 Electroproduction of hypernuclei. E experiment.  Experimental equipment and setup Kaon identification  RICH detector: 2004 vs 2005 Analysis results of C data. Preliminary results of Be, O and H. Conclusions S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006 S. Marrone on behalf of E Collaboration. Dipartimento di Fisica and INFN, Bari.

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 – Indian-Summer School, Rez, Prague 3-7 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 – Indian-Summer School, Rez, Prague 3-7 October 2006

Electroproduction of hypernuclei by the reaction: Nuclear targets and resulting hypernuclei:  9 Be  9 Li  (spin doublets, information on s-s 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)  16 O  16 N  (details of the hypernuclear spectrum also depends on  single particle spin-orbit splitting ) -> 1 H(e,e’K)  for free because of the waterfall target. Experimental requirements: 1.Excellent Energy Resolution: Best performances ever obtained for Beam and High Resolution Spectrometer in Hall-A. 2.Detection at very forward angles (6° to obtain reasonably high counting rates)  Septum Magnets 3.Excellent Particle Identification system (PID) for unambiguous kaon selection  RICH E Experiment: “High Resolution 1p Shell Hypernuclear Spectroscopy” S. Marrone – Indian-Summer School, Rez, Prague 3-7 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 – Indian-Summer School, Rez, Prague 3-7 October 2006

Hall A - Two High Resolution Spectrometers QDQ - Momentum Range: 0.3 –4 GeV/c  p/p : 1 x –  p = =-5% -  –  mr Hadron Arm: 3 Scintillators for trigger, VDC for tracking, 2 Cherenkov Aerogels + RICH for PID In this case the PID is between  /K/p. Two High Resolution Spectrometers (HRS). Electron Arm: 3 Scintillators for Triggers; VDC for tracking;  /eGAS Cherenkov for PID Shower and Preshower for PID.

S EPTUM Magnets in Hall A FWHM = 1.1x10 -4  =20x20 mr 2 Before optimization After optimization Septa Minimal angle between two HRS = 12°. We need 6° to get a high cross section. We use two more magnets to bend the particles, the SEPTA. Optimixed the transfer matrix of the HRS with the Carbon elastic. 12° S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

H adron identification using Aerogel Threshold Cherenkov detectors p k All events  AERO1 n=1.015 AERO2 n=1.055 p k  p h = 1.7 : 2.5 GeV/c Protons = A1A2 Pions = A1A2 Kaons = A1A2 S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

R ICH detector –C 6 F 14 /CsI proximity focusing RICH “ MIP ” Performances : N p.e. # of detected photons (p.e.) and   (angular resolution) Cherenkov angle resolution Separation Power S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

The R ICH detector at Jefferson Lab S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

R ich – PID – Effect of ‘Kaon selection’:  P K Coincidence Time selecting kaons on Aerogels and on RICH: AERO KAERO K && RICH K Pion rejection factor ~ 1000 S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

R ich – PID – Effect of ‘Kaon selection’:  P K Coincidence Time selecting kaons on Aerogels and on RICH, after solving the Aerogel problems. AERO KAERO K && RICH K GREATLY improved AEROGEL performance! S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

Aerogel Kaon selection RICH Kaon selection 12 C(e,e’K) 12 B  Spectroscopy analysis of 12 B  : Aerogel vs. RICH K-selection S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

12 C(e,e’K) 12 B  650 keV FWHM Missing energy (MeV) R esults on 12 C target – Hypernuclear Spectrum of 12 B  g.s. S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

J LAB Hall A E94-107: preliminary comparison with theory for 12 B  hypernucleus Missing energy (MeV) Counts / 200 keV 12 C(e,e’K) 12 B  Two theoretical curves (blue and red), two different model for the elementary K-  production on proton. Same hypernuclear wave- function (by Miloslav Sotona). Red line: Bennhold-Mart (K MAID) Blue line: Sagay Saclay-Lyon (SLA). Curves are normalized on g.s. peak. RESOLUTION: 650 keV FWHM. The relative intensity of first excited-core peak at 2.6 MeV and strongly populated p-Lambda peak at 11 MeV would be better described by K MAID model than SLA. SLA viceversa reproduces better the last peak. S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

J LAB Hall A E94-107: preliminary comparison with theory for 12 B  hypernucleus Missing energy (MeV) Counts / 200 keV 12 C(e,e’K) 12 B  Two theoretical curves (blue and red), two different model for the elementary K-  production on proton. Same hypernuclear wave- function (by Miloslav Sotona). Red line: Bennhold-Mart (K MAID) Blue line: Sagay Saclay-Lyon (SLA). Curves are normalized on g.s. peak. Theory = 4.4 nb/(GeV sr 2 ) Stat ~ 5 % Tot. ~ 20 % g.s. CrossSection = 4.6 nb/(GeV sr 2 ) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

R esults from last year run on 9 Be target Analysis of the reaction 9 Be(e,e’K) 9 Li  (still preliminary) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

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 – Indian-Summer School, Rez, Prague 3-7 October 2006

Missing energy (MeV) Counts / 200 keV Red line: Bennhold-Mart (K MAID) Blue line: Sagay Saclay-Lyon (SLA) Curves are normalized on g.s. peak. J LAB Hall A E-94107: P reliminary R esults on 9 Be target S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

F irst R esults from current experiment on WATERFALL target Analysis of the reaction 16 O(e,e’K) 16 N  and 1 H(e,e’K)  (elementary reaction) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

2005 E-94107: Running on waterfall target Be windows H 2 O “foil” S. Marrone – Indian-Summer School, Rez, Prague 3-7 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 – Indian-Summer School, Rez, Prague 3-7 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 on 12 C and 9 Be targets ( 12 B  and 9 Li  hypernuclei) have been taken. New experimental equipments demonstrated excellent performance. The RICH detector performs as expected and it is crucial in the kaon selection. On-going Analysis of data on 12 C  target  is showing new information on 12 B  and interesting comparison with theory for 12 B  and 9 Li . VERY Promising physics is coming out from the presently running experiment on 16 N  hypernuclear spectroscopy (also with p(e,e’K)  X-Sect. Measurement  S. Marrone – Indian-Summer School, Rez, Prague 3-7 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