PAC38

1. PAC38 August 22, 2011

2. Publications in last year G0 The G0 Experiment: Apparatus for Parity-Violating… NIIM A646, 59 E01-107 Nuclear transparency and effective kaon -nucleon cross section from the PRC 84, 015210 A(e, e'K+) reaction G0 Transverse Beam Spin Asymmetries at Backward Angles in Elastic PRL 107, 022501 Electron-Proton and Quasi-elastic Electron-Deuteron Scattering E04-019 Search for effects beyond the Born approximation in polarization PRL 106, 132501 transfer observables in e↑p elastic scattering E02-019 Scaling of the F2 structure function in nuclei and quark distributions at x>1 PRL 105, 212502 E02-017 Kaon, Pion and Proton Associated Photofission of Bi Nuclei Phys.Atom.Nucl. 73, 1707 E01-006 Probing Quark-Gluon Interactions with Transverse Polarized Scattering PRL 105, 101601 E02-019 New measurements of high-momentum nucleons and short-range Arxiv:1107.3583 structures in nuclei E04-019 Semi-Inclusive Charged-PionElectroproduction off Protons andArxiv: 1103.1649 Deuterons: Cross Sections, Ratios and Access to the Quark-Parton Model at Low Energies Total Publications: 92 PRL: 36 NIM: 11 82 “Hall C” PhDs to date, 5 in last year

3. x>1 – Short Range Correlations R(A, D) at <Q2> =2.7 GeV2 Data also at <Q2> = 3.8 and 4.8 GeV2 Fomin et.al, arXiv: 1107.3583

4. Kaon Transparency A(e,eK+) data for “free” in Pion Color Transparency data set Nuruzzman et.al., Phys. Rev. C 84, 015210 (2011) 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

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

6. LH2 Data Quality 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 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

7. Ancillary Physics Bkg Measurements 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 Measuring the Proton's Weak Charge

8. Run I Polarimetry: Preliminary RecallAphysics = Aexperimental/P . Goal is a 1% determination of P using: 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.

9. Qweak Run II: Nov ’11- May ‘12 • 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 summer down Statistical goal = 2.1%

10. Summer shutdown work • 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 • Disassemble HKS spectrometer and move to storage • Large MollerPolarimeterquadrupole has unstable coil • Partial beamline disassembly in progress to remove quad and repair or replace

11. 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.

12. Schedule Overview Present – November 18, 2011 6 month down SOS decommissioning HKS Removal Moller Quad Repair November 19, 2011 – May 13, 2012 Qweakrunning 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

13. 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 • …

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

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

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