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Hypernuclear Spectroscopy in Hall-A at JLAB

Hypernuclear Spectroscopy in Hall-A at JLAB. S. Marrone on behalf of E94-107 Collaboration. Dipartimento di Fisica and INFN, Bari. Electroproduction of hypernuclei. E94-107 experiment. Experimental equipment and setup Kaon identification  RICH detector: 2004 vs 2005

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Hypernuclear Spectroscopy in Hall-A at JLAB

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  1. Hypernuclear Spectroscopy in Hall-A at JLAB S. Marrone on behalf of E94-107 Collaboration. Dipartimento di Fisica and INFN, Bari. • Electroproduction of hypernuclei. • E94-107 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

  2. High Resolution Hypernuclear Spectroscopy Experiment E94-107 JLABHall AE94-107 COLLABORATION (spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito) • 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 S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  3. Electroproduction of Hypernuclei Hypernucleus N … N L Kaon detected by HRSk Better energy resolution than hadronic induced reactions, BUT smaller cross section K+ L Scattered electron Detected by HRSe g * e’ p beam p High luminosity, high duty cycle, excellent beam energy spread obtained at CEBAF in Hall-A. N … N e nucleus S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  4. E94-107 Experiment: “High Resolution 1p Shell Hypernuclear Spectroscopy” • Electroproduction of hypernuclei by the reaction: • Nuclear targets and resulting hypernuclei: • 9Be  9LiL (spin doublets, information on s-s term of L-N interaction potential) • 12C  12BL (comparison with previous data: better understanding of results with hadron probesand E89-009 in Hall C at Jefferson Lab) • 16O  16NL(details of the hypernuclear spectrum also depends on Lsingle particle spin-orbit splitting ) -> 1H(e,e’K)L for free because of the waterfall target. • Experimental requirements: • Excellent Energy Resolution: Best performances ever obtained for Beam and High Resolution Spectrometer in Hall-A. • Detection at very forward angles (6° to obtain reasonably high counting rates)  Septum Magnets • Excellent Particle Identification system (PID) for unambiguous kaon selection RICH S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  5. Kinematics, Counting rates • Ebeam = 4.016 — 3.777 — 3.656 GeV • Pe= 1.80 — 1.56 — 1.44 GeV/c • Pk= 1.96 GeV/c • qe = qK = 6° • = Eg 2.2 GeV – Q2 = 0.079 (GeV/c)2 Beam current : 100 mA Target thickness : ~100 mg/cm2 Counting Rates ~0.1 – 10 counts/peak/hour S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  6. 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 Two High Resolution Spectrometers (HRS). Electron Arm:3 Scintillators for Triggers; VDC for tracking;p/e GAS Cherenkov for PID Shower and Preshower for PID. Hadron Arm:3 Scintillators for trigger,VDC for tracking,2 Cherenkov Aerogels + RICHfor PID In this case the PID is between p/K/p .

  7. SEPTUM Magnets in Hall A 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° Septa DW=20x20 mr2 Before optimization FWHM = 1.1x10-4 After optimization S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  8. p k All events p Hadronidentification using Aerogel Threshold Cherenkov detectors 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 S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  9. RICH detector –C6F14/CsI proximity focusing RICH “MIP” Cherenkov angle resolution Separation Power Performances: Np.e. # of detected photons (p.e.) and sq (angular resolution) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

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

  11. Rich – PID – Effect of ‘Kaon selection’: Coincidence Time selecting kaons on Aerogels and on RICH: AERO K AERO K && RICH K 2004 p P K Pion rejection factor ~ 1000 S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  12. Rich – PID – Effect of ‘Kaon selection’: Coincidence Time selecting kaons on Aerogels and on RICH, after solving the Aerogel problems. AERO K AERO K && RICH K 2005 K P GREATLY improved AEROGEL performance! p S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

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

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

  15. JLAB Hall AE94-107: preliminary comparison with theory for 12BL hypernucleus 12C(e,e’K)12BL Two theoretical curves (blue and red),two different model for the elementary K-L 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. Counts / 200 keV Missing energy (MeV) 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

  16. JLAB Hall AE94-107: preliminary comparison with theory for 12BL hypernucleus g.s. CrossSection = 4.6 nb/(GeV sr2 ) Stat ~ 5 % Tot. ~ 20 % Theory = 4.4 nb/(GeV sr2 ) Two theoretical curves (blue and red),two different model for the elementary K-L 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. 12C(e,e’K)12BL Counts / 200 keV Missing energy (MeV) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

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

  18. JLAB Hall AE-94107: PreliminaryResults on 9Be target 9Be(e,e’K)9LiL Counts / 400 keV Aerogel Kaon selection RICH Kaon selection Missing energy (MeV) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

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

  20. First Results from current experiment on WATERFALL target Analysis of the reaction 16O(e,e’K)16NL and 1H(e,e’K)L (elementary reaction) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  21. 2005E-94107: Running on waterfall target H2O “foil” Be windows H2O “foil” S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  22. 15N energy spectrum 16NL energy spectrum Coupling of Lp1/2 and Lp3/2 Theoretical model for 16NL excitation-energy on 16O target The structure of underlying nucleus 15N is dominated by: J=1/2-proton-hole state in 0p1/2 shell - ground state J=3/2- proton-hole state in 0p3/2 shell - Excited states at Ex = 6.32 MeV Details of the hypernuclear spectrum at Ex ~ 17-20 MeV depends not only on L-N residual interaction but also on the L single particle spin-orbit splitting (difference in energy of 0p3/2 and 0p1/2 L states) 16O(e,e’K)16NL

  23. 16O(e,e’K)16NL Low counting levels above Ethr. 16O(e,e’K)16NL 2005E-94107: Preliminary spectra of missing energy 1H(e,e’K)L 16O(e,e’K)16NL S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  24. Conclusions: • Experiment E94-107 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 12C and 9Be targets (12BL and 9LiL 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 12Ctargetis showing new information on 12BL and interesting comparison with theory for 12BL and 9LiL. • VERY Promising physics is coming out from the presently running experiment on 16NL hypernuclear spectroscopy (also with p(e,e’K)L X-Sect. Measurement) S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

  25. HYPERNUCLEI and ASTROPHYSICS contd • 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/0005490 • “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/9810361 S. Marrone – Indian-Summer School, Rez, Prague 3-7 October 2006

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