Fisica Nucleare a Jefferson Lab F. Garibaldi - Miniworkshop INFN- Genova 27-02-08

1. Fisica Nucleare a Jefferson Lab F. Garibaldi - Miniworkshop INFN-Genova 27-02-08 • Nuclear Physics at Jefferson Lab • Hypernuclei • Electroproduction of hypernuclei • The experimental Program at Jefferson Lab  the Hall A Setup and Results-New proposal  Hall C prelimiary results White paper on the prospectives of e.m. hypercnulear physics New proposal --> Hall A (Hall A/HallC groups) • Conclusions

2. Nuclear Structure Highlights from the JLab Program Now and In the Future • The Neutron skin of 208Pb • is the neutron distribution in finite nuclei what we have inferred from (e,e) and hadron reactions? • Hypernuclear Spectroscopy • the origin and nature of the inter-nucleon force • the Equation of State for Nuclear Matter • N-N Correlations: short-range, high-momentum physics of nuclei • The microscopy of few-body systems The transition from a nucleon-meson based description of nuclei to a quark-gluon based one has been studied. Further studies to high Q2 of the g.s. form factors of 2H and 3,4He are underway or planned : • Identifying the distance scale to which the description of nuclei in terms of hadrons interacting via an N-N forcemakes sense • How does the nuclear medium modify a hadron or the creation of a hadron? Initial studies of in-medium properties have yielded highly interesting results which will be a major component of the research program with the 12 GeV upgrade Proton form factor • EMC effect • Color Transparency • Hadronization

3. JLab’s Scientific Mission in Nuclear Structure - How are the hadrons constructed from the quarks and gluons of QCD? • What is the QCDbasis for the N-N force? • Where are the limits of our understanding of nuclear structure? To what precision can we describe nuclei? To what distance scale can we describe nuclei? Where does the transition from the N-meson to the QCD description occur? Nuclear Structure Research atJLabiscomplementary to that at facilities using thestrong interaction, such asMSUand LHC today, andRIAin the future

4. Electron Scattering Provides an Ideal Microscope for Nuclear Physics • Electrons are point-like • The interaction (QED) is well-known • The interaction is weak • Vary q to map out Fourier Transforms of charge and current densities:   /q (1 fm  1 GeV/c) CEBAF’s e and CW beams dramatically enhance the power of electron scattering

5. Probing Neutron-Rich Matter  • The neutron distribution: • - probed with hadrons, but highly model-dependent • - neutron “skin” ~ 0.1 - 0.3 fm? • Why is the neutron density interesting? • Fundamental check of Nuclear Many-Body Theory • Essential input for Atomic PV Expts • Neutron Star Structure • 208Pb neutron skin and neutron star crust made of similar material • Mean Field theory predicts that the neutron star transition density and the208Pb neutron skinarecorrelated EOS PREX (R. Michaels, P.A. Souder, G.M. Urciuoli) - Hall A, will run in 2009 • Rate ~ 2 GHz • Stat. Error ~ 15 ppb • Syst. Error ~ 1 to 2 % Atechnically demanding measurement

6. Correlated Strength in Nuclear Spectral Functions Electron-induced proton knock-outhas been studied systematically since high duty-factor electron beams became available, first atSaclay (70’s), then at NIKHEF (80’s-90’s) (Ein ~ 600 MeV) with ~100 keV energy resolution. For complex (A>4) nuclei, thespectroscopic strengthS for valence protons was found to be60-65% oftheIPSMvalue Long-range correlationsaccount for about10%, but the rest was ascribed to short-range N-Ncorrelations, by which strength was pushed to high missing momenta and to energies well above the Fermi edge. Thesekinematics were not accessibleat the accelerators of that era, butthey are at CEBAF.

