R. Michaels, Jlab Seminar, Apr 27, 2011 Lead ( Pb) Radius Experiment : PREX 208 208 Pb E = 1 GeV, electrons on lead Elastic Scattering Parity Violating.

Slides:



Advertisements
Similar presentations
PREX PAC 29 Jan 2006 R. Michaels Jefferson Lab Lead ( Pb) Radius Experiment : PREX Z of Weak Interaction : Clean Probe Couples Mainly to Neutrons ( T.W.
Advertisements

R. Michaels PREX at HE06 July 2006 Lead ( Pb) Radius Experiment : PREX Z of Weak Interaction : Clean Probe Couples Mainly to Neutrons ( T.W. Donnelly,
R. Michaels, Jlab Argonne Dec 19, 2011 Lead ( Pb) Radius Experiment : PREX Pb E = 1 GeV, electrons on lead Elastic Scattering Parity.
Lead ( Pb) Radius Experiment : PREX
R. Michaels, Jlab UGM, June, 2011 Lead ( Pb) Radius Experiment : PREX Pb E = 1 GeV, electrons on lead Elastic Scattering Parity Violating Asymmetry.
Lead ( Pb) Radius Experiment : PREX
Robert Michaels PREX at Trento PREX Workshop 09 Physics Interpretation of PREX 208 Pb E = 1 GeV, electrons on lead Elastic Scattering Parity Violating.
Thomas Jefferson National Accelerator Facility
R. Michaels, Jlab TAMU Mar 6, 2012 Electron Scattering at Jefferson Lab and The Lead Radius Experiment PREX Thomas Jefferson National Accelerator.
Thomas Jefferson National Accelerator Facility
Robert J. Feuerbach Jefferson Lab Constructed from contributions from the HAPPEX Collaboration Hall A Collaboration Meeting December 5, 2005 HAPPEX-II.
Robert Michaels HAMC Hall A Analysis Workshop 09 C HAMC = Hall A Monte Carlo ROOT / C++ Design Somewhat like SAMC & genercone For HRS only. Uses LeRose.
Lead ( 208 Pb) Radius Experiment : PREX E = 1 GeV, Elastic Scattering Parity-Violating Asymmetry PREX : precise measurement of the density -dependence.
Lead ( 208 Pb) Radius Experiment : PREX E = 1 GeV, Elastic Scattering Parity-Violating Asymmetry PREX : density -dependence of the symmetry energy. Nuclear.
Measuring the Neutron and 3 He Spin Structure at Low Q 2 Vincent Sulkosky for the JLab Hall A Collaboration College of William and Mary, Williamsburg VA.
Lead ( Pb) Radius Experiment : PREX Pb E = 1 GeV, electrons on lead Elastic Scattering Parity Violating Asymmetry Spokespersons Paul Souder Krishna.
Compton polarimetry for EIC Jefferson Lab Compton Polarimeters.
1 Electron Beam Polarimetry for EIC/eRHIC W. Lorenzon (Michigan) Introduction Polarimetry at HERA Lessons learned from HERA Polarimetry at EIC.
The neutron radius of 208 Pb and neutron star structure. guitar nebula, neutron star bow wave.
Noise Analysis for PREx - Pb Radius Experiment Presented by: Luis Mercado UMass - Amherst 6/20/2008.
Parity Violation in Electron Scattering Emlyn Hughes SLAC DOE Review June 2, 2004 *SLAC E122 *SLAC E158 *FUTURE.
PN12 Workshop JLab, Nov 2004 R. Michaels Jefferson Lab Parity Violating Neutron Densities Z of Weak Interaction : Clean Probe Couples Mainly to Neutrons.
PREX PAVI06 May 2006 R. Michaels Jefferson Lab Lead ( Pb) Radius Experiment : PREX Z of Weak Interaction : Clean Probe Couples Mainly to Neutrons ( T.W.
LEDA / Lepton Scattering on Hadrons Hypernuclear Spectroscopy: 12 C and 16 O, 9 Be(preliminary) high quality data available. First publication soon. Extension.
Polarimetry of Proton Beams at RHIC A.Bazilevsky Summer Students Lectures June 17, 2010.
Collimator June 1-19, 2015HUGS The collimator is placed about 85 cm from the target and intercepts scattered electrons from 0.78° to 3.8° Water cooled.
Opportunities for Precision Measurements, New Physics Searches & Low Energy Fixed Target Expts at a Modified “FEL” Accelerator Complex R. D. Carlini 12/7/2011.
A U.S. Department of Energy Office of Science Laboratory Operated by The University of Chicago Argonne National Laboratory Office of Science U.S. Department.
A study of systematic uncertainties of Compton e-detector at JLab, Hall C and its cross calibration against Moller polarimeter APS April Meeting 2014 Amrendra.
Z coll =590cm z targ,up =-75cm z targ,center =0cm z targ,down =75cm θ low =5.5mrad θ high =17mrad R inner =3.658cm R outer =11.306cm From center:From downstream:
