Relative thermoluminescent efficiency of LiF:Cu,Mg,P to alpha particles: Theory and experiment

The relative thermoluminescent response of LiF:Cu,Mg,P to 4 MeV alpha particles has been calculated theoretically using the convolution of the radial dose around the alpha particle track with the gamma generated TL dose response function, with the result η (αγ) = 0.04 ± 0.01. Experimentally, the alpha particle generated TL signal was measured with the irradiated side both facing and away from the photomultiplier in order to measure TL light self-absorption with the result μd = 1.32 ± 0.03 (1 SD), and η(αγ) = 0.065 ± 0.01 in reasonable agreement with theory and previous measurements of the fast neutron relative TL response. The very low sensitivity of LiF:Cu,Mg,P to high LET particles is a microdosimetric effect arising from the very rapid saturation of the TL signal at high ionisation density.