[Halld-pid-upgrade] [Revised Logentry] DIRC Hit Pattern data/MC comparison

[jrsteven at jlab.org]

Logentry Text:
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To compare the PMT hit patterns between data/MC, we selected pi+ from rho events in both data (runs 60590-60617) and bggen MC.  The requirements for the track are that it enters bar #3 (4th from the beamline) at a position 0 < x < 5 cm, and the track momentum > 4 GeV (to have a constant cherenkov angle).  This small area allows us to see a unique hit pattern on the PMT plane seen below.  The first image is for photons which travel directly to the optical box with data (top) and MC (bottom):

[figure:1]

The plot below shows photons reflected by the far end of the bars again with data (top) and MC (bottom).  These are separated by a time cut:

[figure:2]

Bottom line: we see clear Cherenkov photon patterns!  More investigation is needed to understand the details and study the photon yield per track.

In the attachments you'll find PDF files which have a page for each of the bars and canvases for different x regions of the bar.  Separate files are there for data and bggen MC for comparison.

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This is a plain text email for clients that cannot display HTML.  The full logentry can be found online at https://logbooks.jlab.org/entry/3650993
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