Fusion–evaporation cross-sections for the 64Ni+100Mo reaction using the dynamical cluster-decay model

The decay of hot and rotating compound nucleus 164Yb*, formed in heavy ion reaction 64Ni+100Mo at both below- and above-barrier energies, is studied on the basis of the dynamical cluster-decay model (DCM) with effects of deformations and orientations of nuclei included in it. There is only one parameter in this model, namely the neck-length parameter, which varies smoothly with the temperature of the compound nucleus at both below- and above-barrier energies, and its value remains within the range of validity of the proximity potential. The emission of light particles (xn, x-neutrons, x = 1–4) as well as the energetically favoured intermediate mass fragments (IMFs) of both the light (5 ≤ A2 ≤ 20) and heavy (40 ≤ A2 ≤ 50) masses, together with the symmetric fission (SF) channel ((A/2) ± 20), is considered as the dynamical collective mass motions of preformed fragments or clusters through the barrier. The light-mass IMFs, the heavy-mass fragments (HMFs) and SF, constituting the fusion–fission (ff) cross-section, contribute only at above-barrier energies, and are compatible with the CASCADE analysis of experimental data. A best fit to data is obtained for two different neck-length parameters, one for light particles (LPs) and another for all other decay channels, the ff cross-section. The barrier height corresponding to the neck-length parameter for LPs gives 'barrier lowering' in a straightforward way for the best-fitted fusion–evaporation cross-sections in DCM, and, in contrast to the (statistical model) analysis of experimental data, results in largest contribution for 1n emission. A further study is called for both the LPs and ff channels.