GlueX Start Counter Meeting, January 10, 2019
- Review minutes from the meeting on December 13
- Calibration and Efficiency
- *new z-dependent SC resolution parameterization (Sean)
- SiPM bias currents (Beni)
- NIM Paper
- Action Item Review
Talks can be deposited in the directory
/group/halld/www/halldweb/html/talks/2019 on the JLab CUE. This directory is accessible from the web at https://halldweb.jlab.org/talks/2019/ .
- FIU: Werner Boeglin, Mahmoud Kamel
- JLab: Thomas Britton, Mark Ito (chair), Simon Taylor, Beni Zihlmann
Review minutes from the meeting on December 13
We went over the minutes and noted that the plan is to do the DIRC commissioning with the liquid hydrogen target and start the PrimEx run with beryllium.
Calibration and Efficiency
SiPM bias currents
Beni has looked into using the SiPM bias-voltage-supply current as a method to monitor radiation damage. He found that these currents have been recorded in the EPICS Archiver. The current if very small, there is a noticeable increase year-to-year by a few percent, roughly consistent from channel-to-channel. He reminded us that each supply channel serves then four SiPM's that read-out one start counter paddle.
We should compare the observed behavior with the BCAL. We should also check with Carl Zorn that the absolute magnitude of the current seen in the Archiver is reasonable.
Werner mentioned that another way to monitor dark rate is to look at pedestal widths of the ADC's.
Mark reported that Eric Pooser has pushed the paper through the Lab approval process, submitted it the the arXiv, and submitted it to NIM. Just this morning Eric reported that the arXiv has assigned a temporary submission identifier, submit/2531925. He also reports that NIM has assigned a reviewer, Peter Krizan, and a manuscript number, NIMA-D-19-00031.
We discussed ideas for insuring reliable operation of the start counter going forward.