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E06-010 / E06-011 Transversity Experiments

Overview, Manpower and Safety Readiness Review, March 19, 2007

Spokesperson: Jian-Ping Chen, Evaristo Cisbani, Haiyan Gao, Xiaodong Jiang, Jen-Chieh Peng

• Goal of the transversity experiments

• Requirements of the transversity experiments

• Collaboration and manpower

• Safety issues

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• Remaining frontier of kT – independent structure functions

• Connections to many other kT – dependent distribution and fragmentation functions

• Major experimental efforts to measure transversity using lepton and hadron beams

Physics Motivation: Transversity

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How to measure transversity?

• Transversely Polarized Drell-Yan

• Semi-Inclusive DIS– Single-hadron (Collins fragmentation function,

H1┴(z))

– Two hadrons (Interference fragmentation function)

– Vector meson polarization– Λ - polarization

• Chiral-odd → not accessible in DIS

• Require another chiral-odd object

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Leading-Twist Quark Distributions

Three have no kT

dependence

The other five are transverse momentum (kT)

dependent (TMD)

( A total of eight distributions)

Semi-inclusive DIS can access all leading-twist quark distributions

Transversity

Sivers function

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Observation of Single-Spin Azimuthal Asymmetry

Longitudinally polarized target

ep → e’πx HERMES

<ST> ~ 0.15

Collins effect: Correlation between the quark’s transverse spin with pion’s pT in the fragmentation process δq(x) • H1

┴ (z).

Sivers effect: Correlation between the transverse spin of the proton with the quark’s transverse momentum f1T

┴ (x) • D(z).

Other higher twist effects could also contribute.

Origins of the sin(Ф) azimuthal asymmetry ?

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Simultaneous fit to sin( + s) and sin( - s)

(s is the azimuthal angle of the target spin)

Use transversely polarized hydrogen target to separate the two effects (Collins vs. Sivers)

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sin( ) moment

~ ( ) ( )

s

q x H z

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sin( ) moment

~ ( ) ( )

s

Tf x D z

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Extraction of Collins functions from the Collins asymmetry measurements

Fits to the Hermes data “Prediction” of the Compass data

, ,1 1 1 1Assuming ( ) (1 ) ( ); ( ) (1 ) (

0.29 0.04, 0.33 0.

)

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fav fav u

fav unfa

nfav favfav unfav

v

H z C z z D z H z C z z D

C C

z

( Vogelsang and Yuan, hep-ph/0507266 )

( , )p e e ( , )d h

, ,1 1

Striking flavor dependence for the Collins frag. function:

/ 1unfavored favoredH H

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Extraction of Sivers functions from the Sivers moment measurements

Fits to the Hermes data “Prediction” of the Compass data

, ,1 1Assuming ( ) (1 ) ( ); ( ) (1 ) ( )

0.81 0.07, 1.86 0.28

u dT u T d

u dS

f x S x x u x f x S x x u x

S

( Vogelsang and Yuan, hep-ph/0507266 )

Striking flavor dependence of the Sivers function (Sd ≈ -2Su)

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Opportunities at JLab for transversity experiments

• High-intensity CW electron beam• High-density polarized 3He target which could be

polarized transversely• Probe valence-quark region similar to HERMES

kinematics, providing complimentary information on transversely polarized neutron

• An independent test of the striking flavor structures of Collins and Sivers functions observed at HERMES/COMPASS

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3He↑(e,e’π+,-)x at Hall-A

• Beam– 6 GeV, 15 μA e- beam

• Target– Optically pumped Rb-K spin-exchange 3He target, 50 mg/cm2, ~42%

polarization, transversely polarized with tunable direction• Electron detection

– BigBite spectrometer, Solid angle = 60 msr, θLab = 300

• Charged pion detection– HRS spectrometer, θLab = -160

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Kinematic coverage of the electron arm

• BigBite spectrometer set at θ=30° at beam-right detecting electrons with 0.5 < E’ < 2.2 GeV.

• The coverage in Bjorken-x is 0.135 < x < 0.405, corresponding to valence-quark region.

• For the four x bins, the range of mean-Q2 is 1.3 < <Q2> < 3.1 (GeV/c)2.

• The coverage in W, the invariant mass of the hadronic system, is 2.33 < W < 3.05 GeV, well above the resonances region.

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Hall-A polarized 3He target

• 40-cm long Rb-K spin-exchange hybrid cell at 10 atm with beam current of 15 μA

• 42% target polarization with spin-flip frequency of 20 minutes

• A third set of Helmholtz coils will be added, together with the laser optics, to allow for vertical polarization of the 3He target

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Kinematic coverage of the hadron arm

• HRSL situated at θ = -16° will measure charged hadrons with mean momentum p = 2.4 GeV/c.

• The fraction of the virtual photon energy carried by the hadron, z = Eh/ν, is z ≈ 0.5 to detect leading pion in the current fragmentation region.

• A cut of W ’ > 1.5 GeV is required to stay away from the delta resonance production region.

