PREX2AuxiliaryMeasurements

PREX Main

Optics and Q2

1. Energy Measurement (Bob, talk to Doug)
   • look for 1e-3 accuracy. Non invasive?
2. VDC/GEM Rate study
   • Do this first! Wednesday?
   • 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
3. Optics Data
   • Sieve in, VDC data. thin Carbon
   • about 500k per run
   • use target lock, about 1 uA
   1. Retake Optics including dp = 0, +-1% (scale all magnets)
   2. shift beam +/- 4mm in horizontal , retake dp = 0 optics
   3. use 90 degree Carbon target
4. Cavity vs Striplines
   • 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. Q2 from damaged target
   • 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
6. Dynamic Thermal-Induced Density Rearrangement
   • Sieve in. S0 on, GEMs on, VDC Off. Production raster.
   • 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 each case

Backgrounds

1. Thin Lead Target to check for inelastics at high-resolution
   • Previously done with different kinematics. could be repeated.
2. Thin C12 to measure diamond background spectrum?
3. Thick C12 to measure diamond background fraction?
4. A_T detectors (Bob) Significant asymmetries found in A_T detectors, requires investigation
5. Pole tip re-scattering Q2 or septum mis-tune, to increase interception on pole tip and improve poletip rescattering estimate
6. Stubby Quartz (Dustin)
   • Replace detector quartz with superelastic stub
   • Integrating measurement
7. Blank PMT (Dustin)
   • Integrating measurement
   • only if stubby quartz shows something
8. Rescattering measurement
   • repeat of previous measurements. Roughly 1 shift
   • 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.

Detectors

1. Linearity Studies (PITA + current scans) --
2. Linearity Studies (LED) --

Moller polarimetry

1. Repeat measurements - need enough granularity to track changing polarization. at least 2x/week = 6 measurements

Compton polarimetry

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