Triaxial Superdeformed Nuclear State Trs

At high-spin rotation,some nuclei are found to be stable,having a major-to-minor axis ratio of 2:1.In virtue of extra-ordinary deformation,such nuclei are called superdeformed nuclei.The vast majority of known superdeformed nuclei are axial symmetry,where two equal moment of inertial are perpendicular to the third axis(often denoted as symmetry axis).Once the loss of such axial symmetry occurs,a nucleus may exhibit a stable triaxial shape,where the rotational angular momentum may be not only perpendicular to the symmetry axis,but also distributed among the three different axes.Usually the triaxial superdeformed nucleus shows a large quadropole-deformation and a clear triaxial deformation parameter.In this paper,in the framework of Cranked Shell Model,two total routhian surface methods based on the Nilsson potential and Woods-Saxon potential have been carried out to analyze nuclear characteristics of triaxial superdeformation respectively. Mainly we make detailed calculations on the high-spin characteristics with example of an odd-A nucleus ¹⁷³Hf by using the first total routhian surface(TRS)method. Then the influence of rotational frequency and the weakening effect of the paring-gap parameterΔduring shaping its triaxial superdeformed state have been considered in the concrete,furthermore the neutron-shell correction energy shows especially important comparing with other parts among the total routhian energy.Additionally, we make great efforts to make the systematical conclusion that the quadropole deformationε₂ and triaxial deformationγshould be 0.40 and 20°(or 30°) approximately in the Z=72 region.Finally the observed high-j intruder band 1/2⁺[431] of ¹⁰⁷Tc has been studied by another TRS method in the cranked Woods-Saxon potential theoretically.A set of deformation parameters equal to 0.35(quadrupole deformationβ₂),0.02(hexadecapole deformationβ₄)and 16°(triaxial deformationγ).