Hall A Status Robert Michaels PAC38 Report, Aug 22, 2011 Thomas Jefferson National Accelerator Facility Recent Activity g2p / GEp 12 GeV Publications

Recent Activity in Hall A Dec 23 Completed DVCS, ran Oct 5 – Dec 23, (C. Hyde) Feb 22 Completed D - Threshold (B. Norum) Mar 9 Completed N-Delta (N. Sparveris) Apr 13 part I of SRC triple coinc. (E. Piasetzky) Apr 15 Completed e08009 He4 (A. Saha) May 6 Review of upcoming g2p/GEp (N. Liyanage, chair) May 8 Completed x > 2 SRC inclusive (P. Solvignon-Slifer) May 13 part II of SRC triple coinc. (E. Piasetzky) May 13 begin 6 mo. Shutdown, prepare for g2p/GEp

E07-007/E : DVCS run summary Goal:  DVCS cross-section at 3 values of Q 2 and 2 beam energies each (6 kinematics)  L/T separation as a function of Q 2 : DVCS 2 /BH-Interf separation & test of scaling  E07-007: proton (LH2 tg) / E08-025: neutron (LD2 tg); only 1 Q 2 (2 kinematics) New dedicated equipment: Expanded PbF 2 electromagnetic calorimeter:  Less radiation damage than previous experiment (selection of blocks & better shielding) 1 GHz sampling electronics (ARS):  Faster transfer speed & buffering implemented (more channels read & less deadtime)  Successfully commissioned during the first week Coincidence trigger module  Reduces data rate by selecting clusters above threshold in the calorimeter C. M. Camacho C. Hyde

E08008: d(e,e'p)n at threshold Early results from elastic Hydrogen data p(e,e'p) Status of Analysis Completed: Helicity decoding BCM Calibrations Optics for the HRS To Do: Timing Calibration – Timing Plane TDC – Pathlength Correction Comparison to previous results Physics analysis L. Selvy B. Norum

CMR measurements extended to a new lowest Q 2 (σ LT,σ ο & C2,M1 precisely measured down to 0.04 (GeV/c) 2 ) mapped CMR in the low-Q 2 region with unprecedented precision puzzling discrepancies of other labs (Bates/MAMI) will be addressed (W-dependence of σ ο =σ Τ +εσ L ) strong constraints to the most modern theoretical calculations insight to the mechanisms that contribute to the presence of non-spherical components in the nucleon wave function Data taking: 02/25/11 to 03/07/11 N→Δ H(e,e’p)π o channel measurements e & p detected in coincidence using HRS’s E beam = 1.16 GeV LH 2 4cm & 15cm I = 15μΑ to 80μΑ Q 2 = (GeV/c) 2 Q 2 = 0.09 (GeV/c) 2 Q 2 = 0.04 (GeV/c) 2 θ pq W (MeV) JLab Projected Measurements Measurement of the Coulomb quadrupole amplitude in the γ*p  Δ(1232) in the low momentum transfer region (E08-010) N. Sparveris et al analysis currently at the preliminary stage

Experiment E08009 Students: S. Iqbal(CSULA), N. McMahon(CNU) Spokespersons: A. Saha, K. Aniol, F. Benmokhtar D. Higinbotham, S. Gilad  Data: Along with SRC data measured 4 He(e,e'p)X reaction channels for P miss from to 1 GeV/c, x b = 1.24, Q 2 = 2 (GeV/c) 2  Goal: Extract Spectral function and compare to 3He (F. Benmokhtar) and 12C (P. Monhagan) taken in almost similar conditions. Comparison will help us understand the interaction of p-n pairs in these Nuclei  Status: First offline look at the data: good run selection, acceptance and coincidence cuts determination, and Target density study were all done.  Near Future: DT & detection efficiency studies, get theoretical calculations 755 MeV/c 625 MeV/c 500 MeV/c 380 MeV/c 150 MeV/c 800 MeV/c Under analysis Missing Energy Spectra

2N-SRC: From Tensor Dominance to the Repulsive Limit JLab Hall-A E (2011) Recoil nucleon Scattered proton Electron (2004)(2011) Schiavilla, Wiringa, Pieper, Carson, PRL 98, (2007). O. Chen E. Piasetzky I. Korover D. Higinbotham

On-Line Identification of Triple coincidence 4 He(e,e'pN) and 4 He(e,e'p) events HAND BigBite JLab Hall-A E (2011)

9 Experiment goals: 1)Verify and define scaling regime for 3N-SRC 2)Isospin effects on SRCs: 48 Ca vs. 40 Ca 3)Study onset of scaling with ratios as a function of relativistic scaling function  2n for 1<x<2 4)First precise data on 3 He and 4 He for x>2 to test FSI and examine IMF distribution  A (  ) K. Egiyan et al, PRL96, (2006) Projected precision CLAS precision ~1.33GeV 2 ~1.58GeV 2 ~1.85GeV 2 ~2.24GeV 2 48 Ca/ 40 Ca x This inclusive experiment ran successfully in April-May The statistics accumulated should allow us to reach the two main goals. Online half statistics P. Solvignon-Slifer J. Arrington x > 2 Experiment E N, 3N SRC (Inclusive)

