Departmental Seminar

Characterization of the heavy-ion fusion reactions mechanism in Cr + W reactions

Ms K. Hammerton
Michigan State University

Heavy ion fusion reactions serve as the primary mechanism for the production of superheavy elements.  A crucial step in this reaction mechanism is the formation of a fully equilibrated compound nucleus.  Compound nucleus fusion can be hindered by orders of magnitude by quasifission, a process in which the dinuclear system breaks apart prior to full equilibration.   Characterization of the quasifission process is vital to providing a complete description of the heavy ion fusion reaction mechanism.  Mass and angle distributions of fragments formed via 8 Cr + W reactions were measured at the Australian National University to explore the interplay between the fusion-fission and quasifission reaction channels with varying neutron-richness.  The reactions were measured in two energy regimes: at 13% above the Bass fusion barrier and at 52.0 MeV of excitation energy in the compound nucleus, E*CN.  At Ec.m./ VBass = 1.13, there is a clear dependence on the neutron-richness.  For the reactions at E*CN = 52.0 MeV, the dependence is less clear and additional factors such as the energy available for rotation play a vital role.  This work demonstrates that quasifission is an important consideration in understanding the heavy-ion fusion reaction mechanism for intermediate mass projectiles.

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