Mller Polarimeter Status Update 1 Mller hardware status
- Slides: 11
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