[Halld-pid] Start Counter Meeting Minutes, April 2, 2020

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_April_2,_2020#Minutes> 
and below.

   -- Mark


    GlueX Start Counter Meeting, April 2, 2020, Minutes

Present: Rupesh Dotel, Tolga Erbora, Mark Ito, Simon Taylor, Beni Zihlmann

There is a recording of this meeting <https://bluejeans.com/s/5BYw8/> on 
the BlueJeans site. Use your JLab credentials to gain access.


      Review minutes from the last meeting

We went over the minutes from March 5 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_March_5,_2020#Minutes> 
without significant comment.


      Calibration and Efficiency

Rupesh showed counter-by-counter time resolution for the start counter 
after the propagation-time calibration. See his slides 
<https://halldweb.jlab.org/wiki/images/f/f5/April2_2020_SC.pdf> for the 
plots. At Sean's suggestion he tried applying constants obtained from 
run 71724 to data from run 71724 itself to see if there was a 
significant improvement over resolution using constants obtained from 
run 71003. Only slight improvement was visible.

The constants from run 71724 have been entered into the default CCDB 
variation for all of the Fall-2019/Spring-2020 run. Rupesh is looking at 
calibrating a few more runs dispersed throughout the run and applying 
them appropriately to smaller time periods of the run.


      Dark Rate Studies

Beni showed the results from dark rate runs. See the plot below. The 
y-axis is the ratio of the area of a Gaussian fitted to the pedestal 
distribution, but using only the low side of the distribution, to the 
area of the entire pedestal distribution, as he described in a GlueX Doc 
from last year 
<https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4138>. 
The x-axis is accumulated coincidences from the pair spectrometer as a 
proxy for beam photon flux. Significant increase in dark current is seen.

<https://halldweb.jlab.org/wiki/index.php/File:Sc_dr_ped.gif>
Development of the Start Counter SiPM Dark rate over the PrimEx and Fall 
19 run period. This is based on the pedestal data reported by the F250 
firmware running in raw mode, unsparsified with no beam, taken with a 
random trigger.

Tolga has started reviewing Beni's code and will try to reproduce these 
results.


      Action Item Review

 1. Obtained calibrations for sub-periods of the recent run. (Rupesh)
 2. Reproduce Beni's dark current results. (Tolga)

Retrieved from 
"https://halldweb.jlab.org/wiki/index.php?title=GlueX_Start_Counter_Meeting,_April_2,_2020&oldid=97848"

  * This page was last modified on 2 April 2020, at 14:19.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.jlab.org/pipermail/halld-pid/attachments/20200402/f1f67a24/attachment.html>