The Ground And Excited States Of Toroidal And Bubble Nuclei

Nuclei as we now know them have sphere-like geometry,but Wheeler suggested that under appropriate conditions the nuclei may exist exotic shape,like toroidal shape.But toroidal nuclei have various instabilities,so whether they are stable or not requires further research.In this thesis,the nuclei with light-mass and intermediate-mass are se-lected as the main research objects.Based on energy density functional theory,the self-consistent energy of nuclei under different conditions is calculated.We first constraint quadrupole moment Q₂₀,then calculate the nuclear Hartree-Fock-Bogoliubov（HFB）en-ergy and cranked Skyrme-Hartree-Fock energy.According to the calculation,when Q₂₀become more negative than a value,we find the nucleus is really a toroidal shape through the output of nuclear density distribution.But the toroidal shape can’t exist stably,if we remove the constraint of Q₂₀,the distribution of nuclear density tends to return to spheri-cal shape.If we carry out the cranking calculations,we are able to locate many high-spin toroidal isomeric sates.Furthermore,it is found that some properties of toroidal nuclei are quite different from those of spherical nuclei.Because toroidal nuclei are in the excited state,they usually store a lot of excitation energy.When they decay to the ground state,they will release enormous energy,which may be used as an energy source in the future.At present,the predicted theoretical value of²⁸Si has been found by colliding²⁸Si on a fixed¹²C target.Therefore,the study of toroidal nuclei is of great practical significance.Bubble nucleus is a kind of nucleus whose density of nuclear matter in the center of nucleus is lower than that in the periphery of the nucleus,and there is still some nuclear matter in the center of the nucleus.At present,it is believed that the reason for this phe-nomenon is the absence of s orbit nucleons or the repulsion effect of Coulomb interaction in the superheavy nucleus region.Current experimental studies on³⁴Si have found that the absence of nucleons in the 2s_1/2orbit leads to the appearance of bubbles in proton den-sity.Bubble nuclei are equivalent to an incomplete toroidal distribution,so the research method is similar to that of toroidal nuclei.It mainly studies the effects of different energy items such as Coulomb,spin-orbit and pairing on the bubble effect.