software Coordinator. See the announcement and job description that Dave circulated for details.

Collaboration Meeting Agenda

Dave will give the 30-minute summary of the state of the offline at an abbreviated session at the upcoming collaboration meeting.

Kalman Filter Progress

Simon presented an updated version of the presentation he made at last Monday's tracking meeting. Improvements include (from his second slide):

  • Improved agreement between geometries in MC and reconstruction for stereo straws
  • Handle cases where the true minimum doca would occur beyond the extent of the straw (still work in progress)
  • Fixed sign error and ordering problems in generation of reference trajectory for central tracks
  • Added energy­loss straggling (very crude – assumes absorbers are thick enough that central limit theorem can be used)
  • Use vector algebra to find predicted measurement for stereo wires

The last item accounted for most of the improvement between last Monday and today.

One plot that he showed showing the residuals as a function of polar angle for ideal tracks (no MCS, no dE/dx, no position smearing) when the Simon-authored swimming routine was used in reconstruction (slide 3) generated a lot of discussion. We agreed that the lack of delta-function residual distributions was due to using different swimming algorithms in event generation vs. reconstruction. Some thought that this could be sorted out later; for now using the same algorithm in both places was enough to make progress on other fronts. Others thought that this might indicate something more fundamental that needs to be addressed sooner to eliminate that possibility. At any rate this made it to the list generated in the brainstorming session (see below).

From Simon's summary:

Transverse momentum resolution for 1 GeV pions improved by a factor of 4 around theta=90° compared to March'09, but dip angle resolution is still poor for some angular regions...

  • Problems in p_T and phi start to occur towards CDC-­FDC transition region and for very backward angles
  • Sensitivity to quality of initial guess for track parameters

Software Brainstorming

We generated a list of topics that were on peoples minds. Numbered only for reference (i. e., unprioritized), they were:

  1. Tracking
    1. transition region
    2. Kalman
    3. swimming algorithm
    4. standard definitions
      • finding
      • fitting
    5. multi-track events
    6. FDC geometry update: Simon
    7. local Lorentz correction for FDC hits
    8. CDC geometry update: Beni
    9. Alternate tracking philosophies
    10. tracking efficiency over-all: single tracks, multi-tracks
  2. Simulation
    1. parametric MC
      • update/expand resolution tables
  3. Miscellaneous
    1. new release
    2. calibration database: firewall penetration
    3. milestone review
    4. reconstruction->PWA interface

Also note that this reflects the focus of the people in the room.

Clearly tracking is our highest priority, summarized by the last item in the tracking section tracking, i. e., efficiency over-all: single tracks, multi-tracks.

  • Beni agreed to look at finalizing the FDC geometry in the MC.
  • Simon agreed to update the FDC geometry.

Action items


Next Meeting