丰中子镁同位素的四极关联特性研究

An Investigation of Quadrupole Collectivity in Neutron-rich Magnesium Isotopes

基于改进的包含同位旋相关项的Nilsson势,使用投影壳模型,对镁同位素低激发谱所反映的四极关联特性进行了讨论。首先研究了单粒子能在反转岛附近的演化情况,集中比较了同位旋相关项的Nilsson势及标准Nilsson势的差异,指出同位旋相关项能够用来描述反转岛核素结构的原因。通过分析实验及计算得到的能谱,发现镁同位素的集体运动特征随着中子数的增加在不断地增强。也计算了晕带中的电四极跃迁几率,指出组态混合在晕带中所起的效应,进一步阐述了反转岛附近的丰中子镁有很好的转子特征。还分析了质子组态及中子组态对g因子的分别贡献,并与现有实验数据进行了比较,挖掘了低激发态的组态信息。

Collective phenomenon in magnesium isotopes is an interesting topic. In order to optimize the description of magnesium isotopes located around the ＂island of inversion＂, we use an isospin-dependent Nilsson potential to define the deformed basis for our projected shell model calculations. Single particle energies in nuclei around ＂island of inversion＂ are calculated and discussed, so as to clarify the effect of isospin-dependence.The low-lying spectra are further investigated, which reflect a clear behavior of quadrupole collectivity in the neutron-rich magnesium isotopes. Electric quadrupole transition properties are also studied. Configuration mixing mechanism of projected shell model has an important influence on these transition properties. From this analysis, we also learn the signal of rotational behavior. Gyromagnetic factors of magnesium isotopes are also calculated. Different contributions from neutron configurations and proton configurations are given separately.