Evaluation of wavelength shifters for spectral separation of barium fluoride emissions

Abstract

Application of the barium fluoride (BaF2) scintillator for characterization of intense radiation fields has been pursued since the fast component was discovered in the early 1980's. Unfortunately, ~ 80% of the scintillator emissions have a slow ~ 600 ns decay time constant. The long decay time hampers the use of BaF2 at high count rates because the slow emissions appear as an afterglow which has an intensity that varies with the interaction rate in the crystal. The temporal separation of BaF2 emissions by spectral separation using wavelength shifting techniques has been explored in this work. Of the wavelength shifting techniques that were examined, the solvent excitation technique showed the greatest potential, but was insufficient by itself to suppress the slow emissions to the desired degree. All the wavelength shifting techniques yield an enhanced ratio of fast to slow photons, but a decreased fast photoelectron yield.