Beam Requirements for PVDIS

1
Beam Requirements for PVDIS
Property Value Run-Avg Hel. Correl. 1-Day Hel. Correl.
Energy 6 and 4.8 GeV dE/E lt 1 ppm lt 5 ppm
Current 100 uA 1 ppm 5 ppm
Position 0 (normal tolerance) 50 nm 250 nm
Angles 0 (normal tolerance) 50 nrad 250 nrad
Transv. Beam Polarization 0 Vert lt 20 Horiz. lt 120 ? same
X or Y
X or Y
Explain another time
2
HAPPEX-3 Fall 2009
Energy ?
150 nm
Diffs helicity-correlated diffs in microns.
0.005 um 5 nm
1 slug 1 period of half-wave plate state
24 hours
Sign corrected put in a sign flip
correlated to half-wave plate, to show the
effect of HCBA on combined sample.
3
Parity Quality Beam good enough for
PVDIS
Big asymmetries, small derivatives wrt beam
parameters
Marginal for PREX ( especially BPM12x
Energy )

• Interception at Injector ?
• Some reductions in diffs after work
  done at injector
• e.g. after Sept 15 and Oct 15
  work
• Largest Component of diffs flips sign with
  half-wave plate
• Could be a Pockel Cell steering
  effect
• Could be electronics pickup from
  Pockel Cell

? Seems ruled out by PC-off runs.
? Speculative hypothesis on next slide.
4

• Speculative Cause of BPM12x (Energy)
  diffs
• Electronics pickup from Pockel Cell ?
• Very small, but amplified somehow
  when slits closed
• Improved injector tune in last week
  seemed to fix it.

(K. Kumar)
? Can affect the beam, as during Happex-He.
? Turns into an Energy diff.

• Strategy
• Watch the slug plots during PVDIS
• If not good enough, may revisit
  pickup issue injector transmission
  issue if PVDIS allows or requires.

5
PVDIS Run Plan

• Down time Oct 28 Nov 4 ?
• Swap detectors, cabling work,
  target work
• Commissioning Nov 4 7
• Establish good detectors, target
  boiling tests, Compton tests, Parity
  quality beam, BCM
  calibration, PVDIS DAQ.
• Production to Dec 23

Take data on LD2 Periodic Auxiliary
Measurements Compton Issues
Moller, Q2 , Backgrounds
Transverse Polarization Test Run (2
shifts, Invasive !)
Explain next week
Backgrounds