SKS (K - ,K + ) X J-PARC Project - - PowerPoint PPT Presentation

SKSを用いた

(K-,K+)反応によるXハイパー核分光

永江 知文 J-PARC Project Office

Day-1 experiments

n L06: New generation spectroscopy of

Hadron Many-Body Systems with Strangeness S=-2 and -1

n X hypernuclei spectroscopy n Hypernuclear gamma-ray spectroscopy

n L10: Study of Dense K Nuclear Systems

Strangeness Nuclear Physics

S=-2 Hypernuclear Spectroscopy

n X hypernuclei/ LL hypernuclei

n only several events of LL hypernuclei reported n X hypernuclear spectroscopy ? n a mixed states of X, LL, and H states ?

n

• K. Ikeda et al., Prog. Theor. Phys. 91 (1994) 74

n need high intensity beams at 50-GeV PS

n (K-,K+) reaction at 1.8 GeV/c

• ex. 208Pb(K-,K+) with 2 g/cm2 thick target

Æ ~6 events/MeV/day

n H dibaryon (ssuudd, I=J=0)

n no evidence so far n mH>2223.7 MeV(very close to 2mL)

n S=-3 W- nuclei, charmed-hypernuclei etc.

S=-2 Systems

(K-,K+) Spectroscopy

n High momentum transfer ~500 MeV/c

n Preference to spin-stretched states like

(π+,K+) reaction

n Simple excitation spectra

n Coulomb-Assisted bound states

(π+,K+) Spectroscopy

n Success at BNL

n ∆E~3 MeV n Up to 89LY

Textbook Example !

X hypernuclei potential ?

n L, S-, X-, K- in Neutron Star Core ?

n Chemical Potential:

mB = mB + kF

2

2mB + U(kF)

US>0, UX<0 US<0, UX<0 US>0, UX>0

Issues in XA potential

n A-dependence of XA potential depth

n Strong p-wave attraction n X-207Tl > 2x X-11B

n Isospin dependence

n How strong is the Lane term ? n X-p-X0n mixing

n Width and XN-LL coupling

Particle Mixing

Entrance to the S=-2 World

n Doorway Reaction:

K-+pÆK++X- at 1.8 GeV/c

Experimental hall (Phase 1)

Toward Phase 2 :

l Extension of the hall to 100 m l Addition of target T2 on A-line and secondary lines l Installation of primary lines of B (with target Tx) and C

SKS@K1.8

(K-,K+) Spectroscopy of X-Hypernuclei

Energy Resolution

n 2 MeVFWHM resolution

n Limited by the SKS resolution

n Widths of the X bound state < 1 MeV? DE 2 = bK +

2 ¥ DpK + 2 + bK - 2 ¥ DpK - 2 + DEstraggling 2

Dp/ pK - = 2 ¥10-4 Dp/ pK + = (0.96 ± 0.13) ¥10-4 pK + (0.092 ± 0.007)(%) \DE ~ 1.892 + 0.312 + 0.52 = 2MeVFWHM

Yield Estimation

n 50 msr, 2g/cm2-thick Pb

Y = IBeam ¥ 2g/cm2 /208g ¥ NA ¥ ds dW ¥ DW¥ fdecay ¥ feff =107 ¥ (2/208) ¥ 6.02 ¥1023 ¥ 0.1¥10-30 ¥ 0.05 ¥ 0.5 ¥ 0.5events/sec @ 6events/MeV /day

n Coulomb-Assisted

bound states

n Large momentum

transfer ~500 MeV/c

n ~6 events/MeV/day

Summary

n Spectroscopy of X-Hypernuclei in the (K-,K+)

reaction

n Our initial goal: Potential depth, mass number

dependence

n Beam line & Spectrometer should be optimized

further

n Spectroscopy of LL-Hypernuclei in the (K-,K+)

reaction

n Next step n Study of excited levels