N≈Z的 Cu-Sn 核β延发质子衰变研究

基于兰州重离子加速器，通过熔合蒸发反应产生28到50闭壳间N≈Z的丰质子Cu-Sn 核。反应产物反冲出薄靶，经兰州充气谱仪快速分离和传输至焦平面，注入硅盒中的Si微条探测器里。产物经β延发质子衰变到孙子核的激发态，处于激发态的核再退激特征γ射线到基态或激发态。利用气体探测器对注入核进行测量、盒状的Si探测器阵列对注入核和质子进行能量-位置-时间关联测量，应用大型Ge阵列探测对特征γ射线进行单谱测量。气体和Si微条探测器组成的望远镜系统可以粗略鉴别注入核质量数A。注入核-p符合可以挑选出A中具有β延发质子放射性的核。p-γ符合可用来识别目标核，获取可靠的谱学数据：提取母核半衰期、建立衰变纲图等。除了寻找具有β延发质子放射性的先驱核外，N≈Z的Cu-Sn蕴含着丰富的同位旋信息，通过这些核衰变性质的研究对于探索同位旋量子数守恒和破缺以及天体核物理有重要意义。

N≈Z proton-rich Cu-Sn nuclei, which are located between the 28 and 50 shell closures, can be produced by the fusion-evaporation reactions. The reaction prodcuts after recoiling from the thin target are separated by the gas-filled recoil separator in Lanzhou and transported to the focal plane and then implanted into the Si-box detector array. The β-delayed proton decays of the precursors can be detected by two gas multiwire proportional counters, the Si-box detector arrar to perform the energy-position-time correlation measurement of the implanted nuclei and protons, and the large HPGe detector array. The mass number A of implanted nuclei can be decided by the telescopic system consisting of gas and Si detectors. The coincidence measurement for implanted nuclei and protons can select the β-delayed proton precursors from the products with A. Proton-γ fast coincidence may largely reduce the γ background and identify the aimed nuclei. According to the measurements of β-delayed proton decays, we can deduce the half lives of parent nuclei, construct the decay level schemes, and so on. Except for searching for the β-delayed proton precursors，the decay study of the N≈Z Cu-Sn nuclei with rich information of isopin would be helpful to explore isospin conservation and breaking as well as nuclear astrophysics.