Nonphotographic alpha autoradiography and neutron-induced autoradiography.

With a new combination of two techniques, (i) alpha-particle or fission fragment registration in thin polymer foils by etching and (ii) automatic counting and magnification of the etched perforations by local evaporation of a thin metal layer with an electric spark, the sensitivity of conventional photographic methods for determining quantity and spatial distribution of alpha emitters, fissile materials, and of elements undergoing (n, alpha) reactions can be drastically improved, without need for darkroom processing and microscopic evaluation.