[Halld-pid] Start Counter Meeting Minutes, March 24, 2016

[Mark Ito]

Folks,

Please find the meeting minutes below and at http://tinyurl.com/hr5s9ym .

   -- Mark
____________________________________________


  GlueX Start Counter Meeting, March 24, 2016, Minutes

The meeting came to order at 10:00 am.

Present:

  * *FIU*: Mahmoud Kamel, Eric Pooser
  * *JLab*: Mark Ito (chair), Simon Taylor, Beni Zihlmann


      Announcements

Beam delivery to Hall D is scheduled for Sunday, March 27.


      Reviewminutes from the last meeting
      <https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_January_28,_2016#Minutes>

  * No progress on the NIM paper or the TDR since the last meeting.


      Calibration Update

Mahmoud gave an update on time propagation delay calibration focusing on 
a comparison between data and simulation. Seehis slides 
<http://argus.phys.uregina.ca/cgi-bin/private/DocDB/ShowDocument?docid=2980>for 
the plots and details.

He showed the results of the calibration for each section of the start 
counter for a sample of recent data (run 10496) and the sim1 simulated 
data. Differences are seen mainly in the nose section, where fits do not 
represent the data very well.

The overall timing resolution is 270 ps for data, but 370 ps for 
simulation. To start with for simulation, there is 300 ps of smearing 
introduced by mcsmear but the reason for poorer resolution than that is 
unclear. Mahmoud may try to go back to a simpler propagation delay 
scheme that uses a constant velocity rather than the section dependent 
velocity (straight/bend/nose) that is the current default.


      Resolutions in mcsmear
      <https://halldweb.jlab.org/wiki/index.php/Mcsmear_20160323#SC_Resolutions>

Sean showed monitoring plots again comparing data and Monte Carlo. He 
has collected a few interesting plots for other subsystems as well. The 
start counter section shows a large number of RF-bucket 
mis-identifications for simulation in the plots from which resolution 
numbers are extracted. The reasons are not clear; RF bucket selection 
for the data looks clean.


      mcsmear parameters
      <https://halldweb.jlab.org/wiki/index.php/Mcsmear_updates#START_COUNTER>

We discussed the parameters used by mcsmear to introduce detector 
effects to the start counter hits. The first line in the table is the 
300 ps mentioned in the discussion of Mahmoud's slides (above). Sean 
proposed using the measured values of the resolution as recorded in the 
CCDB to do time smearing with a channel-dependent width.

We discussed how the other parameters should be measured and indeed 
whether these are the best set of parameters to use. Mark and Simon will 
make a proposal on how the various effects should be parametrized and 
how those parameters should be measured. They will report back to the 
group at a future meeting.


      Multiple ADC hits checks

Sean reminded us that now were are running with npeaks = 3 in the 
FADC-250s and there is a need to study the matching of ADC and TDC hits 
with this new scheme.


      Efficiency measurement

Paul Mattione had commented on Mahmoud's presentation of start counter 
efficiency at theCalibration Meeting 
<https://halldweb.jlab.org/wiki/index.php/March_9,_2016_Calibration#Minutes>. 
There appears to have been some skepticism expressed due to the use of 
protons to measure efficiency. Mahmoud pointed out the he gets the same 
results independent of the particle species. We agreed to circulate 
Paul's points and Mahmoud's response and discuss the issues at the next 
meeting.


      Run Issues

There was one round of pedestal adjustment for the FADCs early in the 
run by Eric and Sergey Furletov. Nothing has been done since. Beni 
advocates doing another round before we start running again, and not 
just for the start counter.

The meeting adjourned at 11:05 am.

Retrieved from 
"https://halldweb.jlab.org/wiki/index.php?title=GlueX_Start_Counter_Meeting,_March_24,_2016&oldid=73947"

  * This page was last modified on 24 March 2016, at 12:18.


-- 
marki at jlab.org, (757)269-5295

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