The Pairing Model And Its Application In Well-deformed Nuclei

With the increase of the number of protons and neutrons,the structure of atomic nuclei presents many new and interesting phenomena.The research on the structure of the nuclear physics has been a frontier field.In the present work,the Nilsson mean-field plus the nearest orbit pairing model is used to study the structures and properties of well-deformed nuclei,employing both proton-proton and neutron-neutron pairing interaction.Firstly,the binding energy,even-odd mass difference,and first pairing excitation energies are investigated systematically for well-deformed nuclei,including three isotopic chains of Ba,W,Os and two isotone chains of N = 94,98,and compared with the corresponding experimental values.The results show that this model can reasonably describe these properties.Secondly,the derived formulas of moments of inertia are given for even-even nuclei,and further applied to calculate the moments of inertia for five chains,comparing with the experimental data.The results show that the calculated values are very consistent with the experimental data.In particular,the typical nuclei on each chain are taken as examples,the contributions,from occupying different orbits for the two particle of broken pair,to the moments of inertia are analyzed in detail.Thirdly,we study the case for odd-A nuclei,which is more complicated than even-even nuclei,since odd-A nucleus has an unpaired nucleon.The derived formulas of moments of inertia are given for odd-A nuclei,and further applied to calculate the moments of inertia for four chains,comparing with the experimental data.The results show that,within the error range,the calculated values are consistent with the experimental data.Similarly,the contributions,from occupying different orbits for the two particle of broken pair and a unpaired valence nucleon,to the moments of inertia are analyzed detailedly for odd-A nuclei.Fourthly,the ground-state occupation probabilities of valence nucleon pairs with different angular momentum for even-even nuclei are calculated.The result show that it is much higher for the even angular momenta than the odd angular momenta.Finally,we maker a preliminary analysis of the quantum phase transition for some nuclei.The information entropy and its derivative are calculated,and results show that they are much more sensitive to the variation of the pairing interaction around N = 90,where there maybe exists obvious quantum phase transition.