Potassium halide detectors: Novel results and applications

We present a review of novel investigation results related with the thermoluminescent and dosimetric properties of detectors based on potassium halides doped with divalent europium, such as KCl:Eu2+, KBr:Eu2+ and the crystalline series KCl1-xBrx:Eu2+. We investigated both the existent defects in the crystals and those that are generated by radiation and their interaction, trapping and room-temperature recombination mechanisms in thermally stimulated light emission. The spectral response during the recombination stage was obtained through simultaneous measurements of temperature, emitted light intensity and emission wavelength by using an automated thermoluminescence system with optical fiber couplings and a diode array as detection device. In this manner, it was possible to identify the involved defects in the thermoluminescent processes. Finally, since all potassium halide crystals contain the isotope 40K (0.0117%) with a half-life of 1.28 × 109 years, a self-irradiation effect is produced with an equivalent irradiation dose of 4.9 μGy/h. Taking advantage of this self-irradiation effect, we develop a new and simple calibration method for thermoluminescent dosimeters, which has a marginal error of ≈ 2%. The shift in the measurements produced by this error is comparable with the obtained error from other sophisticated and expensive calibration methods. Even more, the self-irradiation phenomenon renders the possibility to make corrections in environmental radiation measurements, for including climatic effects and other external factors.