论文标题
富含中子的Scandium同位素的精确质量测量可完善$ n = 32 $和$ n = 34 $ shell关闭的演变
Precision mass measurements of neutron-rich scandium isotopes refine the evolution of $N=32$ and $N=34$ shell closures
论文作者
论文摘要
我们报告了在NSCL的Lebit设施和Triumf的Titan设施中执行的$^{50-55} $ SC同位素的高精度质量测量值。我们的结果可大大减少其不确定性，并表明与先前建议的$^{53-55} $ sc的质量值相比，高达0.7 MEV的显着偏差。这项工作的结果为中子数字$ n = 32 $和$ n = 34 $以上的质子 - 魔术$ z = 20 $的新兴封闭壳现象的描述提供了重要更新。特别是，它们最终使沿$ n = 32 $ isotone的基态结合能中的趋势进行完整而精确的表征，证实了经验性的中子壳间隙能量在双重魔术$^{52} $ CA处达到峰值。此外，我们的数据与其他最近的测量结果相结合，不支持$^{55} $ sc中的封闭中子壳的存在，$ n = 34 $。将结果与来自\ emph {ab intio}和现象学核理论的预测进行了比较，这些核理论都成功地描述了$ n = 32 $中子壳体间隙能量，但在描述$ n = 34 $ jisotone的描述中是高度分散的。
We report high-precision mass measurements of $^{50-55}$Sc isotopes performed at the LEBIT facility at NSCL and at the TITAN facility at TRIUMF. Our results provide a substantial reduction of their uncertainties and indicate significant deviations, up to 0.7 MeV, from the previously recommended mass values for $^{53-55}$Sc. The results of this work provide an important update to the description of emerging closed-shell phenomena at neutron numbers $N=32$ and $N=34$ above proton-magic $Z=20$. In particular, they finally enable a complete and precise characterization of the trends in ground state binding energies along the $N=32$ isotone, confirming that the empirical neutron shell gap energies peak at the doubly-magic $^{52}$Ca. Moreover, our data, combined with other recent measurements, does not support the existence of closed neutron shell in $^{55}$Sc at $N=34$. The results were compared to predictions from both \emph{ab initio} and phenomenological nuclear theories, which all had success describing $N=32$ neutron shell gap energies but were highly disparate in the description of the $N=34$ isotone.
