γγ Angular correlations perturbed by randomly reorienting hyperfine fields

The stochastic model of Blume for time-dependent hyperfine interactions is extended to randomly reorienting fields on the base of the work of Lynden-Bell. Two limiting cases are considered, the so-called diffusion and the strong collision model. Formulas are given for the perturbation factors of the angular correlation function which are valid for any fluctuation rate. Numerical calculations for the nuclear spinI=5/2 are presented.