HYPERNUCLEAR PHYSICS Hypernuclei are bound states of nucleons with a strange baryon (L hyperon).
Extension of physics on N-N interaction to system with S≠0
Internal nuclear shells are not Pauli-blocked for hyperons
Spectroscopy
many body problems
- N interaction
Few-body aspects and YN, YY interaction
Mean field aspects of nuclear matter
Astrophysical aspectL-N force vs N-N force will provide clues to the QCD description of the N-N Force (one-p and one-r exchange suppressed)
Perspectives of Hypernuclear Physics at Jlab in the 12 GeV eraF. Garibaldi on behalf of Jlab hypernuclear collaboration
L N interaction
V
✔ most of information is carried by the spin dependent part
✔ doublet splitting is determined by D, sL, T
(r)
Hypernuclear Spectroscopy
new aspects of hyernuclear structure
production of mirror hypernuclei Charge Symmetry Breaking ?
Hall A Kaon collaborationF.Garibaldi (INFN), S. Frullani (INFN). M.Iodice (INFN), J.LeRose (Jlab), P. Markowitz (FIU),G. Chang (Maryland)
E94-107 - E-98-108 - E 07-01296 collaborators - 30 Institutions,
Hall C hardware contribution
hadron arm
septum magnets
RICH Detector
electron arm
aerogel first generation
aerogel second generation
To be added to do the experiment
Hall A deector setup
✓ p(e,e′K+)L/S The data suggest that not only do the present models fail to describe the data over the full angular range, but that the cross section rises at the forward angles. The failure of existing models to describe the data suggests the reaction mechanisms may be incomplete.
✓ 7Li(e,e’k) 7LHe A clear peak of the 7He ground state for the first time.
CSB term puzzle, (CSB term is essential for A=4 hypernuclei). our understanding of the CSB effect in the N L interaction potential is still imperfect.
✓ 9Be(e,e’K+)9LLi: Disagreement between the standard model of p-
shell hypernculei and the measurements, both for the position of the peaks and for the cross section.
✓ 12C(e,e’K+) 12LB: for the first time a measurable strength with sub-
MeV energy resolution has been observed in the core-excited part of the spectrum. The s part of the spectrum is well reproduced by the theory, the p shell part isn’t. ✓.16O(e,e’K+)16
LN: The fourth peak ( in p state) position disagrees with theory. This might be an indication of a large spin-orbit term SL. Binding Energy BL=13.76±0.16 MeV measured for the first time with this level of accuracy
Hypernuclei in a wide mass range
Neutron/Hyperon star Strangeness matter
Light Hypernuclei (s,p shell)
A 1 20 50 200 1057
Elementary ProcessStrangeness electro-production
Fine structure Baryon-baryon interaction in SU(3) LS coupling in large isospin hypernuclei Cluster structure
Hyperonization
Softening of
EOS ?
Superfluidity
E05-1156,7Li 10,11B 12C 51V 52Cr 89Y
Single-particle potentialDistinguishability of a L hyperon
U0(r), mL*(r), VLNN, ...
Medium - Heavy hypernuclei
E-94-107
208Pb
Bare LN Int.Few body calc. Mean Field TheoryCluster calc.
Shell model
Decay Pion Spectroscopy to Study L-Hypernuclei
12C
-
Weak mesonic two body decay( - 0.1)
1- 0.02- ~150 keV
Ground state doublet of 12ΛB
Precise BΛ Jp and
Direct Production
p
e’
e12C K
+
Example:
LHypernuclear States:Λs (or Λp) coupled to low lying core nucleus
12ΛBg.s.
E.M.
γ*
12ΛB
- Weak 2 body mesonic decay at rest uniquely connects the decay pion momentum to the well known structure of the decay nucleus, B and spin-parity of the ground state of hyperfragment
Summary and outlook Hypernuclear Spectroscopy by e.m. probe successfully
established at Jlab confirming its excellence for studying hypernuclei
The experiments required important, challenging modifications to the Hall A and Hall C detector setup
Crucial contributions from Italian and Japanese collaborations
The new equipment performed excellently.
