GlueX Start Counter Meeting, April 16, 2020

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GlueX Start Counter Meeting
Thursday, April 16, 2020
10:00 am EDT
BlueJeans: 556 286 544


  1. Announcements
  2. Review minutes from the last meeting
  3. Calibration and Efficiency
  4. Dark Rate Studies
  5. Action Item Review


Present: Rupesh Dotel, Tolga Erbora, Mark Ito, Simon Taylor, Beni Zihlmann

There is a recording of this meeting on the BlueJeans site. Use your JLab credentials to gain access.

Review of minutes from the last meeting

We went over the minutes from April 2 without significant comment.

Calibration and Efficiency

Rupesh is working on documenting the calibration procedures that he worked so hard to get going before it fades from memory. He is also thinking about a plan for doing some calibrations for the run just past at appropriate intervals.

Dark Rate Studies

Beni showed plot of the dark rate effects using a new method. Rather using the result from FPGA-providided pedestal measurement, he sums all of the data in the readout window in raw mode to assess pedestal the pedestal value. He has also changed the fit method. Rather than just fitting the low-side of the pedestal distribution to a Gaussian, he constrains the amplitude and the position of the Gaussian peak to within a narrow range around the peak of the pedestal distribution. He showed two plots. On the left is the old method, and the right the new.

Old Method
New Method

We noted that even though the methods are quite a bit different, the trendline and size of the effect are the same.

Tolga has been trying to reproduce Beni's result (old method). He is ready to averate the results of the 30 start counter paddles got get a single plot.

Actin Item Review

  1. Document calibration procedure (Rupesh)
  2. Obtained calibrations for sub-periods of the recent run. (Rupesh)
  3. Reproduce Beni's dark current results. (Tolga)