<gamma> - <gamma> Perturbed Angular Correlation Study of dense Kondo effect.

利用微扰角相关技术，研究了ce4f电子在具有致密近藤效应的Ce化合物中的自旋涨落。摄动角相关可以提供有关Ce自旋动力学的信息，而不受非弹性中子衍射和核磁共振的限制。通过将两个具有1 1/2”NaI（Tl）闪烁体和RCA 8575光电倍增管的探测器替换为两个具有2”闪烁体和Phillips XP-2020光电倍增管的探测器，对用于时间差测量的四个探测器系统进行了改造，使所有四个探测器都相同。为了提高仪器的精度、稳定性、效率和时间分辨率，设计了一套计算机控制接口和新设计的双通道数字脉冲光分析仪。除了对（La-Ce）Si体系和(La-Ce) <Al_2>体系进行补充测量外，还对(La-Ce) <Ni_2>体系进行了摄动角相关测量。（La-Ce） <Ni_2>化合物在整个组成范围和温度范围内波动较大，具有较高的近藤温度。在多轨道安德森模型的基础上，分析了由角相关衰减因子得到的相关时间。在考虑晶体场分裂的情况下，推导出了与高温下的微扰理论和OK时的Hnzawa-Yamada理论相一致的插值公式。将实验数据拟合到计算<T_K>的插值公式中。得到的<T_K>值大大低于其他方法计算的值。近藤系统单重态基态的超精细耦合常数可能是这种差异的来源，这是一个有趣的未来问题。

By means of perturbed angular correlation technique, spin fluctuations of Ce 4f electrons have been studied in Ce compounds which exhibit dense Kondo effect. Perturbed angular correlations can afford information about Ce spin dynamics without limitations encountered in inelastic neutron diffraction and NMR.The four detector system for time differential measurements have been remodeled by replacing two detectors with 1 1/2" NaI(Tl) scintillaters and RCA 8575 photomultipliers by two with 2" scintillaters and Phillips XP-2020 photomultipliers so that all four detectors are the same. An interface for computer control of the whole system and newly designed two channel digital pulse hight analysers were assembled to improve accuracy, stability, efficiency and time resolution of the apparatus.In addition to supplementary measurements on (La-Ce)Si system and (La-Ce) <Al_2> system, perturbed angular correlations were measured on (La-Ce) <Ni_2> system. Having pronounced fluctuations in the whole composition range and the temperature range, the (La-Ce) <Ni_2> compounds were found to have relatively high Kondo temperatures. The correlation time obtained from the attenuation facors of angular correlations were analysed on the basis of multiorbital Anderson model. An interpolation formula consistent with the perturbation theory at high temperatures and with the Hnzawa-Yamada theory at OK was deduced taking into account of crystalline field splitting. The experimental data were fitted to the interpolation formula for the evaluation of <T_K> . The obtained <T_K> values are substantially lower than those evaluated by other methods. The hyperfine coupling constant in the singlet ground state of Kondo system which is a possible origin of the discrepancy is an interesting future problem.