Π polarizability Meeting Nov 2, 2012

From GlueXWiki
Jump to: navigation, search

Meeting Info.

Meeting Time

9:00 EST

Connecting

We meet via Skype. The relevant Skype user names are:

  • Rory Miskimen - rmiskimen
  • Alexander Mushkarenkov - alexander_mushkarenkov
  • Elton Smith - eltonssmith
  • David Lawrence - aehsdad

some phone numbers if needed:

David: (757) 269-5567 Rory: (413) 545-2480

Agenda

  1. Previous meeting: Oct 19, 2012
  2. Acceptance Simulations (David)


Minutes

Attendees: Rory M. (chair), David L., Sascha M.

Rory

  • Contacted Richard Jones about beam polarization optimization. Received long e-mail in response with lots of info.
  • FOM to optimize polarization will include polarization^2 times event rate
  • Need to get correlation between polarization and energy from Richard
  • Still considering a relative measurement where we normalize to the πo cross-section rather than try measuring the absolute photon flux.
    • Photon flux was largest contributor to error bar in PrimEx in Hall-B
    • Hall-D has very long distance between radiator and target and a collimator, making it difficult or impossible to use the tagger for photon flux measurement
    • Pair spectrometer is option, but may not be as precise as πo cross-section measurement.
    • Further study is required
  • We are still missing the azimuthal distribution of the ππ system (not in Elton's plots)

David

  • Reproduced plots shown by Sascha last time of π+ energy with and without secondaries turned on
    • Plots were somewhat consistent, but overall much cleaner than what Sashca saw. Most likely due to a newer version of the Hall-D sim-recon code.
  • Plot of efficiency vs. z-location of target produced using JLab farm
  • Vertex-constraint left on, but the z-location of the constraint was left at z=65cm (i.e. did not match the vertex location) This was an over site
  • Will re-reun with vertex-constraint off and also with it on, but adjusted to match vertex location

Action Items

  • Look at πo cross-section as a function of energy for potential use as normalization reaction (Rory)
  • Get correlation between polarization and energy from Richard (Rory)
  • Update sim-recon version and re-run to confirm Dave's plots (Sascha)
  • Re-run z-vertex scan with vertex constraint off as well as on, but aligned with vertex (David)