Simultaneous study of the 11Li and 10Li nuclei in a microscopic cluster-model

The Li-11 and Li-10 nuclei are investigated in the Generator Coordinate Method involving Li-9+n+n and Li-9+n cluster configurations, respectively. The Li-9 nucleus is described in the shell model with all p-shell wave functions allowed by the Pauli principle. This procedure yields many Li-9 states, defined by a flexible mixing of shell model basis states. Two different nucleon-nucleon interactions are used. We compute some spectroscopic properties of Li-11, such as radii, quadrupole moments and densities. The model predicts a 1/2(-) excited state, but no positive-parity state. With the same conditions of calculation, we study the Li-10 system. We find a 1(+) assignment for the ground state. We present the s phase shifts, and discuss the possible existence of a low-energy virtual s state. The properties of such a state are shown to be partly model dependent. (C) 1997 Elsevier Science B.V.