[Halld-pid-upgrade] [New Logentry] Follow-up Re: DIRC bar-by-bar diagnostics: early Fall 2019

[jrsteven at jlab.org]

Logentry Text:
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As a followup: we can overlay the cherenkov photon distributions for symmetric bars around the beamline to compare the performance.  On DocDB https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4287 there are files with "Mirror" in the name, which overlay the "Mirror" or symmetric bars above and below the beam line.  The good news is for the bar boxes closest to the beamline, the performance is remarkably similar.

For example, on the first page you'll find Bar 0 in blue and Bar 24 in red, being the bars just a below and above the beamline respectively.  In all cases, red histograms correspond to the North (upper) OB and blue histograms correspond to the South (lower) OB.  The bars in bar box 0 begin on page 13 (bar 36+) where you can quantify the lower photon yield with respect to it's symmetric bars

https://halldweb.jlab.org/DocDB/0042/004287/001/DataBarMirrorNphotons.pdf

The photon timing actually doesn't look too bad for bars 37+ (page 14+ in the file below), but further study is needed to determine the impact on the pi/K separation power.

https://halldweb.jlab.org/DocDB/0042/004287/001/DataBarMirrorHitTimeMap.pdf

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