Best characteristics of Hall A and Hall C detectors setup understood
Merging collaborations and getting the best out of the two detectors
in order to best continue into the 12 GeV era
Jlab beam and detectors make it unique in the international panorama for this physics
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YN, YY Interactions and Hypernuclear Structure
Free YN, YY interactionConstructed from limited hyperon scattering data(Meson exchange model: Nijmegen, Julich)
YN, YY effective interaction in finite nuclei(YN G potential)
Hypernuclear properties, spectroscopic informationfrom structure calculation (shell model, cluster model…)
Energy levels, Energy splitting, cross sectionsPolarizations, weak decay widthshigh quality (high resolution & high statistics)
spectroscopy plays a significant role
G-matrix calculation
H.-J. Schulze, T. Rijken PHYSICAL REVIEW C 84, 035801 (2011)
Understanding the N-N ForceIn terms of mesons and nucleons:
Or in terms of quarks and gluons:
V =
Hypernuclei Provide Essential Clues
For the N-N System:
For the L-N System:
Hypernuclei Provide Essential Clues
For the N-N System:
For the L-N System: Long Range Terms Suppressed (by Isospin)
L single particle energiesE05-115 (HKS-HES)
E94-107(Hall A HY)
E01-011(HKS)
Calculation by John Millener, using a Woods-Saxon potential with a depth of 28 MeV and a radius parameter of 1.128 + 0.439A-2/3
The First reliable observation of 7LHe
An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)
A Test of Charge Symmetry Breaking
• Begin with a theoretical description of these nuclei without CSB
The First reliable observation of 7LHe
An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)
A Test of Charge Symmetry Breaking
• Begin with a theoretical description of these nuclei without CSB
• A Naïve calculation of the CSB effect, which explains 4
LH –4LHe
and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.
The First reliable observation of 7LHe
An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)
A Test of Charge Symmetry Breaking
• Begin with a theoretical description of these nuclei without CSB
• A Naïve calculation of the CSB effect, which explains 4
LH –4LHe
and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.
Old result on 7LHe
(M.Juric et al. NP B52 (1973) 1)Inadequate for a serious comparison
-BL (MeV)
-6.730.02 0.2 MeV from a L n n
The First reliable observation of 7LHe
An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)
A Test of Charge Symmetry Breaking Compare with new measurements of 7
LHe Measured shift has the opposite sign to the predicted shift!
• Begin with a theoretical description of these nuclei without CSB
• A Naïve calculation of the CSB effect, which explains 4
LH –4LHe
and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.
-BL (MeV)
-6.730.02 0.2 MeV from a L n n
The First reliable observation of 7LHe
An example of what we learn from HypernucleiA Highlight of JLab E01-011 (HKS)
A Test of Charge Symmetry Breaking Naïve theory does not explain the experimental result.
• Begin with a theoretical description of these nuclei without CSB
• A Naïve calculation of the CSB effect, which explains 4
LH –4LHe
and available s, p-shell hypernuclear data, predicts opposite shifts for A=7 ,T=1 iso-triplet L Hypernuclei.
Present Status of L Hypernuclear Spectroscopy
Updated from: O. Hashimoto and H. Tamura, Prog. Part. Nucl. Phys. 57 (2006) 564.
(2011)
52LV
Tremendous Progress, but More Nuclei and Higher P
recision are Needed
To Fully Understand the L-N/N-N Force Diffe
rences JLab and JPARC Programs
Complementary Additional Measurements Proposed for the 12 GeV Upgrade
The addition of measurements of p decay of hypernuclei will permit
1. Precise (~±20 keV) determination of binding energies of a variety of ground state light hypernuclei
2. Determination and confirmation of ground state spin/parity3. Direct measurement of binding energy differences from
multiple mirror pairs of light hypernuclei at ground state to investigate CSB and Coulomb effect
4. Searching for the neutron drip line limit of light hypernuclei – heavy hyper-hydrogen
5. Searching for evidence of the existence of isomeric hypernuclear states6. Studying impurity nuclear physics – B(E2) measurement and medium effect of
baryons – B(M1) measurement through lifetime
✓Few-body aspects and YN, YY interaction✓Mean field aspects of nuclear matter✓Many body and astrophysical aspect
PR12-10-001 - Study of Light - Hypernuclei by Spectroscopy of Two Body Weak Decay Pions
Fragmentation of Hypernuclei And Mesonic Decay inside Nucleus
Free: L p + p -
2-B: ALZ A(Z + 1) + p -
High yield and unique decay feature allow high precision measurement of 2 body decay pion spectroscopy from which variety of physics may be extracted
- 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
- Decay at rest the pion momentum is uniquely connected to the well known structure of the decay nucleus, allow determination of BL and spin-parity of the ground state of hyperfragments, study CSB
High momentum transfer in the primary production sends most of the background particles forward, thus pion momentum spectrum is expected to be clean with minor 3-boby decay pions: