Heavy ion transfer reaction mechanisms

The reaction mechanism of nucleon transfer between complex nuclei has been and can be studied best for nuclei with well known structural properties. In a careful analysis, even single nucleon transfer shows always effects of higher order interactions. At high incident energies further modifications to the standard analysis may be necessary due transparency of the nuclear surface. In description of the interaction of nuclei with effective potentials describing various higher order effects is necessary. The strong spin-orbit interaction of nuclei is discussed, which is due to higher order couplings. Multistep interactions are dominant in multinucleon transfer. The role of the pairing interaction is discussed in the context of the interaction of very heavy nuclei; here the inelastic excitation in particular by the Coulomb force introduces new aspects. The transfer of α-clusters stands unique, because it is in cleanest form realised with 6Li-nuclei, α-cluster exchange between heavier nuclei is, however, a possible subject of future development. Aspects related to the two-center problem are relevant in many cases. The example of 12C+13C is used to illustrated the molecular orbital aspects. Relations to deeply inelastic collisions are shown, where nucleons are exchanged freely and where two body collisions limit the quasielastic multinucleon transfer. (orig.)