Influence of radiation damage on perturbed angular distributions: The PoPb system

Perturbed angular distribution measurements in a Pb target have been performed for the Po206,208,210(8+) and Po209(17/2-) isomeric levels. Target temperatures were varied from 80 to 575 K and magnetic fields were applied from 0.1 to 6.1 T. The data can be explained with a combined strong magnetic and weak quadrupole interaction, with the quadrupole interaction arising from radiation damage in the host correlated in position with the implanted ion. A perturbation theory treatment of the combined magnetic and quadrupole interaction was developed and provides the basis for the interpretation of the results. The data are consistent with a Lorentzian distribution of electric field gradients centered around zero with half width 2=0.9×1017 V/cm2 at room temperature. At higher temperatures the gradients are weaker indicating that before the measurement begins at 10-8 sec after the implantation, some annealing of the initial damage takes place. NUCLEAR REACTIONS Pb204,206,207,208(±,2n)Po*206,208,209,210, E=24-25.5 MeV. Enriched targets measured (E; ,H,t,T) for isomeric levels. Deduced electric field gradients from radiation damage.