Tuesday, July 26, 2:30pm ETD

Agenda

Presentations:

1. photon simulations (Michael Snider - high school summer student)
2. acceptance plots from collimator optimization study (Sereres)
3. Discussion - Other projects

Minutes

Action items in bold.

Attendance: Mark Pitt, Michael Snider, Michael Gericke, Anna Lee, Damon Spayde, Seamus Riordan, Sereres Johnston, Wouter Deconinck (minutes), Juliette Mammei (chair)

• Michael Snider presented results from his photon background studies (see elog entry 199, link in agenda)
  • attachment 2: previous results could be replicated for ee, ep, ine, and photon background
  • table 1: new results
    • photon background from ep is largest
    • total photon background rate is 13.7 GHz, compared to 171.7 GHz moller rate
  • attachment 1: origin of the photon background is around the collimator edges, similar for all processes
  • attachment 3: simulation with helium, very similar but recent results and not sure if correct
    • thickness of helium only 0.5% (according to Juliette)
    • origin for He study: Roger's suggestion to keep the petal beamline, but fill it with He, primary beam would go through He
    • Mark: why do you expect any difference if most of the photons are shown to come from the collimator edges?
      • Juliette: from the table it seems that 2 GHz of ee photons come from other sources than target and collimator
    • Wouter: primary beam through He not simulated, but Juliette points out small UHV beamline inside He
  • acceptance defining collimator is visible -> not good
  • no photons from target visible (z pos < 4m) -> good
  • Sereres will take this over from Michael

• Sereres presented results from her collimator optimization studies (see elog 200, link in agenda)
  • progress in developing figure of merit and separation according to polar angles
  • attachment 1: radius versus theta_CM -> "eyebrow" (compare to Qweak "moustache")
    • KK rule of thumb: lower right panel should be as vertical as possible by tweaking field map (points to good focusing)
    • reasons for KK's rule of thumb not well understood by those present
    • presented figures use default conductor field map
    • Sereres will make these plots for the proposal field map
    • Sereres will turn off radiation in G4 and compare with results from Tosca
  • attachment 5: top right is how KK wants this to look
    • need to trim using collimators, but without changing the magnet and without affecting FOM
  • Sereres will repeat these studies for different fieldmaps and collimator geometries (looking for input...)
  • attachment 16-17: lower right should be symmetric (as in attachment 15)
  • attachment 20: radial width primarily determined by midrange scattering angles, shrinking this width will reduce photon backgrounds
  • Sereres will look at different detector plan positions, less than 26 m, but 2 m range, e.g. steps of 50 cm

• Other projects listed on Moller simulations page
  • Michael Gericke will update webpage with plan of attack for detector simulations
  • GDML support on central G4 installation is missing

• Meeting time: every two weeks, same time, until fall semester starts, then revisit
• Seamus will move SVN repository from Umass to JLab (someone should tell him)

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