Angular Momentum Projection Of The Nilsson Mean-field Plus Nearest-orbit Pairing Model For Descripting ^18,22Ne

In this thesis,the angular momentum projection for the Nilsson mean-field plus the nearest orbit pairing model is applied to describe low-lying spectra and electromagnetic properties of ^18,22Ne.Since the angular momentum of the model is not a good quantum number due to the deformation,the angular momentum projection is used to project the deformed model into a subspace with definite angular momenta to restore its rotational invariance.Both the exact and approximate angular momentum projection scheme are studied,in which the approximate angular momentum projection scheme is realized within a truncated subspace,so it requires less numerical work.Through the analysis of the two schemes applied to the model with two valence particles in the ds shell,it is observed that the ordering of the low-lying levels obtained from these two projection schemes are almost the same when the model parameter reaches a certain value.Hence,these two projection schemes are applied to describe low excitation spectrum,the electric quadrupole moment and B?E2?values for ¹8?Ne?,while only the approximate projection scheme is applied to describe ²²Ne.In comparing the model results of these two nuclei with the corresponding experimental data,it is shown that the fitting qualities of the two projection schemes for ¹⁸Ne are almost the same,and the experimental data of ²²Ne can be well reproduced by the model after the approximate angular momentum projection.Therefore,it is shown that the angular momentum projection of the model describes low-lying properties of these nuclei well.