Møller Polarimeter Status Update 1.Møller hardware status (detectors and targets) 2.Systematics for SANE 3.Plan Dave Gaskell SANE Collaboration Meeting May 30, 2008

Hall C Møller Polarimeter Superconducting solenoid  Brute force out of plane magnetization Scintillators  set “tune” Calorimeter  measurement

Detectors One dead scintillator on left arm appeared during GEp Scintillators refurbished before G0 Back angle  Additional repairs before GEp

Targets Present target configuration optimized for “high current” running  1-2  A At 100 nA, dP/P=1% (stats) would take 2.4 hours on 4  m target (5.9 GeV) SANE  Replace 1  m foil with 10  m foil  Replace “not accessible” with 20  m foil and make accessible with new actuator Kicker test target 4  m foil 1  m foil Not accessible GEp Configuration

Systematics: G0 Forward Angle SourceUncertaintydAsy./Asy. (%) Beam position x0.5 mm0.15 Beam position y0.5 mm0.03 Beam direction x0.15 mr0.04 Beam direction y0.15 mr0.04 Q1 current2%0.10 Q2 current1%0.07 Q2 position1 mm0.02 Multiple Scattering10%0.12 Levchuk effect10%0.30 Collimator positions0.5 mm0.06 Target temperature50%0.05 B-field direction2o2o B-field strength5%0.03 Spin polarization in Fe0.25 Leakage30 nA0.2 High current extrap.1%/40 uA1.0 Solenoid focusing100%0.1 Elec. DT.100%0.04 Charge measurment0.02 Monte Carlo Statistics0.28 Unknown accelerator changes 0.5 Total1.32 Systematic error budget from G0 Forward Angle expt. dP/P = 1.32%

Systematics: SANE SourceUncertaintydAsy./Asy. (%) Beam position x0.5 mm0.15 Beam position y0.5 mm0.03 Beam direction x0.15 mr0.04 Beam direction y0.15 mr0.04 Q1 current2%0.10 Q2 current1%0.07 Q2 position1 mm0.02 Multiple Scattering10%0.12 Levchuk effect10%0.30 Collimator positions0.5 mm0.06 Target temperature50%0.05 B-field direction2o2o B-field strength5%0.03 Spin polarization in Fe0.25 Leakage30 nA0.2 High current extrap.1%/40 uA1.0 Solenoid focusing100%0.1 Elec. DT.100%0.04 Charge measurment0.02 Monte Carlo Statistics0.28 Unknown accelerator changes 0.5 Total No “high current extrapolation” 2.Leakage more important dP/P < 1.5%?

Systematics: SANE It is unlikely Wien will be set for maximum polarization to Hall C during SANE At 5 pass and high energy (5.9 GeV) small changes in the beam energy can impact the polarization in the Hall Example: Wien set for 80% of maximum in Hall C at 5.9 GeV  1 MeV shift in beam energy gives 2.3% change in polarization in Hall Optimum SANE?

Hall C Møller during GEp Some hint of dependence of polarization on QE!

Collimator Issues General philosophy: Let collimators in front of detectors determine acceptance Collimators between Q1 and Q2 “clean up” backgrounds  do not impact acceptance

Collimator Issues At 5.9 GeV, collimators between Q1/Q2 come close to impinging on acceptance Collimators 6&7 can collide – may cause reproducibility problems

Møller Measurement Plan Measurements desired every 2-3 days Two options: 1.RSS-style general procedure that anyone on shift can follow  Can make measurements anytime – whenever convenient  Results may be a little less reliable 2.G0 Forward-style: “small” group makes all measurements (“small”= at least 5-6 people)  Measurements need to be scheduled  More reliable polarization measurements  smaller systematic errors