1. HYPERNUCLEAR PHYSICS USING CEBAF BEAM PAST AND FUTURE Liguang Tang Hampton University/JLAB 4 th Workshop on Hadron Physics In China and Opportunities with JLAB 12GeV July 16-20, 2012

2. INTRODUCTION – BARYONIC INTERACTIONS Baryonic interaction (B-B) is an important part of nuclear force that builds the “world” - Neutron Stars - Astronomical Scale - Neutron Stars - H H (1p) He  (  - 2p, 2n) C  C (3  ) Understand B-B interactions is one of the essential tasks in Nuclear Physics

3. ,  0 (uds) n (udd) p + (uud)  + (uus)  - (dds)  - (dss)  0 (uss) S Q I S = 0 S = -1 S = -2 I 3 = -1 I 3 = +1/2 I 3 = -1/2 I 3 = +1 I 3 = 0 Nucleon (N) Hyperon (Y) S - Strangeness I - Isospin I - Isospin

4. INTRODUCTION – HYPERNUCLEAR PHYSICS  To understand YN and YY interactions  Producing Y inside of the nucleus  Extract YN and YY interactions by studying the many body system  To study short range interactions in baryonic interactions (OPE is absent in  N interaction)  To better explore nuclear structure using  as a probe (not Pauli blocked by nucleons) and to explore new degree of freedom  Model the baryonic many body system  Study the role and the single particle nature of  in various nuclear medium and density  N and  are the most fundamental interactions. Since  decays only weakly (  N or  N  NN) thus long lifetime, mass spectroscopy  - hypernuclei becomes possible analog to the nuclear mass spectroscopy

5.  Shell Model with 2-B  N Effective Potential (p N s  ) ssss V  N = V 0 (r) + V  (r) s N  s  + V  (r) L N   s  + V N (r) L N   s N + V T (r) S 12  Additional Contribution:  -  coupling   N   N  Contribute to the repulsive core  Introduce an additional term:   Observables:  Ground state single  binding energy  Excitation spectroscopy (levels and level spacing)  Production and production cross sections  Decays V —  SS SNSN T 5 Radial Integrals: Coefficients of operators THEORETICAL DESCRIPTION: 2B POTENTIAL

6. BASIC PRODUCTION MECHANISMS AZAZ  n AZAZ -- K-K- (K,  ) Reaction  Low momentum transfer  Higher production cross section  Substitutional, low spin, & natural parity states  Harder to produce deeply bound states AZAZ  n A ++ K+K+ ( , K) Reaction  High momentum transfer  Lower production cross section  Deeply bound, high spin, & natural parity states A  (Z-1)   p AZAZ e e’e’ K+K+ (e, e’K) Reaction  High momentum transfer  Small production cross section  Deeply bound, highest possible spin, & unnatural parity states  Neutron rich hypernuclei CERN  BNL  KEK & DA  NE  J-PARC (Near Future) Disadvantage: Lack absolute energy calibration and resolution CEBAF at JLAB (MAMI-C Near Future) Advantage: Absolute energy calibration & high resolution

7. 4  He 4H4H 3H3H 7  He 7  Li 6  He B  (MeV) 5  He 9  Be 9  Li 8  Be 8  Li 8  He 7  Be 13  N 13  C 10  B 12  B 11  B 9B9B Important source of data but lack statistics and resolution Reliability: Questionable Nevertheless, emulsion experiments before 80’s provided the most complete set of measured single  binding energy B  of s- and p-shell  -hypernuclei

8. Missing predicted gamma ray Advantages: High resolution (~ few keV) and precise level spacing Disadvantages: low rate (statistics) and unable to measure the ground state binding energy

9. KEK336 2 MeV(FWHM) KEK E369 1.5 MeV(FWHM) High resolution, high yield, and systematic study is essential and is the key to unlock the “gate” Meson beam lacks absolute mass calibration (no free neutron target) BNL 3 MeV(FWHM)

10. ELECTRO-PRODUCTION USING CEBAF BEAM  High quality primary beam allows high precision mass spectroscopy on  -hypernuclei  Producing  and  0 from proton simultaneously allows absolute mass calibration – precise binding energy  Mirror and neutron rich hypernuclei comparing those from (  +,K + ) reaction  Spectroscopy dominated by high spin-stretched spin-flip states  Results are important in determining , S N and V 0 terms from  s states and S  term from states with  at higher orbits

11.  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 + Q D _ D 0 1m Q D _ D Side View Top View Target (1.645 GeV) Phase I E89-009 K+K+ e’ Phase II E01-011 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

