A≈80区核高自旋态磁转动研究

A new type of rotation named magnetic rotation of high spinstate has been the subject of attraction for the nuclear structure physicists during the past decade. It becomes one of the interest research objects S.Frauendorf calculated and predicted that the magnetic rotational band is not only expected in the Pb region, mass ~140 and mass ~100 region, but also in mass~80 region. In order to understand this new excitation mode, more experiments are needed. Our purpose of this work is to investigate the high spin state and search for the magnetic rotational band in mass~80 region. High spin states in the nuclei 84Rb, 80Rb and 85Zr were populated using the heavy-ion fusion evaporation reactions. The new level schemes were constructed for the three nuclei respectively. Fifty new γ transitions and forty levels have been added to the previous scheme of 84Rb. Three magnetic rotational bands have been observed in 84Rb from this work. One of the bands was reported by H.Schnare et al. About thirty γ transitions and twenty levels have been identified in addition to the previous work of 80Rb. The negative parity yrast-like band was extended up to spin 22 and the band crossing was observed at a frequency of 0.49MeV. Signature splitting and inversion was observed and discussed with comparison to their isotopes and isotones. In the proposed level scheme of 85zr, thirty-six γ transitions and twenty-five levels were assigned newly. The positive parity yrast band was extended to spin 49/2+. Besides the first band crossing in the yrast band, the second band crossing has been also observed at spin 33/2+. A sequence enhanced M1 transitions built at spin 17/2- is confirmed as a magnetic rotation band. What is more, an experiment on high spin state of 86Y is carried out. The above experimental results can provide the information for further understanding the behavior of high spin states.

利用重离子熔合蒸发反应及在束γ谱学技术研究质量数Ａ＝８０附近小形变核高自旋态的磁转动带及其特征。并且与理论家合作利用倾斜角推转壳模型（ＴＡＣ）进行理论计算对实验结果进行比较和分析解释。磁转动研究是高自旋态研究中极有意义的较新的研究课题，是一种新的激发模式。实验研究磁转动带可以帮助深入理解原子核高自旋态的行为。