Decade of Hypernuclear Physics Decade of Hypernuclear Physics at JLAB and Future Prospective at JLAB and Future Prospective

in 12 GeV Erain 12 GeV Era

Liguang TangLiguang Tang

Department of Physics, Hampton UniversityDepartment of Physics, Hampton University&&

Jefferson National Laboratory (JLAB)Jefferson National Laboratory (JLAB)

August 8 - 11, 2011, Hadron Physics 2011, Shandong UniversityAugust 8 - 11, 2011, Hadron Physics 2011, Shandong University

Introduction Introduction – Hypernuclei– Hypernuclei• Baryonic interactions are important nuclear physics

issues to extend the QCD descriptions of single nucleon (its form factors, etc…) to strongly interactive nuclear many body system

• A nucleus with one or more nucleons replaced by hyperon, such as , , … a Hypernucleus

• Hypernucleus is a unique tool and a rich laboratory to study YN and YY interactions baryonic interactions beyond NN

• Study hypernuclei is an important gate way to the interaction

Unique Features of Unique Features of -Hypernuclei-Hypernuclei• Long lifetime: -hypernucleus in ground state decays only weakly

via N or N NN, thus mass spectroscopy features with narrow states (< few to 100 keV)

• Description of a -hypernucleus within two-body frame work – Nuclear Core (Particle hole) (particle):

VΛN(r) = Vc(r) + Vs(r)(SΛ*SN) + VΛ(r)(LΛN*SΛ) + VN(r)(LΛ*SN) + VT(r)S12

• Absence of OPE force in N: Study short range interactions

• is a “distinguish particle” to N (i.e. no Bauli Blocking): a unique probe to study nuclear structure

• Trace the single particle nature in heavy hypernuclei allows to study the nuclear mean field

Hypernuclear physics is an important Hypernuclear physics is an important component in nuclear physicscomponent in nuclear physics

Advantage of Electro-production HypernucleiAdvantage of Electro-production Hypernuclei• New spin structure due to photon absorption and large momentum transfer

- Strong spin flip amplitudes- Highest possible spin

• Neutron rich hypernuclei (N-N coupling)

• High resolution1.5 MeV (hadronic production) <500keV

• High accuracyB 50keV is possible

• Technical challenges– Require small forward angles– High particle singles rates– Accidental coincidence rate– Challenging optics and kinematics calibration

A

p

A

e e’

K+

(e, e’K) Reaction

Low-lying states Lowest few and most stable core states (particle hole states) Narrow hypernuclear states with coupled at different shell levels Non-spin flip (natural parity) states or spin flip (unnatural parity) states These states are most studied

Hall A Technique

ee

ee’’

KK++HRS - HadronHRS - Hadron

HRS - ElectronHRS - Electron

SeptumSeptum

• Two Septum magnets- Independent two arms- No problem for post beam- Low e’ singles rate- Low accidental background

• Difficulties- High hadron momentum which which is resolved by RICH detector- High luminosity but low yield rate (long spectrometers and small

acceptances)

Hall C Technique

Zero degree e’ tagging High e’ single rate Low beam luminosity High accidental rate Low yield rate A first important milestone for hypernuclear physics with electro- production

Beam Dump

Target

Electron Beam

　　　　 Focal Plane( SSD + Hodoscope )

K+

K+

QD

_D

0 1m

QD_D

Side View

Top View

Target

(1.645 GeV)

Phase I

K+

e’Phase II

Common Splitter Magnet

New HKS spectrometer large Tilted Enge spectrometer Reduce e’ single rate by a factor of 10-5 High beam luminosity Accidental rate improves 4 times High yield rate First possible study beyond p shell

Hall C Technique – Cont.

