Analysis of the low- and high-energy fusion cross sections: the case of⁵⁸Ni+⁵⁴Fe

Abstract

The importance of the saturation effect of cold nuclear matter (NM) on describing the fusion hindrance phenomenon at extremely low incident energies is investigated for the medium-heavy mass system of 58Ni+54Fe. From the theoretical viewpoint, for considering the mentioned property during the fusion process one can use the double-folding (DF) model which is modified through the repulsive core effects as a basic heavy ion–ion potential. The theoretical calculations of the fusion cross sections are performed using the coupled-channel technique, including couplings to the low-lying and states in target and projectile. It is shown that the corrective effects of the cold NM provide an appropriate description for the energy-dependent behavior of the measured fusion cross sections at extremely low incident energies. Moreover, we find that the calculated results of the astrophysical S factor and the logarithmic derivative based on the modified form of the DF model are in good agreement with the corresponding experimental data at these energies. A discussion is also presented about the predictions of the present sudden approach for the behavior of the fusion cross sections at high incident energies. The obtained results reveal that this behavior depends on the nuclear structure of the reacting nuclei.

Survey of deep sub-barrier heavy-ion fusion hindrance phenomenon for positive and negative Q-value systems using the proximity-type potential

“…We would like to mention that the characteristics of the nuclear ion-ion potential at extremely close distances affect the measurements of the fusion cross sections in the range of microbarn and nanobarn levels [7][8][9]67]. On the other hand, it can be shown that the adjustable parameter in Eq.…”

“…The most notable outcome of such studies is the hindrance phenomenon of heavy-ion fusion at extreme sub-barrier energies. In fact, for medium-heavy-mass systems, it has been found that the fusion cross sections drop rapidly with decreasing energy, so the experimental values of are much steeper than the predicted standard coupled-channels (CC) calculations obtained using a Woods-Saxon (WS) potential [5,[7][8][9][10]. From a practical standpoint, the low-energy fusion hindrance phenomenon in the mentioned mass region can be easily recognized by two important observations.…”

“…According to the literature, the experimental values of the logarithmic derivative must increase slowly with a decrease in the center-of-mass energy of heavy-ion fusion reactions [7][8][9]16,17]. The onset of the sub-barrier fusion hindrance phenomenon can be identified by the intersection between the factor and the constant factor function, .…”

“…From a theoretical point of view, the sudden approach proposed by Mişicu and Esbensen and the adiabatic model proposed by Ichikawa and co-workers were very successful in reproducing the hindrance phenomenon in several cases [7,9]. In 2019, Cheng and Xu [18] employed 13 different phenomenological nuclear potentials (including the KNS model and 12 widely used proximity potentials) to systematically explore the influence of the adiabatic process on the fusion hindrance phenomenon observed in 16 typical fusion reactions.…”