[Halld-pid] Start Counter Meeting Minutes, December 12, 2019

[Mark Ito]

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_December_12,_2019#Minutes> 
and below.


    GlueX Start Counter Meeting, December 12, 2019, Minutes

Present:

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

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


      Review of Minutes from October 31

We went over the minutes 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_October_31,_2019#Minutes> 
without a lot of comment.


      Calibration and Efficiency


        Calibration Incident

We discussed the issue that Sean raised at yesterday's Production and 
Analysis Meeting. Calibration constants for correction of propagation 
times were overwritten about a year ago. The effects do not appear to be 
large, but are visible when looking at resolution as a function of z. 
Sean has yet to quantify the effect, but we know that it is present in 
all of the reconstruction of 2018 data done this year.

The problem was introduced inadvertently, probably during the process of 
a collaborator learning how the calibration database works. We discussed 
what steps could be taken to prevent, or at least reduce the 
probability, of this happening again. There is no solution that is at 
the level flipping some appropriate switch in the system. Restrictions 
have benefits but also costs in implementation, management, and loss of 
efficiency in making calibration changes. That said, something will have 
to be done in the near future.


        Realistic Start Counter Efficiency in mcsmear

Sean brought up the issue in incorporating start counter efficiency as a 
function of z into the simulation. Mahmoud Kamel has performed studies 
on this in the past. Sean suggested he could perhaps write a short note 
summarizing his findings that we could use as a guide in coding. Mark 
will ask Mahmoud about this.


      Dark Rate Studies

At a previous meeting Rupesh agreed to take over doing dark rate 
measurements about every two weeks during the run. As a first step Beni 
will write up the procedure (or find the 
already-written-but-temporarily-lost procedure) and go over it with Rupesh.

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  * This page was last modified on 12 December 2019, at 13:23.

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