decade of hypernuclear physics at jlab and future prospective in 12 gev era liguang tang department...
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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 - Electron
HRS - 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
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)
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/c
Local 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
Co
un
ts (
15
0 k
eV
/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 spectroscopy7He, 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 Ex
0 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