7. Examine very high momentum components via proton knock-out from 3He - Data for two-body (2bbu) and three-body (3bbu) break-up obtained up to large pm values (> 1 GeV/c) - Comparison to most advanced calculations indicate excess strength in both channels of more than order of magnitude (correlations) at pm ~1 GeV/c - Clear need to take into account all possible reaction mechanisms (FSI, MEC, IC,…) pm coverage more than doubled relative to previous experiments

9. 2N-SRC   4o 1.f 1.7f o = 0.17 GeV/fermi3 Nucleons CLAS-First Evidencefor3-N SRC relative momentum of struck nucleon(s) Can the correlations be seen directly in (e,e’pN)? The number of 2-nucleon SRC are 0.3, 1.2 and 6.7 in 4He, 12C and 56Fe, respectively Calculate a2N for the deuteron Analysis shows that 3-N SRC are 10 times smaller than 2-N SRC

10. Ratio of (pp) to (pn) pairs in 12C Scattered Electron Incident Electron E01-015 Triple coincident hadron knock-out (e,e’pn) and (e,e’pp) from 12C Scattered Proton Correlated Partner Proton or Neutron First Experiment to Use BigBite Spectrometer and Neutron Detector in Hall A

11. Summary of SRC findings in 12C Preliminary E07-006 (e,e’pp) Result PRL 99, 072501 (2007) (e,e’pn) Result Being Prepared For Publication

12. Discovery of the first hypernucleus by pionic decay in emulsion produced by Cosmic Rays. Marian Danysz and Jerzy Pniewski, 1952 • Access rich information about hypernuclear and nuclear physics • Used exclusively to determine the binding energy of light (A≤15) hypernuclei in emulsion • Precision: ~ 50 keV • Resolution: ~ 0.5 – 1.0 MeV • Problems: • - Poor statistics • - Calibrations • - Cannot resolve pure 2-body decay • not in the past ~ 20 years –low energy and low yield •   p + - (64%);   n + 0 (36%) • Remain effective even at medium A

13. HYPERNUCLEAR PHYSICS • Hypernuclei are bound states of nucleons with a strange baryon (Lambda hyperon). • Extension of physics on N-N interaction to system with S#0 • Internal nuclear shell • are not Pauli-blocked • for hyperons • Spectroscopy A hypernucleus is a “laboratory” to study nucleon-hyperon interaction (-N interaction - N interaction Unique aspects of strangeness many body problems

14. (r) LN interaction D SL SN T Each of the 5 radial integral (V, D, SL , SN, T) can be phenomenologically determined from the low lying level structure of p-shell hypernuclei

15. HYPERNUCLEI and ASTROPHYSICS • Strange baryons may appear in neutral b-stable matter through process like: • The presence of strange baryons in neutron stars strongly affect their properties. • Example: mass-central density relation for a non-rotating (left) and a rotating (right) star • The effect strongly depends upon the poorly known interactions of strange baryons s More data needed to constrain theoretical models.

16. BNL 3 MeV KEK336 2 MeV Improving energy resolution ~ 1.5 MeV 635 KeV 635 KeV new aspects of hyernuclear structure production of new hypernuclei energy resolution ~ 500 KeV and using electromagnetic probe High resolution, high yield, and systematic study is essential

17. septum magnets RICH detector

18. KAON Id Requirements physics case Signal Vs. Background Pion rejection factor ~ 1000 • Forward angles higher background ofpand p • TOF and 2 Threshold CherenkovNOT sufficient for unambiguous kaon identification • RICH DETECTOR K

19. sp= 4.47 nb/(GeV sr2 th= 4.68 nb/(GeV sr2 ) good agreement with theory E94-107 12C(e,e’K)11LB Red line: Fit to the data Blue line: Theoretical curve: Sagay Saclay-Lyon (SLA) used for the elementary K- electroproduction on proton. (Hypernuclear wave function obtained by M.Sotona and J.Millener) (3+,2+) (3+,2+) 1/2 1- 3/2 2- 1/2 1- 2+ 2+ 3/2 2- admixture admixture The energies of the 1/2- and 3/2- levels of the core are raised primarily by the SNterm because the interaction lN. SN changes the spacing of the core levels (the magnitude can be changed by changing SNor changing the p-shell w.f. of the core) • energy resolution ~650 KeV, the best achieved in hypernuclear production experiments • first clear evidence of excited core states at ~2.5 and 6.5 MeV with high statistical significance • -the width of the strong ppeak and the distribution of strength within several MeV on either side of this peak can put constraints on the hypernuclear structure calculations • -hint for a peak at 9.65 MeV excitation energy (admixture)

