Hall C Meeting January 2008 Juliette M. Mammei Virginia Tech for the Qweak Collaboration Funded by NSF, DOE, SURA, NSFGRF, VT Cunningham Qweak: A Search for New Physics at the TeV Scale

D. Armstrong, T. Averett, J. Benesch, J. Birchall, P. Bosted, A. Bruell, C. Capuano, R. Carlini 1 (Contact Person), G. Cates, S. Chattopadhyay, S. Covrig, CA Davis, K. Dow, J. Dunne, D. Dutta, R. Ent, J. Erler, W. Falk, JM Finn 1, T. Forest, W. Franklin, D. Gaskell, J. Grames, M. Gericke, K. Grimm, FW Hersman, M. Holtrop, P. King, K. Johnston, R. Jones, K. Joo, C. Keppel, M. Khol, E. Korkmaz, S. Kowalski 1, L. Lee, Y. Liang, A. Lung, D. Mack, S. Majewski, J. Mammei, R. Mammei, J. Martin, D. Meekins, H. Mkrtchyan, N. Morgan, K. Myers, A. Opper, SA Page 1, J. Pan, K. Paschke, M. Pitt, B. (Matt) Poelker, T. Porcelli, Y. Prok, WD Ramsay, M. Ramsey-Musolf, J. Roche, N. Simicevic, G. Smith 2, R. Suleiman, E. Tsentalovich, WTH van Oers, P. Wang, S. Wells, S. Wood, R. Young, H. Zhu, C. Zorn 1 Co-pokespersons 2 Project Manager California Institute of Technology, College of William and Mary, George Washington University, Hampton University, Idaho State University, Louisiana Tech University, Massachusetts Institute of Technology, Mississippi State University, Ohio University, Thomas Jefferson National Accelerator Facility, TRIUMF, University of Connecticut, University of Manitoba, University of Mexico, University of New Hampshire, University of Northern British Columbia, University of Virginia, University of Winnipeg, Virginia Polytechnic Institute & State University, Yerevan Physics Institute The Qweak Collaboration

Hall C Meeting January 2008 Weak Charges of Light Quarks EM ChargeWeak Charge EM Charge Weak Charge

Hall C Meeting January 2008 “Running” of sin 2  W Electroweak radiative corrections  sin 2  W varies with Q + +  The “running” curve is normalized by measurements at the Z 0 resonance. Standard Model Prediction Erler, Kurylov & Ramsey-Musolf, Phys. Rev. D 68, (2003)

Hall C Meeting January 2008 Hadronic Structure Contribution PDG SM theoretical estimates of anapole form factor Q p weak Young, Ross, et. al. PRL 99:122003,2007

Hall C Meeting January 2008 Sensitivity to TeV Scale Erler et al., PRD68(2003) Data sets limits on

Hall C Meeting January 2008 Neutral Weak Effective Couplings Young, Ross, et. al. PRL 99:122003,2007

Hall C Meeting January 2008 Erler, Kurylov, Ramsey-Musolf, PRD 68, (2003) Limits on Extensions to the Standard Model

Hall C Meeting January 2008   A phys /A phys  Q p weak /Q p weak Statistical (2200 hours production) 2.1% 3.2% Systematic: Hadronic structure uncertainties % Beam polarimetry 1.0% 1.5% Absolute Q 2 determination 0.5% 1.0% Backgrounds 0.5% 0.7% Helicity-correlated Beam Properties 0.5%0.7% _________________________________________________________ Total 2.5% 4.1%   A phys /A phys  Q p weak /Q p weak Statistical (2200 hours production) 2.1% 3.2% Systematic: Hadronic structure uncertainties % Beam polarimetry 1.0% 1.5% Absolute Q 2 determination 0.5% 1.0% Backgrounds 0.5% 0.7% Helicity-correlated Beam Properties 0.5%0.7% _________________________________________________________ Total 2.5% 4.1% Anticipated Q p Weak Uncertainties Experimental sensitivity: Expected value: A(Q 2 =0.026 GeV 2 ) = ppm !!! Precision measurement:

Hall C Meeting January 2008 Qweak 101  Keep technology simple!  Build on JLab expertise with parity quality polarized beams (1.165 GeV)  Dual Moller and Compton polarimeters (85% polarized beam)  Resistive toroid magnet (particle separation - ~9000A)  Quartz cerenkov detectors in current mode: Rad hard (stable) and rejection of non-relativistic events Low gain PMTs operated in linear current integrating mode Precision 18-bit ADC rapid sampling (equivalent to 26 bit)  Counting mode (sub nA beam current) for Q 2 calibration  World’s highest power LH 2 cryogenic target (~2.5 kW)  Rapid flipping (125 Hz) of beam helicity (up to 500Hz) to suppress beam systematics and target boiling noise

Hall C Meeting January 2008 Target (Design) QTOR +Power Supply (Mapping soon - Bates) R-3 Rotation System (Fabrication) R-2 HDCs (Fabrication and testing) Downstream Pb Shielding (Complete) Beam Experiment Component Status GEMs (Prototype + parts) R-3 VDC (Fabrication) Main Detectors (Components at JLab) Lumis (Design) Collimators (Procurement) New Quartz Scanner (Design) Lumis (Design)

