Symmetric and Asymmetric Quasifission Modes in Reactions with Heavy Ions

摘要

Mass and energy distributions of fission and quasifission fragments in the reactions ~(22)Ne+~(249)Cf, ~(26)Mg+~(248)Cm, ~(36)S+~(238)U~ and (58)Fe+ ~(208)Pb leading to the formation of the Z=108 composite nucleus are reported. In this series of experiments it is shown for the first time that the quasifission process leads to the formation of not only asymmetric fragments but also gives a contribution to the symmetric mass region of fission fragments, most probably caused by the influence of nuclear shells with Z=50 and N=82.