Compton polarimetry for EIC Jefferson Lab Compton Polarimeters.
Neutral pion photoproduction and neutron radii Dan Watts, Claire Tarbert University of Edinburgh Crystal Ball and A2 collaboration at MAMI Eurotag Meeting.
Pb Electroweak Asymmetry in Elastic Electron-Nucleus Scattering -- Weak charge form factor -- most weak charge is carried by neutrons PREX and.
1/33CREX Workshop Jefferson Lab March 16-19, 2013 NASA/CXC/SAO.
PVDIS at JLab 6 GeV Robert Michaels Jefferson Lab On Behalf of the HAPPEX Collaboration Acknowledgement: Talk prepared by Kai Pan (MIT graduate student)
Pb Electroweak Asymmetry in Elastic Electron-Nucleus Scattering : A measure of the neutron distribution PREX and CREX 48 Ca Neutron Skin Horowitz.
May 17, 2006Sebastian Baunack, PAVI06 The Parity Violation A4 Experiment at forward and backward angles Strange Form Factors The Mainz A4 Experiment Result.
Measuring the charged pion polarizability in the  →    −  reaction David Lawrence, JLab Rory Miskimen, UMass, Amherst Elton Smith, JLab.
Electromagnetic probes MAMI, Jefferson Lab & MAX-Lab Daniel Watts University of Edinburgh.
Lecture 9: Inelastic Scattering and Excited States 2/10/2003 Inelastic scattering refers to the process in which energy is transferred to the target,
Proton Charge Form Factor Measurement E. Cisbani INFN Rome – Sanità Group and Italian National Institute of Health 113/Oct/2011E. Cisbani / Proton FF.
SLAC, September 25, 2009 Searching for a U -boson with a positron beam Bogdan Wojtsekhowski Thomas Jefferson National Accelerator Facility  The light.
Compton polarimetry for EIC. Outline Polarized electron beam Compton process Compton polarimeters at Jefferson Laboratory – Parity experiments at Jlab.
Coulomb distortions in the Lead Radius Experiment (PREX) Tim Cooper (Univ. College Fraser Valley) C. J. Horowitz (Indiana)
PREX Issues. Outline New issue: souce systematics and Aug. 07 run. Update on old issues. Progress at SU.
Crystal Ball Collaboration Meeting, Basel, October 2006 Claire Tarbert, Univeristy of Edinburgh Coherent  0 Photoproduction on Nuclei Claire Tarbert,
R. Michaels PREX at PAVI 09 Lead ( Pb) Radius Experiment : PREX Pb E = 1 GeV, electrons on lead Elastic Scattering Parity Violating Asymmetry Spokespersons.
DIS-Parity: Measuring sin 2 θ W with Parity Violation in Deep Inelastic Scattering using Baseline Spectrometers at JLab 12 GeV Paul E. Reimer.
Recent Results in Parity-Violating Electron Scattering at Jefferson Lab: PREX and HAPPEX-III Kent Paschke APS Spring Meeting Anaheim, CA May 1, 2011 HAPPEX.
Thomas Jefferson National Accelerator Facility Operated by the Southeastern Universities Research Association for the U.S. Depart. Of Energy The Department.
Hall A Collab. Mtg, 6/ 2010R. Michaels, JLAB Lead ( 208 Pb) Radius Experiment : PREX E = 1 GeV, Elastic Scattering Parity-Violating Asymmetry PREX : precise.
Pb-Parity and Septum Update Presented by: Luis Mercado UMass - Amherst 12/05/2008 Thanks to Robert Michaels, Kent Pachke, Krishna Kumar, Dustin McNulty.
In the SM to the first order x: variable relevant to the nucleon internal structure Q 2 : Four-momentum transfer squared between the electron and the target.
PV Electron Scattering
Polarized Injector Update
Radiative Corrections to PREX and QWEAK
Parity Violation Experiments & Beam Requirements
Sanghwa Park (Stony Brook) for the PREX/CREX Collaboration
Thomas Jefferson National Accelerator Facility
Parity Violation Experiments at JLEIC
Noise Analysis for PREx - Pb Radius Experiment
Accelerator Issues Raised in Hall A Parity Collaboration Meeting, April B-Team Meeting April 29, 2009.
LEDA / Lepton Scattering on Hadrons
Deep Inelastic Parity Robert Michaels, JLab Electroweak Physics
Lead ( Pb) Radius Experiment : PREX
LEDA / Lepton Scattering on Hadrons
A Precision Measurement of GEp/GMp with BLAST
Physics Interpretation of PREX
Parity – Violating Neutron Density Measurements : PREX, C-REX
Measurement of Parity-Violation in the N→△ Transition During Qweak
Presentation transcript:

