Studies of light neutron-excess systems from bounds to continuum

Makoto Ito

doi:10.1051/epjconf/20111707003

Abstract

The generalized two-center cluster model (GTCM), which can handle various single particle config urations in general two center systems, is applied to the light neutron-rich system, 12 Be= α+α+4N . We discuss the change of the neutrons’ configuratio around two α-cores as a variation of an excitation energy. We show that the covalent, ionic and atomic configuration appear in the unbound region above the α+8 Heg.s. particledecay threshold. The GTCM calculation is also applied to even Be isotopes, and the systematics on the structural changes from bound region to continuum is discussed.

Highlights

In the last two decades, developments of experiments with secondary RI beam have extensively advanced the studies on light neutron-rich nuclei
The molecular orbital (MO) model can describe many kinds of characteristic properties of these isotopes, but they are mainly limited to the analysis on low-lying bound states, and theoretical studies on the highly excited states above the particledecay threshold is still unresearched area
The detailed explanation of generalized two-center cluster model (GTCM) has already been published in Refs. [5,6,7], and we briefl show the formulation of GTCM in the following

Summary

Introduction

In the last two decades, developments of experiments with secondary RI beam have extensively advanced the studies on light neutron-rich nuclei. The Be isotopes can be considered as typical examples of two-center superdeformed systems which build on an α+α rotor of 8Be. Theoretically, molecular orbital (MO), such as the π− and σ+ orbitals associated with the covalent bonding in atomic molecules, have been successful in understanding the low-lying states of these isotopes [1]. The MO model can describe many kinds of characteristic properties of these isotopes, but they are mainly limited to the analysis on low-lying bound states, and theoretical studies on the highly excited states above the particledecay threshold is still unresearched area. In contrast to the situation of theoretical studies, recent experiments on 12Be revealed the existence of many resonant states [2,3,4], which strongly decay into 6Heg.s.+6Heg.s. and α+8Heg.s. Similar resonances, decaying to He isotopes, have been observed in other Be isotopes, such as 10Be=α+6He and 14Be=6He+8He

Framework

Results of the intrinsic structures in 12Be

Monopole strength in 12Be

Results of even Be isotopes

Summary