Pion Meeting March 15 2023 1:00PM ET

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Zoom link: https://jlab-org.zoomgov.com/j/1608212513?pwd=M25LR1hzN3hLWm0xaFFETjZ0U1lQZz09

Attendance

Sudip, Elham, David, Wouter, Carl, Kate

Minutes

1. (David) Will be a meeting later today with Larry Bartozsek (and David, Wouter, Elham) to discuss mechanics for pion detector mounting.
2. (David) No update from Simona on PMT testing.
3. (Elham) Standalone simulations of the pion detector response to incident pions (at the beam momenta available in the M11 beamline at TRIUMF are puzzling. For both 80 MeV/c and 150 MeV/c momenta, GEANT gives similar numbers of PEs per incident pion, despite the fact that the Cerenkov threshold in acrylic for charged pions is 125 MeV/c. Number of PEs is a bit less than number of charged pion hits on the lucite. How can this be? Ideas to debug:
   1. Check to see if this is from rare events that generated lots of PEs, but where most pions generated no PEs (maybe pion knocks out an energetic electron which is the above the Cherenkov threshold)?
   2. Try running with higher pion momenta, where we are clearly above the Cherenkov threshold.
   3. Set the "verbose" output turned on in GEANT, see what kind of events are making the optical photons (maybe these are not Cerenkov photons at all)?
4. (Elham) The azimuthal dependence of the electron/pion rates and the electron/pion PEs in the full remoll simulation, as shown last week are still not understood. Suggest looking to see if the incident azimuthal distributions of pions and Moller electrons on a virtual detector upstream of the Pb donut are understood, and then correlate with what is seen in the lucite. Another idea is to look at the r,z distributions of the vertices for the events in the lucite, but plotted differently for the different azimuthal location of pion detectors (open/closed/transition)
5. (David) We should also remember to try to understand why Neven's Fluka simulation results for the dependence of the lucite signal on position along the detector agrees qualitatively with Elham's G4 results, and with the Mainz beam tests for the long (12 inch wide) prototype, but apparently disagrees with both G4 and the beam results for the short (8 inch wide) detector.
6. (David) Andrew Hurley will provide update at the next MOLLER Optics meeting on putting a Hyperon generator into remoll. We may have him update us at next pion meeting as well.