A microscopic three-cluster model in the hyperspherical formalism

The hyperspherical formalism is applied in the framework of the microscopic generator-coordinate method. Three-cluster systems are described with a single generator coordinate, the hyperradius. This model is a natural extension of previous microscopic theories, and can be applied to bound states and resonances in a range of nuclei exhibiting a cluster structure. As an illustrative example, the model is applied to He-6 and Li-6. Density distributions and electric dipole transition strengths are calculated, including B(E2; 0(+) --> 2(+)) in He-6. The results are consistent with a neutron halo structure for the ground state of He-6, and with a proton-neutron halo structure of its isobaric analog state in Li-6. No 1(-) soft dipole resonance is found in He-6. (C) 2004 Elsevier B.V. All rights reserved.