10 Analysis progressing very well: Detector, optics and beam calibrations are done Detector efficiencies and software cut studies are in progress Left and right arm acceptance study underway Work mostly performed by the Ph.D student: Zhihong Ye (UVa) Spokepeople: J. Arrington (ANL), D. Day (UVa), D. Higinbotham (JLab) and P. Solvignon (JLab) Optics results with mismatched (~12% lower P o ) RQ3 Preliminary results expected Spring 2012 Comment: 40 Ca foil not delivered. The target group made natural calcium target at last minute, but we need to look at target and calibration data to determine uniformity  may limit isospin-dependence extraction. x > 2 Experiment E Analysis Progress

Uva/Jlab Polarized NH 3 Target Low Q 2 g p 2 and G E p Experiments (6 GeV) Scheduled Nov May 2012 Modified Beamline in Hall A 0.02 < Q 2 < 0.40 GeV 2 Jian-Ping Chen A. Camsonne K. Slifer D. Crabb R. Gilman G. Ron D. Day A. Sarty J. Arrington Chicane Magnets Septum Low-current Monitors Local Beam dump Installation is on track Technical Review was on May 6, 2011 (Nilanga Liyanage, et.al.)

BC Sum Rule Spin Polarizability  LT Q2Q2  G E /G M Low Q 2 g2p / GEp

BC Sum Rule Spin Polarizability  LT Q2Q2  G E /G M Low Q 2 Needs low E Low Q 2 Needs low E g2p / GEp

Installation is on Schedule Chicane magnets installed. Arms/Girders sent out for construction. Movable FZ1 stand constructed and in hall. Power supplies ready to be hooked up. Septa magnet installed. Low power dump design sent out for construction New Green Wall for Target racks in place. Detectors/DAQ Checkout underway. Gas Cer looks ok. Left extension to be installed. Left S1M to be installed, Right S1 probably stays. 3 rd Fastbus crate for each arm. Happex DAQ for low noise BPM/BCMs. g 2 p/GEP New spectrometer optics Full simulation (SNAKE+GEANT4) Planning for optics commissioning. 3 dedicated Post-Docs 6+ Students and a large group of onsite collaborators.

Future in Hall A Time (actual years) g2p/GEp 12 mo. Shutdown no promised beam Early Experiments Commissioning SuperBigbite Era Moller SOLID Beam 1 st to Hall A

Early 12 GeV in Hall A Commissioning Early Experiments (new) Hall A Planning Committee to Recommend a Sequence topic for winter 2011 collaboration meeting 12 mo. Shutdown

SuperBigbite Era Large Projects in Hall A Passed 2 thorough technical reviews Split into 3 capital funding projects connected to experiments. DOE Science & Technical Review Oct 13-14, 2011

Moller SOLID Large Projects in Hall A, cont. Highly-rated experiments (designed to move aside and share the hall) Moller: 344 PAC days MIE to be submitted this Fall SOLID: SIDIS & DIS-parity Moller Experiment

Hall A Recent Publications (2010 – 2011) S. Abrahamyan, et.al. Search for a new gauge boson in the A‘ Experiment (APEX). arXiv: [hep-ex] J. Huang, et.al. Beam-Target Double Spin Asymmetry A_LT in Charged Pion Production from Deep Inelastic Scattering on a Transversely Polarized He-3 Target at 1.4 < Q 2 <2.7 GeV 2. arXiv: [nucl-ex] K. Paschke, et.al. New Precision Limit on the Strange Vector Form Factors of the Proton. arXiv: [nucl-ex] X. Qian, et.al., Single Spin Asymmetries in Charged Pion Production from Semi-Inclusive Deep Inelastic Scattering on a Transversely Polarized 3 He Target. Phys.Rev.Lett.107:072003,2011 G. Ron et al. Low Q 2 measurements of the proton form factor ratio $mu_p G_E / G_M$. arXiv: [nucl-ex] A.J.R. Puckett, et.al., Reanalysis of Proton Form Factor Ratio Data at Q 2 = 4.0, 4.8, and 5.6 GeV 2 arXiv: [nucl-ex] S. P. Malace, et.al. A precise extraction of the induced polarization in the 4 He(e,e'p) 3 H reaction Phys.Rev.Lett.106:052501,2011 S. Riordan, et.al., Measurements of the Electric Form Factor of the Neutron up to Q2=3.4 GeV 2 using the Reaction 3He(e,e'n)pp Phys.Rev.Lett.105:262302,2010. E. Fuchey, et.al., Exclusive Neutral Pion Electroproduction in the Deeply Virtual Regime Phys.Rev.C83:025201,2011 J. Glister, et.al. Polarization Observables in Deuteron Photodisintegration below 360 MeV Phys.Lett.B697: ,2011. M. Paolone, et.al., Polarization Transfer in the 4 He(e,e'p) 3 H Reaction at Q^2 = 0.8 and 1.3 (GeV/c) 2 Phys.Rev.Lett.105:072001,2010. M. Coman, et.al., Cross sections and Rosenbluth separations in H-1(e, e-prime K+)Lambda up to Q 2 = 2.35 GeV 2 Phys.Rev.C81:052201,2010. I. Pomerantz, et.al., Hard Photodisintegration of a Proton Pair Phys.Lett.B684: ,2010 G.D. Cates, et.al., Flavor decomposition of the elastic nucleon electromagnetic form factors Phys.Rev.Lett.106:252003,2011

Successful recent running Publications : ~7 per year g2p / GEp is on track. The low-energy beam time is vital. Bright future for the 12 GeV era Summary: Hall A