R. Michaels, Jlab Seminar, Apr 27, 2011 Lead ( Pb) Radius Experiment : PREX Pb E = 1 GeV, electrons on lead Elastic Scattering Parity Violating Asymmetry Spokespersons Paul Souder, Krishna Kumar Guido Urciuoli, Robert Michaels Ran March – June 2010 in Hall A Graduate Students Ahmed Zafar, Chun Min Jen, Abdurahim Rakham (Syracuse) Jon Wexler (UMass) Kiadtisak Saenboonruang (UVa) First Results from

R. Michaels, Jlab Seminar, Apr 27, 2011 Standard Electroweak Model Gauge bosons Left –handed fermion fields (quarks and leptons) = doublets under SU(2) Right-handed fields = singlets under SU(2) Also 3 fermion families + single complex Higgs doublet Spontaneous symmetry breaking of the Lagrangian. Symmetries Lagrangian i = 1,2,3 and Parity Violation

R. Michaels, Jlab Seminar, Apr 27, 2011 A piece of the weak interaction violates parity (mirror symmetry) which allows to isolate it. Negative longitudinal spin Positive longitudinal spin Pb 208 P S (spin) (momentum) Incident electron Target

R. Michaels, Jlab Seminar, Apr 27, 2011 Parity Violating Asymmetry + 2 Applications of PV at Jefferson Lab Nucleon Structure (strangeness) -- HAPPEX / G0 Standard Model Tests -- Qweak, Moller Nuclear Structure (neutron density) : PREX Applications of PV at Jefferson Lab

R. Michaels, Jlab Seminar, Apr 27, 2011 Idea behind PREX Z of Weak Interaction : Clean Probe Couples Mainly to Neutrons ( T.W. Donnelly, J. Dubach, I Sick 1989 ) 0 In PWIA (to illustrate) : w/ Coulomb distortions (C. J. Horowitz) : 5

R. Michaels, Jlab Seminar, Apr 27, 2011 Measured Asymmetry Weak Density at one Q 2 Neutron Density at one Q 2 Correct for Coulomb Distortions Small Corrections for G n E G s E MEC Assume Surface Thickness Good to 25% (MFT) Atomic Parity Violation Mean Field & Other Models Neutron Stars R n PREX Physics Output Slide adapted from C. Horowitz

R. Michaels, Jlab Seminar, Apr 27, 2011 Fundamental Nuclear Physics : What is the size of a nucleus ? Neutrons are thought to determine the size of heavy nuclei like 208 Pb. Can theory predict it ?

