The increasing of B(M1)/B(E2) occurring at large frequency approaching the second BC crossing can be understood as mainly resulted from the mixing of wave function with the 4 quasiparticle band caused by the band crossing.
Most superdeformed bands are located at the strong-coupling orbits, such as neutron 5/2, [624)9/2. A few superdeformed bands lie on high j orbits, i.e., neutron 3/2, 5/2. Our calculated configuration assignments give a satisfactorily explanation to the general behavior, the anomalous change and the band crossing of superdeformed bands in the A ~ 190 mass region.
Anomalous phenomena of the transition probabilities in ~(161)Lu are investigated. The observed drastic increase in the magnitude of the B(M1)/B(E2) after band crossing is a result of nuclear shape change, both in the β deformation and in the γ deformation.
The work done in recent years on HI 13 tandem accelerator in China Institute of Atomic Energy(CIAE), including anomalous band crossing in odd proton nuclei and superdeformed triaxial band in rare earth rigion, nuclear structure in mass A ≈80 and A ≈130 nuclei and measurement of lifetime of high spin states, are briefly introduced.
The signature-dependence of B(M1)-values and dynamical quadrupole moments Q~(1) and Q~(2) after the band-crossing are investigated by meams of the extended particle-rotor model. The calculated values are in qualitative agreement with the measured data. It was noted that in ~(159)Tm the γ-value is quite different before and after the band-crossing.
Using the particle-number-conserving method,the energies of the bands,the band-crossing frequency,the band interaction strength,the aligned angular momentum and the seniority structure of the CSM wave functions of 182Os have been calculated in the cranked shell model(CSM). In the present calculation,coriolis attenuation has been considered. The result shows that the values of Calculation colucides with the experiments fairly good.
Using Particle-Rotor Model, the energy spectra and electromagnetic transitions ofthe negative-parity yrast states, before and after the band-crossing in odd-A Lu isotopes, areinvestigated and compared with the experimental data. It is noted that before and after theband-crossing the moment of inertia of the core is a smooth function of the total angular mo- mentum I and can be described by the ah formula;
Using a simplified model dealing with s-band configuration, the calculated energy spectrum and the B(M1)/B(E2) ratio are compared with experimental data for the negative-parity yrast band in 167Lu before and after the band-crossing.
The dynamical wavelet spectrum of the profile variations reveals large-scale components in the interval 25-50 km/s that move within the-V sin i to V sin i band for the primary star of the system, Aa1, with a band crossing time of 4h-5h.
Band crossing and hybridization effects on superconductivity are investigated within a weak coupling limit of an extended BCS theory.
Shape changes previously suggested to appear in the ground-state band (gsb) of 156Dy and in the s-band above the first band crossing were not supported by the transition probabilities determined in this work.
In 160Ho, the band crossing in the $\pi$7/2- $\otimes$$\nu$11/2- band has been observed for the first time.
The results in the backbending region are qualitatively discussed in terms of the two-band crossing model.
The band-crossing frequencies are found to depend on the number of spectator particles.
The other band, based on πh11/2 ? υg7/2 configuration, is decoupled in nature and shows a band-crossing at ?ω=0.39 MeV due to alignment of an h11/2 quasineutron pair.
The results are consistent with the band-crossing mechanism wherein the aT and eT bands cross as thecH/aH ratio increases.
The energy levels, B(E2) values and gyromagnetic ratio g of some even-even nuclei have been calculated with a double band scheme of band-crossing. Based on these results, the mechanism of backbending phenomena is analyzed, and the possible criterion to distinguish the effects of shape transition, rotation-alignment and pairing collapse are also discussed.
In this paper a three bands intersection model describing the high spin states ofeven-even nuclei have been proposed. This model has the ability to explain the back-bending behaviour in the plot of the moments of inertia versus the rotational angularvelocity, i.e. ■-ω~2 curve, of some even-even nuclei.
The interaction of the rotational three-band, the superband, the g band and theβ band (or γ band), for even-even Nuclei is discussed. The Hamiltonian matrix is diagonalized after solving the secular equation bywhich the parameters in the matrix elemen s are determined. The three-band spectrafor more than ten nuclei have been calculated. The calculated results are found to bein resonable agreement with experimental data, and some informations of three-bandmixing are obtained.