Systematic analysis on cluster components in He-isotopes by using a new AMD approach Niigata University Shigeyoshi Aoyama FB18, August 24 (2006) S. Aoyama, N. Itagaki and M. Oi, PRC74, (2006).

A systematic investigation of the cluster and shell aspects of light neutron-rich nuclei with AMD triple-S. Purpose of our study Contents 3. t+t clustering effect in He-isotopes 2. AMD triple-S (Present Method) 1. Introduction 4. Summary

4 He n n Neutron halo structure of 6 He 4 He+n+n model However, such a simple 4 He+n+n model can not reproduce the binding energy of 6 He. Halo

t+t clustering effects in 6 He Dr. Csoto suggested that the contribution of the t+t channel is substantial. [3N+N]+n+n model ： Arai, Suzuki, Lovas, PRC59(1999) t t

t+t clustering state was observed in 6 He as an excited states. t t

Cluster-shell competition in magic number nuclei (N=8) α nn α nn 12 Be α nn t nn 11 Li t nn t nn 10 He ClusterShell-model-like or cluster? Shell-model-like?

We must solve a 7-body coupled channel problem for 10 He! t nn t nn α n n n n n n ＋

In order to treat the spatial extending wavefunction, we use AMD ＋ GCM. N. Itagaki and S. Aoyama, Phys. Rev. C61, (2000) In order to treat the large model space, we use SVM (Stochastic Variational Method) K. Varga, Y. Suzuki, Y. Ohbayashi, Phys. Rev. C50, 189 (1994) Present Method (AMD triple-S) AMD+GCM+SVM => AMD triple-S (Antisymmetrized Molecular Dynamics with Superposition of Selected Snapshot)

AMD w.f. (Brink-type w.f.) １． The Gaussian center (z) of the AMD w.f. is randomly generated. ２． We solve the frictional cooling equation only for imaginary part.

e.g. N=3,ε=0.05 MeV ３． We regard the AMD w.f. as a basis function for GCM. ４． If the obtained energy decreases, we adopt it. 5. We return to 1, if the energy does not converge. We diagonalize Hamiltonian. This is a kind of SVM technique.

nn α b=1.46fm Volkov No.2 (M=0.6, B=H=0.125) +G3RS The energy convergence of the ground state(0+) of 6 He

Comparison with the conventional AMD The energy of single AMD calcualtion is higher than the present one. The difference is 6.74 MeV. We can reproduce the halo.

Neutron Tail of 6He AMD AMD-tripleS

6 He AMD triple-SRGM 12 C Arai E=-89.62MeV Matsumura and Szuki, NPA739, 238(2004) E= MeV E=-89.4MeV E= MeV E=-28.34MeV PRC68(2003) Kamimura, NPA351, 456(1981) AMD triple-SRGM Comparison with the precise few-body calculation

4 He 5 He 6 He 7 He 8 He 9 He 10 He α n n n n n n 10 He B=H=0.125 B=H=0 Volkov No.2 (M=0.6)+ G3RS Calculated Energies for He-isotopes Energy (MeV) Exp.

4 He 5 He 6 He 7 He 8 He 9 He 10 He α 10 He Single channel Coupled channel Volkov No.2 (M=0.6, B=H=0.00)+ G3RS t+t clustering effects in He-isotopes Energy (MeV) Single channel: α-core model Coupled channel: α-core + (t+t)-core model + t n t n n n n n n n n n Coupled channel problem for 7-body system p 3/2 -orbitp 1/2 -orbit

Summary ・ We understand that the AMD triple-S is useful for the analyses of the cluster-shell aspects of light nuclei. ・ Even for the He-isotopes which have a stiff α- core, the t+t component can not be neglected. We are going to investigate 11 Li and 12 Be. Next