R. Michaels, Jlab Seminar, Apr 27, 2011 Reminder: Electromagnetic Scattering determines Pb 208 (charge distribution) 123

R. Michaels, Jlab Seminar, Apr 27, 2011 Z of weak interaction : sees the neutrons proton neutron Electric charge 1 0 Weak charge Analysis is clean, like electromagnetic scattering: 1. Probes the entire nuclear volume 2. Perturbation theory applies 10

R. Michaels, Jlab Seminar, Apr 27, 2011 How to Measure Neutron Distributions, Symmetry Energy Proton-Nucleus Elastic Pion, alpha, d Scattering Pion Photoproduction Heavy ion collisions Rare Isotopes (dripline) Magnetic scattering PREX (weak interaction) Theory MFT fit mostly by data other than neutron densities Involve strong probes Most spins couple to zero.

R. Michaels, Jlab Seminar, Apr 27, 2011 neutron weak charge >> proton weak charge is small, best observed by parity violation Electron - Nucleus Potential electromagnetic axial Neutron form factor Parity Violating Asymmetry Proton form factor Pb is spin 0 208

R. Michaels, Jlab Seminar, Apr 27, 2011 ( R.J. Furnstahl ) Measurement at one Q is sufficient to measure R 2 N proposed error Why only one parameter ? (next slide…) PREX:

R. Michaels, Jlab Seminar, Apr 27, 2011 Nuclear Structure: Neutron density is a fundamental observable that remains elusive. Reflects poor understanding of symmetry energy of nuclear matter = the energy cost of n.m. density ratio proton/neutrons Slope unconstrained by data Adding R from Pb will eliminate the dispersion in plot. N 208 Slide adapted from J. Piekarewicz

R. Michaels, Jlab Seminar, Apr 27, 2011 Skx-s15 Thanks, Alex Brown PREX Workshop 2008 E/N

R. Michaels, Jlab Seminar, Apr 27, 2011 Skx-s20 Thanks, Alex Brown PREX Workshop 2008

R. Michaels, Jlab Seminar, Apr 27, 2011 Skx-s25 Thanks, Alex Brown PREX Workshop 2008

R. Michaels, Jlab Seminar, Apr 27, 2011 Application: Atomic Parity Violation Low Q test of Standard Model Needs R N (or APV measures R N ) 2 APV Isotope Chain Experiments e.g. Berkeley Yb 17

R. Michaels, Jlab Seminar, Apr 27, 2011 Neutron Stars What is the nature of extremely dense matter ? Do collapsed stars form exotic phases of matter ? (strange stars, quark stars) Crab Nebula (X-ray, visible, radio, infrared) Application :

R. Michaels, Jlab Seminar, Apr 27, 2011 Fig from: Dany Page. J.M. Lattimer & M. Prakash, Science 304 (2004) 536. Inputs: Eq. of state (EOS) Hydrostatics (Gen. Rel.) Astrophysics Observations Luminosity L Temp. T Mass M from pulsar timing PREX helps here (with corrections … ) Mass - Radius relationship pressure density 19

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX & Neutron Stars Crab Pulsar ( C.J. Horowitz, J. Piekarewicz ) R calibrates EOS of Neutron Rich Matter Combine PREX R with Obs. Neutron Star Radii Some Neutron Stars seem too Cold N N Crust Thickness Explain Glitches in Pulsar Frequency ? Strange star ? Quark Star ? Cooling by neutrino emission (URCA) 0.2 fm URCA probable, else not Phase Transition to Exotic Core ?

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX: The entire lab is the experiment CEBAF Hall A Pol. Source Lead Foil Target Spectometers 21

R. Michaels, Jlab Seminar, Apr 27, 2011 Hall A at Jefferson Lab Polarized e - Source Hall A

R. Michaels, Jlab Seminar, Apr 27, 2011 How to do a Parity Experiment Flux Integration Technique: HAPPEX: 2 MHz PREX: 500 MHz (integrating method) Example : HAPPEX

R. Michaels, Jlab Seminar, Apr 27, 2011 Pull Plot (example) PREX Data

R. Michaels, Jlab Seminar, Apr 27, 2011 Halfwave plate (retractable, reverses helicity) Laser Pockel Cell flips helicity Gun GaAs Crystal e beam - Rapid, random helicity reversal Electrical isolation from rest of lab Feedback on Intensity Asymmetry Polarized Electron Source

