J-PARC Day-1 実験の状況・ 実験家から理論屋への要望 T.Takahashi (KEK) Contents 1. Aproved Exp. on J-PARC 2. How to produce S=-2 Systems 3. E05: (K-,K+) Spectroscopy 4. Discussion

Approved Experiments 3 Exp. Proposals concerning to S=  2 system were approved. E03 E05 E07

Approved Proposals of the Investigation on S=  2 Systems Spectroscopy study of  -hypernucleus, 12  Be, via the 12 C(K -,K + ) reaction (E05) – Reaction (Missing mass) spectroscopy –  -hypernuclei,  -hypernuclei –  -A potential at center region Measurement of X rays from  - atoms (E03) – X-rays from  - atomic states –  -A potential at surface region Systematic study of double strangeness systems with an emulsion-counter hybrid method (E07) – Decay (Invariant mass spectroscopy) – X-rays from  - atom –  -hypernuclei,  -hypernuclei

How to produce and study S=  2 systems K  + p  K + +    p(K  )~1.8GeV/c Direct production Reaction Spectroscopy Decay measurements Emulsion X-rays measurements  q ~0.5 GeV/c

E05 Experiment Missing mass spectroscopy of 12 C(K ,K + )X – 12  Be, 12  Be K1.8 beamline & SksPlus spectrometer – 1.8 GeV/c K  & ~1.3 GeV/c K + Missing mass resolution of ~3 MeV/c 2 – Energy and width of bound states To establish methodlogy on spectroscopy of S=  2 systems

K1.8 beamline at J-PARC E.S. Separators Beam Spectrometer K    ~6.9  p/p=3.3x10  (FWHM) 1.2x10 6 K  /spill (Phase-1) High-purity High-intensity High-resolution Proton beam 30GeV-9  A

SksPlus Spectrometer 2.7T(395A) ~1.5T 95°total bend ~7m flight path  x=0.3 mm (RMS) ~30msr  p/p=0.12%

Previous Measurement on 12 C(K ,K  ) – BNL AGS E885 – P K =1.8 GeV/c  M=9.9 MeV/c 2 (FWHM) for p(K ,K + )   P.Khaustov et al, PRC61(2000)0546  20 < E  < 0 MeV 89±14 nb/sr  < 8° 42± 5 nb/sr  <14° Evidence !? V  =  14 MeV

12 C(K ,K + ) 12  Be spectra calculated by W.S. potential P.Khaustov, et al. Phys. Rev. C61(2000) V    [MeV] states  s-state[nb/sr] 0p 3/2   0s 1/2   p-states 0p 3/2  0p 3/2 0p 3/2  0p1 /2 sum  [nb/sr]            E det =0 MeV K.Ikeda, et al, Prog. Theor. Phys. 91 (1994) 747 ; Y.Yamamoto, et al, Prog. Theor. Phys. Suppl. 117 (1994) 281

Expected 12  Be Spectrum V  =  20MeV V  =  14MeV [counts/0.5MeV] -B  [MeV] s  p   E meas. = 3 MeV FWHM One momth Data-taking

(K ,K + ) reaction spectroscopy 生成チャンネルを見る – 基底状態・励起状態の観測 – 多くの標的への適応可能性 –  T = 1 Spectroscopy が成立する条件 –  ≦  M – B Y ＞  M) – Level spacing ＞  M)

考えられるシナリオ 細い（１本の）ピークを観測 – Small Imag. potential Weak  N  interaction –  binding energy Potential (Real) depth ピーク構造が観測されない – 幅が広い – 複数の状態が励起している。 Spin-doublet Core excited states Spectroscopy が成立 ー＞他の標的へ

理論の人に尋ねたい 一緒に考えたいこと（１） どのような状態が考えられるのか？ – Spin / Isopin 生成断面積は？ – 素過程の amplitude spin-flip/spin-non-flip 幅が広いとき、  核は直接反応でどの程 度生成されるのか？

理論の人に尋ねたい 一緒に考えたいこと（２） ＦＩＳを用いた  N 相互作用の研究 – K  d  K +   n – KinematicsQ.F. の End Point 近辺 ? – 断面積 0.1  b/(sr MeV) あれば可能？ – どの位の分解能が必要か？

Kinematics of K  d  K +   n KK pn d KK n  Momentum Dist. in d 2-dim. simple model Relative momentum between n and  

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