Title: In-beam $γ-$spectroscopy of the transitional nucleus $^{217}$Ac Show Chinese title

Title: 在束$γ-$光谱学研究过渡核$^{217}$Ac

Abstract: High-spin states in the transitional $^{217}$Ac nucleus are established up to 3.8 MeV excitation energy and $I^{\pi} =$ 41/2$^+$ with the addition of around 20 new transitions. The structure of the yrast and near-yrast states below the 29/2$^+$ isomer is revisited. The inconsistencies in the level schemes reported earlier are resolved. The level structure above the 29/2$^+$ isomer is established for the first time. Large-basis shell-model calculations with the KHPE interaction are performed to compare the experimentally observed level energies with the theoretical predictions. A comparison with the systematics of the N = 128 isotones suggests that the yrast structures result from a weak coupling of the odd proton to the even-even 216Ra core, which is consistent with the shell-model configurations. Furthermore, alpha decay of the 29/2$^+$ isomer is revisited and the decay scheme established from this work is discussed in the framework of the shell model. Show Chinese abstract

Abstract: 高自旋态在过渡性$^{217}$Ac 核素中已建立至3.8 MeV激发能和$I^{\pi} =$ 41/2$^+$，并增加了约20条新的跃迁。 低于 29/2$^+$异构体的急转态和近急转态的结构被重新审视。 早期报告的能级图中的不一致之处得到了解决。 在 29/2$^+$异构体之上的能级结构首次被建立。 使用 KHPE 相互作用的大基组壳模型计算被进行，以将实验观测到的能级能量与理论预测进行比较。 与 N = 128 同中子素的系统学比较表明，急转结构是由于奇质子与偶-偶 216Ra 核芯的弱耦合，这与壳模型构型一致。 此外，对 29/2$^+$异构体的α衰变进行了重新审视，并在此工作中建立的衰变方案在壳模型框架下进行了讨论。