Electroproduction of hypernuclei. E experiment: Experimental equipment and setup; Preliminary results of Be and O. Conclusions. S. Marrone – HYP 2006, Mainz October 2006 S. Marrone* on behalf of E Collaboration. *Dipartimento di Fisica and INFN, Bari, Italy. 9  Li and 16  N High resolution spectroscopy by electron scattering at Jefferson Lab in Hall-A. OUTLINE

A.Acha, H.Breuer, C.C.Chang, E.Cisbani, F.Cusanno, C.J.DeJager, R. De Leo, R.Feuerbach, S.Frullani, F.Garibaldi, D.Higinbotham, M.Iodice, L.Lagamba, J.LeRose, P.Markowitz, S.Marrone, R.Michaels, Y.Qiang, B.Reitz, G.M.Urciuoli, B.Wojtsekhowski And the Hall A Collaboration J LAB H all A E C OLLABORATION (spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito) S. Marrone – HYP 2006, Mainz October 2006

Electroproduction of Hypernuclei e p K+K+ e’   * N … N nucleus Hypernucleus p beam Scattered electron Detected by HRS e Kaon detected by HRS k  N … N High luminosity, high duty cycle, excellent beam energy spread obtained at CEBAF in Hall-A. Better energy resolution than hadronic induced reactions, BUT smaller cross section S. Marrone – HYP 2006, Mainz October 2006

Nuclear targets and resulting hypernuclei:  9 Be  9 Li  (spin doublets, information on spin-spin and spin-orbit term of  -N interaction potential)  12 C  12 B  (comparison with previous data: better understanding of results with hadron probes and E in Hall C at Jefferson Lab explained in LeRose’s talk)  16 O  16 N  (details of the hypernuclear spectrum also depends on  single particle and spin-orbit splitting)  1 H(e,e’K)  for free because of the water target (Markovitz’s talk, parallel session C1) Experimental requirements: 1.Excellent Energy Resolution: Best performances ever obtained for Beam and High Resolution Spectrometer in Hall-A. ( LeRose’s talk on monday). 2.Detection at very forward angles (6° to obtain reasonably high counting rates)  Septum Magnets (F. Cusanno’s talk parallel session A3). 3.Excellent Particle Identification system (PID) for unambiguous kaon selection  RICH (F. Cusanno’s talk). E Experiment: “High Resolution 1p Shell Hypernuclear Spectroscopy” S. Marrone – HYP 2006, Mainz October 2006

K inematics, C ounting rates E beam = — — GeV P e = 1.80 — 1.56 — 1.44 GeV/c P k = 1.96 GeV/c  e =  K = 6° = E   2.2 GeV – Q 2 = (GeV/c) 2 Beam current : 100  A Target thickness : ~100 mg/cm 2 Counting Rates ~ 0.1 – 10 counts/peak/hour S. Marrone – HYP 2006, Mainz October 2006

Hall A - Two High Resolution Spectrometers QDQ - Momentum Range: 0.3–4 GeV/c  p/p : 1 x –  p = =-5% -  –  mr Detectors: 3 Scintillators for trigger, 2 VDC for tracking, Gas Cherenkov and Showers for PID in Electron Arm. 2 Cherenkov Aerogels + RICH for PID in Hadrom Arm 12° Septa

R esults from 9 Be target Analysis of the reaction 9 Be(e,e’K) 9 Li  (still preliminary) S. Marrone – HYP 2006, Mainz October 2006

Weak Coupling Model “weak coupling model” (parent nucleus) (  hyperon) (doublet state) 8 Li / /2 + 9  Li / /2 + ss / /2 + ss ss Monte Carlo Simulations on 9 Be target.

