Efficient detection and spectrometry of alphas from radon daughters in polycarbonate

Lexan polycarbonate is a major efficient alpha detector in passive radon diffusion chambers used worldwide for indoor radon monitoring. It has an upper detection energy of 1.8 MeV recently extended to 5 MeV using a new single electrochemical etching (ECE) process. However, by applying a process to remove a surface layer to a point close to the Bragg peak, followed by ECE, we have been able to efficiently register even 5.99 and 7.69 MeV alphas from the radon daughters Po 218 and Po 214. A full energy spectrum has also been obtained as reported in this paper. (author)