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 S=-2 @ J-PARC 2. How to produce S=-2 Systems 3. E05: (K-,K+) Spectroscopy 4. Discussion Approved Experiments E03 E05 E07 3 Exp. Proposals concerning to S=-2 system were approved. Approved Proposals of the Investigation on S=-2 Systems • Spectroscopy study of X-hypernucleus, 12XBe, via the 12C(K-,K+) reaction (E05) – Reaction (Missing mass) spectroscopy – X-hypernuclei, LL-hypernuclei – X-A potential at center region • Measurement of X rays from X- atoms (E03) – X-rays from X- atomic states – X-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 X- atom – LL-hypernuclei, X-hypernuclei How to produce and study S=-2 systems K- + p -> K+ + Xp(K-)~1.8GeV/c Dq ~0.5 GeV/c Direct production Reaction Spectroscopy X-rays measurements Decay measurements Emulsion E05 Experiment • Missing mass spectroscopy of 12C(K-,K+)X – 12 12 Be Be, X LL • K1.8 beamline & SksPlus spectrometer – 1.8 GeV/c K- & ~1.3 GeV/c K+ • Missing mass resolution of ~3 MeV/c2 – Energy and width of bound states • To establish methodlogy on spectroscopy of S=-2 systems K1.8 beamline at J-PARC 1.2x106 K- /spill (Phase-1) High-intensity Beam Spectrometer Dp/p=3.3x10-4(FWHM) Proton beam 30GeV-9mA High-resolution E.S. Separators K-/p- ~6.9 High-purity SksPlus Spectrometer 40 ~30msr [msr] 30 20 10 2.7T(395A) 0 1.0 ~1.5T 1.2 p [GeV/c] 1.4 1.6 1.4 1.6 2.5 Dp/p=0.12% • • • 95°total bend ~7m flight path Dx=0.3 mm (RMS) dp [MeV/c] 2.0 1.5 1.0 0.5 1.0 1.2 p [GeV/c] Previous Measurement on 12C(K-,K+) – BNL AGS E885 – PK=1.8 GeV/c DM=9.9 MeV/c2 (FWHM) for p(K-,K+)XP.Khaustov et al, PRC61(2000)0546 -20 < EX < 0 MeV 89±14 nb/sr q< 8° 42± 5 nb/sr q<14° Evidence !? VX = -14 MeV 12C(K-,K+)12 XBe spectra calculated by W.S. potential VX0 [MeV] DEdet=0 MeV states -24 -20 -16 -12 s-state [nb/sr] 0p3/2g 0s1/2 p-states 0p3/2g0p3/2 0p3/2g0p1/2 sum P.Khaustov, et al. Phys. Rev. C61(2000)054603 1- 215 168 123 81 [nb/sr] 0+ 2+ 2+ 29 164 152 345 20 103 93 216 - - K.Ikeda, et al, Prog. Theor. Phys. 91 (1994) 747 ; Y.Yamamoto, et al, Prog. Theor. Phys. Suppl. 117 (1994) 281 [counts/0.5MeV] Expected 12XBe Spectrum pX VX= -20MeV DEmeas. = 3 MeVFWHM One momth Data-taking sX VX= -14MeV -BX [MeV] (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 – DT = 1 • Spectroscopyが成立する条件 – G ≦DM – BY＞G(DM) – Level spacing ＞G(DM) 考えられるシナリオ • 細い（１本の）ピークを観測 – Small Imag. potential • Weak XN->LL interaction – X binding energy • Potential (Real) depth Spectroscopyが成立ー＞他の標的へ • 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 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、LL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XN相互作用の研究 – – – – K- d -> K+ X- n Kinematics Q.F.のEnd Point 近辺? 断面積 0.1 mb/(sr MeV)あれば可能？どの位の分解能が必要か？ Kinematics of K- d -> K+ X- n 2-dim. simple model pn K- K+ n X- d Relative momentum between n and X- Momentum Dist. in d 1 1500 1.8GeV/c 0.8 1.5GeV/c a.u. [GeV/c] 1000 0.6 2.0GeV/c 0.4 500 0.2 0 0 0.05 0.1 p [GeV/c] 0.15 0 -0.15 -0.1 -0.05 0 pn [GeV/c] 0.05 0.1 0.15 Tokai Site of JAEA Photo:21-Dec-2006 7-Feb-2007 23-Feb-2007 Photo:21-Dec-2006 23-Feb-2007