20. H. Hotchi et al., Phys. Rev. C 64 (2001) 044302 E94-107 Hall A Experiment Vs. KEK-E369 12C(e,e’K)12BL 12C(p+,K+)12CL Statistical significance of core excited states:

21. E94-107 Hall A Experiment Vs. FINUDA (at DaFne) 12C(e,e’K)12BL 12C(K-, p-)12CL Statistical significance of core excited states:

22. E89-009 12ΛB spectrum E94-107 Hall A Experiment Vs. HallC E01-011 12C(e,e’K)12BL 12C(e,e’K)12BL 12C(e,e’K+)12B JLAB E01-011 Preliminary NOT checked MM scale s Counts / 150 keV p Accidentals B (MeV) Statistical significance of core excited states:

23. Results on the WATERFALL target - 16O and H spectra 1H(e,e’K)L 1H(e,e’K)L,S L Energy Calibration Run S 16O(e,e’K)16NL Nb/sr2 GeV MeV Excitation Energy (MeV) • Water thickness from elastic cross section on H • Fine determination of the particle momenta and beam energy using the Lambda peak reconstruction (resolution vs position)

24. Results on16Otarget – Hypernuclear Spectrum of16NL [2] O. Hashimoto, H. Tamura, Part Nucl Phys 57, 564 (2006) [3] private communication from D. H. Davis, D. N. Dovee, fit of data from Phys Lett B 79, 157 (1978) [4] private communication from H. Tamura, erratum on Prog Theor Phys Suppl 117, 1 (1994) Comparison with the mirror nucleus16OL

25. New Proposal (Hall A): studying, using waterfall target, different processes Electroproduction of as function of Kaon angle The elementary process on the proton will run 2010(2011) The ratio of the hypernuclear and elementary cross section Contains direct information on the target and hypernuclear structure, production mechanisms Electro-production model predictions From electro-production to photo-production on hydrogen  Selectionof amodel (kinematics very close to the photon point)

26. JLAB Hall C - Second Generation - The E01-011 setup (RUN 2009) To beamdump HKS ENGE Splitter Target E89-009 12ΛB spectrum Electronbeam First step to medium heavy hypernuclei (28Si, 12C, 7Li) Two Major Improvements New HKS Tilt Method Beam: 30 mA , 1.8GeV HKS:Dp/p=2 x 10 -4 FWHM Solid angle 16msr(w/ splitter) G = ~460 keV FWHM Accidentals

27. The Third Generation: (E05-115): HKS + HES + New SPL To investigate hypernuclei in a wide mass range First step to beyond p-shell hypernuclei (main target 28Si, calib. 12C) Spectroscopic study of L hypernuclei in the medium-heavy mass region and p-shell region using the (e,e’K+) reaction (PR08-002 at Jlab - Hall C - in 2009 e’ To the beam dump HES 8-9deg tilt HKS K+ Target 2.5 GeV Electron beam

28. Hypernuclei in wide mass range E94-107 9Be 12C 16O E01-011 7Li 12C 28Si 1 E89-009 12C 20 50 200 1057 A • Neutron/Hyperon star, Strangeness matter Elementary Process • Neutron/Hyperon star Strangeness electro-production Light Hypernuclei (s,p shell) • Hyperonization  • Softening of EOS ? • Superfluidity • Fine structure • Baryon-baryon interaction in SU(3) • LS coupling in large isospin hypernuclei • Cluster structure • Medium - Heavy hypernuclei • Single-particle potential • Distinguishability of a L hyperon • U0(r), mL*(r), VLNN, ... Shell model Few body calc. Bare LN Int. Mean Field Theory Cluster calc.

