Mller Polarimeter Status Update 1 Mller hardware status

Møller Polarimeter Status Update 1. Møller hardware status (detectors and targets) 2. Systematics for SANE 3. Plan 4. Dave Gaskell 5. SANE Collaboration Meeting 6. May 30, 2008

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

Detectors Scintillators refurbished before G 0 Back angle Additional repairs before GEp One dead scintillator on left arm appeared during GEp

Targets Present target configuration optimized for “high current” running 1 -2 m. A At 100 n. A, d. P/P=1% (stats) would take 2. 4 hours on 4 mm target (5. 9 Ge. V) SANE Replace 1 mm foil with 10 mm foil Replace “not accessible” with 20 mm foil and make accessible with new actuator GEp Configuration Kicker test target 4 mm foil 1 mm foil Not accessible

Systematics: G 0 Forward Angle Systematic error budget from G 0 Forward Angle expt. d. P/P = 1. 32% Source Uncertainty d. Asy. /Asy. (%) Beam position x 0. 5 mm 0. 15 Beam position y 0. 5 mm 0. 03 Beam direction x 0. 15 mr 0. 04 Beam direction y 0. 15 mr 0. 04 Q 1 current 2% 0. 10 Q 2 current 1% 0. 07 Q 2 position 1 mm 0. 02 Multiple Scattering 10% 0. 12 Levchuk effect 10% 0. 30 Collimator positions 0. 5 mm 0. 06 Target temperature 50% 0. 05 B-field direction 2 o 0. 06 B-field strength 5% 0. 03 Spin polarization in Fe 0. 25 Leakage 30 n. A 0. 2 High current extrap. 1%/40 u. A 1. 0 Solenoid focusing 100% 0. 1 Elec. DT. 100% 0. 04 Charge measurment 0. 02 Monte Carlo Statistics 0. 28 Unknown accelerator changes 0. 5 Total 1. 32 0. 37

Systematics: SANE Source Uncertainty d. Asy. /Asy. (%) Beam position x 0. 5 mm 0. 15 Beam position y 0. 5 mm 0. 03 Beam direction x 0. 15 mr 0. 04 Beam direction y 0. 15 mr 0. 04 Q 1 current 2% 0. 10 Q 2 current 1% 0. 07 Q 2 position 1 mm 0. 02 Multiple Scattering 10% 0. 12 Levchuk effect 10% 0. 30 Collimator positions 0. 5 mm 0. 06 Target temperature 50% 0. 05 B-field direction 2 o 0. 06 B-field strength 5% 0. 03 1. No “high current extrapolation” 2. Leakage more important d. P/P < 1. 5%? Spin polarization in Fe 0. 25 Leakage 30 n. A 0. 2 High current extrap. 1%/40 u. A 1. 0 Solenoid focusing 100% 0. 1 Elec. DT. 100% 0. 04 Charge measurment 0. 02 Monte Carlo Statistics 0. 28 Unknown accelerator changes 0. 5 Total 1. 32 0. 37

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 Ge. V) 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 Ge. V 1 Me. V shift in beam energy gives 2. 3% change in polarization in Hall SANE? Optimum

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 Q 1 and Q 2 “clean up” backgrounds do not impact acceptance

Collimator Issues At 5. 9 Ge. V, collimators between Q 1/Q 2 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. G 0 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