Main restrictions in the synthesis of new superheavy elements: quasifission or/and fusion-fission

TL;DR

This paper compares theoretical models of superheavy element formation via fusion reactions, analyzing how different nuclear mass models influence predicted evaporation residue cross sections and the roles of quasifission and fusion-fission processes.

Contribution

It provides a comparative analysis of reaction mechanisms and the impact of nuclear mass models on superheavy element synthesis predictions.

Findings

Different mass models significantly affect ER cross section predictions.

Quasifission and fusion-fission are key restrictions in superheavy element synthesis.

Mass values from the Warsaw group lead to smaller ER cross sections.

Abstract

The synthesis of superheavy elements stimulates the effort to study the peculiarities of the complete fusion with massive nuclei and to improve theoretical models in order to extract knowledge about reaction mechanism in heavy ion collisions at low energies. We compare the theoretical results of the compound nucleus (CN) formation and evaporation residue (ER) cross sections obtained for the $^{48}$Ca+$^{248}$Cm and $^{58}$Fe+$^{232}$Th reactions leading to the formation of the isotopes A=296 and A=290, respectively, of the new superheavy element Lv (Z=116). The ER cross sections, which can be measured directly, are determined by the complete fusion and survival probabilities of the heated and rotating compound nucleus. That probabilities can not be measured unambiguously but the knowledge about them is important to study the formation mechanism of the observed products. For this aim, the $^{48}$Ca+$^{249}$Cf and $^{64}$Ni+$^{232}$Th reactions have been considered too. The use of the mass values of superheavy nuclei calculated in the framework of the macroscopic-microscopic model by Warsaw group leads to smaller ER cross section for all of the reactions (excluding the $^{64}$Ni+$^{232}$Th reaction) in comparison with the case of using the masses calculated by Peter M\"oller {\it et al}.