29. Hypernuclei in wide mass range 1 20 50 200 1057 A E05-115＆PR08-002 6,7Li10B,11B 12C 40Ca52Cr 89Y Elementary Process • Neutron/Hyperon star, Strangeness matter Strangeness electro-production Light Hypernuclei (s,p shell) • Hyperonization  • Softening of EOS ? • Superfluidity • Fine structure • Baryon-baryon interaction in SU(3) • LS coupling in large isospin hypernuclei • Cluster structure • Medium - Heavy hypernuclei • Single-particle potential • Distinguishability of a L hyperon • U0(r), mL*(r), VLNN, ... 3rd Gen. Exp. Shell model Few body calc. Bare LN Int. Mean Field Theory Cluster calc.

30. Study of Light Hypernuclei by Pionic Decay at JLAB L.Tang, A. Margaryan, L. Yuan, S.N. Nakamura, J. Reinhold From both Hall C and A hypernuclear programs JLAB PAC 33 • - In the last 20 years or so, mesonic decay has not been really used in study of the hypernuclear/nuclear structure, because of its low momentum and the difficulty to reach high precision with unavoidable thick targets using mesonic beams • Emulsion: cannot resolvetwo body decay and typical resolution is 0.5 – 1.0 MeV • Counter type: resolution is 1.0 – 2.0 MeV Example Time delayed H. Outa et al., “Lifetime measurement of 4H hypernucleus”, INS-Rep.-914 (1992)

31. New Opportunity at JLAB • CEBAF beam and the HKS system • High precision and high yield • Energy resolution: ~130 keV FWHM • B precision: ~10 keV • Simultaneous lifetime measurement (timing resolution ≤80ps) • Wide range of physics

32. Physics Objectives –YN Interactions • Emulsion data of light hypernuclei (primarily the ground states) were used to check theoretical models on YN interaction • Problem of inconsistency and model of choice exist • Recent -spectroscopy program has been successful for spin dependent interactions but unable to measure B • Recent successful spectroscopycannot reachprecision on Bexceeding emulsion data

33. Directly Produced Hypernuclei Indirectly Produced Hypernuclei • Replace emulsion data with a new set of data that has a factor of 2-5 times betterprecision on B to check current and future theories with stringent limits • Separate small ground state doublets • Study charge symmetry breaking in YN interßaction, such as B(4Hg.s.) - B(4Heg.s.) • Search for Highly Exotic Hypernuclei • Impurity Nuclear PhysicsHypernuclear and nuclear structure

34. Technique & Exp. Layout Calibration needed for the absolute HS central momentum Standard Splitter and HKS for K+ Enge & target moved upstream for decay pions Tilted TGT (25mg/cm2) Eff. TGT (50mg/cm2) Standard pre-chicane beam line (E05-115) Local dump for photons Similar luminosity as E05-115 (HKS/HES)

35. Example of Possible G.S. of Light Hypernuclei from 12C Target 5He • Background: • ~97.5% QF  decay • ~2.5% (K+ & -) accidentals 8Li 12B 7Li 9Be 4H 8Be 11B 3H G.S. only (doublet structures are not shown) Estimated based on emulsion data thus may under-estimated for some of the hypernuclei Additional hypernuclei may appear

36. Conclusions • Jefferson Lab ha un ampio programma di ricerca in Fisica Nucleare, complementare a quello delle altre facilities preenti e future • Neutron skin del 208Pb (run 2009) con precisione elevatissima • Spettrocopia Ipernucleare ad alta • risoluzione, primi rilsutati • Correlazioni N-N: short-range, alti momenti • primi risultati quantitativi • Sistemi a pochi nucleoni • - Si e’ studiata la transizione da una descrizione in termini di mesoni a quella in termini di quark e gluoni. Studi ulteriori a piu’ alti Q2 del f.f. • Iniziati studi sulle modifiche degli adroni nel mezzo nucleare o della creazione degli adroni • - studi inziali hanno dato risultati interessanti. Ulteriori studi a 12 GeV 2009 Esperimento in sala C 2010(11) Esperimento in sala A 2014 (?) Esperimentio in sala A

