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

Three different experimental methods of determination of TL light attenuati on coefficients were compared using a specially prepared set of LiF detecto rs with different thickness. The three methods were: (1) a two-detector met hod in which an irradiated detector is covered during readout by another on e; (2) a surface irradiation method in which a detector is twice irradiated with alpha particles and read out first with the irradiated side facing th e PM and then upside-down; (3) a whole volume it-radiation method in which detectors of different thickness are irradiated homogeneously with gamma ra ys. The two-detector method and the surface irradiation method produced con sistent results, while values obtained with the whole volume irradiation me thod were quite different. In the surface irradiation method it is necessar y to take into account the decrease in the distance between the source of l ight and the PM tube, when the detector is read out with its irradiated sid e facing the PM, with respect to the opposite position. Also light reflecti ons from the side walls of the heater were found to play a role. The two-de tector method produces the most reliable results and should be considered a s the reference method. As established using this method, the attenuation f actor for the white, opaque LiF: Mg,Ti detectors applied in all reported me asurements was found to be mu = 1.69 +/- 0.05 mm(-1). (C) 2001 Elsevier Sci ence Ltd. All rights reserved.