[Halld-pid] Start Counter Meeting Minutes, July 23, 2020

[Mark Ito]

Folks,

Please find the minutes here 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_July_23,_2020#Minutes> 
and below.

   -- Mark


    GlueX Start Counter Meeting, July 23, 2020, Minutes

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

There is a recording of this meeting 
<https://bluejeans.com/s/5jg6WswNhsO/> on the BlueJeans site. Use your 
JLab credentials to gain access.


      Announcements

The start of the run has been delayed. All shifts are canceled until 
August 3rd.


      Review of minutes from the last meeting

We went over the minutes from July 9 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_July_9,_2020#Minutes>. 



        Run Readiness

Beni reported the start counter is ready to go, all channels look good 
electronically. The only thing left to check is that the data appears 
properly in the events output by the DAQ. The start counter has been 
moved to Ready in the Hot Check-Out list.


        Pulse-Height Data quality

Rupesh performed fits for individual channels of the start counter to 
the distribution of peak amplitude of the ADC hits. He fit to a Landau 
distribution in a limited region of the distribution to avoid noise hits 
at threshold. Data came from a single run. He did this for several runs. 
Here are the fits from channel 30:

Sc fit 30274.png 
<https://halldweb.jlab.org/wiki/index.php/File:Sc_fit_30274.png> 	Sc fit 
31057.png <https://halldweb.jlab.org/wiki/index.php/File:Sc_fit_31057.png>
Sc fit 40856.png 
<https://halldweb.jlab.org/wiki/index.php/File:Sc_fit_40856.png> 	Sc fit 
42559.png <https://halldweb.jlab.org/wiki/index.php/File:Sc_fit_42559.png>
Sc fit 71350.png 
<https://halldweb.jlab.org/wiki/index.php/File:Sc_fit_71350.png> 	Sc fit 
71839.png <https://halldweb.jlab.org/wiki/index.php/File:Sc_fit_71839.png>

 From the fit parameters, he formed the ratio of the "width" to the 
most-probable value of the Landau distribution, for each channel and for 
each of these runs, and plotted them:

Sc ratios.png <https://halldweb.jlab.org/wiki/index.php/File:Sc_ratios.png>

There is no clear trend. We asked if he could plot the level found in 
each run, averaged in some way over all channels, as a function of beam 
intensity and as a function of time so see if any trends emerge.


        Copying input files to the local disk on the farm

Mark sent a question to Ying Chen on the subject. Here is the email 
exchange:

------------------------------------------------------------------------

Ying,

What is the current idea for how to analyzing data from cache in a farm 
job, in particular for raw data? Should one copy the file from cache to 
the local disk and analyze it from there, or should one analyze the data 
directly from cache? My memory is that the advice on this has changed in 
years past and I don't know which is the current best practice.

-- Mark

------------------------------------------------------------------------

Mark,

I think this depends on how the job access the file. If it just read 
once, it should be good to read from /cache directly.

If there are many small read, we suggest user to copy the file to local 
disk.</div>

By default, Auger will not copy the files to local disk when the input 
files from /mss (only make a link), and files from other location 
(/volatile, /work, /home etc.) will be copied to local disk. The reason 
behind this design is that the files stored on /cache are larger file, 
on /home, /work and /volatile are small files. But in later 2018, I add 
a new attribution (copyOption = link or copy) so user can specified copy 
to link the file.

https://scicomp.jlab.org/docs/node/92

But I don't know whether Swif implements this option yet. If not, user 
still can use the old way to copy the file to local disk.

Ying


      Action Item Review

 1. Document calibration procedure (Rupesh)
 2. Reproduce Beni's dark current results. (Tolga)
 3. Revisit Yi's study of SiPM annealing. (Mark, Beni)
 4. Look up type of SiPMs used in start counter. (Mark)

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  * This page was last modified on 23 July 2020, at 13:06.

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