Angular correlation investigations on radiation damage in palladium after neutron capture

The quadrupole interaction of 111Cd probing nuclei with the electric field gradients (EFG) of point defects have been investigated in the cubic face-centred palladium matrix applying the method of the time-differential perturbed γ-γ angle correlation (DPAC). Low-temperature irradiation (4.6 K) of enriched 110Pd metal with thermal neutrons induces the capture reaction 110Pd(n, γ) and subsequent β-decay, thus leading to the correlated production of the probing nuclei of 111Cd and single point defects which are frozen in localized to the probes. The measurements revealed for a fraction f = 19(1) % of the probing nuclei a discrete distortion with a quadrupole coupling frequence of 86.5 MHz. As to the remaining probes, a weak distortion corresponding to a wide frequency distribution around zero has been observed. Annealing of the discrete probe-induced distortion has been studied by means of isochronous probe tempering. Thus the defect initiating the discrete probe-induced distortion can be regarded to be a vacancy. This has been varified by DPAC - measurement of an irradiated 110Pd monocrystal. (orig.)