3D computation of the shape of etched tracks in CR-39 for oblique particle incidence and comparison with experimental results

Computation of the shape of etch pits needs to know the varying track etch rate along the particle trajectories. Experiments with alpha particles and 7-Li ions entering CR-39 detectors under different angles showed that this function is not affected by the inclination of the particle trajectory with respect to the normal on the detector surface. Track formation for oblique particle incidence can, therefore, be simulated using the track etch rates determined for perpendicular incidence. 3D computation of the track shape was performed applying a model recently described in literature. A special programm has been written for computing the x, y, z coordinates of points on the etch pit walls. In addition, the etch pit profiles in sagittal sections as well as the contours of the etch pit openings on the detector surface have been determined experimentally. Computed and experimental results were in good agreement confirming the applicability of the 3D computational model in combination with the functions for the depth-dependent track etch rates determined experimentally.