Spin-dependent electron scattering from a Polarized 3He Target

And precision measurement of A=3 in Hall B

Dien Nguyen

User Group Meeting

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Outline:q Two Experiments: Polarized 3He And A = 3

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Outline:q Two Experiments: Polarized 3He And A = 3 q Longitudinal Spin –dependent DIS and SIDIS

q PT-dependence of the longitudinal neutron spin structure

q Nuclear corrections to the SIDIS process

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Outline:q Two Experiments: Polarized 3He And A = 3 q Longitudinally Spin –dependent DIS and SIDIS

q PT-dependence of the neutron longitudinally spin structure

q Nuclear correction to SIDIS

q Quasielastic on A = 3q (e,e’): Neutron form factorq (e,e’p): Few-Body nuclear Structureq (e,e’pN): SRCs

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Longitudinally Polarized 3He in CLAS12

q Target conceptual design

q Physics overview

ContextqRecent technical advance by BNL-MIT collaboration (intended for EIC ion

source)

qCryogenically cooled target cell in diffusive contact with pumping cell

qCan locate polarized 3He target in 5T central solenoid of CLAS12

qCan achieve CLAS12 maximum luminosity L = 10^35 /cm2/s at 2.5 muA

q30 PAC days requirement

q The measurements we propose complement the approved ND3 CLAS12 program.

q They also are complementary to ongoing and planned SEOP experiments and can strengthen the science case for the proposed SoLID spectrometer. 7

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Why Polarized 3He ?

q Calculable light nuclear systemq Crucial for the study of neutron spin structureq Complementary to the deuteronq Routinely used in electron scattering since 1980s with

low magnetic field targets

q Polarized 3He is an effective polarized neutron target

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Polarized 3He Targetsq Spin Exchange Optical Pumping (SEOP) of 3He has been an

integral tool for spin physics since SLAC§ JLab 6 GeV era: 13 experiments in Hall A§ JLab 12 GeV era: already 7 approved experiments

q Polarized 3He never used in Hall B§ SEOP 3He is not available within CLAS12 5T solenoid due

to increasing wall relaxation at high magnetic field.

q Metastability Exchange Optical Pumping (MEOP) of 3He operates at much lower pressures§ Used in medical imaging, neutron scattering§ MIT-Bates 88-02 polarized 3He target used double cell

cryotarget (17 K) to increase densityq New development: High Magnetic Field MEOP

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MEOP at High Magnetic Fields: Higher Pressures

Reach > 50% polarization, at 4.7 T and 100 mbar

§ Polarized 3He Ion Source: High field MEOP design by BNL-MIT collaboration for RHIC/EIC

§ Ranked as “must do” in 2017 Jones review§ Highlighted in 2018 NAS assessment of EIC

scienceJ.D. Maxwell et. al., NIM A 959, 161892 (2020)

Gentile, Thomas R., et al. RMP 89.4, 045004 (2017).

1.0

0.6

0.0

1001.0

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Target Concept for CLAS12

§ By combining technologies, increase MEOP target density by 6,000x

§ CLAS12 standard configuration, 20 cm long Al target cell at 5 K

§ Reaches CLAS12 max luminosity with 1.35x1035 nucleon/cm2/s at 2.5 muA

§ Conceptual Design Report on arXiv:1911.06650

+

Nikiel-Osuchowska, et al. EPJ D 67.9, 200 (2013).

Milner, McKeown, and Woodward. NIM A 274 56-63, (1989).

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Proposed Target design

Glass pumping cell- Temperature: 300k- Pressure: 100 mbar- Polarization: 60%

Aluminum cell- Temperature: 5K- Heat exchange: Liquid He supply- Density: increase 60X

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Path to Target Realization

§ Development at JLab (J. Maxwell) with support from JLabTarget Group, Hall B, R. Milner’s MIT Group§ Major equipment: 5T magnet, pulse-tube cryocooler,

pump and probe laser systems, cryostat, pumps§ Lab space: accommodate class 4 lasers and cryogens

§ Prototype used to confirm polarization, pressure and field performance, test convective transfer§ Relaxation due to molecular 3He2

+ expected to be low at high fields, confirm with in-beam tests at UITF

Locate Polarized 3He Gas Target in CLAS12 Central Solenoid (5T)

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Running Assumptions• Incident electron beam

