BLTWG Meeting 04/28/2020

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  • Time: 1:30 EDT
  • JLab meeting room: CEBAF Center F324-325
  • Connecting: detailed instructions are here
  • Conference id: 536076821
  • Present: Richard J., Mark D., Sasha S., Justin S., Hovanes E., Ken L., Dan S., Elton S., Beni Z., Alexander A., Alexandre D.


  1. Announcements
  2. Polarimetry
    • TPOL polarimetry update
    • Polarimetry from hadron decays
  3. Offline analysis
    • changes in TAGM calibration constants
    • coordinated updates to ccdb for 2020 spring run
  4. NIM paper figure on e-beam convergence
  5. Photon beam systematics studies
    • variation in collimator transmission
    • energy-dependent beam profile from fast raster
    • tagging accidentals scan analysis
      • using only 2 side bunches rather than 12 gives the same result (for accidental scaling factors) up to minor changes, however, the large discrepancy between microscope and hodoscope (1.05 vs. 1.1) persists in the spring 19 data for PrimeX. There is also a noticeable difference (2-3%) between hodoscope above and below the microscope and both are significantly larger than the microscope values.This is NOT seen in the fall18 and fall19 data sets. Note, this is done using events with PS data.
    • other beam flux systematics
  6. Presentations at May Collaboration Meeting (new organizational structure -- see Tuesday morning)
    1. beam-related issues confronted by analysis groups
      • Accidental scaling factors and followup on high intensity runs this past Spring
      • Status of flux systematics: overall normalization, energy dependence, etc.
      • Status of polarization systematics: converter thickness comparisons, etc.
    2. other topics?
  7. Any other business