Difference between revisions of "April 20-21, 2020 DIRC"

From GlueXWiki
Jump to: navigation, search
(Monday, April 20)
(Agenda)
Line 16: Line 16:
  
 
=== Monday, April 20 ===
 
=== Monday, April 20 ===
* 9:00 - [https://halldweb.jlab.org/wiki/images/5/56/Geom.pdf Status of geometric reconstruction]  --- Roman
+
* 9:00 - [https://halldweb.jlab.org/doc-private/DocDB/ShowDocument?docid=4435 Status of geometric reconstruction]  --- Roman
 
* 9:45 - [https://halldweb.jlab.org/wiki/images/3/34/AAGlueXDIRC.pdf Status of Cherenkov PDF reconstruction] --- Ahmed
 
* 9:45 - [https://halldweb.jlab.org/wiki/images/3/34/AAGlueXDIRC.pdf Status of Cherenkov PDF reconstruction] --- Ahmed
 
* 10:30 - Break
 
* 10:30 - Break

Revision as of 12:14, 20 April 2020

Meeting Information

GlueX DIRC Meeting
Monday-Tuesday April 20-21, 2020
Remote only

Connection Using Bluejeans

  1. To join via Polycom room system go to the IP Address: 199.48.152.152 (bjn.vc) and enter the meeting ID: 846453895.
  2. To join via a Web Browser, go to the page [1] https://bluejeans.com/846453895 .
  3. To join via phone, use one of the following numbers and the Conference ID: 846453895
    • US or Canada: +1 408 740 7256 or
    • US or Canada: +1 888 240 2560
  4. More information on connecting to bluejeans is available.

Agenda

Monday, April 20

Tuesday, April 21

  • 9:00 - FastDIRC status --- Yunjie
  • 9:45 - Followup discussion and planning future work --- All
  • 11:15 - GlueX bi-weekly meeting

Action items

Here we'll collect a list of specific action items from the discussion to accomplish in the short (prior to reconstruction launch) and long term:


Discussion notes

Roman

  • Slide 2: Kaon distributions have more background SPR plot and likelihood distribution is wider for kaon than pions.
    • Could the timing performance still be worse for kaons than pions?
    • What else would cause kaon background to be higher?
    • How much does this background contribute to to the larger photon yield for kaons?
  • Slide 3: Preferred correction order is always to begin with per-PMT Cherenkov angle correction, since it keeps ring segments connected. Smearing by either track resolution (ring fit) or chromatic correction
  • Per-PMT Cherenkov angle correction
    • Some PMTs with bad correction, could be checked with MC?
  • Ring-fit correction
    • Sensitive to start values for the fits: use average of pion and kaon expected values.
    • How do the the correction factors vary over the DIRC plane?
      • Can we determine a map of expected track corrections as a function of r, phi?
  • Chromatic correction
    • Possible to use MC with varying timing resolutions to see if it follows the expectation. From this we could determine what time resolution would be required to make significant chromatic correction
    • Suggestion to divide time difference by path length to improve performance (from SLAC experience)
  • Comparison of corrections
    • Need to keep track of both SPR improvement and difference between thetaC mean with improvements
    • Kaon DeltaLL narrows as corrections improve performance
  • Kaon photon yield is significantly higher than pion
    • Need to look back at MC for comparison of photon yield between pions and kaons
    • Should cut on thetaC for counting photons be symmetric around pion and kaon peaks separately?
  • Event selection for calibration sample:
    • Look at side-band of phi mass distribution in thetaC plot, quantify pion background
    • For cleaner sample: could use comparison of 2pi and 2k kinfit chi2 values (a la Alex Barnes's study for the phi SDME)
    • For some reason don't see peak for opposite PID, e.g. kaons peaking at positive DeltaLL under pion sample. Concern that timing cut could be biasing tracks which make it into final sample for DeltaLL. Some options to consider:
      • Select poorer kaon sample (e.g. with inverted kinfit chi2 cut) and see if mis-ID'd pions appear
      • Study event selection plots: mass distribution (phi/rho yield), kinfit chi2, etc. after positively identifying a kaon

Ahmed

  • Per-track Cherenkov angle resolution vs photon yield
    • Not applying corrections for per-PMT offsets or ring fitting for this study
    • Correlated term of ~2.5 mrad larger than expected
    • Suggestion: repeat same procedure for kaons in data and
  • For charge separated samples: plot DeltaThetaC on slide 7 in different regions of the DIRC plane (bar and x-position)
    • Do we see any evidence of charge separation?
  • Cherenkov PDF: statistically limited thus far
    • Expected factor ~20 increase with full Spring 2020: 200 B triggers collected, compared to ~10 B triggers in commissioning period
    • Addition of other tagged kaon samples: reactions with Lambdas, K*, Kshort etc. could increase by factors of a "few" with possible additional backgrounds
    • Changing to DeltaThetaC for PDF may also decrease statistics requirement
    • Come back to this study after a significant fraction of Spring 2020 data is available for analysis

General

  • Data/MC comparisons