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High Resolution Hypernuclear Spectroscopy in Hall A

High Resolution Hypernuclear Spectroscopy in Hall A. Hypernuclei, L – N interaction Electroproduction of hypernuclei E94-107 experiment UPDATE Experimental equipment and setup Kaon identification  RICH detector Analysis results of 2004 run Preliminary results of 2005 run

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High Resolution Hypernuclear Spectroscopy in Hall A

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  1. High Resolution Hypernuclear Spectroscopy in Hall A • Hypernuclei, L – N interaction • Electroproduction of hypernuclei • E94-107 experiment UPDATE • Experimental equipment and setup • Kaon identification  RICH detector • Analysis results of 2004 run • Preliminary results of 2005 run • E07-012 proposed experiment • Conclusions Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  2. JLABHall AE94107 COLLABORATION • 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 High Resolution Hypernuclear Spectroscopy experiment E94-107 Update Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  3. Hypernuclei • Hypernuclei are bound states of nucleons with a strange baryon (Lambda hyperon). A hypernucleus is a “laboratory” to study nucleon-hyperon interaction (L-N interaction). • Extension of physics on N-N interaction to system with S0 • Internal nuclear shell are not Pauli-blocked for hyperons. • Experimental goals : • Spectroscopy – Excitation Energy – doublet splitting • Information on L-N interaction Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  4. Data Taking and Future Plan • E94107 experiment has taken data in two separate period on 2004. Data have been collected on solid targets. The second part of the experiment is currently running in Hall A using the waterfall target • January 2004 12C target and commissioning of waterfall target • April 2004 12C target and May 2004 9Be • June 2005 Waterfall target for hypernuclear state production on 16O • Approved Experiment E07012 to study the angular dependence of strangeness electroproduction Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  5. Hypernuclei and L-N interaction “weak coupling model” (parent nucleus) (L hyperon) (doublet state) LN interaction potential: VLN = Vo(r) V central + Vs(r) sN · sLD (spin-spin) + Vso(r) lLN· sL sL (spin-orbit) + Vso(r) lLN· sNsN(spin-orbit) + VT(r) S12 T tensor 9Be9LiL 9Be9LiL 9Be9LiL excitation energy Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  6. 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 N … N e nucleus Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  7. E94-107 Experiment: “High Resolution 1p Shell Hypernuclear Spectroscopy” (spokespersons: F. Garibaldi, S. Frullani, J. Le Rose, P. Markowitz, T. Saito – Hall A Coll.) • 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) • Experimental requirements: • Excellent Energy Resolution (Best performance for Beam and HRS) • Detection at very forward angles (6° to obtain reasonably high counting rates  septum magnets) • Excellent Particle Identification system (PID) for unambiguous kaon selection RICH Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  8. SEPTUM magnets in Hall A Carbon Peaks DW=20x20 mrad2 FWHM = 1.1x10-4 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  9. 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  10. 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 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  11. KAON Id Requirements physics case Signal Vs. Background Monte Carlo • Forward angles  higher background of p and p • TOF and 2 Threshold Cherenkov NOT sufficient for unambiguous kaon identification • RICH DETECTOR Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  12. 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) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  13. The RICH detector at Jefferson Lab Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  14. 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 RICH Pion rejection factor ~ 1000 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  15. Rich – PID – Effect of ‘Kaon selection’: Coincidence Time selecting kaons on Aerogels and on RICH: AERO K AERO K && RICH K 2005 K P GREATLY improved AEROGEL performance! p Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  16. Monte Carlo simulation of 12BL excitation-energy levels produced on 12C target 12C(e,e’K)12BL d a c b Absolute and relative positions of “resolved” levels a,b,c,d, may provide information on parameters of L-N interaction potential and its terms (spin-spin, spin-orbit, tensor, …) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  17. Results from 12C target Analysis of the reaction 12C(e,e’K)12BL Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  18. Spectroscopy analysis of 12BL: Aerogel vs. RICH K-selection 12C(e,e’K)12BL Aerogel Kaon selection RICH Kaon selection Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  19. Results on 12C target – Hypernuclear Spectrum of 12BL Missing energy (MeV) 12C(e,e’K)12BL 635 keV FWHM Experiment SLA Model M. Iodice et al, submitted to Phys Rev Lett, arXiv:0705:3332 Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  20. 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 nucleus15N 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

  21. Preliminary Results on WATERFALL target Analysis of the reaction 16O(e,e’K)16NL and 1H(e,e’K)L (elementary reaction) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  22. 2005E-94107: Running on waterfall target H2O “foil” Be windows H2O “foil” Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  23. 16O(e,e’K)16NL Low counting levels above Ethr. 2005E-94107: Preliminary Analysis 1H(e,e’K)L Preliminary g.s. missing energy: -1.44  0.09 MeV Theor –1.56 MeV 16O(e,e’K)16NL Missing Energy (MeV) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  24. Monte Carlo simulation of 9LiL excitation-energy levels Produced on 9Be target Excitation-energy levels of 9LiL hypernucleus, especially from the first-doublet levels a and b, would provide important information on D, SL and T terms of the L-N interaction. Separation of c and d doublets may provide information on the spin-orbit term SN 9Be(e,e’K)9LiL c d b a Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  25. Results on 9Be target Analysis of the reaction 9Be(e,e’K)9LiL (still preliminary) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  26. 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) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  27. 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) Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  28. proposal for PAC 31 (F. Garibaldi January 0507 - Hall A Collaboration meeting - Jlab) • hypernuclear physics • the electromagnetic approach • recent results • motivation • the elementary reaction • angular distribution • the apparatus • kinematics and counting rates • beam time request • summary and conclusion Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

  29. 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 last year • New experimental equipments showed excellent performance. • The RICH detector performs as expected and it is crucial in the kaon selection. • Submitted paper on 12Ctarget analysisis showing new information on 12BL - interesting comparison with theory for 12BL and 9LiL. • VERY Promising physics is coming out from preliminary analysis on 16NL hypernuclear spectroscopy • Approved Experiment on angular dependence of strangeness electroproduction Francesco Cusanno – Hypernuclear Spectroscopy - Hall A Collaboration Meeting, June 22, 2007

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