GEM Meeting/20190125

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Agenda

• Tao: GEM analyzer/decoder concerns and data characteristic investigations

Minutes

1. Tao - SLAC analysis update, quantifying differences between QDC and GEM multiplicities, and GEM pedestal studies (ask Cameron for SLAC test beam user account on ELOG):
   • Verified that all data is complete in QDC and GEM (no missed events in one or the other)
   • Cross checked Decoder with event counter
     • Two data words encoding event number added to decoder to double check event counts
       • QDC index starts at 0, GEM MPD index starts at 1, so we expect an offset by one in these event counters
   • Trying to find another way to cross check the analysis steps
   • GEM multiplicities appear to be systematically ~15% lower than QDC multiplicities
     • There is a clear correlation of QDC mult to GEM mult, though probably the GEM efficiency is too low and pedestals are maybe an issue too
   • There appears to be a bimodal behavior of events - events with a clear spike in the GEM and low RMS, and events with no clear spike in the GEM and high RMS (and often a large multiplicity in the QDC)
     • It would be nice to see if separating these two kinds of events and looking at just the low RMS ones would clean up the correlation of multiplicities between GEM and QDC
   • Cross-talk slides are also uploaded in the same entry as the pedestal studies entry
2. Bryan: parameter in the APV config files
   • Speed set to 350
   • ADC clock phase needs to be adjusted to remove reflections for large signals causing large RMS's
     • This parameter is for MPD vs. APV clock offset - Dustin set it at 12 at ISU, unknown at SLAC, we can replicate in TEST lab
3. Dustin: CAD files for SLAC test beam, for use in determining simulation geometries and generating images
4. Chandan: Cosmic run in TEST lab
   • I2C issue causes error in 1/3 of events
   • QDC doesn't see the gates, and this happens even though you would expect it not to with low rate cosmics
     • Including a QDC busy veto on MPD reading prevented this from being an issue at SLAC
     • Cosmic running shouldn't actually be busy
       • Diagnose this by looking for timing de-synchronization in cosmic runs, potentially due to bad noisy grounds

Present

Chandan, Cameron, Seamus, Brady Lowe, Bryan Moffit, Dustin, Devi, Joey McCullough, Ryan Richards, Siyu, Tao, Carlos