1. Q weak Overview and Target Status Silviu Covrig Hall C for the Q weak Collaboration Hall C Users Meeting January 23, 2010

2. Why Measure Q weak (p) Q w (p) is a fundamental property of the proton, never before measured Being suppressed in the SM a 4% measurement may provide a window into parity violating physics at the TeV energy scale, complementing colliders It is a standalone precision determination of the Weinberg angle at low Q 2 For a useful check of the running of sin 2  w it’s relative uncertainty has to be <1% Hall C Users Meeting, January 23, 2010 WW g U(1) g SU(2)

3. sin 2 θ W in the Renormalization Scheme Hall C Users Meeting, January 23, 2010 Experiment  sin 2  w ) sin 2  w 133 Cs0.0046 E1580.0054 Q weak 0.0030 MOLLER0.0010 MZMZ 0.0006 Theory Q 2 ~ 0 0.00086

4. Parity Violation Asymmetry h+target e-e- θ h-target e-e- θ Q 2,θ 0 Hadronic form factor correction: from G0, SAMPLE, Happex x, PV-A4 where For Q weak optimum Q 2 ~ 0.03 (GeV/c) 2 Hall C Users Meeting, January 23, 2010

5. 5 ParameterValue Beam Energy1.165 GeV Polarization85% Current150-180  A LH 2 Target 35 cm, 2500 W Production Running Time2544 hours Acceptance:  8⁰ ± 3⁰,  msr Acceptance Averaged Q 2 = 0.026 (GeV/c) 2 Acceptance Averaged Physics Asymmetry = -0.234 ppm Acceptance Averaged Expt'l Asymmetry = -0.200 ppm Integrated Cross Section4.0  b Integrated Rate (all sectors)6.5 GHz (.81 GHz / sector) Basic Q weak Parameters Hall C Users Meeting, January 23, 2010

6. The Q weak Experiment A PV ≈ -200 ppb,  A PV ≈ 5 ppb Source of error Contribution to Counting statistics 2.1%3.2% Hadronic structure -1.5% Beam polarimetry 1.0%1.5% Absolute Q 2 0.5%1.0% Backgrounds0.5%0.7% Helicity- correlated beam properties 0.5%0.7% TOTAL:2.5%4.1% 6 Hall C Users Meeting, January 23, 2010 Gzero 500 ppb HAPPEX 2 130 ppb TRIUMF E497 35 ppb SLAC E158 17 ppb Qweak 5 ppb Beam Properties  I/I < 0.1 ppm Position< 2 nm Angle< 30 nrad Diameter < 0.7  m Energy  E/E < 10 -9

7. 7 The Q weak Apparatus Hall C Users Meeting, January 23, 2010

8. Q weak Magnet: QTOR 9500 Amps 1.2 MW water cooled Power Supply Toroidal magnet with 8 resistive coils 4.3 m long / 1.5 m wide / ~3300 kg/coil Tm 8 Hall C Users Meeting, January 23, 2010

9. Main Detectors – All 8 bars assembled in their light tight boxes – Remaining parts (exoskeleton & support frames) are built – 1st bars ready to install late Feb Tracking System Region I = GEMs Region II = HDC Region III = VDC Both built 4+1 built 4 built Q weak Detectors Hall C Users Meeting, January 23, 2010

10. New Hall-C Compton Polarimeter Compton Polarimeter can run all the time Photon and electron coincidences greatly reduce systematic uncertainties due to backgrounds. < 1% precision is possible by cross-calibrating with existing Møller polarimeter. Hall C Møller <1% precision, but needs dedicated low current runs Hall C Users Meeting, January 23, 2010

11. Q weak Target Design First LH 2 target at JLab designed with Computational Fluid Dynamics (CFD) – FLUENT Cryogenic Loop Highlights 54 liters, 2500 W LH 2 centrifugal pump: 15 l/s (1 kg/s) flow @ <1.5 psid Hybrid heat exchanger: 27 l, both 4 K and 15 K He coolant High power heater: 2500 W Cell 35 cm long in beam, 7.8 liters conical cell LH 2 flows transversely to the beam axis @ ~ 2.9 m/s Steady-state uniform heating (Δρ/ρ) BV ~ 0.7%, transient rastered heating ~ 1.1% Hall C Users Meeting, January 23, 2010

12. LH 2 Target Systematics for Parity Violation A PV measured in helicity pairs + - + - + - … Counting statistics Target density fluctuations r = 5% 10% longer running Target density reduction 10% @I run 10% longer running 2T h fhfh Q weak f h σ 0 (ppm)σ b (ppm) r = 0.05 30 Hz4815 250 Hz13945 Hall C Users Meeting, January 23, 2010

