THERMAL QUENCHING OF LUMINESCENCE IN 6 THERMOLUMINESCENT DOSIMETRY PHOSPHORS .I.

The role played by the thermal quenching of luminiscence in thermoluminescent (TL) dosimeters has not been investigated previously. If thermal quenching is operative in the temperature region of the glow-peak, changes in heating rate which cause the temperature position of the peak to change would result in non-constant light sums. The direct measure of the TL light sum or the glow-peak height as a function of heating rate is technically difficult. The main problem is that the phosphor temperature tends to lag behind the heating-planchet temperature by an amount which is a function of the heating rate and the degree of thermal coupling. Thus a thermocouple attached to the planchet provides an erroneous measure of the phosphor temperature. Initially (Part I of this paper) this problem was side-stepped by studying the thermal quenching of the X-ray-excited radioluminescence under static thermal conditions. Because of the observed similarity of these emission spectra to the corresponding thermoluminescence spectra, the emitting centers involved in both processes are probably the same for each phosphor studied. The resulting curves of brightness vs. temperature were found generally to exhibit large discontinuities in the vicinity of the TL glow-peak temperatures, and were therefore difficult to interpret in terms of quenching of thermoluminescence. For this reason, the measurements of Part II of this paper were undertaken. © 1969.