The 122-14-keV - cascade in Fe57 has been used to detect the precession of the 14-keV state in the hyperfine field produced by a Ni lattice at Fe57 impurity sites. The time-differential perturbed angular-correlation technique was used. The data yield a hyperfine field of -267.52.7 kG at room temperature. The magnitude is in agreement with Mössbauer measurements; the sign is determined here for the first time. The data also yield a half-life of 99.30.5 nsec for the 14-keV state, and an anisotropy coefficient A2=-0.01870.0015 for the 122-14-keV cascade. In addition, the data show the absence of time-dependent perturbations over the experimental time interval of 400 nsec. Based on this, application to the study of critical field fluctuations is discussed. © 1969 The American Physical Society.
