Scattering and self-absorption corrections in the measurement of α-particle emitters in 2π geometry

Accurate measurements of alpha-particle emitting sources with 2pi detectors require corrections due to scattering and self-absorption of alpha-particles from the source and from the backing material. We applied the Monte Carlo computer code SRIM, developed to simulate the transport of ions in matter, to the study of these corrections in the most general case, i.e. to the measurement of alpha-particle emitters with low specific activity, where the self-absorption effect in the source is considerable. The values of the ratio C-2pi/N-0 (counting rate divided by disintegration rate) were calculated for sources of uranium dioxide containing a mixture of U-235 and U-234 mounted on a platinum backing, with a wide range of source thicknesses from 0.0 to 1.1 mg/cm(2). The calculated ratios were in agreement with the available experimental data. The work shows that Monte Carlo simulation of the transport of ions by means of the code SRIM can be a very useful tool to evaluate the corrections needed in the measurement of alpha-particle sources with 2pi detectors. (C) 2003 Elsevier B.V. All rights reserved.