对丰中子晕核11Li的核电荷均方根半径的实验确定, 特别是其与9Li的半径的差值, 将对各种核模型进行灵敏的检验. 选择锂的合适跃迁, 利用激光光谱技术高精度测量该跃迁的同位素移位, 并扣除精确理论计算的质量移位贡献值, 可以用来确定有关同位素的核电荷均方根半径. 就目前能够提供的实验设备和手段, 对于不稳定锂的同位素8,9Li和短寿命丰中子晕核11Li而言, 这是能够得到与核模型相独立的电荷半径值的唯一可行的方法. 这类实验正在德国重离子研究中心(GSI)和欧洲核子中心的ISOLDE/CERN 上计划实施.描述了锂原子的激光激发共振电离途径和进行锂的同位素移位测量的实验装置, 并讨论了采用这种方法测量到的6,7Li的初步结果及其精度, 以及使用该方法研究不稳定核的灵敏性.
A high-resolution isotope shift measurement of lithium isotopes in a suitable transition, combined with an accurate theoretical evaluation of the mass-shift contribution in the corresponding transition, can be used to determine the root-mean-square nuclear charge radii of these isotopes. For the unstable 8,9Li and the short-lived halo nucleus 11Li, this is the only approach available for obtaining nuclear-model-independent values of the charge radii within the reach of present-day facilities. An experiment of this type is currently underway at GSI and planned for ISOLDE/CERN. The laser spectroscopic scheme and the experimental setup for the isotope shift measurement of lithium isotopes is described. The preliminary results is presented and the accuracy and sensitivity of this method is discussed.
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