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Role of the Coulomb interaction, mean fissility, mass asymmetry, and charge asymmetry parameters on the synthesis of heavy and superheavy elements has been examined with respect to the deformation parameters of the projectile and target nuclei explicitly in light of the experimental results. The observed facts are classified into four categories and are then used to study several unsuccessful as well as planned reactions to synthesize the new superheavy elements $Z= 119, 120$. Concrete inference is too difficult to draw from these results because of excessive deviations in evaporation residue cross-section data. It is found that the arbitrary choice of excitation energy for the experiments studied was the root cause of such large deviations. Such a complex issue can be resolved well by theoretical excitation function studies using the advanced statistical model or the dinuclear system model and choosing the excitation energy corresponding to the energy where the excitation function curve shows the maximum. We believe this method may help us to predict whether the estimated evaporation residue cross-section can be measurable within the experimental limit of the existing facilities for the future reactions planned., Comment: 5 figures

Besides right choice of entrance channel, selection of optimal beam energies for synthesis of superheavy elements plays a crucial role. A thorough investigation with the advanced statistical and dinuclear system models on all the experiments performed for the synthesis of the successful superheavy elements Z=104-118 and failed superheavy elements Z=119-120 leads us to infer that improper choice of the beam energies may be responsible for too low production cross sections to measure and thus the cause for the debacle. We have predicted the optimal beam energies to obtain the maximum production cross sections for all the reactions used for the superheavy elements Z=104-120. Hope exploitation of these predictions may be on the cards soon to extend the periodic table for the eighth period, Comment: 5 figures

We have constructed an empirical formulae for the fusion and interaction barriers using experimental values available till date. The fusion barriers so obtained have been compared with different model predictions based on the proximity, Woods-Saxon and double folding potentials along with several empirical formulas, time dependent Hartree-Fock theories, and the experimental results. The comparison allows us to find the best model, which is nothing but the present empirical formula only. Most remarkably, the fusion barrier and radius show excellent consonance with the experimental findings for the reactions meant for synthesis of the superheavy elements also. Furthermore, it is seen that substitution of the predicted fusion barrier and radius in classic Wong formula [C. Wong, Phys. Rev. Lett. {31}, 766 (1973)] for the total fusion cross sections satisfies very well with the experiments. Similarly, current interaction barrier predictions have also been compared well with a few experimental results available and Bass potential model meant for the interaction barrier predictions. Importantly, the present formulae for the fusion as well as interaction barrier will have practical implications in carrying out the physics research near the Coulomb barrier energies. Furthermore, present fusion barrier and radius provide us a good nucleus-nucleus potential useful for numerous theoretical applications., Comment: 4 figures. arXiv admin note: substantial text overlap with arXiv:1901.03515

Coulomb fission mechanism may take place if the maximum Coulomb-excitation energy transfer in a reaction exceeds the fission barrier of either the projectile or target. This condition is satisfied by all the reactions used for the earlier blocking measurements except one reaction 208 Pb + Natural Ge crystal, where the measured timescale was below the measuring limit of the blocking measurements < 1 as. Hence, inclusion of the Coulomb fission in the data analysis of the blocking experiments leads us to interpret that the measured time longer than a few attoseconds (about 2-2.5 as) is nothing but belonging to the Coulomb fission timescale and shorter than 1 as are due to the quasifission. Consequently, this finding resolves the critical discrepancies between the fission timescale measurements using the nuclear and blocking techniques. This, in turn, validates the fact that the quasifission timescale is indeed of the order of zeptoseconds in accordance with the nuclear experiments and theories. It thus provides a radical input in understanding the reaction mechanism for heavy element formation via fusion evaporation processes, Comment: 2 figures

We have constructed empirical formulae for fusion and interaction barrier heights using experimental values available in the literature. Fusion excitation function measurements are used for the former and back angle quasi-elastic excitation function for the latter case. The fusion barriers so obtained have been compared with various model predictions such as Bass potential, Christenson and Winther, Broglia and Winther, Aage Winther, Siwek-Wilczynska and J.Wilczynski, Skyrme energy density function model, and the Sao Paulo optical potential along with experimental results. The comparison allows us to find the best model, which is found to be the Broglia and Winther model. Further, to examine its predictability, the Broglia and Winther model parameters are used to obtain total fusion cross sections showing good agreement with the experimental values for beam energies above the fusion barriers. Thus, this model can be useful for planning any experiments, especially ones aiming for super heavy elements. Similarly, current interaction barrier heights have also been compared with the Bass potential model predictions. It shows that the present model calculations are much lower than the Bass potential model predictions. We believe the current interaction barrier model prediction will be a good starting point for future quasi-elastic scattering experiments. Whereas both the Broglia and Winther model and our interaction barrier model will have practical implications in carrying out physics research near the Coulomb barrier energies., Comment: 16 pages, 6 figures, 6 tables