New HES spectrometer larger Same Tilt Method High beam luminosity Further improves accidental rate Further improves resolution and accuracy High yield rate First possible study for A > 50

Beam2.34 GeV

e’

K+

e

Phase III

Common Splitter Magnet

10/13/09

p(e,e'K+) Production run(Waterfall target)

Expected data from E07-012, study the angular dependence of p(e,e’K+) and 16O(e,e’K+)16N at low Q2

Results on H target – The p(e,e’K+) Cross Section (Hall A)

p(e,e'K+) Calibration run(LH2 Cryo Target)

• None of the models is able to describe the data over the entire range• New data is electro-production – could longitudinal amplitudes dominate?

o

-B(MeV)

-6.730.02 0.2 MeV from n nFirst reliable observation of 7

He JLab E01-011 (HKS, Hall C)

Test of Charge Symmetry Breaking Effect. A Naïve theory does not explain the experimental result.

A Naïve calculation on CSB effect, which explains 4

H – 4He and available s, p-shell

hypernuclear data , gives opposite shifts to A=7 ,T=1 iso-triplet Hypernuclei.

Jlab E05-115

Hall A Result on 9Li Spectroscopy

Spectroscopy is still under study and not yet published.

E94-107 in Hall A (2003 & 04)E94-107 in Hall A (2003 & 04)

s (2-/1-)

p(3+/2+’s)

Core Ex. States

Red line: Fit to the data Blue line: Theoretical curve: Sagay Saclay-Lyon (SLA) used for the elementary K-Λ electroproduction on proton. (Hypernuclear wave function obtained by M.Sotona and J.Millener)

M.Iodice et al., Phys. Rev. Lett. M.Iodice et al., Phys. Rev. Lett. E052501, 99 (2007)E052501, 99 (2007)

~635 keVFWHM

The 12B Spectroscopy (Hall A & C)

K+ _D

K+

1.2GeV/cLocal Beam Dump

E89-009 12ΛB spectrum~800

keVFWHM

HNSS in 2000s p

Phase I in Hall C (E89-009)Phase I in Hall C (E89-009)

Phase II in Hall C (E01-011)Phase II in Hall C (E01-011)~500 keV

FWHM

HKS in 2005 HKS 2005 has incorrect optics optics tune – affecting the line shape The source is found from Phase III 2009 HKS-HES experiment and the correct method is developed 2005 optics tune and kinematics calibration is under redoing together with the 2009 data The goals are

Precise binding energy High resolution Resolve doublet separations

2.1248 1/2-

4.445 5/2-

5.021 3/2-

6.743 7/2-6.793 1/2+

7.286 (3/2, 5/2)+

7.978 3/2+

8.559 5/2-

7Li + (8.665)

0.0 3/2-

11B1-2-S1/2

12B

S1/2

S1/2

S1/21-

0-

2-1-

S1/2

S1/2

S1/2 2-

2+1+2+3+

2+1+

P3/2

P1/2

P3/2

P

P3/2

P

Threshold

0.00.14

Theoryg

2.67

5.745.85

10.4810.5210.9811.05

12.9513.05

F. AJZENBERG-SELOVE and C. L. BUSCH, Nuclear Phystcs A336 (1980) 1-154.g D.J. Millener, Nuclear Phystcs A691 (2001) 93c. P means a mixing of 1/2 and 3/2 states.

The Expected 12B Spectroscopy

Fit 4 regions with 4 Voigt functionsc2

/ndf = 1.19

0.0/13.760.16

Binding Energy BL=13.76±0.16 MeVMeasured for the first time with this level of accuracy (ambiguous interpretation from emulsion data; interaction involving L production on n more difficult to normalize) Within errors, the binding energy

and the excited levels of the mirror hypernuclei 16

O and 16N

(this experiment) are in agreement, giving no strong evidence of charge-dependent effects

Results on 16O target – Spectroscopy of 16 N (Hall A)

F. Cusanno et al, PRL 103 (2009)

B (MeV)

28Si(e, e’K+)28Al

HKSJLAB

Cou

nts

(150

keV

/bin

)

28Al

s

pd

AccidentalsAccidentals

• 1st observation of 28Al

• ~400 keV FWHM resol.• Clean observation of the

shell structures

Peak B(MeV) Ex(MeV) Errors (St. Sys.)

