Soft dipole mode in ${}^{11}$Li and three body continuum

Abstract

Properties of the neutron rich ${}^{11}$Li nucleus are calculated in the framework of the cluster model ${}^9$Li $+n+n$. The formalism of the harmonic oscillator representation of the scattering theory is used for the description of bound and continuum spectrum states in the three-body-democratic-decay approximation. It is shown that this approach allows one to take into account adequately the long asymptotic tail of the ${}^{11}$Li wave function ({\em neutron halo}) and to reproduce correctly the binding energy, radius and ${}^{11}$Li electromagnetic dissociation cross-section on target nuclei. The shape and the energy position of the $B(E1)$ peak corresponding to the soft dipole mode are also in agreement with experiment.

Comments: Presented by A.M.Shirokov as a talk at the Conference 'HALO-94' (Copenhagen, January 1994). LaTeX, 13 pages including 3 figures in postscript (40kb Latex file + 130kb postscript files). Latex sources for printing the figures are available from the authors on request