Variation of the track etch rate along the trajectories of light ions in CR-39

The track etch rate has been found to be described by a generalised function of the restricted energy loss in good approximation along the trajectories of protons, deuterons and alpha particles. Extending the studies to tracks of Li-7, B-11 and C-12 ions, curves for the track etch rates as a function of the depth within the detector were obtained the shape of which is like that of the Bragg curve in principle, In detail, however, systematic deviations from a unique correlation of the track etch rate with the restricted energy loss are observed which are more distinct the heavier the ion and the lower its initial energy, This effect is explained by a gradual increase of the track etch rate to the value expected at a given restricted energy loss. At the beginning of the etching process the track etch rate is, therefore, lower than the value observed for larger depths when the same restricted energy loss is presumed. (C) 2002 Published by Elsevier Science Ltd.