[Halld-pid] Time-of-Flight Meeting Minutes, August 1, 2018

[Mark Ito]

Folks,

Find the minutes below and at

https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_August_1,_2018#Minutes

   -- Mark

______________________________


  Minutes, GlueX TOF Meeting, August 1, 2018

Present:

  * *FSU: * Sasha Ostrovidov
  * *JLab: * Mark Ito (chair), Simon Taylor, Beni Zihlmann

There is a recording of this meeting <https://bluejeans.com/s/57knh/> on 
the BlueJeans site. Use your JLab credentials.

 1. Announcements
 2. Review of minutes from the July 18 meeting
    <https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_July_18,_2018#Minutes>


      Review of minutes from the July 18 meeting

We reviewed the minutes 
<https://halldweb.jlab.org/wiki/index.php/GlueX_TOF_Meeting,_July_18,_2018#Minutes>. 



        Study of amplified base performance

Beni followed Sasha's suggestion from last time and repeated method 3 
using paddle 31 rather than 14. 31 is on the opposite side of the array, 
farther away from the test PMT. He compiled the results, along with 
those from paddle 14, in an updated version of hist note 
<https://halldweb.jlab.org/talks/2018/specialtof.pdf>. There is a 
significant reduction in time resolution when using 31 versus 14.

Sasha suggested that some combination of methods 1 and 2 might give more 
robust results.

The overall conclusion remains the same, that resolution from the 
amplified base is not as that from a regular base.


      Geometry & Alignment

Prompted by Sean's presentation of parametrizations for geometry 
corrections for the TOF, Beni looked at measuring these corrections 
using charged particles. For each track he takes the TOF point closest 
to the projection of the track to the TOF. The projection position is 
used to update a 2D histogram, with separate histograms for each TOF 
paddle, as reported by the TOF point. The procedure was done separately 
for positive and negative tracks. See his plots in the talks directory 
<https://halldweb.jlab.org/talks/2018/tof_plots/> and his draft note 
describing the study 
<https://halldweb.jlab.org/talks/2018/paddlepos.pdf> for details.

Straight lines are fit separately for each half of the paddle 
(left/right or upper/lower). May paddles give fits inconsistent with one 
straight line describing both halves. This is especially true for the 
half-length paddles, as might be expected, but also for the full-length 
paddles. The simplest geometry-correction scheme may not be adequate.

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  * This page was last modified on 4 August 2018, at 12:15.

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