July 31, 2015 PID Upgrade

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Meeting Information

GlueX PID Upgrade Meeting
Friday, July 31, 2015
11 am, EDT
For those people at Jefferson Lab, the meeting will be in room F326

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  1. Announcements
    • Roman visiting JLab next week: meeting Monday 8/2 at 2 pm
    • Ardavan (Hamamatsu Rep) visiting JLab: meeting Tuesday 8/12 at 11 am
  2. Simulation update (Roman)
  3. Focusing optics and mirror status (John)
  4. Mechanical structure and shipping crate (Matt)
  5. Readout (Justin)
  6. Planning for October review (All)
  7. AOB


Attending: JLab: Eugene and Justin, CMU: Curtis, MIT: Mike, GSI: Roman, Joe, and Carsten

  1. Announcements
    • Roman visiting JLab next week: meeting Monday 8/2 at 2 pm
      • During Roman's visit we will discuss Roman's simulations and integrating reconstruction into the GlueX framework.
    • Ardavan (Hamamatsu Rep) visiting JLab: meeting Tuesday 8/12 at 11 am in B101
      • Please let Justin know if you're interested in meeting with Ardavan while he's at JLab.
  2. Simulation update (Roman)
    • angle scan for monochromatic cherenkov
    • angle scan for small expansion volume
    • angle-mirror scan
      • Using monochromatic photons in the simulation Roman pointed out the kaleidoscopic effect in some regions, which is typically smeared out by the chromatic spread of the photons. With a different geometry Roman showed some hit patterns in a split focusing box with 2 smaller expansion volumes, which can be compared via the reconstruction algorithm to the single focusing box. The 3rd link scans the angle of the incoming particles with the mirror angle where you can see regions near the focusing box aren't necessarily optimized.
  3. Focusing optics and mirror status (John)
    • Mike described John's studies of the glass and aluminum mirrors since John was traveling today:
    • The expected reflectivity for the glass mirrors are only provided at an angle of 0 degrees. John made measurements at 14 and 45 degrees and found that the measured reflectivities match the expected values in the visible range. For smaller wavelengths the measured values are consistent with improved reflectivities at larger angles than those provided by the manufacturer. There is a strange feature at 305 nm which is still being understood.
    • The aluminum mirrors had low reflectivity which may be expected since they did not have the final coating layer applied (the coating layer will be applied next week)
    • For the dispersion measurement John setup the optics to have a pathlength of 64 cm, which is similar to the pathlength of photons in the DIRC.
      • The image using the polished aluminum is much better than required to fit within the pixel size of 6x6 mm, so the dispersion is much better than we require
      • The image using the glass was a bit worse, but still fits well within the pixel. John will make a more precise measurement in 2 weeks
    • Summary: The glass option is preferred as it provides better reflectivity, meets the spec for dispersion, and can be done entirely in house
    • Eugene was surprised by the low reflectivity of the aluminum, but maybe a dielectric is needed as well. Also didn't think coating should do much for reflectivity. Also coating usually needs to be done before the aluminum oxidizes to be most effective.
  4. Mechanical structure and shipping crate (Matt)
    • Justin will meet with Tom and Tim in the Hall at 9 am on Monday, to see what space constraints there are in there and where the bar boxes could be stored there at some point.
  5. Readout (Justin)
    • Justin is looking into magnetic shielding options, and Eugene will provide a more accurate field map in that region from his Poisson calculations.
  6. Planning for October review (All)
    • We discussed when complete versions of the TDR could be completed, but didn't reach a conclusion since not everyone was online. Justin put a proposed timeline for updated TDR deadlines on the review webpage, with the goal of having complete sections due on 8/14. The review is now 10 weeks away, so we need completed sections soon to have time for internal review.
  7. AOB
    • Justin mentioned that he received feedback from Jerry Va'vra that cosmic test setup at SLAC could be available to test our prototype, but would require substantial resources, a formal agreement with SLAC management, and some substantial time spent at SLAC (at least ~3 months) to setup and run the cosmic ray telescope. Jerry's suggestion was to consider setting up something equivalent at JLab.