R. Michaels, Jlab Seminar, Apr 27, 2011 P I T A Effect Laser at Pol. Source Polarization I nduced Transport Asymmetry where Transport Asymmetry Intensity Asymmetry drifts, but slope is ~ stable. Feedback on Important Systematic :

R. Michaels, Jlab Seminar, Apr 27, 2011 Intensity Feedback Adjustments for small phase shifts to make close to circular polarization Low jitter and high accuracy allows sub-ppm cumulative charge asymmetry in ~ 1 hour ~ 2 hours 27

R. Michaels, Jlab Seminar, Apr 27, 2011 Methods to Reduce Systematics Voltage change of 58 Volts, added to both the + and - voltages, would zero the asymmetry. A rotatable /2 waveplate downstream of the P.C. allows arbitrary orientation of DoLP A simplified picture: asymmetry=0 corresponds to minimized DoLP at analyzer Perfect DoCP Scanning the Pockels Cell voltage = scanning the retardation phase = scanning residual DoLP Intensity Asymmetry (ppm) Pockels cell voltage offset (V)

R. Michaels, Jlab Seminar, Apr 27, 2011 Two Wien Spin Manipulators in series Solenoid rotates spin +/-90 degrees (spin rotation as B but focus as B 2 ). Flips spin without moving the beam ! Double Wien Filter Crossed E & B fields to rotate the spin Electron Beam SPIN (NEW for PREX) Joe Grames, et. al.

R. Michaels, Jlab Seminar, Apr 27, 2011 Spin Flipper Joe Grames et.al. V-Wien = +90° MFG1I04A = -45° or +45° MFG1I04B = -45° or +45°

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Beam Asymmetries A raw = A det - A Q + E + i x i natural beam jitter (regression) beam modulation (dithering) Slopes from 31

R. Michaels, Jlab Seminar, Apr 27, 2011 Charge Asymmetry / ppm Slug # ( ~ 1 day) ppm

R. Michaels, Jlab Seminar, Apr 27, 2011 Slug # ( ~ 1 day) Units: microns Parity Quality Beam ! Helicity – Correlated Position Differences < ~ 3 nm Wien Flips helped ! Average with signs = what expt feels Points: Not sign corrected

R. Michaels, Jlab Seminar, Apr 27, 2011 Detector slopes measured during run A raw = A det - A Q + E + i x i

R. Michaels, Jlab Seminar, Apr 27, 2011 Hall A Compton Upgrade with Green Laser Sirish Nanda, et. al. 1 % Polarimetry at 1 GeV

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Compton Polarimeter Results

R. Michaels, Jlab Seminar, Apr 27, 2011 Hall A Moller Upgrade Superconducting Magnet from Hall C Saturated Iron Foil Targets 1 % Polarimetry Magnet and Target DAQ Upgrade (FADC) Sasha Glamazdin, et.al.

R. Michaels, Jlab Seminar, Apr 27, 2011 Moller Results Example : Comparing old and new DAQ Thanks, Zafar Ahmed 38

R. Michaels, Jlab Seminar, Apr 27, 2011 High Resolution Spectrometers Elastic Inelastic detector Q Dipole Quad Spectrometer Concept: Resolve Elastic target Left-Right symmetry to control transverse polarization systematic 1 st excited state Pb 2.6 MeV

R. Michaels, Jlab Seminar, Apr 27, 2011 Septum Magnet target HRS-L HRS-R collimator 5 0 Septum magnet augments the High Resolution Spectrometers Increased Figure of Merit collimator

R. Michaels, Jlab Seminar, Apr 27, 2011 Collimators inside Q1 Symmetry in all dimensions to 1 mm

R. Michaels, Jlab Seminar, Apr 27, 2011 Collimators Septum Magnet Top view target HRS-L Q1 HRS-R Q1 PREX Region After Target O-Rings which failed and caused significant time loss

R. Michaels, Jlab Seminar, Apr 27, 2011 Water Cell : Measure Nilanga Liyanage, Seamus Riordan, Kiadtisak Saenboonruang (agrees with survey)

