Self-attenuation of TL light from LiF—a comparison of different experimental methods

Abstract

Three different experimental methods of determination of TL light attenuation coefficients were compared using a specially prepared set of LiF detectors with different thickness. The three methods were: (1) a two-detector method in which an irradiated detector is covered during readout by another one; (2) a surface irradiation method in which a detector is twice irradiated with alpha particles and read out first with the irradiated side facing the PM and then upside-down; (3) a whole volume irradiation method in which detectors of different thickness are irradiated homogeneously with gamma rays. The two-detector method and the surface irradiation method produced consistent results, while values obtained with the whole volume irradiation method were quite different. In the surface irradiation method it is necessary to take into account the decrease in the distance between the source of light and the PM tube, when the detector is read out with its irradiated side facing the PM, with respect to the opposite position. Also light reflections from the side walls of the heater were found to play a role. The two-detector method produces the most reliable results and should be considered as the reference method. As established using this method, the attenuation factor for the white, opaque LiF : Mg,Ti detectors applied in all reported measurements was found to be μ=1.69±0.05 mm −1 .