Electron-hole traps and thermoluminescence of the LaCl3:TR single crystals

LaCl3:TR single crystals can be effectively used in thermoluminescence dosimetry of X and gamma radiation. By means of thermoluminescence and thermo-current methods (77-600 K) we have studied the electron and hole traps, thermoluminescence spectra and mechanisms of recombination in LaCl3-TRCl3 crystals after X irradiation or selective photo-excitation. In undoped LaCl3 we have found the hole centres with activation energy E = 0.13 eV (the peak TL at 111 K) which can be attributed to the self-trapped holes (Vk). The glow curves of LaCl3-TR crystals contain high temperature peaks at 460, 575 and 590 K. These peaks may be used as dosimetric ones and can be attributed to the electron excess impurity centres. In LaCl3 doped with TR3+ ions we have observed TL peaks at 117, 142 and 156 K which are associated with holes located in an environment of Pr, Dy and Sm ions respectively (VkA centres). (author)