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Decade of Hypernuclear Physics at JLAB and Future Prospective in 12 GeV Era Liguang Tang Department of Physics, Hampton University & Jefferson National Laboratory (JLAB) August 8 - 11, 2011, Hadron Physics 2011, Shandong University Introduction – 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 -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 component in nuclear physics Advantage of Electro-production Hypernuclei e (e, e’K) Reaction e’ K+ p - Strong spin flip amplitudes - Highest possible spin A A • New spin structure due to photon absorption and large momentum transfer • Neutron rich hypernuclei (N-N coupling) • High resolution 1.5 MeV (hadronic production) <500keV 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 • High accuracy B 50keV is possible • Technical challenges – Require small forward angles – High particle singles rates – Accidental coincidence rate – Challenging optics and kinematics calibration Hall A Technique • 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) K+ Septum e e’ Hall C Technique Common Splitter Magnet Side View + K _ D K Target D Q Top View _ D D + Phase I K+ Q Electron Beam (1.645 GeV) Target e’ Focal Plane ( SSD + Hodoscope ) Beam Dump Phase II 0 1m Zero degree e’ tagging New HKS spectrometer large High e’ single rate Low beam luminosity Tilted Enge spectrometer Reduce e’ single rate by a factor of 10-5 High accidental rate High beam luminosity Low yield rate Accidental rate improves 4 times A first important milestone for hypernuclear physics with electroproduction High yield rate First possible study beyond p shell Hall C Technique – Cont. Common Splitter Magnet e’ Phase III New HES spectrometer larger Same Tilt Method High beam luminosity Further improves accidental rate K+ Beam 2.34 GeV Further improves resolution and accuracy High yield rate e First possible study for A > 50 Results on H target – The p(e,e’K+) Cross Section (Hall A) p(e,e'K+) Production run (Waterfall target) p(e,e'K+) Calibration run (LH2 Cryo Target) Expected data from E07-012, study the angular dependence of p(e,e’K+) and 16O(e,e’K+)16N at low Q2 o • None of the models is able to describe the data over the entire range • New data is electro-production – could longitudinal amplitudes dominate? 10/13/09 JLab E01-011 (HKS, Hall C) First reliable observation of 7He -6.730.02 0.2 MeV from a n n Test of Charge Symmetry Breaking Effect. A Naïve theory does not explain the experimental result. Jlab E05-115 -B (MeV) A Naïve calculation on CSB effect, which explains 4H – 4 He and available s, p-shell hypernuclear data , gives opposite shifts to A=7 ,T=1 isotriplet Hypernuclei. Hall A Result on Spectroscopy is still under study and not yet published. 9 Li Spectroscopy The 12B Spectroscopy (Hall A & C) E94-107 in Hall A (2003 & 04) Phase I in Hall C (E89-009) ~800 keV E89-009 FWHM 12 ΛB s HNSS in 2000 spectrum ~635 keV FWHM s p p (2-/1-) K+ (3 /2+’s) + Core Ex. States K+ 1.2GeV/c _ D Local Beam Dump 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 Red line: Fit to the data Phase II in Hall C (E01-011) HKS in 2005 ~500 keV FWHM 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. E052501, 99 (2007) The Expected 12B Spectroscopy P P3/2 7Li + a (8.665) 8.559 5/2- 7.978 3/2+ 6.743 1/2+ 6.793 7/2- 5.021 3/2- 4.445 5/2- S1/2 S1/2 3/2- 0.0 11B 3+ 2+ 1+ 2+ 11.05 10.98 10.52 10.48 12- 5.85 5.74 S1/2 2- S1/2 0- S1/2 1- 2.67 21- 0.14 0.0 1/2- 2.1248 13.05 12.95 P3/2 P1/2 P P3/2 (3/2, 5/2)+ 7.286 1+ 2+ Threshold S1/2 S1/2 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. 