Jin Huang PhD Candidate, MIT For MENU 2010 May 31, Williamsburg

 Un-polarized Nucleon Structure Function ◦ Longitudinal Momentum Distribution ◦ Well probed for 50 years over very large kinematic range  Longitudinal Polarized Nucleon Structure Functions ◦ Since “spin crisis” in 1980s ◦ Plotted in fairly large range  Transverse Momentum Dependent (TMD) Partonic Distributions ◦ Sensitive to the transverse structure of the nucleon ◦ Accessible through Semi-Inclusive DIS (SIDIS) ◦ A new phase of study MENU 2010 Jin Huang 2 g 1 = f 1 =

3 f 1T  = g 1T = h 1L  = h1 =h1 = h 1T = h 1T  = Transversity Boer-Mulder Pretzelosity Sivers Helicity Nucleon Spin Quark Spin f 1 = g 1 = : See X. Jiang’s Talk on Thu : This Talk

MENU 2010 Jin Huang 4 Unpolarized Polarized Target Polarized Beam and Target Boer-Mulder Sivers Transversity Pretzelosity f 1 = f 1T  = g 1 = g 1T = h1 =h1 = h 1L  = h 1T  = h 1T = S L, S T : Target Polarization; e : Beam Polarization

 g 1T DF describe quark longitudinal polarization in a transversely polarized nucleon  Such polarization can be non-vanishing only if the Orbital Angular Momentum is non-zero  Extractable from Double Beam-Target spin asymmetry in SIDIS with transversely polarized target: A LT MENU 2010 Jin Huang 5 To leading twist:

 p T weighted could be estimated from data of g 1 DF through Lorentz Invariance Relations and Wandzura and Wilczek Relations Ref to A. Kotzinian and P. J. Mulders, Phys. Rev. D 54, 1229 (1996)  With assumption of p T dependence, then A LT could also be estimated MENU 2010 Jin Huang 6 From A. Kotzinian, B. Parsamyan, and A. Prokudin, Physical Review D (2006)

 No SIDIS A LT Measurement until recent years  COMPASS data ◦ A LT on Deuteron (~= Neutron + Proton) ◦ A LT Mixed with Single Target Spin Asymmetries in COMPASS extra uncertainty MENU 2010 Jin Huang 7 Eur. Phys. J. Special Topics 162, 89–96 (2008)

MENU 2010 Jin Huang 8  Newport News, Virginia  Linear accelerator provides continuous polarized electron beam ◦ E beam = 6 GeV ◦ P beam = 85%  3 experimental halls A B C

MENU 2010 Jin Huang 9  Polarized 3 He Target  Polarized Electron Beam ◦ ~80% Polarization ◦ Fast Flipping at 30Hz ◦ PPM Level Charge Asymmetry controlled by online feed back  BigBite at 30º as Electron Arm ◦ P e = 0.7 ~ 2.2 GeV/c  HRS L at 16º as Hadron Arm ◦ P h = 2.35 GeV/c Beam Polarimetry (Møller + Compton) Luminosity Monitor

Møller Polarimetry Compton Polarimetry  Performed per week  Polarization -> ~80%  Polarization monitoring  Calibrated by Møller MENU 2010 Jin Huang 10 Beam Polarimetry Luminosity Monitor ‑ 010.html

  New narrow bandwidth COMET lasers  Fast spin exchange with K/Rb hybrid cells MENU 2010 Jin Huang 11 Beam Polarimetry Luminosity Monitor Beam ~90% ~1.5 ~8% SS’D

 High luminosity: L(n) = cm -2 s -1  Record high 65% polarization (preliminary) in beam with automatic spin flip / 20min MENU 2010 Jin Huang 12 Beam Polarimetry Luminosity Monitor

 Single Dipole Magnet  Detects electrons  A “big bite” of acceptance ◦ 64 msr ◦ P : 0.7 ~ 2.2 GeV/c  3 Wire Chambers: 18 planes for precise tracking  Bipolar momentum reconstruction  Pre-Shower and Shower for electron PID  Scintillator for coincidence with Left HRS MENU 2010 Jin Huang 13Pre-ShowerShowerScintillators 3 Multi-wire Drift Chambers (18 planes) Beam Polarimetry Luminosity Monitor

 Left HRS to detect hadrons of p h = 2.35 GeV/c  QQDQ magnet configuration ◦ Very high momentum resolution  Vertical Drift Chambers ◦ Tracking  Scintillator trigger planes ◦ 340ps Coinc. Timing Resolution  Gas Cherenkov & Lead-glass blocks ◦ e/hadron separation  Aerogel Cherenkov & RICH detector ◦ π/K separation MENU 2010 Jin Huang 14 Beam Polarimetry Luminosity Monitor Detector Hut D1 Q1 Q2 Q3 Detector Package Detector Package

p T & ϕ h - ϕ S Coverage MENU 2010 Jin Huang 15 Kinematics Coverage Q 2 >1GeV 2 W>2.3GeV z=0.4~0.6 W’>1.6GeV x bin 1 234

 7 PhD Students ◦ 3 Graduated this month  Detector calibration done  Target analysis close to finalization  Extensive data quality checks ◦ Run selection/beam trip cut/yield check/witness channel check  Two analysis teams cross check results ◦ Red Team: Maximum Likelihood Method ◦ Blue Team: Local Pair-Angular Bin-Fit Method ◦ Asymmetry results are consistent  Systematics in progress  Active theory supports MENU 2010 Jin Huang 16 √

 Preliminary 3 He A LT ◦ Systematic uncertainty is still under work ◦ Projected neutron A LT stat. uncertainty : 6~10% MENU 2010 Jin Huang 17 Preliminary Systematic Uncertainty

 First measurement of neutron A LT from polarized 3 He target  Systematic uncertainties is improved by fast beam helicity flip  Data will cover valence range  Promising Kaon A LT data  Submitting first paper in few months  Precision 4D mapping planed after Jefferson Lab 12GeV upgrade MENU 2010 Jin Huang 18

Systematics Table MENU 2010 Jin Huang 19

ItemSystematic Uncertainty N2 dilution 0.3~0.6% Relative Yield Drift PPM Relative MLE Non-local<100PPM Absolute Raw MLE Approximation125PPM Absolute Raw BigBite π− Cont.1~7% of Stat. Uncertainty BigBite Photon-induced electron Cont.~80%, 40%, 10%, 10% of Stat. Uncertainty Random Coincidence Correction10e-4 Absolute Raw HRS Kaon Cont.1.4e-4 Absolute Raw Bin Centering~10%, 6%, 10%, 20% of Stat. Uncertainty Target Density7PPM Absolute Raw Target Polarization5% Relative Beam Polarization3.8% Relative + 3.7% Rel. Left HRS Single Track<5e-5 Absolute Raw BigBite Tracking Quality~1e-4 for Pi-; <5e-5 for Pi+ Absolute Raw Livetime/Charge Asymmetry CorrectionMLE only: <10 PPM level Absolute Raw A_LL leak10~20% for Pi+ 5% for Pi- (Rel. to Stat. Uncer.) MENU 2010 Jin Huang 20