1. 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)

2. 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

3.  (  + ) 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

4. 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. 2 1 3 4 5 6 Atomic Ionic Covalent

5. 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) 2.12 10.19 12.29 12.94 15.09 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) PRC83,044319 (2011)

6. Be isotopes from bounds to continuum : J  = 0 + 8 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

7. Present studies Results of the studies Unified studies of structures of 12 Be and reactions of  + 8 He 1. 12 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