SoLID-Spin Program at 12 GeV JLab

Xin QianKellogg Radiation Lab

CaltechFor SoLID Collabration

1Weihai Workshop

Outline• Nucleon Spin – Transverse Momentum Dependent Parton

Distribution Functions (TMDs)– Semi-Inclusive Deep Inelastic Scattering

(SIDIS)

• Current Status of Single Spin Asymmetry (SSA) Measurements

• Overview of SoLID-Spin Program• Summary

2Weihai Workshop

Nucleon Spin Structure• Understand Nucleon Spin in terms of quarks and

gluons (QCD).

– Small contribution from quarks and gluons’ intrinsic spin

~30% from data “spin crisis”

Nucleon’s spinJi’s Sum Rule

J q

Orbital angular momentum is important!Parton transverse motion + Spin-orbit correlations

Weihai Workshop 3

Transverse Momentum Dependent PDFs

TMD f1u(x,kT)

Longitudinal Direction zTransverse

Plane x-y4Weihai Workshop

A Unified Picture of Nucleon Structure (X. Ji) Wp

u(x,kT,r ) Wigner distributions

PDFs f1

u(x), .. h1u(x)

d2kT

d3r

TMD PDFs f1

u(x,kT), .. h1u(x,kT)

X. Ji PRL 91 (03)

3D imaging

6D Des.

Form FactorsGE(Q2), GM(Q2)

GPDs/IPDs

d2kT drz

d2rT

dx &Fourier Transformation

1D5Weihai Workshop

Leading-Twist TMD PDFs

f1 =

f 1T =

SiversSivers

HelicityHelicity

g1 =

h1 =TransversityTransversity

h1 =

Boer-MuldersBoer-Mulders

h1T =

PretzelosityPretzelosity

g1T =

Worm GearWorm Gear

h1L =

Worm GearWorm Gear(Kotzinian-Mulders)(Kotzinian-Mulders)

Nucleon Spin

Quark Spin

Spin-orbital (trans. mom.) correlation is important!

Very well known

Reasonably known

Weihai Workshop 6

Semi-Inclusive DIS• A DIS reaction in which a hadron h, produced in the

current fragmentation region is detected coincidently with scattered electron (k’).

Parton distribution function (PDF)

Fragmentationfunction (FF)

DXs ~ PDF X FF

h tags struck quark’s flavor, spin andtransversemomentum

Current Fragmentation

h

XhkPk '

Weihai Workshop 7

Access TMDs through SIDIS

SL, ST: Target Polarization; e: Beam Polarization

...]})cos(1[

...]1[

...])3sin(

...)()sin(

)sin([

...])2sin([

...)2cos(

...{

)1(2

)cos(2

2

)3sin(

)sin(

)sin(

)2sin(

)2cos(

,

2

2

2

2

Sh

Sh

Sh

Sh

h

h

LTSheT

LLeL

UTSh

ULSh

UTShT

ULhL

UUh

TUU

hhS

FS

FS

F

F

FS

FS

F

F

y

xyQdPdzddxdyd

d

Unpolarized

PolarizedTarget

PolarizedBeam andTarget

Boer-Mulder

Sivers

Transversity/Collins

Pretzelosity

Weihai Workshop 8

Separation of Collins, Sivers and pretzelocity effects through angular dependence

1( , )

sin( ) sin( )

sin(3 )

l lUT h S

h SSiverCollins

Pretzelosi

UT

tyU

sUT h S

h ST

N NA

P N

A

A

N

A

1

1 1

1

1 1

sin( )

sin(3 )

sin( )Co

PretzelosityU

SiversUT

llins

T h S T

h S

UT

UT h S

TU

UT

TA

H

f

A

D

A h H

h

Weihai Workshop

UT: Unpolarized lepton + Transversely polarized nucleon

9

Collins effect• Access to transversity– Transversity links

quak’s spin tonucleon spin

– Collins FF links quark’s spin to hadron transverse momentum

• Artru model– Based on LUND

fragmentation picture.

