Dr Maurits Evers
Nuclear Physics Department
Nuclear collisions at energies near the fusion barrier show a range of different phenomena which can affect each other. At energies near the fusion barrier, measured fusion cross-sections have been successfully reproduced within the coherent quantum coupled-channels framework. Dissipative processes, which are not treated with the usual coupled-channels formalism, have been linked with the observed suppression of fusion at energies above the barrier. The role of transfer may be a key towards developing a consistent formalism that correctly describes the suppression of fusion seen both at deep sub-barrier and at above-barrier energies.
In this presentation, measurements of the reflected flux at backward angles, performed at the Australian National University and at Legnaro National Laboratory for the reactions 16O,32S,40Ca+208Pb will be presented (see for example, Evers et al., PRC84, 054614 (2011)). Results provide insight into the underlying physical processes, and a new phenomelogical model is proposed to take into account dissipative energy loss as well as coherent channel couplings. This may significantly affect predicted fusion rates in nuclear collisions relevant to astrophysical scenarios as well as in the formation of super-heavy elements.