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Recent results from the Hall C hypernuclear program - JLab E01-011 -

Recent results from the Hall C hypernuclear program - JLab E01-011 -. Osamu Hashimoto Tohoku University. HYP2006 Mainz, October 11-14, 2006. E01-011 hypernuclear collaboration.

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Recent results from the Hall C hypernuclear program - JLab E01-011 -

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  1. Recent results from the Hall C hypernuclear program- JLab E01-011 - Osamu Hashimoto Tohoku University HYP2006 Mainz, October 11-14, 2006

  2. E01-011 hypernuclear collaboration • Y. Fujii, O. Hashimoto (Spokesperson), D. Honda, M. Kaneta, F. Kato, D. Kawama, A. Matsumura, N. Maruyama ,T. Miyoshi, S.N. Nakamura (Spokesperson), H. Nomura, K.Nonaka ,A. Ohtani, Y. Okayasu, M. Sumihama, H. Tamura (Tohoku U) • S. Kato (Yamagata U) • T. Takahashi, Y. Sato, H. Noumi (KEK) • O.K. Baker, M. Christy, L. Cole, P. Gueye, C. Keppel, L. Tang (Spokesperson), L. Yuan (Hampton U) • B. Beckford, S. Gullon, P. Markowitz, J. Reinhold (Spokesperson), C. Vega (FlU) • Ed.V. Hungerford, K. Lan, N. Elhayari, N. Klantrains, Y. Li,S. Radeniya , Murad, V. Rodrigues(Houston) • R. Carlini, R. Ent, H. Fenker, T. Horn, D. Mack, G. Smith, W. Vulcan, S.A. Wood, C. Yan (JLab) • N. Simicevic, S. Wells (Louisiana Tech) • L. Gan (North Carolina, Wilmington) • A. Ahmidouch, S. Danagoulian, A. Gasparian (North Carolina A&T) • M. Elaasar (New Orleans) • R. Asaturyan, H. Mkrtchyan, A. Margaryan, S. Stepanyan, V. Tadevosyan (Yerevan) • D. Androic, T. Petkovic, M. Planinic, M. Furic, T. Seva(Zagreb) • T. Angelescu (Bucharest) • V.P. Likhachev (Sao Paulo) • M. Ahmed (Duke) • B. Hu, Y. Song, C. Yang (Lanzhou)

  3. (e,e’K+) hypernuclear spectroscopy at JLab 1989 The first hypernuclear experiment inHall C, E89-009, approved 1994 Hypernuclear experiment inHall A, E94-107, approved 1995 JLab started physics experiments 1997 Hall C 2nd generation experiment, E97-008, approved, later updated as E01-011 2000 The first (e,e’K+) hypernuclear spectroscopy,E89-009, carried out 2002-2003 High resolution kaon spectrometer (HKS) for the E01-011 experiment under construction 2004Hypernuclear experiment in Hall A, E94-107, carried out 2005Hypernuclear experiment in Hall A, E94-107, carried out The second generation experiment in Hall C,E01-011, carried out The 3rd generation hypernuclear experiment in Hall C, E05-115, approved 2006-2007 New electron spectrometer for the 3rd generation experiment, E05-115, under construction 2008 The E05-115 experiment will be ready for beam in Hall C ( Nue Nakamura’s Talk )

  4. Hypernuclear investigation • Mean field aspects of nuclear matter • A baryon deep inside a nucleus distinguishable as a baryon ? • LN interaction • Flavor SU(3) • LS mixing or the three-body interaction • New form of nuclei Spectroscopy in the wide mass range High resolution and High yield rate

  5. KEK E140a Hasegawa et. al., PRC 53 (1996)1210 A L hyperon in a heavier nucleus L Single particle states -> L-nuclear potential Hotchi et al., PRC 64 (2001) 044302 Si Y La Pb L Single-particle orbits in a nucleus E140a at KEK • Skyrme HF (Yamamoto) • DDRH (Lenske) • Quark-meson coupling • (Saito, Thomas) • ………

  6. Hypernuclear spectroscopy Reaction spectroscopy g-ray spectroscopy • Resolution > 1.5 MeV with meson • beams so far • Applicable to all hypernuclear states • Mass, cross sections, • angular distributions, polarization…. • Each reaction populates • characteristic states • Resolution as good as a few keV • Applicable to the states below • nucleon emission thresholds • Angular distribution, lifetime, • branching ratios… • Powerful for spin dependent interaction Better resolution required Higher yield required Complimentary

  7. Inflight(K-,p) BNL, CERN mb/sr Stopped (K-,p) KEK, BNL Hypernuclear Cross section mb/sr (p+,K＋) JLab (e,e’K+) (g,K＋) nb/sr (p,K＋) 0 500 1000 Momentum transfer (MeV/c) L Hypernuclear production BL=0 (K-,p-) (p+,K+) (p+,K+)

  8. : to be studied by the (e,e’K+) reaction A Expansion of hypernuclear chartby the (e,e’K+) reaction ( ppnp 57(2006) ) Mirror symmetric hypernuclei

  9. Kinematics of the (e,e’K+) reaction in Hall C p(g,K+)L Total cross section 2.0 σtotal(mb) 1.0 Phys. Lett. B 445, 20 (1998) M. Q. Tran et al. 1.2 1.4 1.6 1.8 2 1 Eγ(GeV) K+ detection At very forward angle (~ 0 degrees) Maximum hypernuclear production cross section Target nucleus K+ pK=1.2 GeV/c Eg=1.5 GeV e- Beam pe=0.3GeV/c Ee=1.8 GeV e’ e’ detection = tag virtual photon energy and emission angle At extremely forward angles Advantage : Large virtual photon flux Disadvantage : Huge backgrounds from Bremsstrahlung

