Dosimetry in the high-dose- and high-temperature-range using LIF colour centres

Ionising radiation produces not only thermoluminescence(TL) in alkalihalogenides, but also colour centres and colloids. Those can be measured quantitatively at higher dose levels using absorption and fluorescence spectroscopy. Optical grade LiF crystals can be used for dosimetry in the range from 102 to 107 Gy. A coefficient of variation of 5% was reached in the whole dose range for reproducibility. Due to the high thermal stability of the centres the application is possible at levels of irradiation temperatures up to 250 C, too. Information about the irradiation temperature can be gained from the shape of the spectra. Another advantage in comparison to other high-dose-measurement-systems is the documentary character of the dose information, which is stable even for long storage times. A problem is still the relative high interspecimen scattering, which has to be corrected by individual calibration. Possible applications are the dosimetry in nuclear deposits, in-core dosimetry in the reactor, at accelerators and other fields, where high temperatures and high dose rates are found. (orig.)