彭宁离子阱上相位成像离子回旋共振技术的研究

High precision mass data of exotic radionuclides are very important on studying the evolution of nuclear structure, exploring the borders of isotopic existence and understanding the origin, formation and abundance distribution of elements in nuclear astrophysics. For the rare and short-lived nuclides far away from β stability line, methods with much shorter measurement time, much higher mass resolving power and much higher sensitivity are required due to their extremely low production rates and short life times. The Phase-Imaging Ion Cyclotron Resonance (PI-ICR) technique, which is developed in recent years, is a novel approach to satisfy those requirements. The task of this proposal is to realize this new technique in Lanzhou Penning Trap (LPT), study its details and thus significantly improve the precision of mass measurement at LPT. The mass of reference nuclide 133Cs will be measured by using PI-ICR technique, in which a home-made position-sensitive micro-channel plate detector will be used. It will also provide us a good feasibility to study the r-process related neutron-rich isotopes near the neutron drip line.

高精度的奇异放射性核素的质量数据，对研究原子核结构的演化和探索原子核的存在极限，及理解核天体物理中元素的起源、形成以及丰度分布等，有着重要的意义。对于远离β稳定线的稀有及短寿命核素，由于其极低的产额和极短的寿命，要求测量时间更短、分辨本领和灵敏度更高的测量方法。针对这一需求，彭宁离子阱上的相位成像离子回旋共振技术在近年发展起来。本项目拟在兰州彭宁离子阱LPT上实现这一新技术，研究此技术的细节，从而大幅提高LPT质量测量的精度。方案拟利用自行研制的位置灵敏微通道板探测器，采用相位成像离子回旋共振技术，对参考核133Cs的质量进行高精确测量。项目的实施也将为中子滴线附近r过程相关的丰中子核素的研究奠定基础。

在彭宁离子阱上利用相位成像离子回旋共振技术（PI-ICR）对远离β稳定线的稀有及短寿命核素进行精确的质量测量，具有测量时间短、分辨本领和灵敏度高的优点。项目组掌握了表面离子源应用、BNG离子门束流脉冲化、离子阱系统的射频（RF）馈电以及微通道板（MCP）飞行时间探测等与PI-ICR相关的关键技术。离线测试结果表明，探测器的输出幅度为1.1 V、上升时间为10 ns。由于依托单位研究计划的调整，暂未按原方案在彭宁离子阱设备上在线测试探测器，取而代之的是在多反射飞行时间质谱仪（MRTOF-MS）上进行了检测，并且成功地应用到了实验研究中。采用133Cs1+，MRTOF-MS的最大质量分辨本领达到了66000。该项目的研究成果将为重核的精确质量测量及超重核质量数的直接鉴别提供技术支持。