July 3, 2008 Software

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  1. Review minutes from June. 6, 2008 Software meeting
  2. CLAS12 Tracking Software Status (Sebastien Procureur)
  3. Action Items



The meeting will be at 11:00am in Cebaf Center L102-104.


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), Mac M., Mark I., Simon T., Sebastien P., Beni Z., Elliott W., Elke A., Jim S., Elton S., Eugene C., Alex S.

On the phone: Mihajlo K.

Sebastien gave a presentation on the current status of charged track reconstruction for CLAS12 in Hall-B. The CLAS12 detector consists of a central region with a solenoidal magnetic field and a forward region with a toroidal magnetic field. The tracking systems consists of silicon detectors in the barrel region and drift chambers in the forward region surrounding the torus magnet.

An overview of the basic track finding method was given which included rejection of uncorrelated noise.

The fitting procedure uses a Kalman filter method. The resolution of the left-right ambiguity is integrated into the fitter such that hits for which the L/R is clearly resolved, are used while hits without use the wire position with large errors. Subsequent passes can resolve more hits as the track is refined.

Misalignment studies have been done which demonstrate the effect a specific set of misalignments and translations of the detectors has on the reconstructed track resolution.

Sebastien noted that the result of the fit has a dependence on the starting parameters.

One of the issues CLAS12 has is the matching of tracks from the 2 magnetic field regions. Matching efficiency was shown to be a somewhat strong function of the DC occupancy with 98% at zero percent occupancy and 82% at 7 percent occupancy.

Finally, tracking resolutions were shown for both the drift chambers alone and the drift chambers combined with the forward silicone tracker (FST). The FST provided very large improvements in the vertex resolution and significant improvements in the momentum and angular resolutions. The notable exception was the polar angle theta which showed only a modest improvement with the inclusion of the FST.

Action items

Next Meeting

We will discuss ongoing work on the build system. Updates on simulation and reconstruction will be presented (if any).