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. BaF, is often used in gamma ray timing experiments because of the prompt decay component. It is well known that the light output from BaF, has two decay components: a prompt one at similar to 220nm with a decay constant of around 600ps and a more intense, temperature dependent, slow component at similar to 300 nm 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 BaF, scintillator crystal heated to 220 degrees 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. (c) 2005 Elsevier B.V. All rights reserved.