Projected Shell Model Desecription Of The Triaxial Deformation In The Nucleus Xe Of A-130 Mass Region

The status of study of triaxial deformed nucleus and related current interest are introduced. More comprehensive understandings for the nuclear shape with developments of experimental technology and theoretical model.Now, many interesting nuclear structure problem are related to triaxial deformation, for example, triaxial superdeformed band, chiral doublet bands, wobbling band, moreover, triaxial deformation may play an important role in the superheavy nuclear structure.Theories describing nuclear spectrum, such as cranking shell model（CSM） and conventional shell model（SM） and their merits and demerits are discussed. It is emphasized that the finding of more perfect theoretical model is necessary to describe triaxial deformation more reasonably and precisely.In this paper, we used the triaxial projected shell model（TPSM）, which have overcome the di-sadvantages of CSM and SM, and is a fully quantum theory, describing the highly rotating nuc-lei is a quantum-mechanical one, while the CSM is semi-classical. For example, In the framewo-rk of the CSM, the angular momentum is no longer a good quantum number, and therefore the c-alculated results can not be directly compared with the experimental data. In addition, in this mo-del the assumptions about the nucleus rotating around the fixed axis is not comprehensive. Espe-cially in the study of triaxial deformed nuclei, the nucleus as a quantum system, its rotational ali-gnment is very complicated, it can not be defined an fixed axis for such a nucleus. While SM us-ed the spherical basis. In principle, all the nuclear physics problems can be solved using it, but t-his model is effective treatment for light nuclei, and for heavy deformed nuclei becomes powerl-ess. In contrast, the projected shell model（PSM） is a fully quantum theory. This model uses the intrinsic symmetry breaking base, and then recover the symmetry with the projection method, the advantage is truncated configuration space is very effective. This model not only can simplify co-mplex issues, but also with the experimental values are compared directly, and has been widely used. After the introduction of triaxial deformation, projected shell model will be developed into triaxial projected shell model.We have applied the TPSM to the calculations of the nuclei in A₁30 mass region,systemat-ically studied the rotational band structure of even-even Xe isotopes with the neutron number fr-om 68 to 74. When g take 290,we not only reproduce the experimental ground band and itsg band, but also the configuration mixing calculation reproduce the Yrast band. According to the characteristics of the nuclei in A-130 mass region, we also analyzed the yrast band structure of th-e Xe isotopes, showing that two neutrons in h11/2 orbital break first than two protons.Some possible applications of TPSM are discussed and prospected by the end of this thesis.