Extracting Neutron-Neutron Interaction Strength and Spatiotemporal Dynamics of Neutron Emission from the Two-Particle Correlation Function

作者：Dawei Si, Sheng Xiao, Z. Qin, Yuhao Qin, Junhuai Xu, Baiting Tian, Boyuan Zhang, Haojie Zhang, Renjie Zou, Dong Guo, Yijie Wang, Xiaobao Wei, Yibo Hao, Zengxiang Wang, Tianren Zhuo, Chun-Wang Ma, Yuansheng Yang, Xianglun Wei, Herun Yang, Peng Ma, Limin Duan, Fangfang Duan, Kang Wang, Jun-Bing Ma, Shiwei Xu, Zhen Bai, Yang Guo, Y. Y. Yang, Zhigang Xiao · 发表于：Physical Review Letters · 年份：2025 · DOI：10.1103/physrevlett.134.222301 · 被引用次数：10 · 研究领域：Nuclear Physics and Applications、Nuclear reactor physics and engineering、Atomic and Subatomic Physics Research

The neutron-neutron ($nn$) correlation function has been measured in $25\text{ }\text{ }\mathrm{MeV}/\mathrm{u}\text{ }^{124}\mathrm{Sn}+^{124}\mathrm{Sn}$ reactions. Using the Lednick\'y-Lyuboshitz approach, the $nn$ scattering length and effective range (${f}_{0}^{nn}$, ${d}_{0}^{nn}$), as well as the reduced space-time size ${R}^{(0)}$ of the neutron emission source are simultaneously extracted as (${18.9}_{\ensuremath{-}1.2}^{+1.3}\text{ }\text{ }\mathrm{fm}$, ${1.9}_{\ensuremath{-}1.0}^{+1.3}\text{ }\text{ }\mathrm{fm}$) and $4.12\ifmmode\pm\else\textpm\fi{}0.12\text{ }\text{ }\mathrm{fm}$, respectively. The measured $nn$ scattering length is consistent with the results obtained in the low-energy scattering $^{2}\mathrm{H}({\ensuremath{\pi}}^{\ensuremath{-}},\ensuremath{\gamma})2n$, indicating heavy-ion collisions can serve as an effective approach for measuring $nn$ interactions and further investigating the charge symmetry breaking of nuclear force. The space-time size extracted from momentum-gated correlation functions exhibits clear dependence on the pair momentum, with ${R}^{(0)}=2.8\ifmmode\pm\else\textpm\fi{}0.1\text{ }\text{ }\mathrm{fm}$ and $4.9\ifmmode\pm\else\textpm\fi{}0.2\text{ }\text{ }\mathrm{fm}$ being determined for the high and low momentum neutrons, respectively.