摘要
质子滴线外原子核的质子衰变为研究极端同位旋条件下原子核的结构和稳定性提供了关键的谱学手段。首先总结了近年来质子衰变的实验研究现状,简要介绍了产生质子滴线外原子核的主要途径、质子衰变研究的主要实验方法,以及对滴线核质子衰变机制的认识。在此基础上,介绍了最近开展的对^(18)Mg四质子发射现象的实验研究。通过不变质量法,实验上首次观察到超出质子滴线两个中子的新核素^(18)Mg,确定了其基态和2_(1)^(+)态的衰变能量和衰变宽度。实验测得为远离稳定区原子核中N=8壳层能隙的减弱提供了新的证据。对衰变产物的关联分析表明,^(18)Mg基态主要发生连续两步直接双质子衰变过程,经过中间核^(16)Ne的基态衰变到^(14)O。
Proton decay of nuclei beyond the proton dripline provides a key spectroscopic tool to investigate the nuclear structures and nuclear stabilities under extreme isospin conditions.Recent experimental studies on the nuclear proton decay are first summarized,followed by the brief introduction of the major approaches of producing nuclei beyond the proton dripline,the main experimental methods of studying their proton decays,and the understanding of the decay mechanisms of dripline nuclei.On this basis,our recent experimental research on the four-proton decay of^(18)Mg is presented.The new isotope^(18)Mg,which is located two neutrons beyond the proton dripline,has been experimentally observed for the first time by using the invariant mass method.The decay energies and decay widths of the ground and first 2^(+)states in^(18)Mg have been determined.As the measured excitation energy of the 2_(1)^(+)state in^(18)Mg exceeds that in^(20)Mg,this observation provides an argument for the demise of the N=8 shell closure in nuclei far from stability.The observed momentum correlations between the decay products suggest that^(18)Mg^(g.s.)mainly decays by two sequential steps of prompt 2p decay,passing through the ground state of^(16)Ne.
作者
金瑜
倪磊
华辉
李智焕
牛晨阳
吴鸿毅
JIN Yu;NI Lei;HUA Hui;LI Zhihuan;NIU Chenyang;WU Hongyi(School of Physics and State Key Laboratory of Nuclear Physics and Technology,Peking University,Beijing 100871,China)
出处
《原子核物理评论》
CAS
CSCD
北大核心
2023年第3期327-340,共14页
Nuclear Physics Review
基金
国家重点研发计划资助项目(2022YFA1602302,2018YFA0404403)
国家自然科学基金资助项目(12035001)
