Studies of light neutron-excess systems from bounds to continuum Makoto Ito Department of Pure and Applied Physics, Kansai University I. Introductions : Subjects of present studies II. Formulation III. Exotic structures in 12 Be － highly excited states of Be isotopes and x He+ y He reactions － V. Summaries and Future studies IV. Systematics in even Be isotopes(A = 8, 10, 12, 14, 16) Supported by Prof. K. Ikeda (RIKEN)

Global subjects in our studies Contents of today’s report 1.Structures in 12 Be and monopole transitions (Exp. data are accumulated.) 1. Structural changes with a variation of excitation energy 1. Cluster structures in light 4N nuclei : 8 Be=2 , 12 C=3 , 16 O=  + 12 C Clusters + excess neutrons 2. Light neutron-excess systems ⇒ Typical examples: Covalent structures in Be isotopes (Molecular Orbit) 2. Systematics of 8,10,12,14,16 Be and He+He reactions Introduction Ex. energy “Continuum” 2. Cluster phenomena in continuum ⇒ Interplay of structures and reactions

 (  + ) 2 = ( P z (L) ― P z (R) ) 2 Formulation : example of 10 Be = 2  +2N  + 6 He 6 He+  5 He + 5 He Linear Combination of Atomic Orbital (LCAO)   + 6 He(0 + ) = P z (L) ・ P z (L) + P z (R) ・ P z (R) － 2P z (L) ・ P z (R) = P x (R) ・ P x (R) + P y (R) ・ P y (R) +P z (R) ・ P z (R) Total wave function Pm(a)・Pn(b)Pm(a)・Pn(b) (m,n)=x,y,z(a,b) = L,R Variational PRM Z 12 Be(4N), 14 Be(6N), 16 Be(8N) S 500 ～ 2000 S. D. (Brink WF) with J  projection

Femto-Molecules ： 12 Be=  +  +4N J  =0 + 6 He (0p R )(0p L ) (  + ) 2 8 He 7 He 5 He (-)2(-)2 (-)2(-)2 (  - ) 2 (  + ) 2 Cluster ex. Cluster + S.P. ex. S.P. ex. Energy ( MeV) Degenerate Feature Consisitent to Exp Atomic Ionic Covalent

Monopole strength of 12 Be ： Ratio to S.P. strength All the excited states have a comparable to or a few times larger strength in comparison to the S.P. strength. Ex. Energy (MeV) Simple shell model is difficult to explain M(IS) strength at E < 20 MeV ! Shell model requires 2hw jump of single particle energy (about 35 MeV) PRC83, (2011)

Be isotopes from bounds to continuum : J  = Be 10 Be 12 Be 14 Be 16 Be Deformed MO states (Clusters) Compact MO states (Shell model) Excitation of  -  rel. motion All the cluster states are expected to have large monopole strength. Dimers y He x He

Present studies Results of the studies Unified studies of structures of 12 Be and reactions of  + 8 He Be 2. Systematics in even Be isotopes Feature studies ⇒ Formation of dimers (ionic states) with the 6 He and 8 He clusters Systematic study ⇒ O=  + 12 C+XN 、 Ne=  + 16 O+XN These properties will appear systematically in other light neutron excess system. Systematic studies ⇒ heavier Be isotopes ⇒ Covalent, ionic and atomic structures appears in excited states PRL100 (08), PRC78(R) (08), PR Focus 22(08), PRC83(11), PRC84(11) Structural changes with cluster degrees of freedom will appear in N-rich systems. ⇒ All the excited states have a large monopole strength