13. The Q weak Target CAD model Cryogenic loop during assembly Centrifugal pump 30 Hz, 15 l/s, 1.5 psi Hybrid Heat Exchanger 2500 W Cell Block 13 Hall C Users Meeting, January 23, 2010

14. Flow Pattern 8⁰±3⁰ Acceptance Δp cell = 0.262 psid @ 1 kg/s mass rate e - beam 14 Hall C Users Meeting, January 23, 2010

15. Density Reduction Heating 180 μA: LH 2 245 W/cm 3 Al 3950 W/cm 3 7.5 liters LH 2 flow e - beam 68 cm Δρ/ρ (%) Boiling 15 Hall C Users Meeting, January 23, 2010

16. Q weak Target Safety 4 kg of LH 2 in 2 metal boundaries Safety incidents: Relief (Sudden Loss of Vacuum): 105g/s Δp = 1 atm (ø pipe>2”) Vent (cryo-loop breaks), with fluent: 210 g/s Δp 4”) Release: hydrogen escapes into Hall C – ODH: none – Flammability: possible (556 MJ from burning 4 kg of hydrogen) Hydrogen concentration in normal air 4 < c V <74 % : deflagration 18< c V < 54 % : detonation Sub-sonic waves Shock Waves 16 Hall C Users Meeting, January 23, 2010

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18. Case Study: Rastered Beam Heating Heating densities: same as Q weak cell Raster f x = 24960 Hz f y = 25080 Hz Transient simulation in fluent with ts = 2.25 μs 18 Beam Direction Hall C Users Meeting, January 23, 2010

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20. Schedule Highlights Installation period Nov 2009 – May 2010 Readiness Review July 20, 2009 Target Safety and Design Review Sep 4, 2009 (Passed) Commissioning May 25, 2010 – July 22, 2010 First Run Sep 06, 2010 – May 02, 2011 Second Run Nov 07, 2011 – May 14, 2012 Hall C Users Meeting, January 23, 2010

21. D. Androic, D. Armstrong, A. Asaturyan, T. Averett, R. Beminiwattha, J. Benesch, J. Birchall, P. Bosted, C. Capuano, R. D. Carlini 1 (Principal Investigator), G. Cates, S. Covrig, M Dalton, C. A. Davis, W. Deconinck, K. Dow, J. Dunne, D. Dutta, R. Ent, J. Erler, W. Falk, H. Fenker, J.M. Finn, T. A. Forest, W. Franklin, M. Furic, D. Gaskell, M. Gericke, J. Grames, K. Grimm, D. Higinbotham, M. Holtrop, J.R. Hoskins, K. Johnston, E. Ihloff, M. Jones, R. Jones, K. Joo, J. Kelsey, C. Keppel, M. Khol, P. King, E. Korkmaz, S. Kowalski 1, J. Leacock, J.P. Leckey, J. H. Lee, L. Lee, A. Lung, S. MacEwan, D. Mack, R. Mahurin, J. Mammei, J. Martin, D. Meekins, A. Micherdzinska, A. Mkrtchyan, H. Mkrtchyan, N. Morgan, K. E. Myers, A. Narayan, Nuruzzaman, A. K. Opper, S. A. Page 1, J. Pan, K. Paschke, S. Phillips, M. Pitt, B. (Matt) Poelker, Y. Prok, W. D. Ramsay, M. Ramsey-Musolf, J. Roche, B. Sawatzky, N. Simicevic, G. Smith 2, T. Smith, P. Solvignon, P. Souder, D. Spayde, R. Suleiman, E. Tsentalovich, W.T.H. van Oers, B. Waidyawansa, W. Vulcan, D. Wang, P. Wang, S. Wells, S. A. Wood, S. Yang, R. Young, X. Zheng, C. Zorn 1 Spokespersons 2 Project Manager College of William and Mary, University of Connecticut, Instituto de Fisica, Universidad Nacional Autonoma de Mexico, University of Wisconsin, Hendrix College, Louisiana Tech University, University of Manitoba, Massachusetts Institute of Technology, Thomas Jefferson National Accelerator Facility, Virginia Polytechnic Institute & State University, TRIUMF, University of New Hampshire, Yerevan Physics Institute, Mississippi State University, University of Northern British Columbia, Ohio University, Hampton University, University of Winnipeg, University of Virginia, George Washington University, Syracuse University, Idaho State University, University of Connecticut, Christopher Newport University, University of Zagreb The Qweak Collaboration (Funded by DOE, NSF, NSERC and the State of Va) Hall C Users Meeting, January 23, 2010 21

22. Low Energy Weak Neutral Current Standard Model Tests Q weak : δ(sin 2  W ) ~ 0.3% MOLLER: δ(sin 2  W ) ~ 0.1% 22 APV 133 Cs : δ(sin 2  W ) ~ 0.83% E158 : δ(sin 2  W ) ~ 0.54% Hall C Users Meeting, January 23, 2010

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