Hall C Meeting January 2008 Very clean elastic separation! Main Detectors View Along Beamline of Q Weak Apparatus - Simulated Events Central scattering angle: ~8° ± 2° Phi Acceptance: ~50% of 2π Average Q²: GeV 2 Acceptance averaged asymmetry: –0.234 ppm Integrated Rate (per detector): ~810 MHz Inelastic/Elastic ratio: ~0.4% Central scattering angle: ~8° ± 2° Phi Acceptance: ~50% of 2π Average Q²: GeV 2 Acceptance averaged asymmetry: –0.234 ppm Integrated Rate (per detector): ~810 MHz Inelastic/Elastic ratio: ~0.4% 8 fused silica radiators (Spectrosil 2000) 200cm x 18cm x 1.25cm 5” PMTs (gain = 2000)

Hall C Meeting January 2008 Main Detectors Gluing jig Quartz bar quality control PMT gain vs. voltage Bars, light guides, PMTs, IV preamps delivered. Final testing of 18-bit ADC prototypes

Hall C Meeting January 2008 Target Beam Assembling the heat exchanger Target status Shakedown – with cold He gas Summer ‘08 Neon test – early 2009 High power test – Spring 2009

Hall C Meeting January 2008 Magnet Attaching a coil to the supports Assembled toroid with mapper 9500 A power supply delivered; Field mapping to begin in March

Hall C Meeting January 2008 Tracking system GEM prototype and rotator (LA Tech, Idaho State) Region II HDC (VPI) Region III VDC and rotator (W&M)

Hall C Meeting January 2008 Conclusion DOE spending ¾ finished! most systems are constructing and/or testing on track to be ready in January ’09 scheduled for Sept. or Nov. ’09 ~6 months install, ~4 months commissioning, ~12 months running

Hall C Meeting January 2008 Extra Slides

Hall C Meeting January 2008 Experiment Status

Hall C Meeting January 2008 “DAQ” Tracking System Region I GEMs Region II HDCs Region III VDCs QTOR GEMs – Gas Electron Multiplier HDCs – Horizontal Drift Chamber QTOR – Toroidal Magnet VDCs – Vertical Drift Chamber Trigger Scintillator If the track doesn’t point to the target, or if the kinematics don’t match an elastic event, then it is background

Hall C Meeting January 2008 GEM 1 GEM 2 GEM 3 ~12mm Readout PCB Collection cathode amplifier electron avalanche HDCs – Horizontal Drift Chamber VDCs – Vertical Drift Chamber GEMs – Gas Electron Multiplier GEM 1 GEM 2 GEM 3 ~12mm Readout PCB Collection cathode amplifier electron avalanche sense wire guard wire sense wire guard wire

TRIUMF Custom Low Noise Electronics VME integrator – 18 bit ADC sampling at 500 kHz FPGA sums 500 samples into one data word same resolution as a 26 bit ADC Noise test on bench at TRIUMF Electronic noise is about 3 orders of magnitude below the counting statistics of electron tracks. This permits very sensitive checks with LED light sources and battery powered current sources in only one shift. 2 ppb!

Hall C Meeting January 2008 Indirect search for new physics Qweak measurement will provide a stringent stand alone constraint on Lepto-quark based extensions to the SM. JLAB QweakSLAC E158 Q p weak (semi-leptonic) and E158 (pure leptonic) together make a powerful program to search for and identify new physics.

Hall C Meeting January 2008 M EM M NC Interference gives rise to parity violating asymmetry Q p weak : Parity-Violating Electron Scattering Scatter longitudinally polarized electrons on unpolarized protons

Hall C Meeting January 2008 Parameterize New Physics contributions in electron-quark Lagrangian A 4% Q p Weak measurement probes with 95% confidence level for new physics at energy scales to: g: coupling constant,  : mass scale If LHC uncovers new physics, then precision low Q 2 measurements will be needed to determine charges, coupling constants, etc. Energy Scale of an “Indirect” Search for New Physics

Hall C Meeting January 2008 In the case of a significant deviation from SM... Constraint including Qweak at central value of current measurements Analysis by Ross Young, JLab atomic only with PVES with Qweak If LHC finds a Z′, Qweak will help determine its properties

Hall C Meeting January 2008 ss 137  Q 2, GeV 2 QED (running of  ) QCD(running of  s ) Running coupling constants in QED and QCD

Hall C Meeting January 2008 Why are Precision Measurements far Below the Z-pole Sensitive to New Physics? Precision measurements well below the Z-pole have more sensitivity (for a given experimental precision) to new types of tree level physics, such as additional heavier Z’ bosons.

Hall C Meeting January 2008 R parity (B-L conservation) RPC SUSY occurs only at loop level RPV SUSY occurs at tree level Relative Shifts in Proton and Electron Weak Charges due to SUSY Effects Erler, Ramsey-Musolf, Su hep-ph/