1. Hypernuclear spectroscopy using (K - stop,  0 ) and (e,e’K + ) reactions Doc. dr. sc. Darko Androić University of Zagreb Physics Department

2. Definition and discovery Hyperon – baryon with at least one strange quark Hypernucleus – nucleus with at least one hyperon 1953. M. Danysz i J.Pniewski discovery in photographic emulsion (26km) Disintegration modes

3. Historical overview 1953-1970: visual experimental techniques (emulsions, bubble chambers). 1970  today spectrometry with particle beams from accelerators Binding energy known for cca 30 hypernuclei B  = M core + M  - M hyp

4.  particle the most interesting hyperon!  The lightest hyperon  1115.684 ± 0.006MeV  mass cca 20% larger than n or p mass  Q=0  I=0  S=-1     263 ± 2 ps

5. Summary: hypernuclei from emulsion Binding energy: B  ~ A (cca 1MeV/A) Binding energy difference for mirror nuclei  B  << 0.5MeV n=  n /  p +  n cca 1/3 Q - =  nm /  m ~ A  N improving understanding of NN interaction  N  NN sensitive for difference between baryon-baryon interaction and quark level processes

6. Excited states of hypernuclei and spectroscopy Using strange particle beams (K ± ) Detector systems - fragment identification

7. Former experiments  production on neutron reactions types (K -,  - ) i (  +,K + ) “mirror nuclei” have to be investigated in reactions with simultaneous changing charge and strangeness  production on proton reaction types (K -,  0 ) i (  -,K 0 )

8. Reaction type: (K - (stop),  0 ) E907 p K =682MeV/c

9. NMS and beam line detectors E907

10. Active target E907 ATC parameters Total number of the targets 4 Thickness of individual targets 12.7 mm Target material Graphite Total number of cathode planes 20 Thickness of single cathode plane 3.429 mm Thickness of cathode foil 0.0127 mm Number of cathode strips per plane 64 Capacitance between two strips 12 pF Single strip resistance 0.11  /mm Total number of anode planes 10 Thickness of a single anode plane 3.429 mm Anode wire diameter0.02 mm Wire material gold-plated tungsten Average anode wire tension 72 g Anode potential 2.2 kV Total number of spacer boards 10 Thickness of spacer boards 3.429 mm

11. Resolution E907

12. Results E907

13. E931

14. Topology and calibration E931

15. Particle identification E931

16. Neutron spectrum / coincidences E931 Important theoretical contribution: Zagreb theoretical group of prof. D. Tadić

17. Electroproduction vs meson production of hypernuclei

18. Experiment topology E89-009

19. Event reconstruction E89-009

20. Spectrum E89-009

21. First electroproduction E89-009

22. Experiment topology E01-011

23. HKS details E01-011 Magnet configuration Q-Q-D Momentum acc. 1.2 GeV/c ± 12.5% (1.05–1.35 GeV/c) Momentum resolution (  p/p) 2×10 −4 angle 30 (16) msr position: 7 ◦ (1–13 ◦ ) trajectory 10 m Magnetic field 1.6 T

24. Experimental details E01-011 E e 1.8 GeV E e’ 300 MeV Virtual photon energy 1.5 GeV p( ,K+)  decreases for E  > 1.5 GeV New redesign: 1- New kaon spectrometer HKS (dipole 210t) two quadruple Q1 (8.5 t) i Q2 (10.5 t) 2- new geometry of electron spectrometer (tilt method).

25. Electron arm E01-011

26. p(e,e’K + )  &  0 used for kinematics and optics calibration Counts (300 keV/bin) B  (MeV) Preliminary HKS-JLAB CH 2 target ~ 70 hours  = 630 keV  M  = 24 keV  M  = 8 keV  0000

27. 12 C(e,e’K + ) 12  B used for kinematics and optics calibration Counts (0.15 MeV/bin)  s (2 - /1 - )  p (3 + /2 + s) JLAB – HKS ~ 90 hrs w/ 30  A Preliminary Accidentals B  (MeV)  = ~400 keV FWHM B  g.s. = -11.81 MeV B  p.s = -0.79 MeV C.E #1 C.E #2

28. Accidentals Counts (0.15 MeV/bin) 28 Si(e,e’K + ) 28  Al – First Spectroscopy of 28  Al JLAB – HKS ~140 hrs w/ 13  A Preliminary ss pp B  (MeV)  = ~400 keV FWHM B  g.s. = -18.47 MeV B  p.s = -7.30 MeV

29. Accidentals B  (MeV) Counts (0.2 MeV/bin) 7 Li(e,e’K + ) 7  He – First Observation of ½ + G.S. of 7  He Preliminary JLAB – HKS (~ 30 hrs w/ 30  A) JLAB – HKS (~ 30 hrs w/ 30  A ) ss  = ~467 keV FWHM B  g.s. = -5.69 MeV

30. Conclusion / Future experiment Hypernuclear electroproduction demonstrated kinematical completeness Superior resolution respect meson production experiments (e,e´K + ) channel is charge-mirrored respect (K ±,  ± ); new insight possible quark degrees of freedom have to be included in theoretical calculations Future resolution improvements are required

31. HES scheme E05-115 2.5 GeV electron 7.5 o “tilt” HES HKS Target e’ K+K+ JLab E05-115 (HES): Extend hypernuclear Spectroscopy from lower p-shell to beyond p-shell with a few 100 keV resolution

32. G0: E99-016, E01-115 and E01-116 parity-violating asymmetries in elastic electron scattering from the nucleon