Semi-microscopic calculations of α-cluster states in 18F

Motivated by the striking success of some simple phenomenological cluster models the authors present a microscopic derivation of an effective cluster-core interaction for 18F=14N+α. This case is particularly interesting since the interaction should possess spin-orbit and tensor contributions. The interactions are derived from the shell-model approximation to the ground state of 14N and an α-nucleon scattering potential. The results agree rather well with the phenomenological model except that mixing due to the tensor force is large. This effect leads the authors to re-examine the experimental candidates for cluster states and it is found that mixing with two-particle shell-model states may be important. (Auth.)