PAC38 August 22, 2011

Publications in last year G0The G0 Experiment: Apparatus for Parity-Violating…NIIM A646, 59 E01-107Nuclear transparency and effective kaon -nucleon cross section from thePRC 84, A(e, e'K + ) reaction G0Transverse Beam Spin Asymmetries at Backward Angles in ElasticPRL 107, Electron-Proton and Quasi-elastic Electron-Deuteron Scattering E04-019Search for effects beyond the Born approximation in polarizationPRL 106, transfer observables in e↑p elastic scattering E02-019Scaling of the F2 structure function in nuclei and quark distributions at x>1 PRL 105, E Kaon, Pion and Proton Associated Photofission of Bi Nuclei Phys.Atom.Nucl. 73, 1707 E01-006Probing Quark-Gluon Interactions with Transverse Polarized ScatteringPRL 105, E02-019New measurements of high-momentum nucleons and short-rangeArxiv: structures in nuclei E04-019Semi-Inclusive Charged-Pion Electroproduction off Protons andArxiv: Deuterons: Cross Sections, Ratios and Access to the Quark-Parton Model at Low Energies Total Publications: 92PRL: 36NIM: “Hall C” PhDs to date, 5 in last year

Fomin et.al, arXiv: x>1 – Short Range Correlations R(A, D) at =2.7 GeV 2 3 He2.14± He3.66±0.07 Be4.00±0.08 C4.88±0.10 Cu5.37±0.11 Au5.34±0.6 Data also at = 3.8 and 4.8 GeV 2

Kaon Transparency Nuruzzman et.al., Phys. Rev. C 84, (2011) A(e,eK + ) data for “free” in Pion Color Transparency data set Effective hadron-proton cross derived from transparency A-dependence Curves are scale free cross sections pN x 0.68  + N x 0.81 K + N x 0.65

Qweak Luminosity monitors Luminosity monitors scanner Qweak – measurement of proton weak charge through parity violating electron scattering ongoing in Hall C

LH 2 Data Quality The electron polarity may be reversed every 1 msec by electronic means. An Insertable Half Wave Plate (IHWP) optically flips the polarity before every 8 hour “slug”. The signal must reverse sign. unregressed, uncorrected, blinded Convergence to mean ~rms/sqrt(N). Width is a very important FOM! At 165 μA, total detected rate is 5.83 GHz.  Pure counting statistics: 215 ppm + detector shower fluctuations 232 ppm + current normalization and target 235 ppm Width is understood and about 10% above c.s. 0.8 ppm statistical error in only 6.5 minutes at 165 μA

Ancillary Physics Bkg Measurements Measuring the Proton's Weak Charge7 Aluminum target windows - elastic +QE ~3% dilution of signal, ~20% correction N → Δ asymmetry ~0.1% dilution, ~1% correction Parity conserving, transverse asymmetry on LH2. A very small correction. Est’d error

8 Run I Polarimetry: Preliminary Recall A physics = A experimental /P. Goal is a 1% determination of P using: 1.Basel-Hall C Moeller (e+e  e+e) polarimeter. Invasive. 0.75% accuracy at a few microA. 2. Compton (γ+e  γ+e) polarimeter. Non-invasive. Continuous at full production current.

Qweak Run II: Nov ’11- May ‘12 summer down Statistical goal = 2.1% Qweak to resume in production mode with all essential systems working fine Good parity beam quality at 180 uA Low noise, reliable target Successful ancillary measurements made, will devote 10% to Al. Beamline backgrounds understood and minimized Mature analysis software, well trained analysis and shift crews Modifications to beamline should improve hall efficiency

Qweak maintenance Rebuild target pump, replace windows Minor main detector and region II chamber work Reduce beam current measurement noise Exit window and dump maintenance Summer shutdown work Disassemble HKS spectrometer and move to storage Large Moller Polarimeter quadrupole has unstable coil Partial beamline disassembly in progress to remove quad and repair or replace

SOS Removal SOS must be removed for 12 GeV Detectors, electronics, power, cables, AC, hydraulic plumbing removed. Cables to be reused for SHMS. Removed lead lined walls of electronics hut. doors, roof, lead lining. Detector hut lead panels to be removed.

Schedule Overview Present – November 18, month down SOS decommissioning HKS Removal Moller Quad Repair November 19, 2011 – May 13, 2012 Qweak running May 14, 2012 – September, 2012 Qweak and SOS removal September 2012 Start of SHMS construction September 2014 SHMS/Detector checkout 2015 Engineering Runs Commissioning Experiments

SHMS Detectors Drift chambers – Hampton University PCB boards arriving Nov ‘11 Techniques developed Shower Counter – Yerevan Preshower assembled Heavy Gas – Regina (NSERC) Vessel/Mirror fabrication starting Nobel Gas Cerenkov – UVA (project funded) Mature design Aerogel – CUA led MRI 2 Aerogel indices delivered Detector box fabrication started PCB boards arrive Nov ‘ Good parity beam quality at 180 uA Low noise, reliable target Non-target backgrounds understood and minimized Mature analysis software and analysis crew …

James Madison University performing final cosmic calibration. Expected to complete by 12/31/11. Trigger Hodoscopes 14 Timing S1 Frame currently in William & Mary Shop. Test-fit of nine paddles: done!

Quartz Hodoscope 15 Quartz Bars Arrived Look Good NCAT Students and Cosmic-Ray Test Stand Planned Completion: Deliver to W&M in mid 2012

Approved 12 GeV Hall C Experiments Discussions started with SHMS/HMS Users group to layout plans for commissioning and early experiments (first two years)