PRODUÇÃO DE DOSÍMETROS TERMOLUMINESCENTES À BASE DE MgB4O7: Dy e MgB4O7:Tm

Abstract

The thermoluminescent dosimetry (TL) is a well-established technique for the detection of ionizing radiation in hospitals, clinics, and industrial establishments where there is the need to quantify the radiation. For this practice is require the use phosphors which are sensitive to radiation. Some phosphors are already commonly used in this practice, for example, TLD-100 (LiF: Mg, Ti), CaSO4:Tm and CaSO4:Dy. A compound that was most recently introduced in dosimetry and has many advantageous features to detect neutrons, electrons and gamma is the magnesium tetraborate (MgB4O7), but the undoped material is not good for dosimetry, since signal does not show satisfactory thermoluminescence. The present work presents the analysis of the compound MgB4O7 when doped with rare earth elements, thulium (Tm) and dysprosium (Dy). The production of MgB4O7: Dy and MgB4O7: Tm occurred under acidic conditions. Following the process of crystal growth, several tests were made on phosphors produced to verify the quality of materials as TL dosimeter. Initially, was made the identification of the crystalline phases found in the material, using the technique of X-ray diffractometry, and then were evaluated and compared the TL emission curves of the crystals with two different types of dopants, to this, the samples were irradiated with different radiation sources: 137Cs (0,66 MeV), 60Co (1.25 MeV) and X-rays (0.41 MeV) and based on the results was evaluated the energy dependence of phosphors. Another characteristic analyzed, was the decay of TL signal for the material (fading). The results show that the material can be an excellent TL dosimeter when doped with rare earth elements Dy and Tm.