Probing transfer to unbound states of the ejectile with weakly bound 7Li on 93Nb

The two-step process of transfer followed by breakup is explored by measuring a rather complete set of exclusive data for reaction channels populating states in the ejectile continua of the ${}^7$Li+${}^{93}$Nb system at energies close to the Coulomb barrier. The cross sections for $\alpha +\alpha$ events from one proton pickup were found to be smaller than those for $\alpha +d$ events from one neutron stripping and $\alpha +t$ events from direct breakup of ${}^7$Li. Coupled channels Born approximation and continuum discretized coupled channels calculations describe the data well and support the conclusion that the $\alpha +d$ and $\alpha +\alpha$ events are produced by direct transfer to unbound states of the ejectile.