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CREX Main << CREX Run Plan


  1. Please don't worry if there is a needless test on here, or an important one missing, or bad prioritization.
  2. Lets fix it

Optics and Q2

  1. Energy Measurement (Doug) (non-invasive)
    • Priority High
    • look for 1e-3 accuracy. Non invasive.
  2. Q2 measurement
    • Repeat of Q2 measurement, with improved pedestal noise control.
    • Detector counting mode.
    • S0 trigger
    • production raster and beam position
  3. Optics Data
    • retake watercell,
    • retake optimization data
    • inelastic spectrum data


  1. Stubby Quartz / Blinded Quartz?
    • Longish access to setup and back out, but short data taking period (production conditions).
    • Replace detector quartz with superelastic stub or blinding cap (alternate US/DS and L/R)
    • Integrating measurement. Could normalize increased gain just by lowering beam current in production condition.
    • If surprising results found, continue test or plan second test
  2. Rescattering measurement (~1 shift)
    • Detailed Rescattering Runplan
    • perhaps plan for late april?
    • repeat of previous measurements, but new optics and a crucial cross-check
    • Detune spectrometer up in momentum, to dump elastic peak into spectrometer wall.
    • Measure (integrating mode) signal in main detectors. Requires HV boot-strap to get higher gain (is 10x possible?)
    • should scale all spectrometer magnets.
    • At each dipole setting, also take data with nominal septum
    • Once the elastic peak is out of the focal plane, it should be possible turn on the S3 and S0 scintillator. This should be done when possible, and the T1/T2/T3 trigger rate recorded for each run.
  3. Pole tip re-scattering
    • Requires investigation or planning - do we have an idea here?
    • Q2 or septum mis-tune, to increase interception on pole tip and improve poletip rescattering estimate
  4. A_T detectors
    • Do we want to blind them again?


  1. Linearity Studies (PITA + current scans) (Caryn)
    • These are ongoing - should continue regularly. ~ 1 hour every 3 days.
  2. Linearity LED tests
    • This will be studied off line


  1. Sign check
    • run Moller, Compton, and parity DAQ for quick PITA scan
    • Have we already done this? Parasitic with any PITA scan

Moller polarimetry

  1. Repeat measurements
    • about ~30-60C. Goal: 1-1.5 shifts per measurement.
  2. Q2 scan?
  3. deadtime scan?
  4. target position scan?

Compton polarimetry

  1. No-target runs
  2. Laser polarization optimization
  3. Laser polarization flip
  4. linearity studies