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Y. Kanada-En’yo (YITP, Kyoto Univ.) M. Kimura (Tsukuba) Y. Taniguchi (Kyoto Univ.)

Cluster aspect of light unstable nuclei. Y. Kanada-En’yo (YITP, Kyoto Univ.) M. Kimura (Tsukuba) Y. Taniguchi (Kyoto Univ.). 1. Introduction. innovative models ( GCM,MO.SVM,AMD,..). Cluster physics. Meyer & Jensen, shell structure, mean-field. 1949. coexistence of cluster & mean-field.

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Y. Kanada-En’yo (YITP, Kyoto Univ.) M. Kimura (Tsukuba) Y. Taniguchi (Kyoto Univ.)

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  1. Cluster aspect of light unstable nuclei Y. Kanada-En’yo (YITP, Kyoto Univ.) M. Kimura (Tsukuba) Y. Taniguchi (Kyoto Univ.)

  2. 1. Introduction

  3. innovative models(GCM,MO.SVM,AMD,..) Cluster physics Meyer & Jensen, shell structure, mean-field 1949 coexistence of cluster & mean-field sd, pf-shell Unstable nuclei 1960’s 1970-80’s 1930’s 1990’s- Bethe et al. Weakly Interacting a-particles Cluster & scattering microscopic cluster models (RGM,OCM,GCM) multi a non-a(N, t, 12C, 16O) clusters Clustering in unstable nuclei new-type clustering p-shell, sd-shell nuclei Very light nuclei (A<8) molecular resonances 16O+16O etc.

  4. 12O 13O 14O 15O 16O 17O 18O 19O 20O 21O 22O 11N 12N 13N 14N 15N 16N 17N 18N 19N 20N 21N Exotic 8C 9C 10C 11C 12C 13C 14C 15C 16C 17C 18C 19C 20C 8B 9B 10B 11B 12B 13B 14B 15B 17B 19B 7Be 8Be 9Be 10Be 11Be 12Be 14Be 6Li 7Li 8Li 9Li 11Li 3He 4He 6He 8He 1H 2H 3H n core core structure in light nuclei Exploring concept of cluster: Spatial correlation of multi nucleons triangle α sd-shell α α 3-2 in 14C α α α dilute gas C 0+2 in 12C B Decoupling of Proton and neutrons Be 10C, 16C Li He α α H excited states α α neutron skin Be isotopes 8He,C molecular neutron halo vanishing of magic number 6He,11Li,11Be

  5. Conventional cluster structure Weak coupling picture: Cluters are formed by tightly bound nucleons. Weakly coupled inter-cluster motion is considered. Typical clustering in stable nuclei α 16O 12C α α α α α α 8Be 16O* 12C 20Ne

  6. 16O a Exploring concept of clustering (1) A.Tosaka et al., S. Aoyama et al. Molecular structures halo nuclei:6He, 11Li K.Varga et al., Esbensen et al., Hagino et al. Descouvemont et al. neutron-rich Be isotopes T-type 6He+6He in 12Be V-type α α 2n 2a-core neutron orbit α α core-n di-neutron Seya, Von Oerzten, Descouvemont et al., Itagaki et al., K-E et al. M. Ito et al. correlation Ne, O isotopes Valence neutrons play important roles Yoshida et al., Kimura et al. Furutachi et al.

  7. α α α + 12C(02 ) α α α α α α Exploring concept of clustering (2) a-cluster gas cluster crystalization Dilute 3a gas 14C*(3-2) triangle 16O* Tohsaki et al., Yamada et al., Funaki et al. Wakasa et al., Itagaki et al., Von Oertzen et al. Price et al. Nuclear matter 12,14,15,16C* linear chain a-condensation dineutron-cond. Roepche et al. BEC-BCS matsuo et al.

  8. α α α Exploring concept of clustering (3) Heavier nuclear region Coexistence of cluster & mean-field Itagaki et al. nucleon correlation at surface Superdeformation& cluster Molecular states. 16O 16O Cluster excitation 16O 16O 32S SD + Z=N nuclei: 32S, 40Ca Kimura et al., taniguchi et al.

  9. Contribution of cluster aspects Cluster is one of the essential features in nuclear many-body system. Contribution to recent developments Physics: Halo nuclei, Breaking of magicity Molecular, deformation, new cluster states Methods: less assumption, ab-initio calc. , tensor force, effective nuclear force resonances & continuum Systematic study focusing on cluster phenomena. Question: what is the mechanism of appearance of clusters ?

