[Halld-pid] Start Counter Meeting Minutes, June 1, 2017

[Mark Ito]

Please find the minutes below and on the web in the usual location 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_June_1,_2017#Minutes>.

____________


    Minutes

Present:

  * *FIU*: Werner Boeglin, Mahmoud Kamel
  * *JLab*: Thomas Britton, Mark Ito (chair), Eric Pooser, Simon Taylor

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


      Announcements

Thomas mentioned that he and Dmitry have started developing a new 3D 
event display programs. He encouraged us to start thinking about how we 
would like to visually represent the start counter and its hits.


      Review minutes from the last meeting

We went over the minutes from the meeting on April 20 
<https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_April_20,_2017#Minutes>. 


Most of the discussion was on geometry.

  * The current geometry is based on an idealized geometry from before
    construction was completed. It is does not reflect the details of
    the support structure as built.
  * There are small rotations and translations done in the HDDS XML file
    to make the adjustments suggested by surveys.
  * There are accurate engineering drawings that we can use to bring the
    geometry closer to reality.
  * Werner pointed out that if we want to do studies of acceptance, we
    will need to do studies of efficiency as a function of non-ideal
    displacements/rotations. It would be great to have a parametric way
    of achieving this.


      NIM/TDR

A complete draft of the NIM paper is done. The folks at FIU are 
reviewing the text and creating new figures for it based on Spring 2016 
data.


      Calibration

Mahmoud has been working on measuring attenuation as function of 
position using data. The constants we have been using for reconstruction 
thus far are based on bench measurements at FIU. See his slides 
<https://halldweb.jlab.org/talks/2017/SC_Meeting_6_1_2017.pdf> for 
details and plots.

He measures the position of the minimum ionizing peak as a function of z 
in the start counter as predicted by charged particle tracks. The 
overall behavior is consistent with what we expect from the bench 
measurements. There were suggestions for improvements including for 
example, using finer bins in z.

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

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