By using the ordering alloy Cu₃Au and measuring resistivity changes during and following fast-neutron irradiations under well-controlled conditions in the Radiation Effects Facility at the Intense Pulsed Neutron Source at Argonne National Laboratory, we have studied cascade defect production and irradiation enhanced diffusion between 10 and 460 K. Ordering and disordering rates were measured as functions of irradiation temperature, neutron dose, neutron dose rate, time following cessation of flux, and step annealing. Free and clustered vacancy production was observed. The temperature dependence of the production of total migrating vacancy concentrations was determined. Vacancy sink production was linear with neutron dose and is compared with recent transmission electron microscopy experiments on the production of dislocation loops in this alloy. Time dependent and quasi-steady state vacancy concentrations were measured and compared with solutions of reaction rate equations for irradiation enhanced diffusion. The influence of recombination of vacancies with interstitials is observed at low sink concentrations (low neutron doses).