Li - α Cluster States in Neutron-rich Boron Isotopes and the Resonance Scattering Method

Exotic clustering is acknowledged as one of the most promising research fields that can be investigated by radioactive beams induced reactions. It consists in the description of unstable nuclei as di-nuclear structures where at least one of the components can be unstable itself. Thus one of the basic prescriptions of the standard cluster models, namely the bound structure of the components, that baptized the α-particle as the ideal cluster, may not be satisfied in this framework. As far as Boron is concerned for example, calculations performed in the framework of Antisymmetrized Molecular Dynamics are able to describe the ground state of its very neutron-rich isotopes in terms of two components with Z=2 and Z=3 respectively. The usual way to investigate the presence of such dinuclear configurations is to study the excitation function of nuclear processes where the two clusters are present in the entrance and/or in the final state. In this framework, the excitation function of the 8Li+α elastic scattering was measured using the 8Li beam provided by the LNS radioactive beam facility EXCYT, to the aim of looking for resonances associated to 8Li-α cluster configurations of 12B. The Resonance Scattering Method was used since it allows to measure the excitation function in a wide energy range with a single beam energy (fig. 1). The experiment has been successfully carried out (see Activity report pag 95) and the data analysis is in progress.


M. Lattuada, A. Di Pietro [INFN-LNS], P. Figuera [INFN-LNS], M. Fisichella [INFN-LNS], A. Musumarra [INFN-LNS], F. Pansini, M. G. Pellegriti [INFN-LNS], V. Scuderi, G. Scalia,  D. Torresi, G. Randisi