Systematic analysis on cluster components in He-isotopes by using a new AMD approach

1. FB18, August 24 (2006) Systematic analysis on cluster components in He-isotopes by using a new AMD approach Niigata University Shigeyoshi Aoyama S. Aoyama, N. Itagaki and M. Oi, PRC74, 017307(2006).

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

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

4. t+t clustering effects in 6He t t Dr. Csoto suggested that the contribution of the t+t channel is substantial. [3N+N]+n+n model： Arai, Suzuki, Lovas, PRC59(1999) 1432.

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

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

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

8. Present Method (AMD triple-S) In order to treat the spatial extending wavefunction, we useAMD＋GCM. N. Itagaki and S. Aoyama, Phys. Rev. C61, 024303 (2000) In order to treat the large model space, we useSVM (Stochastic Variational Method) K. Varga, Y. Suzuki, Y. Ohbayashi, Phys. Rev. C50, 189 (1994) AMD+GCM+SVM => AMD triple-S (AntisymmetrizedMolecularDynamics with Superposition of SelectedSnapshot)

9. １．The Gaussian center (z) of the AMD w.f. is randomly generated. AMD w.f. (Brink-type w.f.) ２．We solve thefrictional cooling equationonly for imaginary part.

10. ３．We regard the AMD w.f. as a basis function for GCM. We diagonalize Hamiltonian. ４．If the obtained energy decreases, we adopt it. e.g. N=3,ε=0.05 MeV 5. We return to 1, if the energy does not converge. This is a kind of SVM technique.

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

12. 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.

13. Neutron Tail of 6He AMD-tripleS AMD

14. Comparison with the precise few-body calculation 6He AMD triple-S RGM E= -28.56MeVE=-28.34MeV Arai 12C AMD triple-S RGM E= -89.62MeV E=-89.4MeV Kamimura, NPA351, 456(1981) PRC68(2003) E=-89.62MeV Matsumura and Szuki, NPA739, 238(2004)

15. 10He n n α n n n n Calculated Energies for He-isotopes Volkov No.2 (M=0.6)+ G3RS B=H=0.125 B=H=0 Energy (MeV) Exp. 4He 5He 6He 7He 8He 9He 10He

16. α n n n n n n n n n n t t t+t clustering effects in He-isotopes Volkov No.2 (M=0.6, B=H=0.00)+ G3RS 10He Single channel Energy (MeV) + Coupled channel 4He 5He 6He 7He 8He 9He 10He Coupled channel problem for 7-body system p3/2-orbit p1/2-orbit Single channel: α-core model Coupled channel: α-core + (t+t)-core model

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