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Present: M.D., A.D., S.Š, J.S.

General: The report from the GlueX review is now available.

  • Our own list of points to clarify re. the proposal, based on meeting with Garth and Frank:
    • Change (M. Dalton):
      • "Primary goal" to "Early goal" (meaning what we can learn with an easy analysis)
      • "Secondary goal" to "longer term goal" (meaning it involves a more complicated analysis)
    • Clarify that the proton GDH running integral has overshot the sum rule predictions and while the missing part is expected to be negative from Regge, the evidence for that from ELSA data is anecdotal. (M. Dalton)
    • Add the running integral plot to the proposal (make the running integral for the neutron), with the LEGS data included. Specify that this is all the data available so far. (M. Dalton)
    • Clarify that our simulated prediction of the proposed measurement were obtained using the best Regge estimate available. It was unclear to Garth and Frank what was in the simulated data. (M. Dalton)
    • Instead, or in addition, to Fig. 1, use the PDG figure that show the pomeron-related increase of the unpolarized cross-section. (M. Dalton)
    • The illustration based on Fig. 1 on what we would have missed (the divergence of the unpolarized integral) if unpolarized data stopped at 2.9 GeV seems to not have been clear to Garth and Frank. (M. Dalton)
    • Clarify and extend the discussion on the 25% improvement of accuracy for the verification on the proton GDH sum rule. (A. Deur)
    • Illustration of what we could learn about quark substructure:
      • Make it more prominent in the introduction.
      • Mention it in the conclusion
      • Instead (or in addition) of assuming that we will find that the sum rule is valid, and computing the compositeness limit within this assumption, discuss what we would learn on quark compositeness if the sum rule is violated by, say, 3σ. (A. Deur)
    • Remove in details on HDice. (Just say we are using FROST, unless a bigger program warrant the use of HDice) (A. Deur)
    • Clarify that the 3 PS settings are different from the (unique) tagger setting. (M. Dalton)
    • Clarify the XEFT part (Garth thought we were directly measuring the Forward Compton reaction). (Simon Širca)

  • M.D.:
    • Started rewriting the proposal.
    • Worked with Lubomir on (unpolarized) BH event generator. Good progress. Now can reproduce the CLAS BH generator.
    • Still need to implement the POLARIZED BH event generator from Simon.
    • Need to stress that verifying the SR on the neutron is as important as the proton.
  • S.Š:
    • Got neutron data sets for p and n from MAMI and ELSA.
    • Will look into a better g1 parameterization in the resonance region and will stitch resonance to DIS using Fermi-Dirac.
    • Will re-involve David Florjancic in BH/Compton event generator.

  • A.D.:
    • Checked feasibility of low energy run with Eugene, Jay and Todd Satogata. Possible, but if E<6 GeV, the beam set-up will be longer and more difficult due to the not well-known field of the beamline magnet when operated below 50% of their nominal current. Need to update the proposal with a more detailed 4-6 GeV section, including possible difficulties.
    • Wrote to Steven Bass regarding quark compositeness.
    • Got Feedback from Steven Bass regarding the proposal. Implemented his suggestions (discussion on fixed pole still to be added).
    • Ran simple simulation to see what we could achieve with a 1 week run at 4 GeV (3.5 days on D, 1 day D->H switch, 2.5 days on H).
      • Plots: [proton], [neutron], [deuteron]
    • In proposal section 8.7 Removed mention of the 7 GeV scale for the quark running mass.
    • Looked up possible CLAS data on GDH and updated the proposal with them. Bottomline:
      • GDH data for specific channels only.
      • Up to 3.1 GeV for pi+pi- and 2.5 for pion photoprodction.
      • Only for proton
      • Rates was limited to 4 kHz.