Disturbance of the gamma angular distribution by correlated radiation damage after nuclear reactions in lead and silver

The effect of electric field gradients on the disturbed γ angular distribution after nuclear reactions was investigated using a time differential method in an external magnetic field. Isomeric states of the nuclei 210Po, 109Cd and 113Sn have been used as probes. Measurements in the temperature range from 100 K to close under the melting point of the respective metal have been performed. A temperature-dependent damping of the modulation amplitude prior to the beginning of the observation time was found in all three probes. This damping increases at decreasing temperature and has the following values at 100 K : lead 50%; silver, 70% and 60% respectively. In the systems 210PoPb and 109CdAg, there is during the observation time also a slow damping of the modulation amplitude, which also increases at decreasing temperature. Both effects are discussed with respect to radiation damage in metal correlated to the probe. For that purpose, the dynamic and the static perturbation interaction are compared. It is shown that the static model alone yields a consistent description of the results of the measurement. (orig.)