Missing energy (MeV) Counts / 400 keV 9 Be(e,e’K) 9 Li  Aerogel Kaon selection RICH Kaon selection J LAB Hall A E-94107: P reliminary R esults on 9 Be target S. Marrone – HYP 2006, Mainz October 2006

Red curve: elementary process by Benhold-Mart (K MAID) - Hyp w.f. by M.Sotona Blue line: elementary process by Saghai Saclay- Lyon (SLA)- Hyp. W.f. by M.Sotona Black line: elementary process by Saghai Saclay- Lyon (SLA)- Hyp. W.f. by J.Millener Curves are normalized on g.s. peak. ANALYSIS of the reaction 9 Be(e,e’K) 9 Li  Missing energy (MeV) Counts / 200 keV S. Marrone – HYP 2006, Mainz October 2006

F irst R esults from the experiment on WATERFALL target Analysis of the reaction 16 O(e,e’K) 16 N  S. Marrone – HYP 2006, Mainz October 2006

2005 E-94107: Running on waterfall target Be windows H 2 O “foil” S. Marrone – HYP 2006, Mainz October 2006

Theoretical model for 16 N  excitation-energy on 16 O target The structure of underlying nucleus 15 N is dominated by: (i)J=1/2-proton-hole state in 0p1/2 shell - ground state (ii)J=3/2- proton-hole state in 0p3/2 shell - Excited states at Ex = 6.32 MeV Details of the hypernuclear spectrum at Ex ~ MeV depends not only on -N residual interaction but also on the single particle spin-orbit splitting (difference in energy of 0p3/2 and 0p1/2  states) Coupling of  p1/2 and  p3/2 16 O(e,e’K) 16 N  15 N energy spectrum 16 N  energy spectrum

2005 E-94107: Preliminary spectra of missing energy 1 H (e,e’K)  16 O(e,e’K) 16 N  Low counting levels above E thr. 16 O(e,e’K) 16 N  S. Marrone – HYP 2006, Mainz October 2006

A nalysis on 16 N  spectrum : FIT to the data S. Marrone – HYP 2006, Mainz October 2006

15 N energy spectrum 16 N  energy spectrum A nalysis on 16 N  spectrum : COMPARISON with models High energy excited MULTIPLETS seems NOT WELL reproduced by the model.  -interaction here is in p-state and is poorly known…. S. Marrone – HYP 2006, Mainz October 2006

16 O(e,e’K) 16 N  E Hall A Experiment Vs. KEK-E O(  ,K + ) 16 O  S. Marrone – HYP 2006, Mainz October 2006

16 O(e,e’K) 16 N  E Hall A Experiment Vs.  -ray spectroscopy at BNL 16 O(K -,    ) 16 O  S. Marrone – HYP 2006, October 2006

C onclusions: Experiment E at Jefferson Lab: GOAL is to carry out a systematic study of light hypernuclei (shell-p). The experiment required important modifications on the Hall A apparatus. Good quality data in term of resolution and SNR on 9 Be and 16 O targets have been taken. New experimental equipments demonstrated excellent performance. The RICH detector performs, as expected, crucial role in the kaon selection. Preliminary analysis of data on 9 Be  target  is showing new information  and interesting comparison with theory for 9 Li . VERY Promising physics is coming out from the present data analysis on 16 N  hypernuclear spectroscopy (also with p(e,e’K)  Cross-Section  In the Oxygen case, we have started the normalization procedures to extract the cross sections. S. Marrone – HYP 2006, October 2006

There is growing evidence that hyperons appears the first of the strange hadrons in neutron stars at around twice normal density….The onset of the hyperon formation is controlled by the attactive hyperon-nucleon interaction wich can be extracted from hypernucleon scattering data and hypernuclear data (J. Shaffner-Bielich et al: Hyperstars: Phase Transition to (meta)-Stable Hyperonic matter in neutron Stars, arXiv: astroph/ “ Additional experimental data from hypernuclei will be useful in establishing the foundations of high density matter models. This is especially relevant for the hyperon-nucleon interactions, for which relevant systems are more likely to be produced in current accelerators than for hyperon-hyperon interactions” in S. Balberg et al: Roles of hyperons in Neutron Stars, arXiv: astro-ph/ H YPERNUCLEI and A STROPHYSICS contd S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006