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Q 2 Measurements Use constructed position at target for precise correction of beam position 44

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Integrating Detectors DETECTORS UMass / Smith Detector Package in HRS

R. Michaels, Jlab Seminar, Apr 27, 2011 High Resolution Spectrometers Momentum (GeV/c) 4.4 MeV 12 C

R. Michaels, Jlab Seminar, Apr 27, 2011 Pure, Thin 208 Pb Target Momentum (GeV/c) Lead 5- State 2.6 MeV

R. Michaels, Jlab Seminar, Apr 27, 2011 Detector integrates the elastic peak. Backgrounds from inelastics are suppressed. Momentum (GeV/c)

R. Michaels, Jlab Seminar, Apr 27, 2011 Backgrounds that might re-scatter into the detector ? Run magnets down: measure inelastic region Run magnets up : measure probability to rescatter No inelastics observed on top of radiative tail. Small systematic for tail. Detector cutoff

R. Michaels, Jlab Seminar, Apr 27, 2011 Diamond LEAD Three bays Lead (0.5 mm) sandwiched by diamond (0.15 mm) Liquid He cooling (30 Watts) Lead / Diamond Target 50

R. Michaels, Jlab Seminar, Apr 27, 2011 Initial Running After ~ 5 days Non-stat Noise ! Synching Raster Eliminated Noise due to Target Non-uniformity Flat NOT Flat This eliminated the ….

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Target Density Intact Melted Failure happens fairly suddenly after ~1 week Y Y X X 52

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Better Best Target thickness vs run # Thick diamond target degraded the least 0 +/- 1% 4.5 %5.6 % 8 % Melts

R. Michaels, Jlab Seminar, Apr 27, 2011 integrate wait Beam Current Detector (1 of 4) An instability in Pockel Cell bleeds into the itegration gate. Depends on helicity. Pockel Cell Error : Affected 1 st week (discarded data) Want small time constants, and same for detectors and bcm time Response to pulsed beam

R. Michaels, Jlab Seminar, Apr 27, 2011 y z x + - A T > 0 means Beam-Normal Asymmetry in elastic electron scattering i.e. spin transverse to scattering plane Possible systematic if small transverse spin component New results PREX Small A T for 208 Pb is a big (but pleasant) surprise. A T for 12 C qualitatively consistent with 4 He and available calculations (1) Afanasev ; (2) Gorchtein & Horowitz Still very preliminary

R. Michaels, Jlab Seminar, Apr 27, 2011 Error SourceAbsolute (ppm)Relative ( % ) Polarization (1) Beam Asymmetries (2) Detector Linearity BCM Linearity Rescattering Transverse Polarization Q 2 (1) Target Thickness C Asymmetry (2) Inelastic States00 TOTAL Systematic Errors (1) Normalization Correction applied (2) Nonzero correction (the rest assumed zero)

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Physics Result ppm at Q 2 = GeV 2 Statistics limited ( 9% ) Systematic error goal achieved ! (2%) 9.2 % 2.0 %

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Asymmetry (P e x A) ppm Slug ~ 1 day (blinded, raw)

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Physics Interpretation

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Errors in the asymmetry Absolute (ppm) Relative (%) Polarization % Detector Linearity % BCM Linearity % Re-scattering 0 0 Transverse Polarization % Q % Target Thickness % Asymmetry 12 C % Inelastics 0 0 TOTAL SYSTEMATIC % STATISTICAL ERROR % Asymmetry leads to R N ( theory curve, not integrated over acceptance ) Neutron Skin = R N - R P = fm arXiv: [nucl-th] Shufang Ban, C.J. Horowitz, R. Michaels Preliminary estimate from C.J. Horowitz 60

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX – II Proposal Future ?

