1. 不安定核物理と理研 RI * ビームファクトリー 本林 透（理研仁科加速器研究センター） * radioactive isotope - first realization of next-generation exotic beam facilities

2. Aug. 06KEK RIKEN CNS KEK RCNP SPring-8 Major Facilities for Nuclear Physics (Science) in Japan J-PARC TRIAC 1.J-PARC 2.RIKEN (RIBF) 3.RCNP (+SPring8) H. Sakai secondary beams high-precision beams

3. Aug. 06KEK Behaviors <= different n- and p- numbers A challenge: extension in the n-p plane RI beams v.s. E x, I, T, , …. new nuclear dynamics nuclear response in high isospins explosive nuclear burning isotope production secondary reaction Nucleus with protons and neutrons

4. Aug. 06KEK Atomic nuclei (isotopes) stable ~300 known ~2,700 total~10,000 ? Projectile Fragmentation In-flight U fission / fragmentation 78 Ni 10 particles/sec. (Goal)

5. Aug. 06KEK target projectile  ~ 0 v ~ v beam wide range of (unstable) nuclei regardless of chemical properties E > 50 MeV/nucleon ( “ fast ” ) projectile fragmentation ISOL + reacceleration

6. Aug. 06KEK 50 - 90 MeV/nucleon DALI HODO spectroscopy of unstable nuclei / nucl. astrophysics DALI ( 208 Pb) invariant mass - unbound states particle ID  ray - bound states strong (light) RI beams

7. fast RI beams at RIKEN Ring Cyclotron (1987) + RIPS (~1990) <= LBL, GANIL (LISE) fast “ RI-beam ” or “ RNB ” by fragmentation the most intense beams for some light nuclei  - and Q-moments for neutron-rich nuclei nuclear radii <= interaction cross section light drip-line nuclei ( 11 Li etc) Coulomb dissociation for astrophysics w. RI beam ( 14 O,.) Intermediate-energy Coulomb excitation ( 32 Mg,..)  spectroscopy w. secondary fragmentation ( 34 Mg,..) charge exchange, (p,p ’ ), … low energy reactions w. degraded beams (fusion, astro.) RI Beam Factory (RIBF) RI beams: fragmentation / in-flight fission phase I: first beam in 2006 phase II: under consideration

8. Aug. 06KEK Fate of magic numbers N=(8,) 20 Coulomb excitation (p,p’) 2ndary fragmentation

9. Aug. 06KEK Coulomb excitation of 32 Mg (N=20) RI beam ( 32 Mg)  rays (DALI -NaI(Tl) array) Charged particles (Si stack -  E-E) Target ( 208 Pb) particle ID for ejectiles ( 32 Mg) Doppler-shift corrected spectrum ~50 A MeV  -ray energy => state ID emission angle => Doppler correction γ beam θ E 2+2+ 0+0+ γ 300 s -1 350 mg/cm 2

10. Aug. 06KEK DALI2* * Detector Array for Low Intensity radiation 160 NaI(Tl) crystals 4x8x16 cm 3  E~9% (FWHM) @ 662 keV  ~9 deg. For 1 MeV  (  =0.3,  /  =10%)  E=8.7%  =20% High efficiency Doppler-shift correction

11. Aug. 06KEK Disappearance sd-pf shell gap(N=20) in 32 Mg and 30 Ne B(E2:0 + ->2 + ) [e 2 fm 4 ] 2 + location / B(E2) of N = 20 nuclei In-beam  spectroscopy with Coulex / (p,p ’ ) Motobayashi et al., PLB 346 (95) 9 Yanagisawa et al., PLB 566 (03) 84

12. Aug. 06KEK 32 Mg 34 Si  -rays associated with 1 H( 34 Si, 34 Si*) 1 H and 1 H( 32 Mg, 32 Mg*) 1 H (p,p’) -- neutron transition (M n ) high statistics -  or  coincidence

13. Aug. 06KEK Island of inversion transitional “normal” E(2 + )/ E(2 + ) sd B(E2)/ B(E2) sd N=20 Z=10 36 S 34 Si 32 Mg 26 Ne 28 Ne 30 Ne (coulex) ( 34 Mg)

14. Aug. 06KEK 16 C - decoupling of p/n motion (shape) Coulomb-nuclear interference Lifetime (p,p ’ ) (Q moment of neighbors)