- Energy = 10.6 GeV- Current = 2.5 μA (upgrade beam dump)- Polarization = 80%

• Target: MEOP- Thickness = 3 x 1021 /cm2/s- Polarization = 50%

• Luminosity: 4.5 x 1034 3He/cm2/s• 30 PAC days, CLAS12 standard configuration

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Precision measurements to study Transverse Momentum Dependent (TMD) parton distributions

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SIDIS measurements (𝝅!/#, 𝑲!/#)

kT

High precision 5-D (𝒙, 𝒛, 𝑷𝑻, 𝑸𝟐, 𝝓𝒉) 𝐨𝐧 𝐍𝐞𝐮𝐭𝐫𝐨𝐧

𝑄! = 𝑘 − 𝑘" 2

𝑥 = 𝑄!/(2𝑞𝑃)

𝑧 = (𝑞𝑃#)/(𝑞𝑃)

𝑃$: Hadron Transvered momentum

𝜙#: Angle between lepton and hadron planes

Kinematic coverage of this proposal:

0.05 < 𝑥 < 0.7 1 < 𝑄! < 9

0.2 < 𝑧 < 0.9 0 < 𝑃$ < 1.3

𝑘$: Quark Transvere momentum

Transverse momentum of hadrons in SIDIS provides access to orbital motion of quarks

(GeV/c)2

(GeV/c)

Spin and flavor dependence of kT distribution

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PT-dependence of the double spin asymmetry provides access to kT-dependence of polarized quarks

M.Anselmino et al hep-ph/0608048

B.Musch et al arXiv:1011.1213

g1q=Dq=(q+-q-)/2

𝐹%%~ 𝑔& ∗ 𝐷& 𝑎𝑛𝑑 𝐹'' = 𝑓& ∗ 𝐷&

𝐴%%~(!!(""

and 𝐴'% ~("!(""

𝐹'%~ ℎ&% ∗ 𝐻& ∗ sin(2𝜙)

Nuclear Corrections to the SIDIS Process• The SIDIS process is fundamental to the scientific agenda of JLab

12 Gev and EIC.• It is typically (naively) described in terms of PWIA and a

convolution of nucleon and sub-nucleon d.o.f.• However, known processes violate this simplistic picture, e.g. FSI.• Spin-dependent precision SIDIS on

calculable light nuclei (2H, 3He) is anexcellent starting point to develop understanding of SIDIS in nuclei.

• ND3 and polarized 3He in CLAS12 offer the ideal experimental configuration to pursue this.

FSI: Generalized Eikonal Approx.

Kaptari et al. PRC (2014)

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Physics overviewProposed physics program:q PT-dependence of the longitudinal neutron spin

structureq Nuclear correction to SIDISq Di-hadron SIDISq Quark-gluon correlations

Future physics opportunities:qDeeply Virtual Exclusive processesqTagged DISqTransversely polarized target (in development)qQuasi-elastic scattering

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Physics overviewPhysics program focus on:

q PT-dependence of the neutron spin structure

q Nuclear correction to SIDIS

Simulation: First Full reconstruction chain

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qCLASDIS generator was used

qThe simulation was run with different helicities

qThe extracted asymmetry uncertainties are corrected for dilution and Pt and Pb.

qProjection of asymmetry absolute uncertainty

LUND STRING

CLADIS generator Full GEMC

IN BENDING

Reconstruction

CLARA FRAME

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Unprecedented precision: Sub-percent level

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Charged Pion PT projectionsPT dependent projection for different bin in Q2

0.0 0.5 1.0TP

0.2-

0.0

0.2

LLA )+p(e,e'

This Proposal on Neutron

>5 2Q

>1 2Q

<221 <Q

<423 <Q

0.0 0.5 1.0TP

0.2-

0.0

0.2

)-p(e,e'

< 0.6 && z>0.3B0.1 < x

qMeasure PT dependence: providing access to spin and flavor dep of kTdistribution of valence quarks

qMeasure in different Q2 bins: test the validity of underline theory (PT << Q)

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Proposal projection measurementsx dependent projection

1-10 1X

0.5-

0.0

0.5

LLA (e,e')

This Proposal on Neutron

HERMES on Proton

1-10 1X

0.5-

0.0

0.5

)+p(e,e'

Z > 0.3

HERMES on Proton

1-10 1X

0.5-

0.0

0.5

)-p(e,e'

HERMES on Proton

Z > 0.3

qTo study x dependence of g1(x, kT) integration over full PT and phi rangeqData on ALL provides important input in global analysis of polarized PDF qStatistics is significant to determine different dependence

Collins fragmentation: Longitudinally pol. target

qProvide the access to transverse pol. quark in longitudinal pol. neutron

qProvide the access to Collins fragmentation function

𝐴!"

