The dynamical cluster-decay model (DCM) of Gupta and Collaborators has been used to study the decay of various Pt-isotopes 176,182,188,196 Pt * formed in 64 Ni+ 112,118,124 Sn and 132 Sn+ 64 Ni reactions. The evaporation residue (ER) and fission cross-sections (σ ER and σ fiss ) are calculated in reference to available experimental data at near-and sub-barrier energies. The calculated σ ER show excellent agreement with experimental data at all incident center-ofmass (c.m.) energies, with the characteristics of emitted light particles (LPs) showing a change with the increase of the iso-spin N/Z ratio of compound nucleus (CN). The only parameter of DCM, the neck-length parameter, for 196 Pt * becomes much smaller, compared to other 176,182,188 Pt * isotopes, and more so at higher c.m. energies, possibly due to additional eight neutrons of the radioactive 132 Sn nucleus. Another interesting result of the DCM calculation is that, similar to other well-known 64 Ni+ 58,64 Ni and 64 Ni+ 100 Mo) reactions, an inbuilt 'barrier lowering' effect is also shown operating for σ ER as well as σ fiss at sub-barrier energies in these reactions. Furthermore, the calculated σ fiss shows a significant contribution of quasifission (σ qf ) at the highest one or two energies, and, due to the deformation and orientation effects of fission fragments, shows a change of the mass distributions from a predominantly symmetric to a predominantly asymmetric one with the increase in the N/Z ratio of CN. This change in fission mass distributions provides the possibility of fine-/sub-structure in fission products of Pt * isotopes.

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The role of deformations and orientations of nuclei is studied for the first time in cluster decays of various radioactive nuclei, particularly those decaying to doubly closed shell, spherical 208 Pb daughter nucleus. Also, the significance of using the correct Q-value of the decay process is pointed out. The model used is the preformed cluster model (In this model, cluster emission is treated as a tunneling of the confining interaction barrier by a cluster considered already preformed with a relative probability P 0 . Since both the scattering potential and potential energy surface due to the fragmentation process in the ground state of the parent nucleus change significantly with the inclusion of deformation and orientation effects, both the penetrability P and preformation probability P 0 of clusters change accordingly. The calculated decay half-lives for all the cluster decays investigated here are generally in good agreement with measured values for the calculation performed with quadrupole deformations β 2 alone and "optimum" orientations of cold elongated configurations. In some cases, particularly for 14 C decay of Ra nuclei, the inclusion of multipole deformations up to hexadecapole β 4 is found to be essential for a comparison with data. However, the available β 4 -values, particularly for nuclei in the mass region 16 A 26, need be used with caution.

The dynamical cluster-decay model (DCM) is used to study the odd-mass nuclear systems 213 Fr * (with N = 126) and 217 Fr * (with N = 130) formed in 19 F + 194,198 Pt reactions. The measured anomaly in fission anisotropy for 213 Fr * in this reaction is said to be due to either the possible role of the magic N = 126 shell of the compound nucleus (CN) or the presence of a noncompound nucleus component, such as quasifission, in the fission cross section. Our calculations are made within the DCM for the fragments having quadrupole (β 2 ) deformations with orientations of compact, hot configurations, compared with spherical as well as β 2 -β 4 deformed considerations. For quadrupole deformed fragments (with "optimal" orientations), the calculated fission cross-sections (as well as the evaporation residue cross-sections) match the data nearly exactly, without invoking a significant contribution from quasifission. The calculated fission mass distribution for the two systems is quite similar for either of the spherical, β 2 -alone deformed, and β 2 -β 4 deformed choices of fragments. A small hump or shoulder is seen in fragment preformation yields for the deformed case (β 2 or β 2 -β 4 ) in both the systems due to a deformed closed shell around Z 2 = 36 and a spherical magic shell around Z 1 = 50, which for 213 Fr * (N = 126) decay is somewhat more pronounced as compared to 217 Fr * (N = 130). Note that the magic shell of the CN proton/neutron number plays no role in DCM.

The decay of compound nucleus 202 Pb *, formed in entrance channel reaction 48 Ca +154 Sm at different incident energies, is studied by using the dynamical cluster-decay model (DCM) where all decay products are calculated as emissions of preformed clusters through the interaction barriers. The calculated results show an excellent agreement with experimental data for the fusion-evaporation residue cross-section σ ER together with the fusion-fission cross-section σ FF (taken as a sum of the energetically favored symmetric [Formula: see text] and near symmetric A=65–75 plus complementary fragments), and the competing, non-compound-nucleus quasi-fission cross-section σ QF where the entrance channel is considered not to loose its identity (and hence with preformation factor P0=1). The interesting feature of this study is that the three decay processes (ER, FF and QF) are quite comparable at low energies, ER being the most dominant, whereas at higher energies FF becomes most probable followed by ER and QF. The prediction of two fission windows, the symmetric fission (SF) and the near symmetric fission (nSF) whose contribution is more at lower incident energies, suggests the presence of a fine structure effect in the fusion-fission of 202 Pb *. This result is attributed to the shell effects (magic shells) playing effective role in the fragment preformation yields for 48 Ca +154 Sm reaction at lower excitation energies, giving rise to "shoulders", to an otherwise Gaussian FF mass distribution, responsible for the QF process. As a further verification of this result, absence of "shoulders" (hence, the QF component) in the decay of 192 Pb * due to 48 Ca +144 Sm reaction is also shown to be given by the calculations, in agreement with experiments. The only parameter of the model is the neck-length ΔR which shows that the ER occurs first, having the largest values of ΔR, and the FF and QF processes occur almost simultaneously at lower incident energies but the FF takes over QF at higher incident energies. In other words, the three processes occur in different time scales, QF competing with FF at lower incident energies.