Studies of nuclear structure of neutron-rich rare-earth nuclei via detemination of spin and nuclear matrix elements

我们用β-伽马衰变谱方法研究了质量数为150附近的富中子核。对于~(150)Ce，根据伽马-伽马符合关系建立了详细的衰变方案。它包括18个激发能级和54个伽马射线，并提供了比已发表的数据更多的能级结构信息。用延迟符合技术测定了149-150Pr和149Nd激发态的半衰期。其中，首次发现149Pr的87和126keV能级的半衰期分别为4.2(5)ns和1.0(2)ns；150Pr的110keV能级的半衰期大于10 ns，而详细的数据分析正在进行中。这个能级是通过E_1伽马射线发射引起的，它通常表现为短的半衰期，而在邻近的核中没有观察到长的半衰值，因此从核结构的角度来看，结果是有吸引力的。

We have studied neutron-rich rare-earth nuclei around a mass number of 150 by means of beta-gamma decay spectroscopy methods. For 150Ce, a detailed decay scheme was constructed on the basis of gamma-gamma coincidence relations. It includes 18 excited levels and 54 gamma-rays, and gives more information on the level structure than that in the published data. For 149-150Pr and 149Nd, half-lives of excited levels were determined using the delayed coincidence technique. Among them, half-lives of 87- and 126-keV levels in 149Pr were first found to be 4.2(5) and 1.0(2)ns, respectively; The 110-keV level in 150Pr shows a half-life longer than 10ns, while detailed data analysis is now in progress. This level depopulates via E1 gamma-ray emission, which usually shows short half-lives; Long half-life values are not observed in the neighboring nuclei, so that the results are attractive from a view point of nuclear structure.