Synthesis of superheavy elements is a long-standing important subject in nuclear physics. In the neighbourhood of (Z = 114, N = 184), superheavy elements are expected to exist, i.e. to be stable against fission by our knowledge of extreme stability of closed shell structure. Recently the Z = 112 element was synthesized by the GSI group with so-called cold fusion reaction. The reaction mechanism is not well understood, but cross sections are empirically inferred to be much smaller for heavier elements. We therefore propose to explore another way, the so-called hot fusion reaction. There we can apply dissipation-fluctuation dynamics to fusion as well as fission processes. In a preliminary analysis, we employ the Smoluchovski equation which is valid for cases of strong dissipation, and solve the fusion-fission problem. As a compromise between larger fusion probability and smaller fission probability, i.e. larger survival probability, we find an optimum excitation energy of the reaction. It is shown that the optimum condition is most stable, and the optimum residue cross section becomes large, if a neutron-rich compound nucleus is formed at the beginning. This is due to a quicker cooling by successive evaporations of neutrons with small separation energies.

Ort: Wilhelm-Klemm-Str. 9, Hörsaal 404

Zeit: 17 Uhr c.t.

Einladender: Weiguny