MOLLER Pion Background Meeting Friday, March 10, 2017 9:00am EST

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Previous Meeting: MOLLER_Pion_Background_Meeting_Friday,_March_3,_2017_9:00am_EST

Meeting Information

BlueJeans Call Information


Phone Number: 1-888-240-2560

Meeting ID: 624029893


  • Wouter: General simulation updates. WM ELOG
  • Scott: Lead wall thickness determination.
  • Jacob: Pion detector optimization.
  • Any new business?


Attendees: David, Wouter, Paul

Not Attending: Jacob(spring break), Scott(spring break)

Scribe: Kurtis

  • Wouter: Pion detector, lucite element geometry update.
    • Looking at the first attachment in the his ELOG. Side view of the five layer lucite detector volume(blue) attached to an air light guide(red). We see a pion coming in from the right generating Cherenkov light in the air light guide. This light doesn't make it to the PMT face(gray circle), thus the detectors will probably have to be given a slight rotation.
    • Attachments 3 & 4 show a weird drawing artifact of the simulation visualization.
    • Attachment 5 is a top view of a pion passing through the air light guide.
    • Attachment 7 is a close of the optical photons in the air light guide entering the gray PMT face. Note some optical photon tracks don't make it into the PMT face but make it pass the PMT face. This effect is due to the fact that the end of the air light guide is square and the PMT face is circular and lies just inside of the end of the air light guide.
    • Attachment 8 shows that some hits are not recorded on the surface of the PMT face. This is due to the way simulation stores the hits for a given sensitive volume, either pre or post step in that volume.
    • For lucite the Cherenkov angle is approximately 48 degrees, Wouter suggestions including a rotation of somewhere between no rotation and 45 degrees. That included the number optical photos detected from 29 to 396.
    • Will still have to explore what angle the air light guide must in order to get the optimal number of optical photons.
    • Also found a bug in Geant4, submitted to the Geant4 collaboration for inclusion on the next software version release. Created a temporary fix for remoll.
    • This bug would also effect the main quartz simulation group if they go with GDML implementation of the main detector rings.
    • David/Wouter - By included a rotation that would also reduce the amount of lucite we would need. The next steps would be to optimize the angle, need to worry about azimuthal uniformity of the pions, uniform light generation, uniformity of response along the face of the detector, "resolution" of each detector, time distribution of light arriving at the PMT face, and PMT face signal characteristics.
    • David - In counting mode, long pulses will cause pile-up and dead times. Need to look at the time spectrum from dilution measurements.
    • Wouter - Requests? Possibly try a different type of light guide, plastic, to remove the TIR and possibly suppress background tracks passing through the light guide.
    • Wouter - Should speak with Michael and Dustin with their input on general detector geometry consideration. David - Should chat with them soon.