[en] The validity of the track formation model proposed by Fleischer, Price and Walker was tested for a sensitive cellulose nitrate track detector using protons, deuterons and α particles. Quantitative data are given on the threshold energies and etchable track lengths of these particles. The same data were also calculated for ³H, ³He, ⁶H, and ⁸He by means of the model of primary radiation density presented in the paper. A simple empirical relation was found for the evolution of the etch ratio along the particle trajectory. (author)