[Halld-pid] Time-of-Flight Meeting Minutes, December 16, 2020

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_December_16,_2020#Minutes> 
and below.

   -- Mark

__________________________________________


    GlueX TOF Meeting, December 16, 2020, Minutes

Present: Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting 
<https://bluejeans.com/s/uFOTouCmW62/>. Log into the BlueJeans site 
<https://jlab.bluejeans.com> first to gain access (use your JLab 
credentials).


      More on the Gain Study

We went over additions Beni made to his study 
<https://logbooks.jlab.org/entry/3857729gain> since the last meeting. In 
particular he plotted amplitude spectra for individual PMTs overlaying 
the data from the high intensity and low intensity runs. All show clear 
minimum ionizing peaks. The difference in the mean value in the 
histograms, reported last time, is indeed due to taking the average over 
the entire histogram, with the high intensity runs having many more hits 
a low pulse height, as we speculated last time.

The anomaly in PMT 69 is revealed as a broad peak in the pulse height 
spectrum around 3500 counts. The rate in this peak seems independent of 
beam intensity. The minimum ionizing peak is present in both high and 
low intensity runs and at a typical value of pulse height, so at some 
level the PMT is working with an unremarkable gain. It is hard to 
imagine that a broken light guide is causing the strange behavior. This 
tube remains a candidate for replacement.

Beni also reported that he has looked at the signal from PMT 69 on the 
scope and could not see anything out of the ordinary.


      Action Item Recap

 1. Decide on when to ship PMTs to JLab from FSU (Mark, Paul Eugenio)
 2. Prepare a complete draft of the TOF NIM paper. (all)
 3. Make a plan for TOF repair during the SAD, including Paul in the
    discussion. (all)


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