12 B Theoryg Results on 16O target – Spectroscopy of 16 N (Hall A) F. Cusanno et al, PRL 103 (2009) Fit 4 regions with 4 Voigt functions c2/ndf = 1.19 Binding Energy BL=13.76±0.16 MeV Measured 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 16O and 16N (this experiment) are in agreement, giving no strong evidence of charge-dependent effects 0.0/13.760.16 28 Al Spectroscopy of 28Si(e, HKS HKS (Hall C) 2005 JLAB Counts (150 keV/bin) s st observation of 28 Al • 1 Al 28 e’K+)28Al Wider • ~400 keV FWHM resol. • Clean observation of the shell structures d p (Hall C) Narrower Peak B(MeV) Ex(MeV) Errors (St. Sys.) #1 #2 #3 KEK E140a SKS 28Si(+,K+)28 Accidentals B (MeV) Si -17.820 -6.912 1.360 0.0 10.910 19.180 ± 0.027 ± 0.135 ± 0.033 ± 0.113 ± 0.042 ± 0.105 Additional Data By HKS-HES (Hall C, 2009) • 2009 data analysis is ongoing • Current analysis: kinematics calibration and spectrometer optics optimization • Additional data for existing spectroscopy 7 9 He, Li, and 12B (more statistics and better precision) • New data: – – 10 Be (puzzle of gamma spectroscopy) 52 V (further extend beyond p shell) New Concept in 12 GeV Era: Study of Light -Hypernuclei by Spectroscopy of Two Body Weak Decay Pions Fragmentation of Hypernuclei and Mesonic Decay inside Nucleus Free: 2-B: p + A Z A(Z + 1) + Decay Pion Spectroscopy to Study -Hypernuclei Example: Direct Production e’ 12 * e K+ C Ground state doublet of Precise B Jp and p 12 B E.M. 21- Hypernuclear States: s (or p) coupled to low lying core nucleus C 12 12 B ~150 keV 0.0 Weak mesonic two body decay 12 Bg.s. Decay Pion Spectroscopy for Light and Exotic -Hypernuclei Fragmentation Process Example: e’ K+ 12 e C * 12 B p * Fragmentation (<10-16s) s 4 Highly Excited Hypernuclear States: s coupled to HighLying core nucleus, i.e. particle hole at s orbit a H 4 Hg.s. a 4 He Access to variety of light and exotic hypernuclei, some of which cannot be produced or measured precisely by other means Weak mesonic two body decay (~10-10s) Study of Light Hypernuclei by Pionic Decay at Jlab Technique and Precision • 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 Jlab Major Physics Objectives • Precisely determine the single binding energy B for the ground state of variety of light hypernuclei: 3H,4H, ..., 11Be, 11B and 12B , 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, 8Li and 8Be, 10Be 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, 7H 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 Jlab Illustration on the Main Features Comparison of Spectroscopic and Background - Production SPECTROSCOPY BACKGROUND e e e * * - K+ p A1 VS Z 1 stop A2 K+ p(n) AZ A (Z-1) e AZ Z2 A1( - ,(-) N (A-1) Z’ Z1+1) (Z-1) = Z1+Z2; A=A1+A2 Light Hypernuclei to Be Investigated p Previously measured 6 Mirror pairs (b) 5 7 4 6 3B background Li 3/2+ 0 3 1 2 He 1/2+ 2 1 8 Li 1- ? 3 8 B 3/2+ 9 Li 8 Be Jp=? 1/2+ 6 Ex 1 6 7 Li He 0 8 5/2+ Li Li 17HeEx 8 He 0 H 3 4 H 4 5 H 5 6 H 6 7 H 7 8 9 1- B 9 8 Li Be 9 2- Li 10 B 10 Be 10 Li 12 9 11 Additions from B Li and its B continuum 11 Be (Phase II: 79Be H target) 0 19He Ex 2 Ex H 8 9 10 11 12 A Illustration of Decay Pion Spectroscopy (c) 1- Additions from 12B and its continuum 12 B (Phase III: 9 Be 11 B Jp=? 10 B 10 9 He 11 Be Li 5/2+ (b) 6 3B background Li 8 1- He 9 Li Li 1- ? 5/2+ 3/2+ 0 1 Ex 0 1 Ex and its continuum target) 0 1- ? 6 3 He H 7 1/2+ 7 He 0 110.0 2 0 1 E 2 x Ex 0+ 4 6 H H 5 H Ex 0 120.0 - Momentum (MeV/c) H 2- 3/2+ 5/2+ PMin 100.0 (Phase II: 9Be target) Li 1/2+ 3B background 90.0 8 1/2+ (a)2-B decay from 7 He (Phase I: H Additions from 9Li and its continuum 3/2+ 1/2+ 7 8 3B background 8 B 7Li target) 10 Be 8 Be 9 B 12C 130.0 2 PMax Ex 140.0 Experimental Layout (Hall A) in 12GeV Era 64mg/cm2 22mg/cm2 K+ HRS - Electron - HES - Pions HKS - Kaons Trigger I: HRS(K) & Enge() for Decay Pion Spectroscopy Experiment Trigger II: HRS(K) & HRS(e’) for Mass Spectroscopy Experiment A E89-009, E01-011, E05-115(Hall C) 1 E94-107(Hall A) 20 50 7 10 16 52 H, Future Li, 9Be, B, 12C, O, 28Si, Cr mass spectroscopy Elementary Process Strangeness electro-production Light Hypernuclei (s,p shell) 200 1057 Neutron/Hyperon star, Strangeness matter Hyperonization Softening of EOS ? Fine structure Baryon-baryon interaction in SU(3) coupling in large isospin hypernuclei Cluster structure Decay Pion Spectroscopy (Light Hypernuclei) Precise B of ground state CSB Spin-parity Jp of ground state Extreme isospin N system … Medium/heavy Hypernuclei Single particle potential Distinguish ability of a hyperon Uo(r), m*(r), VNN, … Summary • 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