Radioisotope identification using an energy-weighted algorithm with a proof-of-principle radiation portal monitor based on plastic scintillators

In this study, we validated the feasibility of an energy weighted algorithm that highlights a characteristic area including the Compton edge as a single peak in a proof-of-principle radiation portal monitor system with a plastic scintillator measuring 50 × 100 × 5 cm3. We measured the energy weighted spectra with steel shielding and the dynamic movements of the 137Cs and 60Co sources. The results showed that the peak locations of each source could be identified under shielded or dynamic motion conditions, each within a maximum difference of 0.08 MeV. •Energy weighted algorithm evaluated with spectra for 137Cs, 60Co, 226Ra, and 22Na.•Large plastic scintillator employed that measured 50 × 100 × 5 cm3.•Shielded or moving radioactive sources discriminated with energy weighted spectra.•Minimum measurement time for peak detection evaluated.