Contents Introduction Motivation to Study S2 System Experiments

Contents • Introduction Ø Motivation to Study S=-2 System • Experiments at Early Stage Ø Spectroscopy of X-Nucleus • Future Plans • Summary 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

Motivation to Study S=-2 Systems • New sector of Baryon-Baryon interaction Ø A little information on B-B Int. n n n LL XN XN->LL weakly attractive ? weak or strong • Very dynamic system Ø Mixing of XN and LL • Significant step toward multi-strangeness systems Ø 2007/11/11 Core of neutron stars J-PARCハドロン実験施設ビームライン整備拡充に向けて

S=-2 System XN->LL coupling Mixing effect is more significant in S=-2 system 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

X Potential and B-B Int. Models UX , GX and Partial Wave Contributions in Nuclear Matter Model T NHC-D 0 1 -2. 6 -3. 2 0. 1 -2. 3 -2. 1 -3. 0 -0. 2 -0. 0 0 1 -0. 9 -1. 3 -0. 5 -8. 6 -1. 0 -0. 8 6. 3 -18. 4 7. 2 -1. 7 1. 2 -0. 8 Ehime ESC 04 d* 0 1 1 S 0 3 S 1 1 P 1 3 P UX -0. 7 -3. 1 -1. 9 -6. 3 -25. 2 0. 9 0. 3 -0. 4 -2. 4 -1. 7 -0. 7 -4. 2 -22. 3 0. 5 1. 5 -0. 5 -1. 3 -1. 2 -1. 9 -2. 8 -12. 1 12. 7 Ø Ø Ø 2007/11/11 no t-channel meson exchange odd-state attraction strong A-dependence of VX small width 0 1 3 P GX 2 • OBE (NHC-D, Ehime) 3 P (Me. V) • ESC 04 d* – strong attraction of 3 S 1(T=0) – large width J-PARCハドロン実験施設ビームライン整備拡充に向けて

X Potential and Impact on Neutron Stars • Strange hadrons appear in the core of neutron star. . . • What kind of hadrons? / How much density? Ø Ø depends on mass, charge, and interaction Negative baryons are favored. S- was supposed to be important. However its interaction with neutron matter is found to be strongly repulsive. • X- and its interaction should be important. US<0, UX<0 • 2007/11/11 US>0, UX<0 US>0, UX>0 J-PARCハドロン実験施設ビームライン整備拡充に向けて

How to produce and study S=-2 systems Direct production Reaction Spectroscopy (E 05) X-hypernuclei, LL-hypernuclei X-rays Measurements (E 03) K- + p -> K+ + Xp(K-)~1. 8 Ge. V/c Decay measurements Emulsion (E 07) LL-hypernuclei 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

Previous Studies on X-Hypernuclei and X Potential (1) • Dover & Gal; Analysis of old emulsion data Ann. of Phys. 146 (1983) 309 • X-Captured events at KEK E 176 Prog. Thoer. Phys. 89 (1993) 493 Phys. Lett. B 355 (1995) 45 • Analysis by Yamamoto Few-Body Syst. Suppl. 9 (1995) 145

Previous Studies on X-Hypernuclei and X Potential (2) (K-, K+) Missing Mass Spectroscopy BNL-E 885 KEK-E 224 T. Fukuda et. al, PRC 58(1998)1306 DM=14 Me. V P. Khaustov et al, PRC 61(2000)0546 DM=22 Me. V Evidence !? V = -14 Me. V 0. 21± 0. 07 mb/sr 60 ± 45 nb/sr EX<7 Me. V -20<EX<0 Me. V -20 < EX < 0 Me. V 89± 14 nb/sr q< 8° 42± 5 nb/sr q<14°

E 05　(K-, K+) Spectroscopy on 12 C ー 12 XBe ー • (K-, K+) reaction at p=1. 8 Ge. V/c Ø Missing mass resolution ~3 Me. V/c 2(FWHM) • K 1. 8 beamline@J-PARC Ø Ø Ø High intensity High purity H. R. spectrometer 1. 4 x 106 /spill @ Phase 1 K-/p- = 6. 9 Dp/p ~3. 3 x 10 -4(FWHM) • Sks. Plus spectrometer Ø Ø 2007/11/11 Dp/p = 1. 2 x 10 -3 (FWHM) ~30 msr J-PARCハドロン実験施設ビームライン整備拡充に向けて

