 contribution of s-quarks to 4He nucleus E01-003: E91-004 Update Parity Violation in 4He(e,e’) at Q2 = 0.6 (GeV/c)2 E. Beise PAC19 Hall A collaboration experiment approved in 1992 for 85 days of beam, “A” rating  contribution of s-quarks to 4He nucleus Physics overview and update Comparison w/ other experiments Experiment update/status target DAQ test data Updated Beam request: 65 days at I=100 mA, Pe =0.80

E91-004 History Conditionally approved by PAC 5 (Jan 92) Endorsed as Hall A collab. Experiment (June 92) Reviewed by “Parity Technical Committee” (July 92) (chair: B. Barish) “The proponents have made a convincing argument that the systematic effects… are under control.” “The real running conditions at forward angles must be investigated.” “The main challenge is attaining the required statistical precision. It would not make sense to attempt this experiment if the conditions are significantly less than those proposed.” “The critical piece of apparatus is the high density helium target…” Full approval by PAC 7 (85 days): “A” rating (Dec 93) Technical Requirements spectrometers commissioned  Pmax = 3.2 GeV/c high current pol’d beam (1998) high power 4He target (2000)  to be upgraded 2001/2002 Expected performance of pol’d beam  reduction in required beam hours for same measurement. Ready to request scheduling if reapproved by PAC19

Measurement of Strange Quark Effects Using Parity Violating Update to JLAB Experiment E-91-004 Measurement of Strange Quark Effects Using Parity Violating Elastic Electron Scattering from 4He at Q2 = 0.6 (GeV/c)2 E.J. Beise, H. Breuer, C.C. Chang, N. Chant, J.J. Kelly, P. King, and P.G. Roos University of Maryland, College Park MD 20742 B. Filippone, J. Gao, K. Gustafsson, T. Ito, J. Martin, and R.D. McKeown W.K. Kellogg Radiation Laboratory, Caltech, Pasadena, CA 91125 J.P. Chen, O. Hansen, K. deJager, J. Gomez, J.H. Mitchell, J.J. LeRose, N. Liyanage, R. Michaels, S. Nanda, A. Saha, and B. Wojtsekhowski Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 G.G. Petratos, M. Katramatou, and K. McCormick Kent State University, Kent, OH 44242 D.S. Armstrong, T. Averett, J.M. Finn, and J. Roche College of William and Mary, Williamsburg, VA 23187 W. Korsch and D. Dale University of Kentucky, Lexington, KY 40506 K. Aniol, M. Epstein, and D. Margaziotis California State University at Los Angeles, Los Angeles, CA 90032 M. Pitt Virginia Polytechnic Institute, Blacksburg, VA 24061 J.A. Templon The University of Georgia, Athens, GA 30602 J. Calarco The University of New Hampshire, Durham, NH 03824 P. Markowitz Florida International University, Miami, FL 33199 X. Jiang Rutgers University, New Brunswick, NJ 08854 P. Ulmer Old Dominion University, Norfolk, VA 23529 R. Wilson Harvard University, Cambridge, MA 02138 A Hall A Collaboration Experiment

Parity Violating Electron Scattering polarized electrons unpolarized target for a proton: forward angles backward angles electroweak radiative corrections Z exchange anapole

Proton experiments and strange form factors SAMPLE: Q2 = 0.1 HAPPEX: rules out pure pole-type models now limited by neutron EM form factors Mainz PVA4 (in progress) : HAPPEX II: Q2 = 0.1 G0: complete separation of GMs, GEs, and GAe 0.12  Q2  1.0 total program ( 40 days each): 1 forward angle 3 backward angle H2 3 backward angle D2 quasielastic

Heavy Baryon Chiral PT constrained by SAMPLE 97 constrained by HAPPEX 98 at Q2 = 0.5 (GeV/c)2