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Predictions of Collins asymmetry on neutron

1 14n unfav favUTA d H u H

1 1 1 1/ /unfav fav unfav favH H D D

1 1/ 1unfav favH H

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Instrumentation Request for E06-010/E06-011• Beam

– Polarization: above 75%– Energy: 6 GeV– Current: 25 μA

• Target (talk by Jian-Ping Chen)– 40-cm long Rb-K hybrid polarized 3He target at

10 atm– > 40% target polarization with spin-flip period

of 20 minutes– Third sets of vertical Helmholtz coils and

associated laser opticvs for vertical polarization

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Instrumentation Request for E06-010/E06-011• HRS-L spectrometer (talk by A. Camsonne)

– Momentum range: 0.6-2.4 GeV/c – VDC1, VDC2, S1, Short gas Cherenkov, A1,

S2M, Preshower/shower – RICH for π/K separation (talk by E. Cisbani)

• Bigbite spectrometer (talk by X. Jiang)– Electron detection package– Wire-chamber-2 upgrade (talk by M. Shabestrai)– Gas Cherenkov (talk by B. Sawatzky)– Shielding and collimation

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Hall A Transversity Experiments CollaborationThe Institutions

California State Univ., Duke Univ., Florida International. Univ., Univ. Illinois, JLab, Univ. Kentucky, Univ. Maryland, Univ. Massachusetts, MIT, Old Dominion Univ., Rutgers Univ., Temple Univ., Penn State Univ., Univ. Virginia, College of William & Mary, Univ. Sciences & Tech, China Inst. Of Atomic Energy, Beijing Univ., Seoul National Univ., Univ. Glasgow,

INFN Roma and Univ. Bari, Univ. of Ljubljana, St. Mary’s Univ., Tel Aviv Univ.

A. Afanasev, K. Allada, J. Annand, T. Averett, F. Benmokhtar, W. Bertozzi, F. Butaru, G. Cates, C. Chang, J.-P. Chen* (Co-SP), W. Chen, S. Choi, C. Chudakov, E. Cisbani*(Co-SP), E. Cusanno, R. De Leo, A. Deur, C. Dutta*, D. Dutta, R. Feuerbach, S. Frullani, L. Gamberg,

H. Gao* (Co-SP), F. Garibaldi, S. Gilad, R. Gilman, C. Glashausser, J. Gomez, M. Grosse-Perdekamp, D. Higinbotham, T. Holmstrom, D. Howell, M. Iodice, D. Ireland, J. Jansen, C. de Jager, X. Jiang* (Co-SP), Y. Jiang, M. Jones, R. Kaiser, A. Kalyan*, A. Kelleher, J. Kellie, J.

Kelly, A. Kolarkar, W. Korsch, K. Kramer, E. Kuchina, G. Kumbartzki, L. Lagamba, J. LeRose, R. Lindgren, K. Livingston, N. Liyanage, H. Lu, B. Ma, M. Magliozzi, N. Makins, P. Markowitz, Y. Mao, S. Marrone, W. Melnitchouk, Z.-E. Meziani, R. Michaels, P. Monaghan, S. Nanda, E. Nappi, A. Nathan, V. Nelyubin, B. Norum, K. Paschke, J. C. Peng*(Co-SP), E. Piasetzky, M. Potokar, D. Protopopescu, X. Qian*, Y. Qiang, B. Reitz, R. Ransome, G. Rosner, A. Saha, A.

Sarty, B. Sawatzky, E. Schulte, S. Sirca, K. Slifer, P. Solvignon, V. Sulkosky, P. Ulmer, G. Urciuoli, K. Wang, Y. Wang*, D. Watts, L. Weinstein, B. Wojtsekhowski, H. Yao, H. Ye, Q. Ye,

Y. Ye, J. Yuan, X. Zhan, X. Zheng, S. Zhou, X. Zong

Collaboration members (104 members)

* : Cospokesperson; * : Ph.D students

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Manpower and collaboration responsibilities• 4 Ph.D thesis students stationed at JLab

– Chiranjib Dutta and Allada Kalyan (U. Kentucky)– Xin Qian (Duke U.) and Youcai Wang (UIUC)

• 3 Postdocs– Xiaodong Jiang (Rutgers), Yi Qiang (Duke), Lingyan Zhu (UIUC)

• Responsibilities– Duke: Bigbite detector tests, 3He target, simulations– FIU: HRS detectors– JLab: Bigbite, Polarized 3He target, HRS, DAQ– INFN: RICH and HRS-PID– UIUC: HRS aerogel and RICH, vertical coils, Runplan– Rutgers: Bigbite detectors, shielding, trigger and DAQ, Runplan– Temple: Bigbite Cherenkov, 3He target– W&M: Pol 3He target and cells– U. Kenntucky: Bigbite detector, trigger and DAQ, 3He target– U. Virginia:: Bigbite MWDC, 3He target

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Milestones • Polarized 3He target

– New oven for cell testing: April 1, 2007– Vertical coils test: June 1, 2007– Cell production: 10 by July 1, 2007, 20 by Dec. 1, 2007– Laser optics line: Nov. 1, 2007– Complete system test: Nov. 1, 2007– Ready for installation: Jan. 1, 2008

• Bigbite detectors– MWDC-1, MWDC-3 readout check: May 30, 2007– MWDC-2 delivered to JLab: June 10, 2007– Three chambers readout and tracking test: Sept. 1, 2007– Gas Cherenkov detector commissioning with cosmics: Oct. 1, 2007– Integration of MWDC, Cherenkov, Pre/shower: Dec. 1, 2007

• RICH– RICH frame ready: Sept. 2, 2007– RICH assembled in Rome: Nov. 16, 2007– RICH ready for installation: Dec. 10, 2007

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Safety issues

• Safety at the detector lab and Hall-A

– Laser, fire, high pressure cells, electric and magnetic fields, oven, radiation, hot surface

– All safety documents will be updated

– All necessary trainings will be arranged

• We will work closely with the JLab safety officers to ensure that the proper procedures are in place

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Summary• Significant progress has been made in the

preparation for the Hall-A transversity experiments (Details are presented in later talks)

• The responsibilities of the collaborating institutes have been clearly defined. Four Ph.D students on the transversity experiments are stationed at JLab.

• The collaboration anticipates data-taking around March 2008. The first transversity measurement on polarzied 3He target should provide interesting new information on the novel nuclear structure functions and fragmentation function.