[Halld-pid] Start Counter Meeting Minutes, March 21, 2019

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_21,_2019#Minutes> 
and below.

   -- Mark

_____________________________________


    Minutes, GlueX Start Counter Meeting, March 21, 2019

Present:

  * *JLab: * Sean Dobbs, Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting <https://bluejeans.com/s/QISGJ/> on 
the BlueJeans site <https://jlab.bluejeans.com/>. Use your JLab 
credentials to authenticate.


      Announcements

The Start Counter NIM paper has been published 
<https://mailman.jlab.org/mailman/private/gluex-collaboration/2019-March/005133.html>. 
The record in JLab's publication database has been updated as has the 
GlueX wiki's list of publications.


      Review minutes from the meeting on February 7

We went over the minutes 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_February_7,_2019#Minutes>. 
Sean plans to talk to Mahmoud Kamel about the status of the comparison 
between data and Monte Carlo.


      SiPM dark rate measurement

Beni has analyzed data taken under the following conditions

  * read-out threshold set below pedestal
  * read-out of all SiPM detector systems (start counter, BCAL, etc.)
  * random trigger at 2 kHz
  * raw mode

He integrates over all samples and normalizes to the number of events. 
Histograms are fit to a Gaussian from the low side to just over the peak 
on the high sides. The idea is to count events in the high-side tail of 
the distribution. The data from two runs are shown. The red points were 
taken in the middle of the Beryllium target run, the blue points are 
from yesterday. He showed some representative channels from the start 
counter.

H4.gif <https://halldweb.jlab.org/wiki/index.php/File:H4.gif> 	H5.gif 
<https://halldweb.jlab.org/wiki/index.php/File:H5.gif>
H19.gif <https://halldweb.jlab.org/wiki/index.php/File:H19.gif> 	H20.gif 
<https://halldweb.jlab.org/wiki/index.php/File:H20.gif>

He believes that there is an effect seen, but more analysis is needed.

Beni wants to talk to Carl Zorn about what expectations for dark rate 
are. Also he has yet to look at other detector systems.

He also mentioned that there is a procedure to anneal the SiPM to 
partially cure an elevated dark rate due to neutron radiation damage. We 
could consider this if the damage is severe.

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  * This page was last modified on 22 March 2019, at 16:29.

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