Role of different nuclear charge radii parameterizations on the thermal equilibrium in nuclear reaction

We emphasize the role of nuclear charge radii parameterizations on the thermal equilibrium by studying the correlation between maximal value of average temperature achieved in highly interacting nuclear matter and nuclear stopping for mass symmetric and asymmetric reactions over the entire collision geometry within the framework of isospin-dependent quantum molecular dynamics (IQMD) model. Our study reveals that the increase in available phase space at initial stage through different nuclear charge radii parameterizations, enhance the temperature of nuclear system and reduces the nuclear stopping for both types of reactions. The influence of nuclear charge radii on the thermalization is more pronounced for mass symmetric reactions compared to mass asymmetric reactions. Moreover, the lighter colliding pair are good probe to study the role of nuclear radius in thermalization

Recent experimental results in sub- and near-barrier heavy ion fusion reactions

Recent advances obtained in the field of near and sub-barrier heavy-ion fusion reactions are reviewed. Emphasis is given to the results obtained in the last decade, and focus will be mainly on the experimental work performed concerning the influence of transfer channels on fusion cross sections and the hindrance phenomenon far below the barrier. Indeed, early data of sub-barrier fusion taught us that cross sections may strongly depend on the low-energy collective modes of the colliding nuclei, and, possibly, on couplings to transfer channels. The coupled-channels (CC) model has been quite successful in the interpretation of the experimental evidences. Fusion barrier distributions often yield the fingerprint of the relevant coupled channels. Recent results obtained by using radioactive beams are reported. At deep sub-barrier energies, the slope of the excitation function in a semi-logarithmic plot keeps increasing in many cases and standard CC calculations over-predict the cross sections. This was named a hindrance phenomenon, and its physical origin is still a matter of debate. Recent theoretical developments suggest that this effect, at least partially, may be a consequence of the Pauli exclusion principle. The hindrance may have far-reaching consequences in astrophysics where fusion of light systems determines stellar evolution during the carbon and oxygen burning stages, and yields important information for exotic reactions that take place in the inner crust of accreting neutron stars.Comment: 40 pages, 63 figures, review paper accepted for EPJ

Spin distribution measurement for 64Ni + 100Mo at near and above barrier energies

Spin distribution measurements were performed for the reaction 64Ni + 100Mo at three beam energies ranging from 230 to 260 MeV. Compound nucleus (CN) spin distributions were obtained channel selective for each evaporation residue populated by the de-excitation cascade. A comparison of the spin distribution at different beam energies indicates that its slope becomes steeper and steeper with increasing beam energy. This change in slope of the spin distribution is mainly due to the onset of fission competition with particle evaporation at higher beam energies

Spin distribution as a probe to investigate the dynamical effects in fusion reactions

The spin distributions are measured for the compound nucleus 80Sr populated in the reactions 16O+64Zn and 32S+48Ti. The comparison of the experimental results for both the systems shows that the mean γ-ray multiplicity values for the system 32S+48Ti are lower than those for 16O+64Zn. The spin distribution of the compound nucleus populated through the symmetric channel is also found to be lower than the asymmetric channel. Present investigation directly shows the effect of entrance channel mass asymmetry on the reaction dynamics

Heavy ion collision dynamics of 10,11B+10,11B reactions

The dynamical cluster-decay model (DCM) of Gupta and collaborators has been applied successfully to the decay of very-light (A ∼ 30), light (A ∼ 40−80), medium, heavy and super-heavy mass compound nuclei for their decay to light particles (evaporation residues, ER), fusion-fission (ff), and quasi-fission (qf) depending on the reaction conditions. We intend to extend here the application of DCM to study the extreme case of decay of very-light nuclear systems 20,21,22Ne∗ formed in 10,11B+10,11B reactions, for which experimental data is available for their binary symmetric decay (BSD) cross sections, i.e., σBSD. For the systems under study, the calculations are presented for the σBSD in terms of their preformation and barrier penetration probabilities P0 and P. Interesting results are that in the decay of such lighter systems there is a competing reaction mechanism (specifically, the deep inelastic orbiting of non-compound nucleus (nCN) origin) together with ff. We have emipirically estimated the contribution of σnCN. Moreover, the important role of nuclear structure characteristics via P0 as well as angular momentum ℓ in the reaction dynamics are explored in the study