37. International Hypernuclear Network • PANDA at FAIR • 2012~ • Anti-proton beam • Double -hypernuclei • -ray spectroscopy • SPHERE at JINR • Heavy ion beams • Single -hypernuclei • HypHI at GSI/FAIR • Heavy ion beams • Single -hypernuclei at • extreme isospins • Magnetic moments • MAMI C • 2007~ • Electro-production • Single -hypernuclei • -wavefunction • JLab • 2000~ • Electro-production • Single -hypernuclei • -wavefunction • FINUDA at DANE • e+e- collider • Stopped-K- reaction • Single -hypernuclei • -ray spectroscopy • (2012~) • J-PARC • 2009~ • Intense K- beam • Single and double -hypernuclei • -ray spectroscopy for single  • JLab, HπS • Electro-production • Single -hypernuclei at • normal and extreme isospins • Binding energies • π - decay spectroscopy • Impurity nuclear physics Basic map from Saito, HYP06

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39. Comparison with BB interaction models D SL SN T (MeV) ND -0.048 -0.131 -0.264 0.018 NF 0.072 -0.175 -0.266 0.033 NSC89 1.052 -0.173 -0.292 0.036 NSC97f 0.754 -0.140 -0.257 0.054 ( “Quark” 0.0 -0.4 ) Exp. 0.4 -0.01 -0.4 0.03 G-matrix calc. by Yamamoto Strength equivalent to quark-model LS force by Fujiwara et al. • Spin-orbitforces (SL , SN)cannot be explainedbymesonmodels. Data seems tofavor quark models. --but9LBe calculation byFujiwara et al. (quark+meson) cannot reproduce it. • Tensor forces (T) is well explained bymeson-exchange models. Courtesy H. Tamura

40. Hall A - Two High Resolution Spectrometers QDQ - Momentum Range: 0.3 –4 GeV/c Dp/p : 1 x 10-4 – Dp = =-5% - DW = 5 –6 mr - septum magnet - 1(+1) Cherenkov thr.aerogels - RICH in the hadron spectrometer

41. ph = 1.7 : 2.5 GeV/c p k p AERO1 n=1.015 AERO2 n=1.055 Pions = A1•A2 Kaons = A1•A2 Protons = A1•A2 Kaon Identification through Aerogels Pion rejection factor ~ 1000 K

42. N. of detected photoelectrons RICH detector –C6F14/CsI proximity focusing RICH “MIP” Cherenkov angle resolution Separation Power Performances - Np.e. # of detected photons(p.e.) - and  (angular resolution) maximize minimizee

43. Results on12CSpectrum target – Hypernuclear of12BL • BACKGROUND level is very low  Signal/Noise Ratio is very high • Clear evidence of core excited peak levels between the ground state and the strongly populated p-Lambda peak at 11 MeV • Quasi free K-Lambda production dominate the spectrum above 13 MeV

44. 4 peaks reproduced by SM calc. but • the second peak should be a doublet (J = 1-/2-) • 3rd and 4th peak narrow • --> very small pLspin-orbit splitting

45. Analysis of the reaction 9Be(e,e’K)9LiL Red line: Benhold-Mart (K MAID) Blue line: Saghai Saclay-Lyon (SLA) Curves are normalized on g.s. peak. Black line: Millener wave function preliminary Counts / 200 keV Counts / 200 keV Missing energy (MeV)

46. The proposed project capable to provide precise binding values of known hypernuclei and have a great potential to extend this landscape

49. Exotic Hypernuclei Different decay channels of excited 7He* hypernucleus (Majling, 2006).

50. JLAB Hall CExperimental setup - The Second Generation Exp. At Jlab - The E01-011 setup First step to medium heavy hypernuclei (28Si, 12C, 7Li) 12C(e,e’K+)12B JLAB – HKS ~ 120 hrs w/ 30A Preliminary Results on Carbon Target s G = ~400 keV FWHM Preliminary NOT checked MM scale p Counts / 150 keV Beam: 30 mA , 1.8GeV HKS:Dp/p=2 x 10 -4 FWHM Solid angle 16msr(w/ splitter) Accidentals B (MeV)