A METHOD FOR THE PREPARATION OF VERY THIN AND UNIFORM ALPHA-RADIOACTIVE SOURCES

The method is based on the electrodeposition of alpha-emitters as hydr oxides on stainless steel cathodes rotating at constant angular veloci ty. A new electrochemical cell, which has been described elsewhere, wa s designed. This design takes into account the hydrodynamic behaviour of the rotating disc electrode. Electrochemical and physicochemical st udies allowed us to predict the best conditions for each alpha-emitter , in order to obtain very thin and uniform deposits with a minimal cur rent density value. These included determining the dependence of the d eposition yield and uniformity on the cathode rotation speed, solution pH, deposition current density and deposition time. Controlling the o ptimum values of hydrodynamic, electrochemical and physicochemical pro cess conditions then gives reproducible deposition uniformity and yiel ds. The thickness and uniformity of the alpha-sources were characteris ed by high resolution alpha spectroscopy with PIPS detectors. These so urces are specially suitable for spectroscopic, alpha-particle emissio n probabilities and isotopic ratio studies. Using this method values l ess than or equal to 10 keV for the energy resolution and 100 to 1 for the peak to valley ratio have been obtained.