A scintillator assembly including an entrance surface for receiving charged particles into the scintillator assembly, the charged particles including first charged particles at a first energy level and second charged particles at a second energy level. A first scintillator structure configured for receiving the first charged particles and generating a corresponding first signal formed of first photons with a first wavelength of λ1, a second scintillator structure configured for receiving the second charged particles and generating a corresponding second signal of second photons with a second wavelength of λ2, and an emitting surface for egress of a combined signal from the scintillator assembly, the combined signal including the first and second photons, and at least one beam splitter for receiving the combined signal and separating the combined signal to first and second photons.