15. Aug. 06KEK Decoupling of n- and p-distributions in 16 C ?  -decay lifetime measurement - new recoil-shadow method  ~75±23ps, B(E2: 2 +  0 + ) ~ 0.3 W.U. - the slowest ? E2 transition 16 C+ 208 Pb inelastic Coulomb-nuclear interference M n /M p = 7.6±1.0 16 C+ 1 H inelastic neutron-sensitive a large  M n >> M p ~B(E2) for 0 +  2 + W.U. B(E2) / sys. <= Ex In-beam  measurements with fast 16 C RI beams Imai et al. (2003) award talk tomorrow Elekes et al. (2003) c.f. 15 B: Q, 12 C inel., (p,p’)

16. Aug. 06KEK 16 C + 208 Pb Inelastic scattering 2+ excitation: almost only by neutrons. Coulomb-nuclear Interference in angular distribution “ egg-like ” structure ? strong p-n interaction Elekes et al., Phys. Lett. B586 (2004) 34 Japan-Hungary (ATOMKI) collaboration lifetime, (p,p’)

17. Aug. 06KEK Electric quadrupole moments for neutron-rich B isotopes Ueno, Asahi,..

18. Aug. 06KEK exotic nuclear structure shell closure behaviors of p & n - correlated / decoupled astrophysics solar fusion explosive burning 28 O: particle unstable Magic # (N=20) disappears. new magic #, N=16 neutron halo Magic # (N=8) disappears. molecular structure neutron skin 16 C: “ egg ” structure ? decoupled n-motion 32 Mg: large deformation Z N explosive hydrogen burning solar neutrino production heavy hydrogen new 2n correlation

19. Aug. 06KEK N＝ZN＝Z Stable Neutron excess Excitation energy N＜ZN＜Z N≫ZN≫Z

20. Aug. 06KEK 135 MeV/nucleon for light nuclei 350 MeV/nucleon up to U fRC IRC SRC BigRIPS zero degree (spectrometer) SHARAQ RIBF - 2006, 2007 / to be constructed Slow RI new injector use of IRC beams independent operation of AVF / RILAC / new cyclotron complex pol. d capability: kept SAMURAI Rare RI RIng SCRIT

21. Aug. 06KEK SRC

22. Aug. 06KEK 1 p  A (goal) (5x10 12 pps)

23. Aug. 06KEK log(Intensity/day) A 1 d -1 1 s -1 A Ni intensity (RIBF) 238 U+ 9 Be -> fission 350 AMeV, 1p  A  data : K.H. Schmidt Group (GSI) Ni isotopes E(2 + ) B(E2) Terasaki (QRPA) Kanno et al. Yamagami PRC (2005) HFB+QRPA HF+BCS Coulex, (p,p’) -   life, mass RR elastic, inelastic - scatt.

24. Aug. 06KEK NN cross section Data from Particle Data Group http://pdg.lbl.gov/ (p,p’): sensitive to neutron > proton E2 E1 M1 Coulomb excitation = proton

25. Aug. 06KEK NN effective interaction Transparent nucl. Interior single scattering p-elastic => density large V  /V 0 spin-isospin modes GT, spin dipole …

26. Aug. 06KEK M1/E2: factor of ~5 increase

27. Aug. 06KEK Zero-degree spectrometer particle ID / momentum analysis e.g. inbeam  spectroscopy γ 132 Sn From BigRIPS γdetector 132 Sn 133 Sn 131 Sn

28. Aug. 06KEK beam transport -  spectroscopy SAMURAI - large acceptance SHARAQ - high resolution Rare RI Ring - mass SCRIT - e-RI collision beams to RIPS SLOWRI- slow beams RIKEN RI Beam Factory ?

29. Aug. 06KEK RI Beam Factory (1st stage - RI beam production) 2007: “day-one” experiments 2008-: regular program RIBF extension - experimental equipments 2007-2010?: construction 23rd INPC (INPC07): Tokyo, June 3-8, 2007 http://www.inpc2007.jp/ satellite meetings: pre: DREB - Direct Reactions with Exotic Beams post: nuclear structure +  International Workshop: Mar. 13-18, 2006 International Users Meeting: Aug. 3-4, 2006 http://ribfwww.riken.go.jp/exp/RIBF_uec/ Workshop for collaborations in day-one in Oct. 2006 1st RIBF PAC: Dec. 2006 or 2007