The interpretation of alpha energy spectra from particulate sources

Abstract

This paper examines the possibilities for using alpha energy spectrometry to determine the particle size characteristics of radioactive aerosols. Results are given of Monte Carlo calculations of the energy spectra of spherical and ellipsoidal particles as a function of particle size and orientation. The spectra for log-normal distributions of spherical particles as a function of the mass median diameter, MMD, and the geometric standard deviation, σ g, are also given. The materials considered are (U, Pu)O 2 and (U, Pu)C. Two simple empirical parameters are used to relate peak shape and peak broadening to particle size, shape and orientation. For log-normal distributions, both MMD and σ g are derived uniquely using these two parameters. Experimental alpha spectrometry results on a log-normal distribution of (U, Pu)O 2 particles are compared with the calculations and with inertial spectrometer and optical counter results.