GlueX Start Counter Meeting, November 17, 2016

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GlueX Start Counter Meeting
Thursday, November 17, 2016
11:00 am EST
CEBAF Center, Room F326/327


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration/Efficiency Update
    • Sean: comparison to MC
  4. Run Readiness
  5. NIM/TDR
  6. Action Item Review




Talks can be deposited in the directory /group/halld/www/halldweb/html/talks/2016 on the JLab CUE. This directory is accessible from the web at .



  • FIU: Werner Boeglin, Mahmoud Kamel
  • JLab: Thomas Britton, Mark Ito (chair)

There is a recording of this meeting on the BlueJeans site.

Efficiency Studies

Mahmoud showed results from his latest efficiency study. Efficiency was calculated sector by sector. In the denominator are the number of track intersecting a particular sector. In the numerator are the number of tracks with matching start counter hits where the hits have loose cuts defined by Paul Mattione's SC efficiency tree. Mahmoud then applies a timing cut (for tracks in the numerator) and a phi angle cut, measured from the phi at the center of the counter (again only for track in the numerator). He does this for various settings of the phi cut. He repeats the procedure with an additional z "vertex" requirement (this time in the denominator[?] both[?]).

As the secretary understands it, this yields the probability that the phi measurement of a track which fires the start counter is within a particular phi angle miss amount from the center of the counter, given that the tracking projects the track to hit that start counter, whatever that projection criteria may be. We agreed that this was not exactly efficiency.

Mahmoud wanted to repeat these studies for various bins in momentum and z-position (at the start counter[?]), but did not find those quantities in the tree.

In the end we did not come to a conclusion on the best way to characterize efficiency.

We did agree that a different front should be opened. As Sean Dobbs had suggested in a previous private communication, it is important to compare the "efficiency", however that is defined, between Monte Carlo and data. That work can start right away, and need not wait for the ultimate definition of start counter hit efficiency. As far as that definition is concerned, Mark thought that a simpler approach might be more efficient; he will give Mahmoud a call after the meeting to discuss this.

Run Readiness

Mark went through Hot Check-Out for the start counter. Eric Pooser and Mahmoud both looked at the histograms from the cosmic test run and did not see any anomalies.