  10. ds/dW (nb/sr) Angle (deg) Angular distributions of scattered electrons and kaons Electron Angular Distribution Kaon Angular Distribution Sotona

  11. The first (e,e’K+) spectroscopy experiment(JLab E89-009) • Electron spectrometer --- Enge split pole • Kaon Spectrometer --- SOS (Short Orbit Spectrometer) • Splitter magnet • 0 degree tagging geometry SOS Ee = 1.7,1.8 GeV w = Eg = 1.5 GeV pK = 1.2 GeV qe = 0 degrees qk = 0-7 degrees

  12. (1-,2-) (2+,3+) 90 80 (1-,0-) 70 (2-,1-) 60 50 40 -15 -10 -5 0 5 10 15 12LB spectrum of E89-009 Ground state doublet Binding energy BL = 11.4 ± 0.5 MeV ~ 750 keV(FWHM) 292 hrs 0.66 mA Emulsion data BL = 11.37 MeV ds/dW nb/sr/0.3 MeV Cross section 140±17(stat) ±18(sys) nb/sr Motoba’s calculation Jp cross section 1- 2- 152 nb/sr T. Miyoshi et al., Phy. Rev. Lett. 90, 232502(2003) -BL(MeV)

  13. What limited the E89-009 experiment ? • Hypernuclear yield rate • High accidental background rate due to Brems electrons limited luminosity • Kaon solid angle limited detection efficiency • Energy resolution • The kaon arm limited hypernuclear mass resolution (1) A high-resolution large-solid-angle kaon spectrometer (HKS) (2) New experimental configuration “Tilt method”

  14. The HKS spectrometer system for E01-011 (1) High resolution Kaon Spectrometer (HKS) Maximum momentum 1.2 GeV/c Dispersion 4.7 cm/% Momentum resolution 2 x 10-4(FWHM) Solid angle 30 msr w/o splitter 16 msr w splitter Momentum acceptance 12.5 % (2) Tilt method for the electron arm

  15. E01-011 setup in Hall C To beam dump HKS K+ ENGE Splitter e’ e’ Electron beam Electron beam From upstream K+ To beam dump

  16. Kinematical regions of electrons and kaons Real data 12LBgr band

  17. HKS detectors HKS exit p,K+,p+,e+

  18. Time of flight w/ cherenkov cut p Kp btof – bK After cherenkov cut p Kp

  19. Tilt method e’ 8 degree The electron spectrometer (ENGE) vertically tilted by 8 degree --- Normal to the dispersive plane of the splitter magnet --- Higher luminosity Higher hadron rates

  20. Beam currents, singles rates & trigger rates E01-011 “Tilt method” works !!

  21. Expected yield comparison of E01-011 and E89-009

  22. p(e,e’K+)L/S0 reactions on CH2 targets E89-009 E01-011 8.8 mg/cm2, 0.5 or 1.0 mA, 183 hours 450 mg/cm2, 1.5 mA, ~ 70 hours  1.43 MeV (FWHM) 1.47 MeV (FWHM) 0 12C(e,e’K+) quasi-free Accidental

  23. 12C(e,e’K+)12LB spectra E89-009 E01-011 292hrs 0.66A s p ~ 90 hrs 30 A ~ 800 keV Counts (0.25 MeV/bin) ds/dW nb/sr/0.3 MeV Preliminary Accidentals Hypernuclear excitation spectrum -BL(MeV) T. Miyoshi et al., Phy. Rev. Lett. 90, 232502(2003)

  24. Sotona,Motoba 12C (p+,K+)12LC KEK-E336 SKS BL = 10.8 MeV BL = -0.2 MeV 12LCg.s yield rate ~20 /hr (1 g/cm2 target) Reaction spectra on a 12C target Preliminary JLAB – HKS ~ 90 hrs w/ 30A 12C (e,e’K+)12LB s p (Preliminary) Core excited BL (s) = 11.5 MeV BL(p) = 1.0 MeV Counts (0.2 MeV/bin) Counts (0.25 MeV/bin) 12LBg.s yield rate ~8 /hr (0.1 g/cm2 target) Accidentals B (MeV)

  25. Reaction spectra on a 28Si target 28Si(p+,K+)28Si reaction SKS KEK E140a BL (s)= 16.6 MeV BL (p)= 7.0 MeV Motoba with full (sd)n wave function 28Si(e,e’K+)28Al reaction Preliminary p s 750 keV (FWHM) ( Preliminary ) BL (s)= 18.1 MeV Counts (0.25 MeV/bin) BL (p)= 7.4 MeV Accidentals 28Si enriched target used B (MeV)

  26. Reaction spectrum on a 7Li target Preliminary 30 hrs 30A 7Li(e,e’K+)7He reaction s BL = 5.4 MeV ( Preliminary ) 960 keV (FWHM) Counts (0.4 MeV/bin) Accidentals B (MeV) Sotona E. Hiyama, et al., PRC53 2078 (1996)

  27. Evolution of (e,e’K+) spectroscopy at JLab 2000 2004-2005 2005 2008? ( ) expected

  28. Summary • Precision hypernuclear spectroscopy by the (e,e’K+) reaction plays an essential role in the investigation of hadronic may-body systems that contain “strangeness”. • The 2nd generation experiment in Hall C, JLab E01-011, has been performed in 2005, installing the new kaon spectrometer (HKS) and adopting so-called “tilt” geometry for the electron spectrometer. • Resolution as good as ~700 keV(FWHM) and yield rate of 7-8 counts/hr for the 12LB ground state doublet were realized. • Preliminary spectra for a 28Si target as well as those for 12C and 7Li targets are presented, and compared with calculated spectra and (p+,K+) reaction spectra.

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