[Halld-pid] Start Counter Meeting Minutes, June 2, 2016

[Mark Ito]

Folks,

Please find the minutes below and at https://goo.gl/dYg4gJ .

   -- Mark
__________________


  GlueX Start Counter Meeting, June 2, 2016, Minutes

Present:

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


      Geometry

Simon is close to submitting a pull request with new geometric 
parameters for the start counter. He is currently dealing with an 
overlap issue with the CDC. He is using the recently done survey as a 
guide for the changes. It shows a tilt larger than we thought we had, 
0.3 degrees down. (For comparison we had 0.6 degrees in Fall 2014.) On 
the upstream end the start counter is 3.4 mm above nominal.

Simon is also working on widening the cut for matching charged tracks to 
the start counter in the nose region. Previous studies have shown the 
phi distribution of tracks at the intersection with the start counter 
not centered on the nominal counter center. The shift is not always in 
the same direction.


      Calibration

After working with Sean to correct the propagation time calibration 
implementation, Mahmoud measured time resolution for three 
representative runs.

Run 	Sigma (ps)
11366 	286
11405 	284
11455 	293

He tried running with run-by-run calibrations and did not see an 
improvement over the single set of constants already present in the CCDB 
(improvement of 3 ps). We will go ahead and use the single set.


      Efficiency

Mahmoud showed start counter hit efficiency using crossing charged 
tracks. If he requires more than 20 hits on the charged track, the 
efficiency goes up to 99%. Unfortunately, there are not enough tracks in 
the forward part of the nose that satisfy this criteria to get a 
meaningful efficiency measurement there.


      NIM/TDR

Eric is back in action in Newport News and will be working on the NIM 
paper.


      Swiss Efficiency

Beni noted that the Gotthard Base Tunnel was recently completed on time 
and under budget, apropos of nearly nothing.

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  * This page was last modified on 3 June 2016, at 15:24.


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

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