Qweak Overview and Target Status Silviu Covrig Hall

Qweak Overview and Target Status Silviu Covrig Hall C for the Qweak Collaboration Hall C Users Meeting January 23, 2010

Why Measure Qweak(p) • Qw(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 Te. V 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% g. U(1) W g. SU(2) Hall C Users Meeting, January 23, 2010

sin 2θW in the Experiment d(sin 2 qw) sin 2 qw 133 Cs 0. 0046 E 158 0. 0054 Qweak 0. 0030 MOLLER 0. 0010 MZ 0. 0006 Theory Q 2 ~ 0 0. 00086 Hall C Users Meeting, January 23, 2010 Renormalization Scheme

Parity Violation Asymmetry e- θ h+ e- target Q 2, θ h- target 0 where For Qweak optimum Q 2 ~ 0. 03 (Ge. V/c)2 Hall C Users Meeting, January 23, 2010 θ Hadronic form factor correction: from G 0, SAMPLE, Happexx, PV-A 4

Basic Qweak Parameters Parameter Value Beam Energy Polarization Current 1. 165 Ge. V 85% 150 -180 A LH 2 Target Production Running Time Acceptance: , j, DW 35 cm, 2500 W 2544 hours 8⁰ ± 3⁰, , 37 msr Acceptance Averaged Q 2 Acceptance Averaged Physics Asymmetry Acceptance Averaged Expt'l Asymmetry < Q 2 > = 0. 026 (Ge. V/c)2 < A > = -0. 234 ppm < A > = -0. 200 ppm Integrated Cross Section Integrated Rate (all sectors) Hall C Users Meeting, January 23, 2010 4. 0 b 6. 5 GHz (. 81 GHz / sector) 5

The Qweak Experiment APV ≈ -200 ppb, DAPV ≈ 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% Backgrounds 0. 5% 0. 7% Helicitycorrelated beam properties 0. 5% 0. 7% TOTAL: 2. 5% 4. 1% Hall C Users Meeting, January 23, 2010 Beam Properties • • • DI/I < 0. 1 ppm Position < 2 nm Angle < 30 nrad Diameter < 0. 7 m Energy DE/E < 10 -9 Gzero HAPPEX 2 TRIUMF E 497 SLAC E 158 Qweak 500 ppb 130 ppb 35 ppb 17 ppb 5 ppb 6

The Qweak Apparatus Hall C Users Meeting, January 23, 2010 7

Qweak Magnet: QTOR • Toroidal magnet with 8 resistive coils • 4. 3 m long / 1. 5 m wide / ~3300 kg/coil • Tm 9500 Amps 1. 2 MW water cooled Power Supply Hall C Users Meeting, January 23, 2010 8

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

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

Qweak 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 @ <v> ~ 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

LH 2 Target Systematics for Parity Violation fh APV measured in helicity pairs + - + - … 2 Th Counting statistics Target density fluctuations r = 5% 10% longer running Target density reduction 10% @Irun 10% longer running Qweak fh σ0 (ppm) σb (ppm) r = 0. 05 30 Hz 48 15 250 Hz 139 45 Hall C Users Meeting, January 23, 2010

The Qweak Target CAD model Cryogenic loop during assembly Centrifugal pump 30 Hz, 15 l/s, 1. 5 psi Hybrid Heat Exchanger 2500 W Cell Block Hall C Users Meeting, January 23, 2010 13

Flow Pattern e- beam 8⁰± 3⁰ Acceptance Δpcell = 0. 262 psid @ 1 kg/s mass rate Hall C Users Meeting, January 23, 2010 14

Density Reduction Δρ/ρ (%) e- beam Boiling LH 2 flow Heating 180 μA: LH 2 245 W/cm 3 Al 3950 W/cm 3 7. 5 liters 68 cm Hall C Users Meeting, January 23, 2010 15

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

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Case Study: Rastered Beam Heating densities: same as Qweak cell Raster Beam Direction fx = 24960 Hz fy = 25080 Hz Transient simulation in fluent with ts = 2. 25 μs Hall C Users Meeting, January 23, 2010 18

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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

The Qweak Collaboration (Funded by DOE, NSF, NSERC and the State of Va) 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. Mac. Ewan, 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 Hall C Users Meeting, January 23, 2010 21

Low Energy Weak Neutral Current Standard Model Tests E 158 : δ(sin 2 W ) ~ 0. 54% MOLLER: δ(sin 2 W ) ~ 0. 1% Qweak : δ(sin 2 W ) ~ 0. 3% APV 133 Cs : δ(sin 2 W ) ~ 0. 83% Hall C Users Meeting, January 23, 2010 22

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