首次通过$^{92}$Rb的$\beta^-$衰变至$^{92}$Sr在远离稳定线核中观测到矮偶极共振的精细结构
First observation of the fine structure of the Pygmy Dipole Resonance in a nucleus away from stability via the $β^-$ decay of $^{92}$Rb to $^{92}$Sr
- University of Liverpool（利物浦大学）
- Simon Fraser University（西蒙菲莎大学）
- University of York（约克大学）
- University of Jyväskylä（于韦斯屈莱大学）
- International Centre for Advanced Training and Research in Physics (CIFRA)（国际高级培训与物理研究中心）
- Helmholtz Zentrum Hereon（亥姆霍兹海雷恩中心）
- CERN（欧洲核子研究组织）
- TRIUMF（特利安夫实验室）
- University of Guelph（圭尔夫大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
通过$^{92}$Rb的$\beta^-$衰变研究$^{92}$Sr，首次观测到远离稳定线核中矮偶极共振的精细结构，并利用壳模型与多重对易子模型解释了能级依赖的log~$ft$值。
AI中文摘要：
在TRIUMF的放射性离子束设施ISAC上，利用GRIFFIN谱仪对通过$^{92}$Rb（$J^{\pi}=0^-$，$Q_{\beta}=8095(6)$~keV）的$\beta^-$衰变布居的$^{92}$Sr激发态进行了全面的$\gamma$射线谱学研究。GRIFFIN谱仪的高$\gamma$射线效率与产生的强铷束流相结合，使得864条$\gamma$射线跃迁被置于能级纲图中，共布居190个激发能级，其中大多数为首次识别。$^{92}$Sr中低自旋态的激发能在大规模壳模型计算下直至5~MeV范围内均得到很好重现。$\beta$衰变布居强度与近期采用模块化总吸收谱学的研究结果高度一致，表明Pandemonium效应受到显著抑制。实验图像以前所未有的细节揭示了log~$ft$值的能级依赖性。这些log~$ft$值被多重对易子模型计算很好地重现，该模型识别了激发态波函数中使得低有效Q值下高激发能级得以布居的特征，这些能级属于矮偶极共振。
英文摘要：
A comprehensive $γ$-ray spectroscopy study of excited states in $^{92}$Sr populated via $β^-$ decay of $^{92}$Rb ($J^π=0^-$, $Q_β=8095(6)$~keV) was performed with the GRIFFIN spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high $γ$-ray efficiency of the GRIFFIN spectrometer combined with the intense rubidium beams produced allowed for 864 $γ$-ray transitions to be placed in the level scheme with 190 excited levels populated, most of them identified for the first time. The excitation energies of low-spin states in $^{92}$Sr are well reproduced by large-scale Shell Model calculations up to 5~MeV. The $β$-feeding intensities are in very good agreement with results from a recent study employing Modular Total Absorption Spectroscopy, indicating a significant suppression of the Pandemonium effect. The experimental picture reveals the energy level dependence of log~$ft$ values in unprecedented detail. These log~$ft$ values are well reproduced by Multiple-Commutator Model calculations that identify the features in the excited levels' wavefunctions that enable the population of high-lying levels with a low effective Q-value that belong to the Pygmy Dipole Resonance.
