Magnetic Field Simulation and Mapping for the Qweak Experiment. Peiqing Wang University of Manitoba

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1 Magnetic Field Simulation and Mapping for the Qweak Experiment Peiqing Wang University of Manitoba Winter Nuclear and Particle Physics Conference (WNPPC'07), Banff, Alberta, Feb. 2007

2 Background of the Qweak Experiment at Jefferson Lab Parity violating electron proton scattering to test Running of the Weak Mixing Angle Standard model prediction: sin2θw varies with momentum transfer Q of the interaction process called running of weak mixing angle J. Erler & P. Langacker, Particle Data Group 2006 p Qweak = 1 4 sin 2 θ w In experiment,all extracted valuesofsin2θmustagreewith thestandard modelprediction,or new physicsisindicated!!

3 Setup of Qweak Experiment A(Q 2 π 0) = GF απ 2 p Q Q weak + Q4 B Q 2 4πα 2 π= Canadian contribution (NSERC) up to$420k Cdn forconstruction ofmagnetcoils,managed bytriu M F Equipment must select & detect scattered electrons at small angles G ev,p = 0.8 ( )

4 Qweak Toroidal Magnet (QTOR) Open geometry allows the electrons to pass through 1. Incident beam energy ~1.165GeV 2. Scattering angle ~8o 3. Deflection angle of elastic electrons ~10o 4. Magnetic field integral ~0.67 T m 1. 8 coil packages 2. Each coil package consists of a double pancake structure 3. Hollow, water cooled copper conductor

5 Simulate the magnetic field Method: the magnetic field was calculated using the Biot Savart Law and performing numerical integration over the distribution of conductor current density. Procedure: Define proper coordinate system Setup the position and orientation for each current element Perform numerical integration The conductor is divided into small bars, each small bar acts as a current element. Visualization of current element positions

6 Realistic model for magnetic field simulation Manufactured coil dimensions have many inconsistencies with design specifications Leads Exit end Center Entrance end Actual coil dimensions were put into simulation programs.

7 Some simulation results The magnetic field on the median plane at sector 1 over Phi = 0o, R = 0~250cm, z = 250~250cm. DC Current: 8615 A Temperature: 20 oc BΦ Sector 1 R [cm]

8 Properties of the QTOR magnet Smallanglescattered electrons, Large field integral Largeanglescattered electrons,small field integral Focusing the elastic electrons on detector bars Separating the elastic and inelastic electrons Inelastically scattered electrons (blue tracks), are swept away from the detectors Elastically scattered electrons (red tracks) are focused onto the detectors

9 Tracing the electron trajectories Electron distribution on detector bar at a distance 570 cm to magnet center X (θ) Inelastic electrons Detector bar elastic electrons Y (Φ)

10 Magnetic field mapping device Precise, 3 d field mapping device built by Canadian group for G0 will be used to Magnetic field probes map the field and verify coil locations/symmetry Toroidal magnet and support structure 4m Designed & assembled by TRIUMF Field Mapper

11 The control and data acquisition system The main GUI of the supervisory control and data acquisition software The layout of control system Designed & assembled by TRIUMF

12 Determination of coil locations Requirements for coil misalignments: ±1.5mm (position), ±0.1 (orientation) Method: measure zero crossings of specific B field components to infer coil locations: Simulated results: Good agreement: recovered offsets agree within rounding error of starting conditions

13 Status and to do s Magnetic field simulation has been done for as built magnet coils QTOR assembly in support structure is underway Field mapping will be carried out this fall at MIT Bates Manufactured coils The installation of the Qweak experiment is expected to be carried out at Jefferson Lab by 2009 A coil on its carrier Coil stand

14 TheQweak Collaboration Qweak Collaboration Spokespersons Carlini, Roger (Principal Investigator) Thomas Jefferson National Accelerator Facility Finn, J. Michael College of William and Mary Kowalski, Stanley Massachusetts Institute of Technology Page, Shelley University of Manitoba Qweak Collaboration Members Armstrong, David College of William and Mary Averett, Todd College of William and Mary Benesch, Jay Thomas Jefferson National Accelerator Facility Birchall, James University of Manitoba Bosted, Peter Thomas Jefferson National Accelerator Facility Bruell, Antje Thomas Jefferson National Accelerator Facility Capuano, Carissa College of William and Mary Cates, Gordon University of Virginia Chattopadhyay, Swapan Thomas Jefferson National Accelerator Facility Covrig, Silviu University of New Hampshire Davis, Charles TRIUMF Dow, Karen Massachusetts Institute of Technology Dunne, James Mississippi State University Du t t a, Dip an gkar - Mis s iss ip p i St at e Un iver s it y Ent, Rolf Thomas Jefferson National Accelerator Facility Erler, Jens University of Mexico Falk, Willie University of Manitoba Forest, Tony Idaho State University Franklin, Wilbur Massachusetts Institute of Technology Gaskell, David Thomas Jefferson National Accelerator Facility Gram es, Joe - Thomas Jefferson National Accelerator Facility Gericke, Michael University of Manitoba Grimm, Klaus College of William and Mary Hersman, F. W. University of New Hampshire Holtrop, Maurik University of New Hampshire King, Paul Ohio University Johnston, Kathleen Louisiana Tech University Jones, Richard University of Connecticut Joo, Kyungseon University of Connecticut Keppel, Cynthia Hampton University Khol, Michael Massachusetts Institute of Technology Korkmaz, Elie University of Northern British Columbia Lee, Lawrence TRIUMF Liang, Yongguang Ohio University Lung, Allison Thomas Jefferson National Accelerator Facility Mack, David Thomas Jefferson National Accelerator Facility Majewski, Stanislaw Thomas Jefferson National Accelerator Facility Mammei, Juliette Virginia Polytechnic Inst. & State Univ. Mammei, Russell Virginia Polytechnic Inst. & State Univ. Martin, Jeffery University of Winnipeg Meekins, David Thomas Jefferson National Accelerator Facility Mkrtchyan, Hamlet Yerevan Physics Institute Morgan, Norman Virginia Polytechnic Inst. & State Univ. Myers, Ka t h er in e - Geo r ge Was h in gt on Un ivers it y Opper, Allena Geo r ge Was h in gt on Un iver s it y Pan, Jie - Un iver sit y o f Man it o ba Pas ch ke, Ken t - Un iver s it y o f Vir gin ia Pitt, Mark Virginia Polytechnic Inst. & State Univ. Poelker, B. (Matt) Thomas Jefferson National Accelerator Facility Porcelli, Tracy University of Northern British Columbia Prok, Yelena Massachusetts Institute of Technology Ramsay, W. Desmond University of Manitoba Ramsey Musolf, Michael California Institute of Technology Roche, Julie Ohio University Simicevic, Neven Louisiana Tech University Smith, Gregory Thomas Jefferson National Accelerator Facility Suleiman, Riad Thomas Jefferson National Accelerator Facility Tsentalovich, Evgeni Massachusetts Institute of Technology van Oers, W.T.H. University of Manitoba Wang, Peiqing University of Manitoba Wells, Steven Louisiana Tech University Wood, Stephen Thomas Jefferson National Accelerator Facility Young, Ross Thomas Jefferson National Accelerator Facility Zhu, Hongguo University of New Hampshire Zorn, Carl Thomas Jefferson National Accelerator Facility 2/1/2007