Tuesday, July 26, 2:30pm ETD

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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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