Revisit to the yield ratio of triton and $^3$He as an indicator of neutron-rich neck emission

• DOI: 10.48550/arxiv.2311.07095
• Publication Date: 2023-01-01
• Authors: Wang, Yijie; Wan, Mengting; Diao, Xinyue; Xiao, Sheng; Qin, Yuhao; Qin, Zhi; Guo, Dong; Si, Dawei; Zhang, Boyuan; Tian, Baiting; Guan, Fenhai; Wu, Qianghua; Wei, Xianglun; Yang, Herun; Ma, Peng; Hu, Rongjiang; Duan, Limin; Duan, Fangfang; Ma, Junbing; Xu, Shiwei; Hu, Qiang; Bai, Zhen; Yang, Yanyun; Wang, Jiansong; Liu, Wenbo; Su, Wanqing; Wei, Xiaobao; Ma, Chunwang; Li, Xinxiang; Wang, Hongwei; Zhang, Yingxun; Warda, Michał; Dobrowolski, Arthur; Nerlo-Pomorska, B...; Pomorski, Krzysztof; Ou, Li; Xiao, Zhigang
• Keywords: Nuclear Theory (nucl-th); Nuclear Theory; FOS: Physical sciences; Nuclear Experiment (nucl-ex); 7. Clean energy; Nuclear Experiment

The neutron rich neck zone created in heavy ion reaction is experimentally probed by the production of the $A=3$ isobars. The energy spectra and angular distributions of triton and $^3$He are measured with the CSHINE detector in $^{86}$Kr +$^{208}$Pb reactions at 25 MeV/u. While the energy spectrum of $^{3}$He is harder than that of triton, known as "$^{3}$He-puzzle", the yield ratio $R({\rm t/^3He})$ presents a robust rising trend with the polar angle in laboratory. Using the fission fragments to reconstruct the fission plane, the enhancement of out-plane $R({\rm t/^3He})$ is confirmed in comparison to the in-plane ratios. Transport model simulations reproduce qualitatively the experimental trends, but the quantitative agreement is not achieved. The results demonstrate that a neutron rich neck zone is formed in the reactions. Further studies are called for to understand the clustering and the isospin dynamics related to neck formation.