MOLLER Pion Background Meeting Friday, March 17, 2017 9:00am EST

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Previous Meeting: MOLLER_Pion_Background_Meeting_Friday,_March_10,_2017_9:00am_EST

Meeting Information

BlueJeans Call Information


Phone Number: 1-888-240-2560

Meeting ID: 624029893


  • Wouter: General simulation updates. Dilbert ELOG 76
  • Scott: Lead wall thickness determination.
  • Jacob: Pion detector optimization.
  • Any new business?


Attendees: Kurtis, David, Seamus, Wouter, KK

Not Attending:

Scribe: Kurtis

  • Wouter - Dilbert ELOG 76, have now mitered the light guide connection to the lucite volume.
    • Attachment 1 - Side of the lucite volumes with the mitered air core light guide. Currently keeping the lucite perpendicular to the incoming beam, only putting the light guide at an angle.
    • Attachment 5 - Close up of optical photons (in yellow) filling up the lucite and air light guide volumes.
    • KK - What QE for the PMT are you using? What range of wavelengths are we accepting. KK - Wet air cut off at ~200 nm, dry air cut off at ~180 nm. Wouter - Geant4 should take into account the present of the air because it does included an absorption length. KK - We should confirm if Geant4 is treating the air in the light guide properly.
    • David - Qweak PMTS: 200 to 900 nm, with a peak QE of 23% at 260 nm.
    • Attachment 3 & 4 - Show the number of detected PEs with various detector rotations. The scatter of the points is not representative of the uncertainty with those simulations. Higher stats simulations will have to used before these optimization studies can be completed.
    • David - Worried about the electromagnetic events. Scott will start working on this soon to confirm we do see good separation between the pion signal and the electron signal with the lead wall. Also want to investigate the different size of pulse signals we seen in our pion detectors from electrons and pions.
    • Wouter - Using bluejeans to give a visual tour of the present pion detector geometry implemented into the simulation with GDML.
    • KK - Is that gap between the pion detectors optimized? Wouter - Presently placed at our best estimate, don't want to move them to close together because of potential cross-talk between. KK - So an azimuthal smearing is occuring? Wouter - Yes
    • David - Also need to investigate the rates seen in the open/closed sectors. That would then allow us to optimize each individual detector size.
    • KK - Now implementing real scintillation response for main detector light guide. Something to consider in the future for the pion detector light guides.
    • Wouter/KK - Expecting efficiency of detected optical photons when talking about lucite light guide angle to drop when light guide has a positive angle (positive point back towards target)
    • Seamus - Possibly vary the lead wall thickness in the azimuth because of the momentum dependence. David - Would probably work for the open vs close. But still have to worry about the transverse asymmetries that must be mapped in the azimuthal plane.
  • KK - Should also bring in Michael, Dustin, Paul once a more formal design has been constructed. They can review and give opinions.