Research at the argonne linac

In this Report work on subbarrier fusion of atomic nuclei carried out during the past few years is reviewed. We begin by outlining the techniques developed to measure the rare events of physical interest emphasizing the nuclear and atomic processes taking place during formation of the evaporation residues. The principal, hitherto unexpected, features of the data for subbarrier fusion of massive nuclei are then presented. We slow that these fusion data may be characterized by cross sections whose magnitude both far exceed static quantal tunnelling expectations and depend upon detailed structural properties of the collision partners. Included are discussions of data for 1p-shell systems and of the heaviest residues yet synthesized. We present a simple and elegant description of the underlying dynamic processes in terms of couplings of intrinsic degrees of freedom of the collision partners to the tunnelling degree of freedom. Various types of couplings are discussed. We see that an essential feature of channel coupling is the production of an eigen spectrum of potential barriers. We then end this Report with a summary of several recent studies of partial wave distributions and of quasielastic scattering at near and subbarrier energies.