Experimental technique to measure thoron generation rate of building material samples using RAD7 detector

• RAD7 is used for the determination of thoron generation rate (emanation).
• The described model takes into account the thoron decay and attenuation.
• The model describes well the experimental results.
• A single point measurement method is offered at a determined sample thickness.

Thoron (220Rn) is the second most abundant radon isotope in our living environment. In some dwellings it is present in significant amount which calls for its identification and remediation. Indoor thoron originates mainly from building materials. In this work we have developed and tested an experimental technique to measure thoron generation rate in building material samples using RAD7 radon-thoron detector. The mathematical model of the measurement technique provides the thoron concentration response of RAD7 as a function of the sample thickness. For experimental validation of the technique an adobe building material sample was selected for measuring the thoron concentration at nineteen different sample thicknesses. Fitting the parameters of the model to the measurement results, both the generation rate and the diffusion length of thoron was estimated. We have also determined the optimal sample thickness for estimating the thoron generation rate from a single measurement.