State-of-the-art instruments for measuring radon/thoron and their progeny in dwellings--a review

Radon and radon progeny measurements are conducted world-wide for the assessment of the radiation dose to workers and the general public. In the last 10 years, a variety of instruments have been developed that utilize different principles of detection for different measurement applications. The various instruments and methods used today depend on whether radon or radon/thoron progeny are being measured, the type of radiation being detected, and also the duration of the measurement. Other important design criteria are applicability, portability, convenience, reliability, and cost considerations. The instruments under consideration use the following detection systems: pulse ionization chambers, electret ionization chambers, scintillation detectors with zinc sulfide ZnS(Ag), alpha particle spectrometers with silicon diodes, surface barrier or diffused junction detectors, registration of nuclear tracks in solid-state materials, and gamma-ray spectometry with NaI(TI) scintillation crystals or germanium lithium (GeLi) semiconductors. Discussed in this paper are the advantages and disadvantages of the various portable instrumentation used for measuring radon, thoron, and their progeny. Also provided is guidance for their application in the field.