Role of Entrance-channel Dynamics in Heavy Element Synthesis

Abstract

In heavy element synthesis, the population surviving quasi-fission and fusion-fission is far out in the tail of the distribution of reaction outcome probabilities, and should be sensitive to slight changes in the reaction conditions. Because of the extremely low yields of very heavy elements, it is difficult to make detailed and systematic exper- imental studies. However, studies of less-fissile systems can give valuable information relevant to the formation of super-heavy elements. Measurements made at the ANU, Canberra, to study the influence of entrance-channel properties on the subsequent reaction dynamics are presented. New and surprising data show that the entrance- channel mass-asymmetry plays a role in the compound nucleus formation probability, even when forming a nucleus as light as 216Ra. The influence of different physical configurations, related to different contact barrier energies, on superheavy element formation is discussed