Etched track radiometers in radon measurements: a review

Passive radon radiometers, based on alpha particle etched track detectors, are very attractive for the assessment of radon exposure. The present review considers various devices used for measurement of the volume activity of radon isotopes and their daughters and determination of equilibrium coefficients. Such devices can be classified into 8 groups: (i) open or "bare" detectors, (ii) open chambers, (iii) Rn-222 chambers with an inlet filter, (iv) advanced Rn-222 radiometers, (v) multipurpose radiometers, (vi) radiometers based on a combination of etched track detectors and an electrostatic field, (vii) radiometers based on etched track detectors and activated charcoal and (viii) devices for the measurement of radon isotopes and/or radon daughters by means of track parameter measurements. Some of them such as the open detector and the chamber with an inlet filter have a variety of modifications and are applied widely both in geophysical research and radon dosimetric surveys. At the same time, some of the radiometers are still in the development phase. CR-39 has become the state-of-the-art etched track detector for environmental radon. However, due to their ability to work in the open mode, cheapness, possibility of utilization of spark track counters and/or smaller measurement error, other types of alpha particle sensitive detectors such as cellulose nitrate (LR 115) or polycarbonate (Makrofol E) are often used for radon measurements in the environment. In the last decade a number of papers devoted to development of multipurpose radiometers, theoretical models which enable calculation of the dosimeter response and investigation of the permeability of various filters to radon, have been published and are reviewed. (C) 1999 Elsevier Science Ltd. All rights reserved.