4He: PV in a J=0,T=0 System dGsE   0.06  0.02 M.J. Musolf, et al., Phys. Rep. 239 (1994) 1. G(q)  isospin breaking contribution < 1% Ramavataram, Hadjimichael + Donnelly, PRC50 (1994) 1175. RV  vector weak radiative corrections  1% M.J.M., et al., PR 239 Fs  nuclear strangeness form factor nuclear structure largely cancels in APV in “1-body” limit: E00-114: Q2 = 0.1 (GeV/c)2 GsE(t)  rst drs   0.5 theory: this exp (E91-004): 0.6 (GeV/c)2 dFs   3.5  10-3 dGsE   0.06  0.02 Contribution from meson exchange Musolf, Schiavilla+Donnelly, PRC 50 (94) 2173

E91-004: 4He(e,e’) elastic scattering sensitive only to GEs potential probe of non-nucleonic strangeness at Q2 = 0.6 (GeV/c)2 w/ 60 days production beam (100 mA, 80% pol’n) dAexp = 17 ppm dFs   3.5  10-3 dGsE (stat)   0.06

Meson Exchange and Nuclear Strangeness 1-p exchange violates G-parity dominant 2-body contributions from pair + transition currents low Q2: Musolf+ Donnelly, PLB 318 (1993) 263 Q2 > 0.5 : Musolf,Schiavilla+Donnelly, PRC 50 (1994) 2173 could contribute as much as 15% to APV first term depends on value of ms sign of grps uncertain grps(Q2) unknown Goity+Musolf, PRC 53 (1996) 399 Ito+Ramsey-Musolf, PRC 58 (1998) 2595

Musolf, Schiavilla + Donnelly, PRC 50 (1994) 2173 assumes rs = -2.0 ms = -0.20 grps = +0.26 location of minimum in Fs largely determined by non-strange MEC contributions If assume 100% uncertainty in grps contribution, then (dGsE)MEC   0.02 (dGsE)EXP   0.06

Experimental Requirements Q2 = 0.6 (GeV/c)2 Ebeam = 3.3 GeV q = 13.5° HRS2 in single-arm d/d = 1 nb/sr elastic rate = 780 Hz (per arm) tracking preferable add small trigger scintillator to minimize QE rate use two separate DAQ systems to minimize dead time DW = 6.5 msr per arm w/ no spectrometer collimators from G.G. Petratos

Helium Target (Cal State LA group) Cell in house (7075-T6 Al, 13 mil walls) pressure tested to 30 atm operate at 5.8 K, 15 atm will also be used for E00-114, E00-118 To Be Done: target manifold collimators for windows upgrade loop for higher power Existing (10 cm “tuna can”) cell has been tested to 100 mA: E97-111 scaler data 6% drop

Data Acquisition Test setup July 2000: (R. Michaels) (run 2 independent DAQs for each spectrometer) 20% dead at 2.5 kHz per spect. Rate dependence well understood use addt’l trigger scintillator to minimize rate from QE events

Tracking tracking desired for background reduction total triggered rate into VDCs < 10 kHz from study of high rate (70  300 kHz) data (E94-004), rate dependence would result in negligible false asymmetry (but overall tracking efficiency was low…) want tracking efficiency  90% to minimize loss of statistics E97-111 data: y vs. x at focal plane added trigger scint target walls not subtracted

4He(e,e’) data from 97-111 Oct 2000 10 cm “tuna can” cell no collimation of target windows E91-004 kinematics S1-S2 trigger, no particle ID all data empty subtracted cut on S1 diagonal cut

Beam Properties and Systematic Errors Flip helicity at 30 Hz: dAmeas in 30 msec = 18% HAPPEX achieved results far better than required for E91-004 Run HAPPEX DAQ simultaneously to feedback on intensity potential issue: how to synch different DAQ systems will be tested during pol’d 3He run summer 2001 (overall dAmeas (pol’d 3He)  100 ppm at some kinematics…) Parameter measurement req’d in 30 msec HAPPEX Energy dE/E 110-3 10-6 Position dx 0.5 mm 20 mm Angle dq 0.3 mrad 30 mrad Intensity dI/I 0.5 % 30 ppm