spin-dependent electron scattering from a polarized he ... · polarized 3he target and precision...
TRANSCRIPT
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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