[Halld-pid] Start Counter Meeting, November 17, 2016

[Mark Ito]

Folks,

Find the minutes below and at 
https://halldweb.jlab.org/wiki/index.php/GlueX_Start_Counter_Meeting,_November_17,_2016#Minutes 
.

   -- Mark

_________________


    GlueX Start Counter Meeting, November 17, 2016, Minutes

Present:

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

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


      Efficiency Studies

Mahmoud showed results from his latest efficiency study 
<https://halldweb.jlab.org/talks/2016/SC_meeting_Nov17_2016.pdf>. 
Efficiency was calculated sector by sector. In the denominator are the 
number of track intersecting a particular sector. In the numerator are 
the number of tracks with matching start counter hits where the hits 
have loose cuts defined by Paul Mattione's SC efficiency tree. Mahmoud 
then applies a timing cut (for tracks in the numerator) and a phi angle 
cut, measured from the phi at the center of the counter (again only for 
track in the numerator). He does this for various settings of the phi 
cut. He repeats the procedure with an additional z "vertex" requirement 
(this time in the denominator[?] both[?]).

As the secretary understands it, this yields the probability that the 
phi measurement of a track which fires the start counter is within a 
particular phi angle miss amount from the center of the counter, given 
that the tracking projects the track to hit that start counter, whatever 
that projection criteria may be. We agreed that this was not exactly 
efficiency.

Mahmoud wanted to repeat these studies for various bins in momentum and 
z-position (at the start counter[?]), but did not find those quantities 
in the tree.

In the end we did not come to a conclusion on the best way to 
characterize efficiency.

We did agree that a different front should be opened. As Sean Dobbs had 
suggested in a previous private communication, it is important to 
compare the "efficiency", however that is defined, between Monte Carlo 
and data. That work can start right away, and need not wait for the 
ultimate definition of start counter hit efficiency. As far as that 
definition is concerned, Mark thought that a simpler approach might be 
more efficient; he will give Mahmoud a call after the meeting to discuss 
this.


      Run Readiness

Mark went through Hot Check-Out for the start counter. Eric Pooser and 
Mahmoud both looked at the histograms from the cosmic test run and did 
not see any anomalies.

-- 

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

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