GlueX TOF Meeting, August 2, 2016

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GlueX Time-of-Flight Meeting
Tuesday, August 2, 2016
10:00 am EDT
JLab: CEBAF Center, Room F227


  1. Announcements
  2. Review of minutes from the previous meeting
  3. PMT order
  4. Cosmic data
  5. Calibration Updates
  6. NIM paper



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 .



  • FSU: Sasha Ostrovidov
  • JLab: Mark Ito (chair), Simon Taylor, Beni Zihlmann

PMT order

  • Mark received a quote from Hamamatsu for more extra spare PMTs].
  • Beni remarked that 24 PMTs was chosen to cover the possibility of replacing the innermost counters that have the highest rate.
  • At Eugene's suggestion, we will add 6 more tubes to the order bringing the total to 30, just in case they are needed.

Cosmic data

Beni has taken more cosmic data, this time at 1200 V on the tubes. He is now requiring an ADC and a TDC hit on both ends of the counter, with all 4 hits in time with each other.
1200 V, paddle 12 of horizontal plane
1200 V, paddle 21 of horizontal plane
  • The new requirements clean up a lot of the noise seen at low amplitude in the plots from the last meeting, though a noise band is still visible.
  • The effect on time resolution is still open. Trying to time one layer against the other (crossed) layer is not giving good results. Beni will try the same technique with higher voltages to see if that makes any difference.
  • Sasha pointed out that we have to look at efficiency as well, though that may may be hard to asses with cosmic data.

PMT currents during the Spring 2016 run

Beni made some estimates based on data we took in the Spring. Note that the recommended maximum current is 100 μA and we want to be well below that.

  • paddle 14, up, MIP at 900 counts => 450 mV peak, assuming triangle pulse => 1.4×10-10 C/pulse. At 22 kHz => 3 μA.
  • paddle 2, 600 kHz, => 85 μA, yikes!

Next Meeting

We will meet next week in our normal time slot. We will discuss the run plan for re-commissioning the TOF.