Parity Violating Neutron Densities Z 0 of Weak

Parity Violating Neutron Densities Z 0 of Weak Interaction : Clean Probe Couples Mainly to Neutrons ( T. W. Donnelly, J. Dubach, I Sick ) 2 Low Q elastic nucleus scattering In PWIA -- but must account for Coulomb distortions (C. J. Horowitz) PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Parity Violating Asymmetry 2 + Applications : • Nucleon Structure (strangeness) • Nuclear Structure (neutron density) • Standard Model tests ( PN 12 Workshop JLab, Nov 2004 ) R. Michaels Jefferson Lab

0 Z sees the neutrons proton neutron Electric charge 1 0 Weak charge 0. 08 1 PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

PREX in Hall A at JLab Lead Foil Target Polarized e. Source Hall A PN 12 Workshop JLab, Nov 2004 Pol. Source Hall A CEBAF R. Michaels Jefferson Lab

Physics Impact of Lead Parity Measured Asymmetry Correct for Coulomb Distortions Weak Density at one Q 2 Mean Field & Other Models Small Corrections for Atomic Parity Violation G n E s GE MEC 2 Neutron Density at one Q Assume Surface Thickness Good to 25% (MFT) Neutron Stars Rn PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

R. J. Furnstahl ) protons & neutrons R. Michaels Jefferson Lab

Pb Parity : Neutron Stars ( C. J. Horowitz, J. Piekarweicz ) R n calibrates EOS of Neutron Rich Matter Crust Thickness Explain Obs. Glitches in Pulsar Frequency ? Combine R n with Neutron Star Radius Exotic Core ? (strange matter, quark star) Some Neutron Stars too Cold Crab Pulsar ( from hubblesite. org ) PN 12 Workshop JLab, Nov 2004 Cooling by neutrino emission (URCA) 0. 2 fm URCA probable, else not R. Michaels Jefferson Lab

Optimum Kinematics for Lead Parity: <A> = 0. 5 ppm. E = 850 Me. V, Accuracy in Asy 3% 1 month run 1% in Rn PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

High Resolution Spectrometers Spectrometer Concept: Resolve Elastic detector Inelastic Quad target Dipole PN 12 Workshop JLab, Nov 2004 Q Q R. Michaels Jefferson Lab

Septum Magnets (INFN) • Superconducting magnets • Commissioned 2003 -4 Electrons scattered at 6 deg sent to the HRS at 12. 5 deg. PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Integrating Detection • Integrate in 30 msec helicity period. • Deadtime free. -4 • 18 bit ADC with < 10 • But must separate backgrounds & inelastics ( PMT tron HRS). Integrator Calorimeter (for lead, fits in palm of hand) elec nonlinearity. ADC s PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Lead Target 208 Pb Liquid Helium Coolant 12 beam C Diamond Backing: • High Thermal Conductivity • Negligible Systematics m red e rast , m Bea PN 12 Workshop JLab, Nov 2004 m 4 x 4 R. Michaels Jefferson Lab

Polarized Electron Source Laser Ga. As Crystal Gun Pockel Cell flips helicity Halfwave plate (retractable, reverses helicity) e - beam • Rapid, random helicity reversal • Electrical isolation from rest of lab • Feedback on Intensity Asymmetry PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Beam Asymmetries Araw = Adet - AQ + E+ i xi Slopes from PN 12 Workshop JLab, Nov 2004 • natural beam jitter (regression) • beam modulation (dithering) R. Michaels Jefferson Lab

Helicity Correlated Differences: Position, Angle, Energy “Energy” BPM Scale +/- 100 nm BPM Y 2 Position Diffs avg ~ 10 nm BPM Y 1 Negligible Systematic Error BPM X 1 BPM X 2 PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Polarimetry Møller: d. Pe/Pe ~ 3 % (foil polarization) Compton: 2% syst. At present 2 analyses based on either electron or photon detection Electron only Photon only Superlattice: Pe=86% ! PN 12 Workshop JLab, Nov 2004 Preliminary: 2. 5% syst (g only) R. Michaels Jefferson Lab

Upgrade of Compton Polarimeter (Nanda, Lhuillier) To reach 1% accuracy: • Green Laser • Integrating Method PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Summary -- Neutron Skin • R n is Fundamental to Nuclear Physics • HAPPEX program to demonstrate most technical aspects • Polarimetry Upgrade needed • Planned 2 -day test run in 2005 PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

extra slides -- PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Moller Polarimetry with Atomic Hydrogen Target ( E. Chudakov, V. Luppov) H atoms Ultra Cold Traps • Polarization ~ 100% • Density Solenoid 8 T • Lifetime > 10 min Polarimetry beam Trap • 1% stat. err. in 30 min at 30 A • Low background • High beam currents allowed (100 A) • Goal: ~ 0. 5 % systematic error PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

Polarized Source High Pe High Q. E. Low Apower • Optical pumping of solid-state photocathode • High Polarization controls effective analyzing power Intensity Attenuator PN 12 Workshop JLab, Nov 2004 Slow helicity reversal Tune residual linear pol. • Pockels cell allows rapid helicity flip • Careful configuration to reduce beam asymmetries. • Slow helicity reversal to further cancel beam asymmetries R. Michaels Jefferson Lab

Beam Modulation to Calibrate Sensitivity to Beam Systematics PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab

PITA Effect Polarization Induced Transport Asymmetry Intensity Asymmetry Laser at Pol. Source where Transport Asymmetry drifts, but slope is ~ stable. Feedback on PN 12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab