A method for the preparation of very thin and uniform alpha-radioactive sources

The method is based on the electrodeposition of alpha-emitters as hydroxides on stainless steel cathodes rotating at constant angular velocity. A new electrochemical cell, which has been described elsewhere, was designed. This design takes into account the hydrodynamic behaviour of the rotating disc electrode. Electrochemical and physicochemical studies allowed us to predict the best conditions for each alpha-emitter, in order to obtain very thin and uniform deposits with a minimal current density value. These included determining the dependence of the deposition yield and uniformity on the cathode rotation speed, solution pH, deposition current density and deposition time. Controlling the optimum values of hydrodynamic, electrochemical and physicochemical process conditions then gives reproducible deposition uniformity and yields. The thickness and uniformity of the alpha-sources were characterised by high resolution alpha spectroscopy with PIPS detectors. These sources are specially suitable for spectroscopic, alpha-particle emission probabilities and isotopic ratio studies. Using this method values less than or equal to 10 keV for the energy resolution and 100 to 1 for the peak to valley ratio have been obtained.