R. Michaels, Jlab Seminar, Apr 27, 2011 Future ?

R. Michaels, Jlab Seminar, Apr 27, 2011 Other Nuclei ? Shape Dependence ? RNRN RNRN Surface thickness arXiv: [nucl-th] Parity Violating Electron Scattering Measurements of Neutron Densities Shufang Ban, C.J. Horowitz, R. Michaels

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX : Summary Fundamental Nuclear Physics with many applications Achieved a 9% stat. error in Asymmetry (original goal : 3 %) Systematic Error Goals Achieved !! Significant time-losses due to O-Ring problem and radiation damage Proposal for PREX-II in preparation

R. Michaels, Jlab Seminar, Apr 27, 2011 Extra Slides

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Corrections to the Asymmetry are Mostly Negligible Coulomb Distortions ~20% = the biggest correction. Transverse Asymmetry (to be measured) Strangeness Electric Form Factor of Neutron Parity Admixtures Dispersion Corrections Meson Exchange Currents Shape Dependence Isospin Corrections Radiative Corrections Excited States Target Impurities Horowitz, et.al. PRC

R. Michaels, Jlab Seminar, Apr 27, 2011 Lead Target PAVI 09 Liquid Helium Coolant Pb C Diamond Backing: High Thermal Conductivity Negligible Systematics Beam, rastered 4 x 4 mm beam (2 x I in proposal)

R. Michaels, Jlab Seminar, Apr 27, 2011 Noise (integrating at 30 Hz) PREX: ~120 ppm Want only counting statistics noise, all others << 120 ppm New 18-bit ADCs improve beam noise. Careful about cable runs, PMTs, grounds loops.. Test: Use the Luminosity Monitor to demonstrate noise (next slide) (HAPPEX data)

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Optimum Kinematics for Lead Parity: E = 1 GeV if = 0.5 ppm. Accuracy in Asy 3% n Fig. of merit Min. error in R maximize: 1 month run 1% in R n (2 months x 100 uA 0.5% if no systematics) 5

R. Michaels, Jlab Seminar, Apr 27, 2011 Luminosity Monitor A source of extremely high rate Established noise floor of 50 ppm

R. Michaels, Jlab Seminar, Apr 27, 2011 Pb Radius vs Neutron Star Radius The 208 Pb radius constrains the pressure of neutron matter at subnuclear densities. The NS radius depends on the pressure at nuclear density and above. Most interested in density dependence of equation of state (EOS) from a possible phase transition. Important to have both low density and high density measurements to constrain density dependence of EOS. – If Pb radius is relatively large: EOS at low density is stiff with high P. If NS radius is small than high density EOS soft. – This softening of EOS with density could strongly suggest a transition to an exotic high density phase such as quark matter, strange matter, color superconductor, kaon condensate… PAVI 09 (slide from C. Horowitz)

R. Michaels, Jlab Seminar, Apr 27, 2011 Liquid/Solid Transition Density Thicker neutron skin in Pb means energy rises rapidly with density Quickly favors uniform phase. Thick skin in Pb low transition density in star. PAVI 09 FP TM1 Solid Liquid Neutron Star Crust vs Pb Neutron Skin 208 Pb Neutron Star C.J. Horowitz, J. Piekarawicz

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 PREX: pins down the symmetry energy (1 parameter) ( R.J. Furnstahl ) energy cost for unequal # protons & neutrons PREX PREX error bar Pb 208 Actually, its the density dependence of a 4 that we pin down.

R. Michaels, Jlab Seminar, Apr 27, 2011 PREX Constrains Rapid Direct URCA Cooling of Neutron Stars Proton fraction Y p for matter in beta equilibrium depends on symmetry energy S(n). R n in Pb determines density dependence of S(n). The larger R n in Pb the lower the threshold mass for direct URCA cooling. If R n -R p <0.2 fm all EOS models do not have direct URCA in 1.4 M ¯ stars. If R n -R p >0.25 fm all models do have URCA in 1.4 M ¯ stars. PAVI 09 R n -R p in 208 Pb If Y p > red line NS cools quickly via direct URCA reaction n p+e+ (slide from C. Horowitz)

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 At 5 0 the new Optimal FOM is at 1.05 GeV (+/- 0.05) (when accounting for collimating small angle, not shown) ~1 GeV

R. Michaels, Jlab Seminar, Apr 27, 2011 PAVI 09 Optimization for Barium -- of possible direct use for Atomic PV 1 GeV optimum