[Halld-pid] Start Counter Meeting Minutes, June 29, 2017

[Mark Ito]

Please find the minutes below and at 
https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_June_29,_2017#Minutes 
.

_________________________


    Minutes

Present:

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

There is a recording of this meeting <https://bluejeans.com/s/R6Hz4/> on 
the BlueJeans site <https://jlab.bluejeans.com/>.


      Efficiency and Attenuation

Mahmoud showed updated results on two topics. Please see his slides 
<https://halldweb.jlab.org/talks/2017/SC_Meeting_6_29_2017.pdf> for the 
details.


        Efficiency

After adjusting his timing cuts for both the signal and the accidental 
background, efficiency is back to values we have seen before, overall 
about 97% percent.


        Attenuation

The fits to minimum ionizing peaks are now converging nicely. He finds 
very reasonable results for peak position as a function of z-position in 
the counter, consistent with expectations from the bench tests at FIU 
obtained during construction.

There are still four problem counters that have anomalously low 
statistics. Mahmoud will review whether something may have gone wrong 
with the timing cut for these counters.


        Mcsmear

Beni has started looking at comparisons between Monte Carlo and data for 
the start counter. Below he plots the time distributions for the 30 
counters; data on top, Monte Carlo below. Data is significantly wider 
and is offset in time from the simulation. This is work in progress; the 
explanations are not known at this point.

 1. Data MC comparison, Example of timing for events with no charged
    tracks:
    DATA: Sc paddle vs time DATA.gif
    <https://halldweb.jlab.org/wiki/index.php/File:Sc_paddle_vs_time_DATA.gif>
    MC: Sc paddle vs time MC.gif
    <https://halldweb.jlab.org/wiki/index.php/File:Sc_paddle_vs_time_MC.gif>


      NIM Paper

Eric has received comments on the draft from Werner. He will incorporate 
them as well as the attenuation plots from Mahmoud when they become 
available in their final form. He feels on track for the August 1 deadline.


      Meeting Time

We will continue to meet at 11:30 am for the next few meetings.

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

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