Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
RIKEN Nishina Center, Wako, Saitama 351-0198, Japan.
Phys Rev Lett. 2019 Feb 8;122(5):052501. doi: 10.1103/PhysRevLett.122.052501.
One of the most exotic light neutron-rich nuclei currently accessible for experimental study is ^{40}Mg, which lies at the intersection of the nucleon magic number N=28 and the neutron drip line. Low-lying excited states of ^{40}Mg have been studied for the first time following a one-proton removal reaction from ^{41}Al, performed at the Radioactive Isotope Beam Factory of RIKEN Nishina Center with the DALI2 γ-ray array and the ZeroDegree spectrometer. Two γ-ray transitions were observed, suggesting an excitation spectrum that shows unexpected properties as compared to both the systematics along the Z=12, N≥20 Mg isotopes and available state-of-the-art theoretical model predictions. A possible explanation for the observed structure involves weak-binding effects in the low-lying excitation spectrum.
目前可用于实验研究的最奇特的轻丰中子核之一是 ^{40}Mg，它位于核子幻数 N=28 和中子滴线的交点处。首次通过在 RIKEN Nishina 中心的放射性同位素束工厂中进行的从 ^{41}Al 中去除一个质子的反应，对 ^{40}Mg 的低激发态进行了研究，该反应使用了 DALI2 γ射线阵列和 ZeroDegree 谱仪。观察到两个 γ 射线跃迁，表明激发谱与沿 Z=12、N≥20 的 Mg 同位素的系统学以及现有的最先进的理论模型预测相比具有出乎意料的性质。观察到的结构的一种可能解释涉及低激发谱中的弱束缚效应。
