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Spectroscopy of Light to Medium Mass Lambda Hypernuclei Jefferson Lab Experiment E01-011. Joerg Reinhold Florida International University presented at PANIC05 October 24, 2005. Hypernuclear Spectroscopy. Hypernucleus: one or more nucleons replaced by a hyperon, L , S or X.
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Spectroscopy of Light to Medium Mass Lambda Hypernuclei Jefferson Lab Experiment E01-011 Joerg Reinhold Florida International University presented at PANIC05 October 24, 2005
Hypernuclear Spectroscopy Hypernucleus: one or more nucleons replaced by a hyperon, L , SorX • Characteristics • No Pauli blocking ==> probing deep inside the nucleus • Narrow intrinsic width (~100 keV) • L single particle energies in excitation range of more than 20 MeV • Spin dependent L-N interactions (s.s. & s.o.) much weaker than N-N case • What to learn • Hyperon nucleon interaction, i.e. at low momentum • Spin dependent interactions • L effective mass and potential depth in the nuclear medium • Identity of L as function of A H. Hotchi, et al., Phys. Rev. C64, 044302 (2001)
Previous L Hypernuclear Spectroscopyestablished major shell structure 12C(p+,K+)L12C KEK DE = 2 MeV (FWHM) BNL DE = 3 MeV (FWHM) P.H. Pile, et al., Phys. Rev. Lett. 66, 2585 (1991) T. Hasegawa, et al., Phys. Rev. C53, 1210 (1996)
Experimental Considerations High resolution spectrometers at low momentum
E89-009 Results T. Miyoshi, et al., PRL90, 232502 (2003) Theoretical line is a superposition(not a fit) with strength from [19] and positions from[20].
New Jlab E01-011 ExperimentSpectroscopic study of L hypernuclei up to the medium heavy mass region by the (e,e’K+) reaction • North Carolina A&T U. • Minnesota University • Louisiana Tech. U. • Yerevan Physics Institute • University of Zagreb • University of Bucharest • University of Sao Paulo Tohoku University Yamagata University KEK Osaka EC University Hampton University Florida International U. Houston University TJNAF
Tilt method for ENGE to reduce the accidental rate • Scattered electrons • (0.2 to 0.4 GeV/c) • (1) Bremsstrahlung • (2) Møller scattering • (3) Virtual photons Locate ENGE with 7.74 degree. to avoid (1) and (2) processes.
Optimization of the tilt angle Accept region. Side view
HKS + ENGE + Splitter HKS ENGE Splitter
Expected Energy Resolution ~400 keV
Trigger condition • HKS (Kaon trigger) --- 12 kHz - 1X & 1Y & 2X & AC & WC AC -pion rejection, WC -proton rejection ( 1X - 2X -1.1 MHz ) • ENGE --- 1.2 MHz Hodoscope 1layer & 2layer • Coincidence trigger ~500 Hz DAQ dead time ~5% *Rates are with carbon target (100 mg) , 26 mA 1X 1Y AC 2X WC K+ HKS arm
Calibration: CH2(e,eK) HNSS 2000 HKS 2005 210 lambdas 1390 lambdas
12C(e,eK)12LBwith imperfect on-line reconstruction On-line Preliminary Do not quote! ~1000 counts in g.s. (full set ~ 2500 in g.s.
28Si(e,e’K)tracking algorithm and reconstruction matrix NOT optimized On-line Preliminary Do not quote!
Summary • 12C 12LB (>1000 counts in g.s.) • Precision analysis of core excited states • p-orbit states splitting ? • comparison with the mirror hypernucleus, 12LC • 28Si 12LAl (expected up to 1000 counts in g.s.) • The first precision spectroscopy beyond the p-shell • ls splitting in the p, d orbits ? • Other targets (6Li, 9Be, 10B, 51V, 89Y) • Rate study for heavier targets, new experiment for 51V approved • p-shell spectroscopy • Target mass dependence --- quasifree K+ electroproduction