Formation and growth of tracks in nuclear track materials

This paper reviews some aspects of solid-state nuclear track detectors (SSNTDs) and their applications in the radon and other research fields. Several geometrical models for the track growth given in the literature are described and compared. It is found that different models give close results for the dimensions of track openings. One of the main parameters that govern track formation is the bulk etch rate Vb. Dependences of Vb on different parameters such as the preparation procedures, etching conditions, irradiation before etching, etc. are examined. A review of existing methods for determination of the bulk etch rate and track etch rate Vt is also given. Examples of Vt functions for some detectors are presented. Some unsolved questions related to Vt and some contradictory experimental results published in the literature are also summarized in the paper. Applications of SSNTDs for radon and progeny measurements are discussed. New designs of diffusion chambers that have appeared in the last few years are portrayed. A review of analytical and Monte Carlo methods for the calculation of the calibration factors in radon measurements is presented. Particular attention has been given to methods of long-term passive measurements of radon progeny with SSNTDs. These measurements are rather difficult and there is not yet a widely accepted solution. One possible solution based on the LR 115 SSNTD is outlined here. Methods for retrospective radon measurements are also described. Various applications of SSNTDs in other fields of physics and other sciences are briefly reviewed at the end of the paper