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 revie w considers various devices used for measurement of the volume activity of radon isotopes and their daughters and determination of equilibrium coeffic ients. Such devices can be classified into 8 groups: (i) open or "bare" det ectors, (ii) open chambers, (iii) Rn-222 chambers with an inlet filter, (iv ) advanced Rn-222 radiometers, (v) multipurpose radiometers, (vi) radiomete rs based on a combination of etched track detectors and an electrostatic fi eld, (vii) radiometers based on etched track detectors and activated charco al and (viii) devices for the measurement of radon isotopes and/or radon da ughters 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 modifi cations and are applied widely both in geophysical research and radon dosim etric surveys. At the same time, some of the radiometers are still in the d evelopment phase. CR-39 has become the state-of-the-art etched track detect or for environmental radon. However, due to their ability to work in the op en mode, cheapness, possibility of utilization of spark track counters and/ or smaller measurement error, other types of alpha particle sensitive detec tors such as cellulose nitrate (LR 115) or polycarbonate (Makrofol E) are o ften used for radon measurements in the environment. In the last decade a n umber of papers devoted to development of multipurpose radiometers, theoret ical models which enable calculation of the dosimeter response and investig ation of the permeability of various filters to radon, have been published and are reviewed. (C) 1999 Elsevier Science Ltd. All rights reserved.