K 1. 8 beamline Primary proton beam 50 Ge. V-15 m. A Length (m) Double-stage of electrostatic separators 45. 853 Acceptance (msr. %) Beam spectrometer Dp/p~3. 3 x 10 -4(FHWM) 30 Ge. V-9 m. A 1. 4 K-(p) intensity (ppp) 　　　　　　@1. 8 Ge. V/c 6. 6 E+06 1. 4 E+06 @1. 5 Ge. V/c 2. 7 E+06 0. 54 E+06 @1. 1 Ge. V/c 0. 38 E+06 0. 08 E+06 Electrostatic separator Single rate @ MS 2 　　　　@ 1. 8 Ge. V/c K-/(p-+m- ) @ FF 　　　　　　　@ 1. 8 Ge. V/c X/Y(rms) size @ FF (mm) 750 k. V/10 cm, 6 m× 2 ＞ 33 E+06 ＞ 8 E+06 4 3. 5 19. 8/3. 2 Singles-rate of B. S. assumed 0. 6 s ext. 13. 3 MHz@upstream 3. 0 MHz@downstream 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

Sks. Plus spectrometer • • • SKS 95°total bend ~7 m flight path Dx=0. 3 mm (RMS) 2. 7 T ~30 msr 1. 5 T SKS(existing) 2007/11/11 D magnet (modification) Dp/p=0. 12% J-PARCハドロン実験施設ビームライン整備拡充に向けて

E 05 Expected Yield Ø Ø Ø • • • 1. 4 x 106 K-/spill 0. 7 sec. FT (2. 3 MHz@FF) 95% running efficiency 3 cm (5. 4 g/cm 2) target 30 msr fdecay ~0. 5 fana ~0. 7 1 month data-taking 6. 8 evts/day 48 evts/week ~200 evts/month P. Khaustov et al, PRC 61(2000)0546 p. X [counts/0. 5 Me. V] • 60 nb/sr • 4. 0 x 1010 K-/day VX= -20 Me. V s. X VX= -14 Me. V -BX [Me. V] 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

After E 05 … • No narrow peak Ø Ø No bound state Broad width Direct production of LLnucleus (LL spectroscopy ) • Obs. bound state(s) Ø Heavier targets for mass dependence n n Ø • Quasi-free shape analysis • Atomic X-ray measurement Ø n reaction p-n-X-(n-n-X 0) state Spin-isospin structure (K-, K 0) reaction n 2007/11/11 Narrow width for high-l 3 He(K-, K+) n Ø … Coulomb-assisted states n Other than nuclear spectroscopy is necessary to study XN int. 27 Al, 40 Ca, 89 Y, Isospin DI=0 excitation J-PARCハドロン実験施設ビームライン整備拡充に向けて

X Single-Particle Energy 0 s. X W. S. pot. (w/o Coulomb) p. X E [Me. V] -10 f. X 12 C d. X -20 27 Al 40 Ca NHC-D Ehime ESC 04 d* -30 89 Y -40 0 20 40 60 80 100 A 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

208 Pb(K-, K+) Woods-Saxon potential Centrifugal barrier Low nuclear density region Spectrum S. Tadokoro, H. KObayashi and Y. Akaishi, Phys. Rev. C 51 (1995) 2656. Suppression of XN->LL Conversion Very narrow peaks with a large orbital angular momentum. 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

Yield for heavier targets • Cross section ? ∝A 1/3 (best case? ) • Target (thickness) ∝ 1/A • Yield for the same intensity and time Ø Y∝A-2/3 • Y(89 Y) = (12/89)-2/3 Y(12 C) = 0. 26 Y(12 C) • Y(208 Pb)=(12/208)-2/3 Y(12 C)=0. 15 Y(12 C) • Higher intensity & long beam time are necessary. 2007/11/11 J-PARCハドロン実験施設ビームライン整備拡充に向けて

If 50 Ge. V-15 m. A is achieved　… • 6. 6 x 106/spill with 0. 7 s FT Ø Ø Ø 14 MHz singles rate @ downstream 55 MHz singles rate @ upstream 1. 5 x 1011 K- /day O. K. N. G. ? x 3. 75 • Why N. G. ? Ø Ø Detector rate ability Accidental backgrounds other than wire chamber fast device / analysis • 1. 7 s FT Ø Ø 20 MHz singles rate @ upstream 1. 2 x 1011 K-/day x 3 • Give up point-to-point condition of B. S. Ø Ø 2007/11/11 Larger beam size at upstream loose resolution. How much? J-PARCハドロン実験施設ビームライン整備拡充に向けて

