Introduction

Modern thermoluminescence recording equipment can vary from the very simple to the extremely sophisticated. The nucleus of all the various designs is a light detection system, a sample heater and a temperature control unit but the designs of each of these components are many and varied. Enhanced sophistication in design is introduced if glow-curves below room temperature are required, if there is a need to record emission spectra at different glow-curve temperatures, or if simultaneous thermally stimulated current measurements are to be recorded. Extensive use of computer-controlled apparatus is becoming more and more popular and many research groups develop their own computer-based operating system. With the large numbers of microcomputers commercially available, an experimenter is faced with a wide choice of options. A typical schematic arrangement is shown in figure 9.1.

In the sections that follow, a general description of some of the necessary components for thermoluminescence detection will be given (although the exact details of the apparatus design will depend on the experimenter's individual requirements). In Appendix B, a list is given of the addresses of suppliers of commercial thermoluminescence equipment. Reference to published papers will be limited to those wherein the technique or apparatus described is particularly useful or novel, although the reader may wish to refer to two articles which deal with instrumentation for thermoluminescence in some depth – these are by Manche (1979) and by Julius (1981).

Early history

Soon after J. J. Thomson's discovery of the electron in 1897, Drude (1900) showed that most of the characteristic features of a metal could be understood, at least qualitatively, by supposing that some of the electrons were able to move freely through the metal, and a few years later Lorentz worked out the theory more rigorously on the basis of classical statistical mechanics. The outstanding quantitative success of this Drude – Lorentz theory was the explanation it gave of the Wiedemann – Franz law, the proportionality to absolute temperature T, of the ratio of thermal to electrical conductivity. Moreover the predicted constant of proportionality came out close to the experimental value (though less close in Lorentz's more rigorous calculation). However the theory was quite unable to explain why the free electrons did not make a large contribution to the specific heat and later, when electron spin had been discovered, it was not clear why the free electrons did not contribute a large paramagnetic susceptibility varying as 1/T.

It is just over 50 years ago that Pauli (1927) made a major breakthrough by showing that if the recently discovered Fermi–Dirac statistics were used rather than classical statistics in working out the theory, the difficulty about spin susceptibility essentially disappeared. The calculated paramagnetic susceptibility then became independent of temperature and much feebler, roughly comparable to the experimental value.