Relationship between track size and energy for alpha particles in CR-39

In an attempt to use CR-39 as alpha spectrometer in radon daughters monitoring, the relationship between track size and energy for alpha particles in the plastic nuclear track detector CR-39 was studied by exposing samples of this detector to alpha particles of different energies (up to 7.7 MeV). For the alpha particles whose azimuthal incidence angle was close to zero a well-defined curve correlating α-energy and the area of the etch-cone openings was obtained. The mean α-energy loss rate (-dE/dx) in CR-39, calculated using Bethe's theory, was observed to be proportional to the track's areas, when α-energy was higher than 2 MeV. Possible applications of these results concerning radon daughters monitoring are discussed. (author)