Kotzinian-Mulders Asym

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qDetermine spin-dependent inclusive DIS and SIDIS from

neutron with unprecedented precision

qStatistical precision over an unmatched kinematic range.

qCan uniquely explore TMDs and polarization of sea quarks in

the nucleon

q Nuclear correction to SIDIS process

CLAS12 + polarized He-3 target:

Polarized 3He Proposal SummaryTarget Beam Energy Beam current Beam time

Polarized 3He 10.6 GeV 2.5 μA 30 PAC days

A=3: Helium-3 + Tritium @ CLAS12

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q Quasielastic on A = 3q (e,e’): Neutron form factorq (e,e’p): Few-Body nuclear Structureq (e,e’pN): SRCs

• 3He(e,e’) / 3H(e,e’) @ xB = 1 sensitive to 𝜎n / 𝜎p• Measured @ Hall A \w limited Q2 coverage• CLAS12 covers Q2 = 0.1 - 14 GeV2 (complementing RG-B)• Only measurement sensitive to very low Q2

(e,e’): Neutron Form Factor

0.7

0.8

0.9

1

1.1

1.2

1.3

0.1 1

6.6 GeV, 40 days2.2 GeV, 2 days

Hall A 2018

(under analysis)

Gn M/µ

nG

dip.

Q2[GeV

2/c2]

Bartel (DESY)

Lachniet (CLAS)

Anderson (Hall-A)

Anklin (Mainz)

Kubon (Mainz)

Markowitz (Bates)

Diehl

Miller

Guidal

A. Lachniet et al. PRL (2009) 28

• Unique test of few-body nuclear structure.

• Hall A showed importance of using Helium & Triton BUT \w limited statistics

• CLAS12: x0.1 luminosityx100 acceptance => x10 statistics + larger

kinematical coverage!

(e,e’p): Few-body nuclear structure

0.2 0.4 0.6 0.8 1 [GeV/c]

missp

4-10

3-10

2-10

1-10

1

]M

eV2

srnb

) [m

iss

(ps

CC1CK+H AV183

H CD-Bonn3

He AV183

He CD-Bonn3

This Proposal

H3

He3

0 0.2 0.4 0.6 0.8 1 [GeV/c]

missp

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

PWIA

s /

EXP

s

H3He+3CracowSargsian-FSI

This proposal

R. Cruz, D. Nguyen et al. PRL (2020)

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• Recent CLAS6 Nature paper relate SRCs to NN interaction @ short-distance.

• Data analyzed using the GCF factorized cross-section approximation.

• A=3 systems exactly calculatable => Precision tests of 2N interactions!

(e,e’pN): SRCs

1%

10%

100%

400 500 600 700 800

A. Schmidt et al.

This work

Rat

io

Missing Momentum [MeV/c ]

C(e, e 0pn)/C(e, e 0p)

C(e, e 0pp)/C(e, e 0p)

A. Schmidt et al. Nature (2020)

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A=3: Helium-3 + Tritium @ CLAS12

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Dave Meekins

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A=3: Helium-3 + Tritium @ CLAS12

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Thank you !

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Back up slides

141414

Quark distributions at large kT

Understanding of modification of kT widths in nuclei is important also for nucleon TMDs

H. Avakian, DPWG Feb 22

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3He vs ND3: High PT

0.0 0.5 1.0TP

0.2-

0.0

0.2

LLA )+p(e,e'

This Proposal on Neutron

E12-07-107 on ND3

HERMES on Proton

0.0 0.5 1.0TP

0.2-

0.0

0.2

)-p(e,e'

< 0.6B0.1 < x > 12z > 0.3 & Q

HERMES on Proton

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0.0 0.5 1.0 1.5TP

10

210

310

410

510

Count

)-p(e,e'

> 5 GeV2Q

CLAS12

SOLID

0.0 0.5 1.0 1.5TP

10

210

310

410

510

610

Count

)+p(e,e'

> 5 GeV2Q

CLAS12 vs SoLID: PT coverage at high Q2

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SoLID vs CLAS12: Q2 coverage

2 4 6 8 102Q

210

310

410

510

610

710

Count

)-p(e,e'

CLAS12

SOLID

2 4 6 8 102Q210

310

410

510

610

710

Count

)+p(e,e'

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CLAS12 vs SoLID: Di-hadron

2 4 6 8 102Q

410

510

Count

)-p+p(e,e'

CLAS12

SOLID

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