A STOCHASTIC-MODEL FOR TRANSIENT MAGNETIC-FIELDS AS OBSERVED BY PERTURBED ANGULAR-DISTRIBUTION OF GAMMA-RAYS

A stochastic model is introduced to study the transient magnetic field (TF) experienced by the nuclei of fast ions traversing a ferromagneti c medium. The field is assumed to arise primarily from the bound elect rons of the ion, polarized by the internal magnetic field of the ferro magnetic specimen. Spin-flip scattering is considered to be the domina nt mechanism for polarization transfer from the host to the ion. Elect ron capture and loss mechanisms are also taken into account in a pheno menological manner. An analytical expression is derived for the TF whi ch depends on the electron capture and loss cross-sections. The result for the perturbation factor is shown to be more general than that der ived by Abragam and Pound and reduces to their result in the appropria te limit.