The TL phenomenon of solids and natural radioactivity enable dating. Traps can keep for a long time excess carriers excited by radiation. For example, there are some kinds of traps in quartz and feldspar, which can keep the excess carriers at room temperature for 100 000 years. During the heating the excess carriers are released. Those which recombine with luminescent centres release their energy as TL emission. Fundamental experiment consists in recording this light versus temperature and its result is called the glow curve. The more radioactive energy means the more carriers captured by traps. In this way, TL is a measure of dose (TL dosimetry) or time of accumulation of the stable natural radioactivity (TL dating).
All problems mentioned above as well as the search for new materials for TL dating implies the necessity of fundamental investigations of the TL mechanism in minerals. The Thermoluminescence Dating Laboratory at Nicholas Copernicus University in Torun was established in 1988. It consists of cooperating laboratories designed to deal with different problems. One of them is sample preparation performed by the Thermoluminescence and Sedimentology Laboratory of the Institute of Geography. The TL and dosimetry problems are solved by the Thermoluminescence and Dating Laboratory in the Institute of Physics.
The Thermoluminescence and Dating Laboratory specialistic equipment consists of high and low temperature TL arrangements. For the basic investigations of TL, the laboratory can carry out the Gobrecht-Hoffman analysis which allows for the study of trap parameters. The multiplex spectroscopy arrangement records the TL emission spectra. The excitation equipment of our laboratory includes an X-ray tube applied for basic research. For dating, a high-power cobalt source installed in the Institute of Chemistry is used. The dosimetric part of our laboratory is equipped with the analyser of natural radioactive contaminations (AZAR-Polon) and multichannel gamma-spectrometer (MCA100-Canberra).
Some of our research involves international collaboration. Of particular importance are our scientific contacts with the Dating Laboratory of the University of Helsinki (Dr Högne Jungner).