Weihai Workshop

11 HhA TCollins

10

Rich Physics in TMDs (Sivers Function)• Correlation between nucleon spin with quark orbital

angular momentum

Burkhardt : chromodynamic lensing

Final-State-InteractionYD

qTSIDIS

qT ff

11Important test forFactorization

11 DfA TSivers

Weihai Workshop 11

Current Status on TMD• Collins Asymmetries - Sizable for proton (HERMES and COMPASS)

Large at high x, large for - but with opposite signUnfavored Collins fragmentation as large as favored (opposite

sign) Also see Belle's data. - consistent with 0 for deuteron (COMPASS)

- small for neutron (JLab Hall A)• Sivers Asymmetries - non-zero for + from proton (HERMES), consistent with COMPASS

results at high Q2? - consistent with zero for - from proton and for and - from

deuteron - negative values for neutron + , small for - (Hall A)• Very active theoretical and experimental study• RHIC-spin, JLab (CLAS12, HallA/C 12 GeV), Belle, FAIR (PAX)

Future EIC• Global Fits/models by Anselmino et al., Yuan et al. and …

12Weihai Workshop

E06010: arXiv: 1106.0363, PRL in press

Weihai WorkshopSee X. Jiang’s talk 13

• High 1036 N/cm2/spolarized luminosity

• Achieved Performance:– Transverse/Vertical and

Longitudinal PolarizedTarget

– >60% polarization– Fast Spin Flip

• Large acceptanceenables 4-D mappingof asymmetries

• Full azimuthal-angle coverage -> smaller systematic uncertainties

SoLID Setup for SIDIS on 3He

~90% ~1.5% ~8%

Effective pol. neutron target

14Weihai Workshop

SoLID Setup for SIDIS on 3He• Tracking: GEM Tracker.– Shared R&D with Super

BigBite• Electron Identification:– E&M calorimeter for large

angle and high momentum– E&M calorimeter and light gas

Cerenkov for forward angle• Pion identification:– Heavy Gas Cerenkov and TOF

(Multi-Resistive Plate Chamber)

• Fast pipeline DAQ (Similar to Hall D)

• See Z. W. Zhao’s talk for simulation

Progressive Tracking, Mom. res. 1%, polar angular res. 0.3 mr, azimuthal angular res. 5 mr, 0.8 cm vertex res with realistic magnetic field simulation and 200 um GEM pos. res. Shoot for 100 ps TOF resolution, (60 ps intrinsic resolution from MRPC) 15Weihai Workshop

SIDIS L.-G. Cherenkov: Optical system

)11

(cos

2

rxix

R

Focusing optimized for central ray: for SIDIS kinematics (BaBar) => (9.3 + 14.3)/2 = 11.8 deg

mirror the tonormal and

ray incident between angle

ray reflected

mirroron ray incident

rxix

One spherical mirror

Slide from S. Malace16Weihai Workshop

SIDIS L.-G. Cherenkov: Focusing “-scan”: at fixed polar angle check collection efficiency as a function of the azimuthal angle

Example: 14.3 deg & 3.5 GeV

Example: 14.3 deg & 1.5 GeV

Collection efficiency dependence of : small effect at isolated kinematics

Slide from S. Malace 17Weihai Workshop

• Two main choices– High resolution, radiation hardness, 100ps timing

• SciFi ECal– Simulation shown in last meeting

• W-Ecal resolution is not enough• Pb-Ecal (with >50% SciFi ratio) works

– Require large area light readout– Not cheap

• Shashlik Type– Pickup/Readout photon with wave-length shifting fiber, small light

read out area

Weihai Workshop 18

Choice of CalorimeterTypical Pb SciFi

Hertzog, NIM, 1990

Typical ShashlikPolyakov, COMPASS Talk, 2010

Talk from J. Huang

Weihai Workshop 19

Scan for best shower and preshower thickness

Reach Best rejection @ 3~5rad

length

Reach Best rejection @ 3~5rad

length

Total rad length

Total rad length

No

pres

how

er s

epar

ation

Electron Efficiency

1/ (Pi rejection)Minimal is best

Reach Best rejection @ ~20

rad length

Reach Best rejection @ ~20

rad length

Total rad length

Can not contain

EM shower More hadron shower

Electron Efficiency

Talk from J. Huang

• L2: additional detector, simple pattern matchhttps://www.jlab.org/exp_prog/electronics/trigdaq/PipelineTriggerElectronics_S&T09.pdf

Ben Raydo Talk

20Weihai Workshop

ROCROC

ROCROC

ROCROC

ROCROC

ROCROC

ROCROC

ROCROC

ROCROC

ROCROC

Front-End

Crates

Read O

ut

Con

trolle

rs

~60 crates~50MB/s out

per crate

EB1Event Builder

stage 1

EB1Event Builder

stage 1

EB1Event Builder

stage 1

EB2Event Builder

stage 2

EB2Event Builder

stage 2

Staged Event Building

blocked event fragments

partially recombined event fragments

N x M array of nodes (exact number to be determined by available hardware at time of

purchase)

Level-3 Trigger

and monitori

ng

full events

L3 FarmL3 Farm

nodenode

nodenode

nodenodenodenode

nodenodenodenode

nodenode

Raid

Dis

k

EREvent Recorder

Event Recording

300MB/s in300MB/s out

• All nodes connected with 1GB/s links

• Switches connected with 10GB/s fiber optics

L3 Farm (slide from A. Camsonne)

Weihai Workshop21

Natural Extension of E06-010

• Both transverse and longitudinal polarized target.