12.  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 Beam 2.34 GeV e’ K+K+  e Phase III E05-115 Common Splitter Magnet

13. 6GEV PROGRAM HIGHLIGHTS 6GEV PROGRAM HIGHLIGHTS  00 Allowing precise calibration of mass scale p(e, e’K+)  and  0 (CH2 target)

14. -B  (MeV) -6.68  0.02  0.2 MeV from  nn 7  He E94-107 in Hall A (2003 & 04)  s (2 - /1 - )  p (3 + /2 + ’s) Core Ex. States ~635 keV FWHM 12  B 6GEV PROGRAM HIGHLIGHTS– CONT. K+K+ _ D K+K+ 1.2GeV/c Local Beam Dump E89-009 12 Λ B spectrum ~800 keV FWHM HNSS in 2000 ss pp Phase I in Hall C (E89-009) Phase II in Hall C (E01-011) B  (MeV) 28 Si(e, e’K + ) 28  Al (Hall C E01-011) HKS JLAB Counts (150 keV/bin) 28  Al ss pp dd Accidentals Phase II in Hall C (E01-011) ~500 keV FWHM HKS in 2005 12  B 16  N (Hall A) F. Cusanno et al, PRL 103 (2009) 16  N F. Cusanno et al, PRL 103 (2009) ss pp Phase III in Hall C (E05-115) ss pp

15. 6GEV PROGRAM TECHNIQUE SUMMARY  Hall A experiment (Pair of Septums + two HRS)  Advantage: Almost no accidental background and be able to study elementary process at low Q 2 at forward angle  Disadvantage: Low yield rate and cannot study heavier hypernuclei  Hall C experiment (Common Splitter + HKS + HES/Enge)  Advantage: High yield rate and high precision in binding energy measurement  Disadvantage: High accidental background and solid targets only Future program: Combination

16. EXPERIMENTAL LAYOUT IF IN HALL C HKS - Kaons Enge - Pions HES - Electrons Hodoscope Lucite Č Drift Chamber 64mg/cm 2 22mg/cm 2 K+K+ -- Trigger I: HKS(K) & Enge(  ) for Decay Pion Spectroscopy Experiment Trigger II: HKS(K) & HES(e’) for Mass Spectroscopy Experiment

17.  High quality with low background  High precision on binding energy and high resolution  High yield rate which leads to wide range of physics:  Elementary production at forward angle  Detailed and precise level structure of light and medium heavy hypernuclei (shell models)  Precise shell structure of heavy hypernuclei (single particle nature and field theory)  High efficiency and productivity: one exp.  Four 6GeV experiments  New physics: Decay pion spectroscopy (Light Hypernuclei)  Precise ground state B   Determination of ground state J p  Search for neutron rich limit (high Isospin states   ) Technical Features of Future Program

18. DECAY PION SPECTROSCOPY TO STUDY  -HYPERNUCLEI 12 C  - Weak mesonic two body decay 1-1- 0.0 2-2- ~150 keV Ground state doublet of 12  B B  and  Direct Production p e’ e 12 C K +K + Example:  Hypernuclear States:  s (or  p ) coupled to low lying core nucleus  12  B g.s. E.M.  ** 12  B

19. DECAY PION SPECTROSCOPY FOR LIGHT AND EXOTIC  -HYPERNUCLEI Fragmentation Process p e’ e 12 C Example: K +K +  ** s 12  B * Highly Excited Hypernuclear States:  s coupled to High-Lying core nucleus, i.e. particle hole at s orbit    4H4H Fragmentation (<10 - 16 s)  4  H g.s.  4 He  - Weak mesonic two body decay (~10 - 10 s) Access to variety of light and exotic hypernuclei, some of which cannot be produced or measured precisely by other means

20. 110 ~ 160 MeV/c110.05 ~ 160.05 MeV/c110.1 ~ 160.1 MeV/c 110.15 ~ 160.15 MeV/c 110.2 ~ 160.2 MeV/c Possible observation 4  H ground state Central Mom. : 133.5 MeV/c → B Λ ( 4 Λ H) : ~ － 1.60 MeV Width : 97 keV/c FWHM Target straggling loss was not corrected Spec-C momentum calibration was not yet done MAMI-C Short Test Run on Decay Pion Spectroscopy

21. SUMMARY  Hypernuclear Physics is an important part of nuclear physics  Program with CEBAF beam is the only one that provides precise B  and features as Precision mass spectroscopy program  Future program will be highly productive