#1 -17.820 0.0 ± 0.027 ± 0.135 #2 -6.912 10.910 ± 0.033 ± 0.113 #3 1.360 19.180 ± 0.042 ± 0.105

Spectroscopy of Spectroscopy of 2828Al (Hall C)Al (Hall C)

HKS (Hall C) 2005

Wider Narrower

• 2009 data analysis is ongoing• Current analysis: kinematics calibration and

spectrometer optics optimization• Additional data for existing spectroscopy

7He, 9

Li, and 12B (more statistics and better precision)

• New data:– 10

Be (puzzle of gamma spectroscopy)

– 52V (further extend beyond p shell)

Additional Data By HKS-HES (Hall C, 2009)Additional Data By HKS-HES (Hall C, 2009)

New Concept in 12 GeV Era:New Concept in 12 GeV Era:Study of Light Study of Light -Hypernuclei by Spectroscopy -Hypernuclei by Spectroscopy

of Two Body Weak Decay Pionsof Two Body Weak Decay Pions

Fragmentation of Hypernuclei Fragmentation of Hypernuclei and and

Mesonic Decay inside NucleusMesonic Decay inside Nucleus

Free: Free: p + p + --

2-B: 2-B: AAZ Z AA(Z + 1) + (Z + 1) +

--

Decay Pion Spectroscopy to Study Decay Pion Spectroscopy to Study -Hypernuclei-Hypernuclei

12C

-

Weak mesonic two body decay

1- 0.02- ~150 keV

Ground state doublet of 12B

Precise B Jp and

Direct ProductionDirect Production

p

e’

e12C K

+

Example:

Hypernuclear States:s (or p) coupled to low lying core nucleus

12Bg.s.

E.M.E.M.

*

12B

Decay Pion Spectroscopy for Light and Exotic Decay Pion Spectroscopy for Light and Exotic -Hypernuclei-Hypernuclei

Fragmentation ProcessFragmentation Process

p

e’

e 12C

Example: K +

*

s12B*

Highly Excited Hypernuclear States:s coupled to High-Lying core nucleus, i.e.particle hole at s orbit

4H

Fragmentation (<10-16s)

4Hg.s.

4He

-

Weak mesonic two body decay (~10-10s)

Access to variety of light and exotic hypernuclei,

some of which cannot be produced or measured

precisely by other means

• High yield of hypernuclei (bound or unbound in continuum) makes high yield of hyper-fragments, i.e. light hypernuclei which stop primarily in thin target foil

• High momentum transfer in the primary production sends most of the background particles forward

• Precision does not depend on the precisions of beam energy and tagged kaons

• The momentum resolution can be at level of ~170keV/c FWHM, powerful in resolving close-by states and different hypernuclei

• B can be determined with precision at a level of 20keV

• The experiment can be carried out in parasitic mode with high precision hypernuclear mass spectroscopy experiment which measures the level structures of hypernuclei

• Physics analysis is more complicated while achieving high resolution is rather simple

Study of Light Hypernuclei by Pionic Decay at JlabStudy of Light Hypernuclei by Pionic Decay at JlabTechnique and PrecisionTechnique and Precision

• Precisely determine the single binding energy B for the ground state of variety of light hypernuclei: 3

H,4H, ..., 11

Be, 11B and 12

B , i.e. A = 3 – 12 (few body to p shell)

• Determine the spin-parity Jp of the ground state of light hypernuclei• Measure CSB’s from multiple pairs of mirror hypernuclei such as: 6

He and 6Li, 8

Li and 8Be, 10

Be and 10B.

• CSB can also be determined by combining with the existing emulsion result for hypernuclei not measured in this experiment

• Search for the neutron drip line limit hypernuclei such as: 6H, 7

H and 8H which

have high Isospin and significant - coupling• May also extract B(E2) and B(M1) electromagnetic branching ratios through

observation of the isomeric low lying states and their lifetimes.

