Practical applications of beta-ray backscattering for thickness measurement of surface layers

Several advantages are characteristic for the measurement of thickness and thickness uniformity of surface layers (oxides, coating, paints, resins etc.) using radioactive techniques. Especially suitable technique is that based on β-ray backscattering. The instruments can be made in portable form, the majority of pure β-ray emitting isotopes can be used without strict protective measures. The measurement depends on the effects of the backscattering agent's thickness, atomic number, on the β-ray energy and on the geometrical arrangement. The measurement and the results are described, and some practical applications are demonstrated. The use of 45Ca or 90Sr + 90Y isotopes for the thickness determination of acrylic dye layer is shown. (R.P.)