The natural TL intensity level is given in krad of light emmitted from the sample at a temperature of 250°C. This analysis technique is mainly applied to ordinary chondrite finds from Antarctica and gives an approximate measure for the terrestrial age and thermal/irradiation history of a meteorite.
The induced TL properties of a meteorite sample are characterized by three significant features of the glow curve, the TL sensitivity, normalized to a known standard (Dhajala for unequilibrated meteorites, Kernouve for equilibrated meteorites), the temperature where the TL maximum occurs (peak temperature) and the FWHM (full-width-at-half-mean) value of the peak curve. The measured samples has previosly to be annealed to 500°C to erase present natural TL and then exposed to a 250 mCi 90Sr beta source until the absorbed dose amounts to 2.0 krad.
The induced TL properties are a measure for the metamorphism state of a meteorites and are primarily governed by the amount and structural state of containing feldspar. The induced TL sensitivity is an important parameter for the subtype classification of unequilibrated chondrites.
About 3,500 TL measurements values for approx. 1,750 meteorites are stored in MetBase.