The high precision makes these above into a set of crucial and extremely valuable physics variables which are longed for determination of the correct models needed in description of the Y-N and Y-Nucleus interactions.

Study of Light Hypernuclei by Pionic Decay at JlabStudy of Light Hypernuclei by Pionic Decay at JlabMajor Physics ObjectivesMajor Physics Objectives

e e

* K+

p

AZ

A(Z-1)

A1Z1 stop

A2Z2

(Z-1) = Z1+Z2; A=A1+A2

-

A1(Z1+1)

SPECTROSCOPYSPECTROSCOPYe e

* K+

,(-) p(n)

AZ (A-1)Z’

-

N

BACKGROUNDBACKGROUND

VSVS

Comparison of Spectroscopic and Background Comparison of Spectroscopic and Background -- Production Production

Study of Light Hypernuclei by Pionic Decay at JlabStudy of Light Hypernuclei by Pionic Decay at JlabIllustration on the Main FeaturesIllustration on the Main Features

(a)2-B decay from 7He

and its continuum

(Phase I: 7Li target) 1/2+

PMaxPMin 0 2Ex Ex0 2

4H

0+

7He

1/2+

3/2+5/2+

3H

6He

1- ?6H

5H

90.0 100.0 110.0 120.0 130.0 140.0- Momentum (MeV/c)

3B background

(b)

3B background

20Ex

10Ex 10

Ex 10Ex

2-

3/2+

5/2+

1/2+

9Li

8He

1-

8Li

7H

1/2+

3/2+

7Li

1- ?

6Li

Additions from 9Li and its

continuum

(Phase II: 9Be target)

(c) Additions from 12B and its

continuum

(Phase III: 12C target)

12B1-

11Be

11B 10

Li

10Be

5/2+Jp=?10B

9He

9Be

9B

8H

8Be

8B 3B background

Illustration of Decay Pion SpectroscopyIllustration of Decay Pion Spectroscopy

Experimental Layout (Hall A) in 12GeV Experimental Layout (Hall A) in 12GeV EraEra

HRS - ElectronHRS - Electron

HKS - KaonsHKS - KaonsHES - PionsHES - Pions

64mg/cm2

22mg/cm2 K+

-

Trigger I: HRS(K) & Enge(Trigger I: HRS(K) & Enge() for Decay Pion Spectroscopy Experiment) for Decay Pion Spectroscopy ExperimentTrigger II: HRS(K) & HRS(e’) for Mass Spectroscopy ExperimentTrigger II: HRS(K) & HRS(e’) for Mass Spectroscopy Experiment

Light Hypernuclei (s,p shell)Fine structureBaryon-baryon interaction in SU(3) coupling in large isospin hypernucleiCluster structure

A 1 20 50 200 1057

Elementary ProcessStrangeness electro-production Neutron/Hyperon

star,Strangeness matter Hyperonization

Softening of EOS ?

Medium/heavy HypernucleiSingle particle potentialDistinguish ability of a hyperon Uo(r), m*(r), VNN, …

E89-009, E01-011, E05-115(Hall C)E94-107(Hall A)

H, 7Li, 9Be, 10B, 12C, 16O, 28Si, 52Cr

Future mass spectroscopy

Decay Pion Spectroscopy(Light Hypernuclei)

Precise B of ground stateCSBSpin-parity Jp of ground stateExtreme isospinN system…

SummarySummary• High quality and high intensity CW CEBAF beam at JLAB

made high precision hypernuclear programs possible. Programs in 6GeV era were successful.

• Together with J-PARC’s new programs, as well as those at other facilities around world, the hypernuclear physics will have great achievement in the next couple of decades.

• The mass spectroscopy program will continue in 12 GeV era with further optimized design

• The new decay pion spectroscopy program will start a new frontier