19-23 april 2010 dis 2010 / florence neutron single target spin asymmetries in sidis

21 Apr 2010 / DIS10 / Florence E. Cisbani: n SSA @ JLab/Hall A 1

19-23 April 2010

DIS 2010 / Florence

Neutron Single Target Spin Asymmetries in SIDIS

(at JLab HallA)

E. CisbaniINFN Rome and Italian National Institute of Health

on behalf of the 6 GeV Transversity collaboration

http://hallaweb.jlab.org/experiment/transversity/


Outline

• Single Spin Asymmetries in SIDIS on transversely polarized target

• “Transversity” Experiment in HallA– Kinematic– Target– Detectors (HRS + BB)– Hadrons Production

• JLab 12 GeV prospective – “SIDIS” Experiment with SBS– “Transversity” Experiment with SoLID

Ongoing analysis thanks to the excellent work of several PhD Students:C. Dutta (Kentucky), J. Huang (MIT), A. Kalyan (Kentucky), J. Katich (W&M), X. Qian (Duke), Y. Wang (UIUC), Y. Zhang (Lanzhou U)


From SIDIS to SSA to DFFF

Pretzelosity

Evaristo Cisbani

Deltaq - deltaq = k2/M2 * Pretzelosity Pretzelosity difference between elicity and transversity: a measure of the relativistic effects!


Hep

ex-0

802.

2160

Fro

m D

IS20

09F

rom

Pap

pala

rdo

/ Tra

nsve

rsity

200

8

Collins Moments on proton/deuteronCOMPASS/deuteron

proton

Proton:• K- and - with opposite sign, strong flavor

dependence (but K errors significant)!• K+ and + consistent with u dominance• COMPASS compatible with HERMES

Deuteron: consistent with 0, expected asymmetry on neutron as large as on proton

Larger effects at larger x


PLB

673(

2009

)127

COMPASS/deuteron

Sivers Moments on proton/deuteron

PR

L103

(200

9)15

2002

Proton:• K+ twice + conflict with u dominance

expectation• K- and - consistent with 0• COMPASS proton not fully compatible to

HERMESDeuteron: consistent with 0, expected asymmetry on neutron as large as on proton

NEW DATA FROM COMPASS/ProtonSEE H. Fischer and A. Martin talks in this conference

HERMES on p


6 GeV CEBAF (< 2013)Max Current: 200 A

Max Energy: 0.8 - 5.9 GeV

Long. Polarization: 85%




JLab Accelerator Facility


Transversity on neutron: Hall A experimental setup• Beam e-:

5.9 GeV, 15 mA

• Neutron Target: High pressure polarized 3He

pol. 65%, 50 mg/cm2 x 40 cmLuminosity: 1036/s/cm2

• Electron Arm (BigBite): E’=0.72.2 GeV,=30°, =64 msr

• Hadron Arm (HRS Left): Ph =2.35 GeV/c ± 5%,=30°, =6 msr, p/K ID

• Kinematic region: Q2 ~ 2.2 GeV2,

x ~ 0.130.45, z ~ 0.5

• Measure Collins, Sivers and Pretzelosity

• Beam e-: 5.9 GeV, 15 mA

• Neutron Target: High pressure polarized 3He

pol. 65%, 50 mg/cm2 x 40 cmLuminosity: 1036/s/cm2

• Electron Arm (BigBite): E’=0.72.2 GeV,=30°, =64 msr

• Hadron Arm (HRS Left): Ph =2.35 GeV/c ± 5%,=30°, =6 msr, p/K ID

• Kinematic region: Q2 ~ 2.2 GeV2,

x ~ 0.130.45, z ~ 0.5

• Measure Collins, Sivers and PretzelosityData Taking:

Nov/08 – Feb/09Data Taking:

Nov/08 – Feb/09

E06-010

e+3He→e’+(K)+X


3He (n) Polarized Target

• Polarized 3He ~ polarized neutron target

• Use 3 COMET lasers (narrow line, high power) for optical pumping of Rb vapor

• Fast spin exchange (via K) by 3He hyperfine

interaction in oven; small part of N2 to quench

soft photon depolarization of Rb

• Polarized 3He diffuses to the target chamber

• Transverse Horizontal (In-plane) and Vertical orientations

• 20 minute spin flip

• NMR and EPR polarimetries

• Superior performances:

– Steady 65% polarization @ 15 uA beam (world record)


Electron Arm (BigBite)


Hadron Arm: HRS-L

1.27

NIM A522 (2004) 294


Measured Phase Space

DIS: Q2>1, W>2.3, Mx>1.6, 0.3<z<0.7

Mx


Preliminary

Hadron Identification• Aerogel Cherenkov Counter

rejection > 98%

• Time of Flight– K/ separation at 4

• RICH proximity focusing detector– K/ separation at 3.8

data from APS2010 / Y. Wang

Ph = 2.33 – 2.47 GeV/c

Strongestquality cuts


Projected Stat. on Asymmetries

Work in progress

Preliminary results expected to be released within summer/2010 !