(K-, K 0) reaction • (K-, K+) can excite only DI=1, but (K-, K 0) can excite DI=0. Ø Isospin dependence • K 0 is measured by KS ->p+p-. Ø Ø Opening angle h~35°@1. 3 Ge. V/c How to distinguish K 0 and K 0 bar n Ø Resolution n 2007/11/11 Tagged with weak decay ~10 Me. V is OK, but a few Me. V is ? J-PARCハドロン実験施設ビームライン整備拡充に向けて

Summary • Physics of S=-2 Ø Ø Baryon-baryon interaction High density matter • Experiments at early stage Ø Ø Ø Spectroscopy of X-nucleus Emulsion exp. X-rays of X-atomic state • Future Ø Ø Ø 2007/11/11 Spectroscopy for heavy targets (K-, K 0) reaction High intensity beam & handling technology J-PARCハドロン実験施設ビームライン整備拡充に向けて

NHC-D Target 12 C s w/o Coul. 27 Al s w/o Coul. p w/o Coul. 40 Ca s w/o Coul. p w/o Coul. 89 Y s w/o Coul. p w/o Coul. d w/o Coul. f E G [Me. V] -4. 4 -1. 9 Ehime E G [fm] [Me. V] 0. 5 3. 2 3. 7 -4. 5 -1. 9 -14. 9 -8. 4 -7. 1 -2. 0 0. 7 0. 4 0. 3 2. 0 2. 2 3. 4 4. 0 -19. 7 -10. 8 -13. 7 -5. 7 0. 6 0. 5 0. 4 -31. 4 -16. 4 -26. 2 -12. 0 -20. 6 -7. 3 -14. 8 0. 6 0. 5 0. 4 0. 3 ESC 04 d* WS E G [fm] [Me. V] 0. 3 0. 2 3. 1 3. 7 -4. 6 -2. 1 4. 6 3. 9 3. 3 3. 7 -2. 2 -13. 4 -7. 3 -5. 9 -1. 1 0. 2 0. 1 2. 3 2. 6 3. 6 4. 5 -10. 1 -4. 7 -5. 2 -0. 8 5. 7 4. 7 2. 8 1. 9 3. 0 3. 4 4. 1 5. 1 2. 2 2. 4 3. 0 3. 3 -18. 7 -9. 9 -11. 5 -3. 9 0. 2 2. 4 2. 6 3. 3 3. 7 -14. 1 -6. 2 -9. 3 -2. 4 5. 9 4. 9 3. 3 2. 5 3. 0 3. 4 3. 9 4. 5 2. 3 2. 5 3. 0 3. 2 3. 5 3. 9 4. 1 -29. 8 -15. 0 -23. 6 -9. 8 -17. 3 -4. 6 -11. 0 0. 2 0. 1 2. 5 2. 8 3. 3 3. 6 3. 9 4. 4 4. 6 -22. 4 -8. 5 -17. 8 -5. 3 -13. 3 -2. 0 -8. 7 6. 5 5. 2 3. 9 2. 8 2. 4 1. 7 1. 6 3. 0 3. 7 4. 0 4. 6 4. 7 5. 5 5. 4 r r r E -5. 1 -6. 5 -1. 2 -9. 0 -4. 6 -0. 2

E 07 Systematic Study of Double Strangeness Systems with an Emulsion-counter Hybrid Method l t l l i (12 C) • Double L Hypernuclei Ø expected ~100 events Ø extend known species u species dependence of DB LL u decay form p rb l l # of absorbed X- # of LLhypernuclei # of twin hypernuclei • H-dibaryon 4 (expected) 1 1987 -1997 (KEK-E 176) 80 1 2 • X-Nucleus Interaction Ø twin hypernuclei Ø X-ray from atomic states 1998 -present (KEK-E 373) ~800 7 (1) 3 • Unknown Phenomena J-PARC E 07 ~10000 ~100 20 -30? 1965 D. Davis Aug. 24, 2007 Dense and Cold Nuclear Matter and Hard Exclusive Processs

E 03 K- Measurement of X rays from X- Atom target • K+ X- X- Nuclues potential Ø X ray Real part n Ø Imaginary part n Energy (arb. ) n . . . l=n-3 • l=n-1 l=n-2 X . . . nuclear absorption . . . Z X Ø • Width X ray yield Regardless of potential detail Ø Z Level energy shift attractive / repulsive strong / weak absorption Complementary to E 05 Ø Ø E 03 surface region of the potential E 05 inner part of the potential l (orbital angular momentum) Aug. 24, 2007 Dense and Cold Nuclear Matter and Hard Exclusive Processs