VARIATIONS OF THE TRACK ETCH RATES ALONG THE ALPHA-PARTICLE TRAJECTORIES IN 2 TYPES OF CR-39

The simulation of track formation processes in nuclear etched track de tectors requires a quantitative formulation of registration criteria o n the basis of the ratio of track etch to bulk etch rate. Whereas the bulk etch rate is measurable with sufficient accuracy by means of rela tively simple techniques the track etch rate has been determined up to now indirectly by measuring the track diameters on the detector surfa ce and assuming a constant etch rate along the particle trajectories. In deeper detector layers this assumption is, however, not valid becau se the energy loss strongly increases at the end of the particles rang e. The aim of the studies described was the direct experimental determ ination of the track etch rate as a function of the depth within the d etector as well as the derivation of the relationship between the etch rate and the actual particle energy within the detector.