• Attack 6/8 leading twist TMDs

• Much wider phase space– Also data at low and high

z value to access target frag. and exclusive channels.

11

11

11

)cos(

)sin(

)sin(

DgA

DfA

HhA

TshLT

TshSiversUT

TshCollinsUT

22Weihai Workshop

Transversity• The third PDFs in addition to f1 and g1L

• 10% d quark tensor charge with world data• Test Soffer’s inequality |h1T| <= (f1+g1L)/2 at large x

h1T =

23Weihai Workshop

Map Collins, Sivers and Pretzlosity asymmetries in a 4-D (x, z, Q2, PT)

24Weihai Workshop

Sivers Function• Correlation between nucleon spin with quark angular momentum• Important test for factorization• Different sign with twist-3 quark-gluon corr. dis. at high PT?

– Kang, Qiu, Vogelsang and Yuan: arxiv: 1103.1591– Search for sign change, also PT weighted moments (Boer, Gamberg, Musch)

f 1T =

YD

qTSIDIS

qT ff

11

UUT

UUUTTTJUT

dP

APJdPA

Sh

Sh

)sin(

)sin()(

Also in x

25Weihai Workshop

Pretzlosity:• Direct measurement of relativistic effect of quark?

PRD 78, 114024 (2008)• Direct measurement of OAM? PRD 58, 096008 (1998)• First non-zero pretzlosity asymmetries?

h1T =

26Weihai Workshop

Worm-gear functions:• Dominated by real part of interference

between L=0 (S) and L=1 (P) states• No GPD correspondence• Lattice QCD -> Dipole Shift in mom. space.• Model Calculations -> h1L

=? -g1T

• Connections with Collinear PDFs through WW approx. and LIR.

h1L =

g1T =

Worm Gear

Cent

er o

f poi

nts:

)()(~ 11 zDxgA TLT )()(~ 11 zHxhA LUL

27Weihai Workshop

SIDIS Factorization Test at 11 GeV– With proton/deuteron/3He unpolarized data in a large

phase space coverage.• Understand SIDIS process (Factorization , PT dependence)

• Complementary to Hall C RSIDIS, PT dependence studies.

• Complementary to Hall B SIDIS, PT dependence studies.

• Understand the Nuclear effect in the light nuclei.

28Weihai Workshop

A New Proposal of TSSA Measurement of a Transversely Polarized Proton (NH3)

• PAC report for 3He SoLID-Spin Proposal

Weihai Workshop 29

• 3 cm long NH3 target• 1035 N/cm2/s polarized luminosity• 5 T holding field • line of flames• Optics property of magnetic field

70% Polarization

Projections @ 120 days

Weihai Workshop 30About a factor of 4-5 worse than neutron measurement due to lower luminosity and larger dilution, but asymmetry is also larger with proton

Bright Future for TMDs• Golden channel of Electron-Ion Collider

– See Abhay Despande’s talk

• Sea quark TMDs Gluon Sivers? What happened at very low x? SIDIS vs. dipole model

• Test Collins-Soper Evolution for high vs. low Q2 at large x. 31Weihai Workshop

Summary• SIDIS is a powerful tool to study Parton dynamics

in the amplitude level (TMDs)– Spin-OAM correlation, flavor dependence etc.

• SoLID is an ideal device to study SIDIS– High luminosity, large acceptance and full azimuthal

coverage– Will provide ultimate precision (4-D) of SSA/DSA, at

high-x (valence), low Q2 region, which is crucial input to global analysis.

– Test SIDIS factorization, PT dependence at JLab12 (complementary to SIDIS programs in Hall B/C)

32Weihai Workshop

Weihai Workshop 33

Weihai Workshop

Quark Tagging Technique

)9

2()

9

4()

9

1()

9

1()

9

4(

)9

1()

9

8()

9

1()

9

4()

9

4(

..

pp

SC

nnn

ppppp

uddduN

duduuP

u quark dominated

Sensitive to d quark

)( du )( du

duudunfav

uddufav

DDDDD

DDDDD

favunfavn

unfavfavn

favunfavp

unfavfavp

DuDd

DuDd

DdDu

DdDu

24

24

8

8

u quark dominatedu quark dominatedSensitive to d quarkSensitive to u quark

34