(Extend measurement

to x=0.4)


JLab at 12 GeV

and

the SSA measurements

prospective in Hall A


CEBAF 12 GeV upgrade

CHL-2CHL-2

Upgrade magnets Upgrade magnets and power and power suppliessupplies

add Hall D (and beam line)

12 GeV CEBAF

(>2013)Max Current: 90 AMax Energy Hall A,B,C: 10.9 GeVMax Energy Hall D: 12 GeVLong. Polarization: 75-85%





Peculiarity of JLab Phase Space

Access unexplored valence region

(high Q2 requires high luminosity)

from TMD-Duke / M. Contalbrigo

Hall A is already running at 1036 and will likely reach few 1037 (in polarized experiments)

1037


SSA on n in the 11 GeV era in Hall A

• SIDIS on and K (conditionally approved, 01/2009) – short term

– G. Cates, E. Cisbani, G.B. Franklin, B. Wojtsekhowski

– Similar layout of the 6GeV experiment at higher luminosity and acceptance

• HRS replaced by a new large acceptance spectrometer (SBS), improved target

– 2D binning on the relevant variables: x, P and z, for both hadrons and Q2 dependence

– High x valence region (with overlap to HERMES, COMPASS, JLab6 data)

– Proposal: http://hallaweb.jlab.org/collab/PAC/PAC34/PR-09-018-sidis.pdf

• SoLID-Transversity experiment (approved, 01/2010) – medium term

– J.-P. Chen, H. Gao, X. Jiang, J.-C. Peng, and X. Qian

– Use solenoid magnet• 2 angular coverage optimal systematics control

– Precision measurement in 4D phase space (x, z, P and Q2)

– Extended phase space coverage

– Proposal: http://hallaweb.jlab.org/collab/PAC/PAC35/PR-10-006-SoLID-Transversity.pdf


SIDIS: Experimental Setup

Beam: 50 A, E=8.8 and 11 GeV (80% long. Pol.)Target: 65% polarized 3He GEn(2)/PR-09-016 Luminosity: 1.4×1037 cm-2s-1 , 0.05 sr

e+3He→e’+(K)+X HERMESRICH

Measure the SSA of SIDIS processes n(e,e’p)X and

n(e,e’K)X

BB: e-arm at 30o

= 45 msrGEM TrackerGas CherenkovShower GMn/PR-09-019

SBS:h-arm at 14o

= 50 msrGEM trackerexcellent PID / RICHHadron CALO

PAC34 Conditionally Approved experiment

Most of the equipments from EM Form-Factors experiments

Event rate: ~104×HERMES60 days of production expected stat. accuracy:

1/10 of proton HERMES


SIDIS: A new target

from SBS-IV / G.D. Cates


SIDIS: Hadron PID HERMES RICH

Very stable performance (n/(naerogel-1)= 1%, 9 years)Stored at UVa under safe/controlled conditions(also additional wall of spare Aerogel)

5.5 GeV K+

14.6 GeV e-1.5 GeV -

REAL DATA from NIMA 479 (2002) 511

C4F10 gas


SIDIS: Q2 coverage

Current Transversity Exp. E06-010

Prop. Exp. Ebeam = 8.8 GeV

Prop. Exp. Ebeam = 11.0 GeV

We will investigate the Q2 dependence of the Sivers and Collins functions, with overlap in the region of HERMES; reveal higher twist effects.

Analysis of the Q2 effect will use also the results of 6 GeV E06-010 Transversity experiment


Azimuthal Coverage

0.15 < x <0.65h_cent. = 14°

Ebeam = 11 GeV4 target spin

directions

Complete coverage of the Collins, Sivers and “Pretzelosity” azimuthal angles with 4 target spin directions

(with 8 target spin directions even better uniformity)

Partial coverage of h but in sin/cos sensible regions

h


SIDIS: Expected Statistical Accuracy on K

• Superior quality of Kaon data

• Extend at higher x with partial overlap with existing data on proton, deuteron and expected results of HallA Transversity 6 GeV DF from CTEQ5M

FF from DSSRate normalized to HERMES/p+d K production


SoLID: experimental setup

from JLab-PAC35 / X. Qian

E10-006 PAC35 Approved experiment

Solenoid magnetic field (2 azimuthal coverage)

Polarized target in a fringe field similar to 6 GeV experiment

Tracking: GEM technology

CALO + Cherenkov threshold for PID

Multi-RPC for timing

Large part of the setup used for PVDIS experiment


SoLID: Phase Space

from JLab-PAC35 / X. Qian


SoLID: Projected Data

xfrom JLab-PAC35 / X. Qian


Summary• 6 GeV “Transversity” Experiment on and K

– Data taken on n in 3 months (Nov/08 – Feb/09)

– Almost completed analysis for -SSA

– First results to be released soon (likely before Summer/2010)

• 12 GeV Prospective (after 2013)– Two SSA experiments proposed on 3He target in HallA

– Will provide data on Transversity/Sivers/Pretzelosity in the valence region at different Q2 using the same physics mechanism but complementary instrumental approaches different time scale and projected performance:

• SBS-SIDIS: and K SSA with quite improved statistics

• SoLID-Transversity: SSA with ultimate precision

– both will benefit of JLab luminosity and 3He polarized targets progress

19-23 april 2010 dis 2010 / florence neutron single target spin asymmetries in sidis

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