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Minutes of the 09/17/2019 HD-GDH meeting

Present: E. Chudakov, A. Deur, S. Sirca, J. Stevens.

  • Remainder: If we want to be submit to the next PAC a GlueX collaboration proposal, we need a proposal in decent shape to submit to the GlueX collaboration by mid-February. Two points to keep in mind:
    • Only the technical parts need to be worked on. The physics motivations are probably good enough and can be refined after mid-February. We should focus on the technical aspects for now.
    • JLab manpower will be available up to thanksgiving. After that, the run starts until April 2019 and that will consume most of the Hall D staff time.
  • Alexandre discussed the list of tasks to do, to be given below.
  • Justin discussed a strategy for the simulation and what needs to be simulated, see the document
  • The strategy for the simulation would be that M. Dalton first set-up the simulation and later he and Simon's student work on the various questions the simulation should answer.
  • We discussed the necessity to have the drift chambers on (both on, FDC/CDC on only, none on?). Unless the rate is unacceptable for the DC or that the event size is hurting us, it seems beneficial to have the DC on, given that
    • The solenoid magnetic field need to be on for the target
    • DC are useful for background subtraction (in particular possible leptonic events from polarized e- in the target)
    • Identifying individual channels in addition to measuring the total cross-section may be useful data.
    • We won't add to much to the aging of the DC (short experiment)
  • List of tasks to do. Primary responsible (secondary responsible):
    • Set-up a wiki page for the experiment. A. Deur
    • electron beam helicity reporting and charge asymmetry control for Hall D. M. Dalton (A. Deur)
    • Should we have a beam hardener? How to design it? A. Deur
    • Refined photon flux and rate estimates. J. Stevens.
    • Simulation and background, detector setup and trigger optimization. M. Dalton, S. Sirca, J. Stevens:
      • Should drift chambers be on (FDC?, CDC?)
      • Need to understand the nu-dependent efficiency of the detectors (tagger)
      • Need to understand the global efficiency of the detectors, for absolute cross-section determination
      • Does the nu-dependent background creates a sizable nu-dependent detector inefficiency?
      • There are possible helicity dependent backgrounds we need to consider:
        • electrons should be highly polarized in the FROST target. This will create a polarized Compton background. We need to estimate the Compton rate. A. Deur will look into the electron polarization and Compton asymmetry.
        • Do the nuclei other than free protons get polarized in a FROST target? If so, we will have a small polarized hadronic background.
      • We will have a azimuthally and polar dependence of the asymmetry. Furthermore the raw asymmetry depends on nu (physics+photon beam polarization nu-dependence). If the detectors have significant localized inefficiencies, then it would generate nu-dependent inefficiencies.Study the possible polarized backgrounds, see previous item. A. Deur
  • Study the possible polarized backgrounds, see previous item. A. Deur
  • Possibility and benefits of a lower (9 GeV) run. Alternative: instrument a small nu-tagger. A. Deur
  • Refine some of the physics motivation:

Hyperfine splitting of muonic hydrogen: S. Sirca DIS -> diffractive physics transition: A. Deur Constraint on quark compositeness: A. Deur

  • Next meeting will be Monday Oct. 7th, 8am (JLab time) in room A110.