Effect of Oriented Nuclei on the Competing Modes of α and One-Proton Radioactivities in the Vicinity of Z = 82 Shell Closure

The purpose of the present work is to investigate the alpha (α) emission as competing mode of one proton emission using the preformed cluster decay model (PCM). PCM is based on the quantummechanical tunneling mechanism of penetration of the preformed fragments through a potential barrier, calculated within WKB approximation. To explore the competing aspects of α and one proton radioactivity, we have chosen emitters present immediately above and below the Z = 82 shell closure i.e. 177Tl and 185Bi by taking into account the effects of deformations (β2) and orientations of outgoing nuclei. The minimized values of fragmentation potential and maximized values of preformation probability (P0) for proton and alpha fragment demonstrated the crucial role played by even Z - even N daughter and shell closure effect of Z = 82 daughter, in 177Tl and 185Bi, respectively. The higher values of P0 of the one proton further reveal significance of nuclear structure in the proton radioactivity. From the comparison of proton and α decay, we see that the former is heavily dominating with larger values of P0 in comparison to the later. Theoretically calculated half-lives of one proton and α emission for spherical and deformed considerations have also been compared with available experimental data.

Appearance / Disappearance of Magic Number in Light Nuclei

The shell structure of a nucleus is important to study their observed characteristic features. The classic magic numbers are successful in explaining the nuclear properties for nuclei lying near the stability line. The advent of radioactive ion beam facilities has permitted to examine nuclei in their extreme proton to neutron ratio. The light exotic nuclei were found to exhibit unique shell closure behaviour which is different from the medium mass nuclei near the stability line. The two nucleon separation energy difference systematics was used as a probe to study the magic character of light nuclei. New proton and neutron magic numbers were predicted among the available even Z isotopes and even N isotones. For certain systems, the classic magic numbers were found to be non-magic, while for some systems the magic property is retained even at the drip lines. The shell closure behaviour predicted is found to depend on the version of the mass table.

Enhanced Fission Probability of Even-Z Fragments in the Decay of Hot and Rotating 210Rn* Compound System

Mass and charge distribution of the cross-section for the fission fragments obtained in the decay of hot and rotating compound system formed in the reaction 48Ca + 162Dy → 210Rn* at an incident energy 139.6 MeV has been calculated using the dynamical cluster-decay model. Isotopic composition for each element belonging to the symmetric mass region has been obtained. The shell closure at N=50 for light and at Z=50 for heavy mass binary fragments gives a deep minima in the fragmentation potential at touching configuration and governs the fission partition of the compound system. The fission fragments of the symmetric mass region have their dominating presence along with strong odd-even staggering i.e., even-Z fission fragments are more probable than the odd ones, similar to the observed trends of the yield.

Decay Nature of Radionuclide Released From Triga Mark-II Reactor

Considering a hypothetical accident, the deposition of radio krypton (85Kr) has been studied that is released from TRIGA MARK-II reactor by its decay behavior. The measurement of radiological ground concentration leads to the study of the emission process of 85Kr nucleus, and the site-specific data related to this measurement have been analyzed later on. In this work, the radioactivity in the reactor core and release rate as well as Gaussian diffusion factor have also been considered. It is observed from the data analysis that the maximum concentration of 85Kr in ground is 1.115E+3 Bq/m2 in South (S) direction. Here, the nuclear binary fission has been presented with the greater probability of production of magic nuclei where the reactions found to be endoergic where a nuclear reaction occurs with the absorption of energy. Doubly magic nuclei like 4He, 16O, 40Ca, and 48Ca have also been identified as fission fragments that follow the nuclear shell closure. The results of this work will be an important guide in the study of radionuclide splitting into several nuclei as well as for accidental scinerio. GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 7, Dec 2020 P 57-61

Shape isomerism and magicity in Ni isotopes

A systematic study of shapes in Ni [Formula: see text] isotopes has been made in the Relativistic–Hartree–Bogoliubov (RHB) formalism with two types of density-dependent NN interactions which are based on the range of meson-exchange. The constraint calculations assuming the axial and triaxial-symmetry predict the shape isomerism in the case of [Formula: see text] isotopes. Significant jumps at [Formula: see text] in the binding energy per nucleon (BE/A) and in the [Formula: see text] correspond to the neutron shell closure, and [Formula: see text] as doubly magic nuclei. The present calculation supports the recently reported calculations using the non-relativistic Hartree–Fock (HF) Skyrme SIII [1] interaction predicting the importance of tensor parameter in order to reproduce the experimental findings of the proton level crossing at [Formula: see text]. The results obtained are in agreement with experiment and with other theoretical studies.