  10. 2. Topics 2-1. Molecular states: 12Be ,13B 2-2. Cluster gas-like states: 12C, 11B(11C), 8He

  11. 2-1. Molecular states: 12Be ,13B

  12. ± - + + α α + 0 2 + 0 1 2-1. Molecular states in 12Be,13B Breaking of magicity (N=8) in 12Be Formation of 2a+molecular orbitals (2.24MeV) intruder state 2.24 MeV s-orbital s2 12Be Deformed ground state with d-wave components α α Experiments: Iwasaki et al., Navin et al., Pain et all. Bond role

  13. + 0 2 + 0 1 α α Success of AMD for 12Be VAP calculation with AMD method 12Be positive parity states with normal spins Exp. (2.24MeV) (c) + + AMD (b) intruder (a) α α Breaking of N=8 magicity Formation of 2a+molecular orbitals Y.Kanada-En’yo et al., PRC 68, 014319 (2003)

  14. α α α α Search for MO states of 13B Experimental report 4He(12Be,13Bg) S. Ota et al. jps meetring, Mar 2007 proton intruder configuration MO states ? 12Be 13B one proton

  15. Excited states of 13B studied with AMD VAP calc. of AMD MV1(m=0.65)+G3RS(ls=3000) 13B(-) 13B(+)

  16. Proton intruder state in neutron-rich nuclei 13B(1/2+1) Present calc. Hyper deformation ? proton neutron 4He(12Be,13Bg) Experiments By Ota et al. - + + α α

  17. deformed bands with MO structure in 13B Deformed bands in Ex < 10 MeV MO structure in 13B Proton intruder state one proton 12Be 13B

  18. 2-2. Cluster gas-like states: 12C*, 11B*(11C*), 8He*

  19. + + + 01 02 03, 4 α α α α α α 2-2. Cluster gas-like states Tohsaki et al., Yamada et al., Funaki et al. Wakasa et al., 12C 16O α A.Tohsaki et al., (2001) Funaki et al.(2003) chain ? 16O(0+5) ? α α α Dilute clustergas Bosonic behavior 11C, 11B K-E. , Kawabata et 10.3 MeV α 7.65 MeV α t 8Be+a Itagaki, K-E. , Kawabata et 13C ,14C α α p3/2 + α α α α 3a+p3/2closed

  20. + + 02 01 α α α - - - - 3/24 3/22 3/21 3/23 A candidate in 11B(11C) three-center cluster states in 11B and 11C Y. K-E. PRC(2006) 11B(11C) AMD by Y.K-E. 12C Mysterious 3/2-3 state: Weak beta & M1 transitions Dilute 3a gas Dilute 2a+t α 2a+t 10.3 t α 7Li+a 8.5 7.65 MeV 8Be+a t α α Strong E0 transition Kawabata et al. by (d,d’) α p3/2 p3/2 + α α 3a+p3/2closed

  21. α α α + 12C(02 ) Dineutron gas ? a-condensation di-neutron in dilute neutron matter Roepche et al.(1998) Matsuo et al.(2006) di-neutrons in halo nuclei (6He, 11Li) Dilute 3a gas T-type 16O* V-type Tohsaki et al., Yamada et al., Funaki et al. 5, 7H ? Aoyama, et al.

  22. a Two dineutrons in 8He 12C 8He Dilute clustergas Excited States ? 12C(02+) 6He(01+) = a + a a 12C(01+) 8He(01+) V-type T-type = α p3/2 + p3/2 α α

  23. Possible dineutron gas-like state of 8He AMD+GCM calc. suggests dineutron gas-like state 8He 8He(02+) r.m.s.n.r.=3.1 fm 4He+4n 6He+2n 01+ p3/2 Volkov No.2 MV1 MV1 r.m.s.n.r.=2.6 fm m=0.58 b=h=0 m=0.62 b=h=0 m=0.56 b=h=0.15 AMD+GCM with effective N-N interactions(MV1, Volkov)

  24. Dineutron structure: analogy to 12C(0+2) 12C(0+2) 8He(0+2) SU(3)-limit a Dineutron component at large distance a a a SU(3)-limit (C) 12C(02+) g.s. g.s. 8He(02+) S-fac=0.47 r (fm) r (fm)

  25. 3. Summary 1. Molecular states: 13B* 2. Dineutron gas-like state: 8He* AMD(VAP) AMD(GCM)

  26. α α α α α α α α αcondensation Dineutron Condensation ? MO intruder p3/2 p3/2 α Breaking of N=8 magicity α α 12C 8He 13B 12Be Variation in the energy-isospin plane Systematic study covering a wide region of the energy-isospin plane is essential to understand nuclear many-body systems Excitation energy Unstable Stable Isospin symmetry

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