Three-body analysis of the occurrence of Efimov states in 2n halo nuclei such as B-19, C-22, and C-20 - art. no. 051303

By employing separable potentials for the binary, i.e., n-n and n-core subs ystems, we compute the three-body integral equations to solve for the 2n-se paration energies in the ground and excited states of halo nuclei like B-19 , C-22, and C-20. We show through numerical analysis and also from analytic al considerations that Borromean-type halo nuclei like B-19 and C-22, where n-n and n-core are both unbound, are much less vulnerable to respond to th e existence of the Efimov effect. On the contrary, those nuclei, like C-20 in which the halo neutron is supposed to be in the intruder low lying bound state with the core, appear to be the promising candidates to search for t he occurrence of Efimov states at energies below the n-(nc) breakup thresho ld which can be within the experimental limits to measure.