The German thoron progeny chamber—Concept and application

Following completion of the project “Generation and characterisation of reference atmospheres of thoron decay products for the calibration of measuring devices for thoron decay products”, the Physikalisch-Technische Bundesanstalt (PTB) now operates a thoron progeny chamber in which 220Rn (thoron), 222Rn and its progenies can be made available under almost all ambient conditions. This allows all measuring systems to be calibrated under realistic climatic conditions with an accuracy unique worldwide.