Potassium halide detectors: Novel results and applications

We present a review of novel investigation results related with the thermol uminescent and dosimetric properties of detectors based on potassium halide s doped with divalent europium, such as KCl : Eu2+, KBr : Eu2+ and the crys talline series KCl1-xBrx : Eu2+. We investigated both the existent defects in the crystals and those that are generated by radiation and their interac tion, trapping and room-temperature recombination mechanisms in thermally s timulated light emission. The spectral response during the recombination st age was obtained through simultaneous measurements of temperature, emitted light intensity and emission wavelength by using an automated thermolumines cence system,with optical fiber couplings and a diode array as detection de vice. In this manner, it was possible to identify the involved defects in t he thermoluminescent processes. Finally, since all potassium halide crystal s contain the isotope K-40 (0.0117%) with a half-life of 1.28 x 10(9) years , a self-irradiation effect is produced with an equivalent irradiation dose of 4.9 mu Gy/h. Taking advantage of this self-irradiation effect, we devel op a new and simple calibration method for thermoluminescent dosimeters, wh ich has a marginal error of approximate to 2%. The shift in the measurement s produced by this error is comparable with the obtained error from other s ophisticated and expensive calibration methods. Even more, the self-irradia tion phenomenon renders the possibility to make corrections in environmenta l radiation measurements, for including climatic effects and other external factors.