For collisions between deformed and oriented nuclei, the fragmentation theory is extended for the generalized nuclear proximity potential, with deformations included up to the hexadecupole deformations. For co-planar nuclei, the orientations are shown to get optimized (uniquely fixed) by the signs of their quadrupole deformations alone, not affected by the signs of their hexadecupole deformations. The optimum orientations are obtained for both the ‘hot compact’, and ‘cold elongated’ configurations of any two colliding nuclei. The hexadecupole deformations are shown to help fusion (hot or cold), depending on the choice of the reaction partners. Calculations are made for the 208Pb- and 48Ca-induced reactions and the neighbouring deformed nuclei. The calculated fragmentation potentials for optimally oriented nuclei, compared with both nuclei taken spherical, show that the excitation energy of the potential energy minima is significantly lowered for cold (elongated) fusion of deformed nuclei, but it remains nearly the same for at least the asymmetric hot (compact) fusion reactions. A number of new minima (target–projectile combinations) arise due to the cold and nearly symmetric hot fusion of deformed, optimally oriented nuclei.

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The complex fragments (or intermediate mass fragments) observed in the low-energy 58 Ni+ 58 Ni→ 116 Ba * reaction, are studied within the dynamical cluster decay model for s-wave with the use of the temperature-dependent liquid drop, Coulomb and proximity energies. The important result is that, due to the temperature effects in liquid drop energy, the explicit preference for α-like fragments is washed out, though the 12 C (or the complementary 104 Sn) decay is still predicted to be one of the most probable α-nucleus decay for this reaction. The production rates for non-α like intermediate mass fragments (IMFs) are now higher and the light particle production is shown to accompany the IMFs at all incident energies, without involving any statistical evaporation process in the model. The comparisons between the experimental data and the (s-wave) calculations for IMFs production cross sections are rather satisfactory and the contributions from other ℓ-waves need to be added for a further improvement of these comparisons and for calculations of the total kinetic energies of fragments.

The dynamical cluster-decay model (DCM) is developed further for the decay of hot and rotating compound nuclei (CN) formed in light heavy-ion reactions. The model is worked out in terms of only one parameter, namely the neck-length parameter, which is related to the total kinetic energy TKE(T ) or effective Q value Q eff (T ) at temperature T of the hot CN and is defined in terms of the CN binding energy and ground-state binding energies of the emitted fragments. The emission of both the light particles (LP), with A 4, Z 2, as well as the complex intermediate mass fragments (IMF), with 4 < A < 20, Z > 2, is considered as the dynamical collective mass motion of preformed clusters through the barrier. Within the same dynamical model treatment, the LPs are shown to have different characteristics compared to those of the IMFs. The systematic variations of the LP emission cross section σ LP and IMF emission cross section σ IMF calculated from the present DCM match exactly the statistical fission model predictions. A nonstatistical dynamical description is developed for the first time for emission of light particles from hot and rotating CN. The model is applied to the decay of 56 Ni * formed in the 32 S + 24 Mg reaction at two incident energies E c.m. = 51.6 and 60.5 MeV. Both the IMFs and average TKE spectra are found to compare resonably well with the experimental data, favoring asymmetric mass distributions. The LPs' emission cross section is shown to depend strongly on the type of emitted particles and their multiplicities.