2026-08-19 理化学研究所,高エネルギー加速器研究機構
図1 理研とKEKが共同開発した停止低速RI精密質量分析システム（CRISMASS）
＜関連情報＞
- https://www.riken.jp/press/2026/20260819_2/index.html
- https://journals.aps.org/prl/abstract/10.1103/krq1-t8pr
エキゾチックな48−50 Ar同位体の質量測定：ダブルマジック52Caの陽子・中性子相互作用および=32サブシェルの頑健性の探求 Mass Measurements of Exotic 48−50Ar Isotopes: Probing Proton-Neutron Interaction of the Doubly Magic 52Ca and the Robustness of =32 Subshell
C. Y. Fu, W. D. Xian,,, T. Niwase, M. Rosenbusch, M. Wada, A. Scalesi,, V. Somà, J. Lee, H. Ishiyama et al.
Physical Review Letters Published: 6 August, 2026
DOI: https://doi.org/10.1103/krq1-t8p
Abstract
High-precision multireflection time-of-flight mass spectrometry has been applied at BigRIPS-SLOWRI of the Radioactive Isotope Beam Factory (RIBF). The atomic mass of 50Ar was measured for the first time, and the mass value of 49Ar was determined to be 674 keV lower than the one from a previous − TOF measurement, with a precision improved by a factor of 250. The new mass data enable us to determine the empirical proton-neutron interaction strength in the unconventional doubly magic nucleus 52Ca. This strength exhibits a conspicuous variation across shell closures, analogously to what observed in classical doubly magic nuclei. Meanwhile, our measurements support the existence of a weak shell effect at =32 in Ar isotopes. To supplement these experimental findings, theoretical calculations were performed for the isotopes of interest, which, compared with data, illustrate the capacity of ab initio expansion methods to capture key quadrupole correlations in doubly open-shell nuclei via an explicit account of nuclear deformation.
