Alpha-particle analysis of a triple isotope 239Pu – 241Am – 244Cm source by nuclear track methodology

This work presents a new approach using nuclear track in solids methodology (NTSM) for the energy analysis of alpha-particles. This method is based on the quantitative relationship between the energy deposited in the polycarbonate by the geometrical parameters of the developed track after the chemical etching. We used separated calibrated sources of ²³⁹Pu and ²⁴¹Am, and a mixed source with ²³⁹Pu, ²⁴¹Am and ²⁴⁴Cm. CR-39 polycarbonate manufactured by Landauer Inc.^® was selected as the detector material, because of its excellent response to these energies. The chemical etching was done in two steps: (a) pre-etching to avoid the irregularities on the surface of the material, and (b) chemical etching to develop the track. In both processes the temperature and pH of the solution need to be very controlled. The geometrical characteristics of the formed tracks were analyzed automatically by Digital Image System. The results show a distribution of track diameters as a function of the energies analyzed analogous to the pulses produced on the conventional electronic detection system.