Suppression of the slow component of scintillation light in BaF2

BaF2 is a common scintillator material used for the detection of gamma radiation due to its relatively high stopping power, radiation hardness and high luminescence. BaF2 is often used in gamma ray timing experiments because of the prompt decay component. It is well known that the light output from BaF2 has two decay components: a prompt one at ò220nm with a decay constant of around 600 ps and a more intense, temperature dependent, slow component at ò300nm with a decay constant around 600 ns which hinders fast timing experiments. We report here the development of a gamma ray detector based on a BaF2 scintillator crystal heated to 220 °C for which the intensity of the slow component is reduced to (1±1)%. The analysis of the temperature dependent intensity using a model including a single thermally activated quenching mechanism is consistent with the slow component arising from a self-trapped exciton with an activation energy E=(0.25±0.01)eV.