PREX2AuxiliaryMeasurements

PREX Main

Optics and Q2

1. Energy Measurement (Doug) (non-invasive)
   • Priority High
   • Can be performed Day shift Monday or Tuesday?
   • look for 1e-3 accuracy. Non invasive.
2. Optics Data (Cip) (1-1.5 shifts)
   • requires access to prepare, about 8-10 hrs data, access to backout
   • Sieve in, VDC data. thin Carbon
   • about 500k per run
   • use target lock, about 1 uA
   • no raster
   • Does not (strictly) require counting mode quartz detectors
   1. Beam position dependence Completed. (Got +/- 3mm)
      • shift beam +/- 4mm in horizontal , retake dp = 0 optics
   2. Vertical beam position dependence Completed
      • shift beam +/- 2mm in horizontal , and +/-3mm in vertical.
      • Used both thick and thin C targets due to small thin target size
   3. Target Z comparison Completed
      • use 90 degree Carbon target, Compare y-targ reconstruction to 45 degree carbon target
   4. Retake Optics Data (Cip) (Completed)
      • including dp = 0, +-1% (scale all magnets)
3. Dynamic Thermal-Induced Density Rearrangement (Bob, Chandon, Siyu, Cip) (4 hours)
   • High Priority (unless we can measure significant density variation at low current)
   • requires access to prepare, 3 hrs data + analysis, access to backout
   • Sieve in. S0 on, GEMs on, VDC Off. Production raster.
   • Does not require counting mode in quartz detectors _except_ for actually measuring Q2
   • 1uA
   • Pb10
   • Measure scattering density over target x vs y
   • 70uA
   • Repeat measurement of scattering density over target x vs y
   • If different, do the same on a pristine target
   • Evaluate Q2 (for specific sieve holes?) in each case
4. Cavity vs Striplines (Cip) (~1.5 hrs) summary
   • High Priority
   • measure carbon hole location with 50nA cavity lock and spot++
   • measure carbon hole with 0.5uA tgt lock and spot++
   • show these are the same, within a 1mm or so
5. Final Q2 measurement (Bob, Chandon, Siyu, Dustin) (4 hours?)
   • Priority (?)
   • Repeat of Q2 measurement, with improved pedestal noise control. Requires long (1hr +) access to reduce noisy pedestals
   • Detector counting mode.
   • S0 trigger
   • Lead target
   • production raster and beam position
   • Use cavity lock, low current
6. VDC/GEM Rate study (Bob, Chandon, Siyu)
   • Completed (awaiting results)
   • Requires access, 3 hrs data, access to back out
   • Detector counting mode.
   • S0 trigger
   • Lead target
   • production raster and beam position
   • Use cavity lock, low current
   • start at low S0 rate (50kHz?) and go up in rate to 500 kHz, in several steps (50, 100, 200, 500 kHz)
   • turn off VDC, continue up to 2MHz rates in GEMs (1MHz, 2MHz)
   • Compare Q2 measurements at each rate from GEMS and VDC to look for rate dependence
7. Q2 from damaged target (Bob)
   • Completed (awaiting results)
   • measure Q2 from most damaged target (Pb10?)
   • compare to Q2 from pristine target
   • If these are different - we need a plan to correct for damage or measure all used targets
   • can be combined with previous study, add 1 hr for target move and measurement

Backgrounds

1. Stubby Quartz / Blinded Quartz (Dustin) (4 hours?)
   • Very High priority. Wednesday Swing? Thursday Day?
   • 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 (Bob, Cip?) (~1 shift)
   • High Priority
   • 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 leg to get higher gain (is 10x possible?)
   • should scale all spectrometer magnets _except_ Q3.
3. Thin Lead Target to check for inelastics at high-resolution (Bob) (~1.5 hour, including setup/backout)
   • Medium Priority Do if we can.
   • valuable illustration and cross-check for presentation/publication
   • Does NOT require detector counting mode - could be done anytime with low current running
4. Pole tip re-scattering (Bob, Cip?)
   • 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
5. A_T detectors (Dustin)
   • Significant asymmetries found in A_T detectors, requires investigation and planning
6. Thin C12 to measure diamond background spectrum? (Bob)
   • All our optics data was taken with this, so presumably we have enough for this measurement already
7. Thick C12 to measure diamond background fraction? (nope - priority none)
   • I'm unclear on the value of this, since we are not set up terribly well for yields at very different rates, the radiation is so different, and I don't know how accurately the targets are known.

Detectors

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

Other

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 2x/week. Goal: 1-1.5 shifts per measurement.
   • need enough granularity to track changing polarization.
2. IHWP IN/OUT
3. Copper false/asymmetry
4. Target uniformity

Compton polarimetry

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