ETD

Archivio digitale delle tesi discusse presso l'Università di Pisa

Tesi etd-05282014-212857


Tipo di tesi
Tesi di laurea magistrale
Autore
MARINI, ANDREA
URN
etd-05282014-212857
Titolo
Synthesis and characterization of KLBMg glass as a new material for OSL and TL dosimeters
Dipartimento
INGEGNERIA CIVILE E INDUSTRIALE
Corso di studi
INGEGNERIA NUCLEARE
Relatori
relatore Prof. d'Errico, Francesco
relatore Prof.ssa De Sousa Lalic, Susana
relatore Dott.ssa Oliveira, Raquel Aline Pessoa de
relatore Dott. Ciolini, Riccardo
Parole chiave
  • dosimetry
  • optically stimulated luminescence
  • glass
  • KLB
  • KLBMg
Data inizio appello
16/06/2014
Consultabilità
Completa
Riassunto
Nowadays, radiations are employed in a wide range of technological and industrial processes, and also in a large number of medical applications, both for diagnosis and therapeutic purposes. Since exposure may lead to harmful effects, in all of these situations a dosimetric evaluation system must be implemented. Passive solid state dosimeters are widely used for this purpose, namely semiconducting and insulating materials that luminesce under thermal or optical stimulation. The possibility of making dosimeters with different kinds of glasses was studied recently. Among these glasses, lithium potassium borate (KLBMg) exhibited good characteristics, especially for high dose measurements. In the present study, a new formulation of KLBMg, where magnesium oxide is added as a major component of the glass network rather than a dopant, has been synthetized and characterized. Magnesium oxide is known to modify the glass network making it more stable, while reducing ion mobility. The physical characteristics of this glass were investigated with analytic methods. The amorphous structure of the material was confirmed by x-ray diffraction techniques; the glass transition, melting and crystallization temperatures were determined by differential thermal analysis and the mass reduction due to heating was evaluated by thermo-gravimetric analysis. Water adsorption or dilution effects can deteriorate the dosimeters and modify their sensitivity. Therefore, two different tests were performed in order to evaluate the hygroscopicity of the glass exposed to liquid water and moisture. The wavelength of the emitted light was also studied. This work is the first investigation on this material as an OSL dosimeter. The luminescent properties of three different compositions with 0, 5 and 11% molarity of magnesium oxide, respectively, were exanimated. The glow curve, dose response curve, reproducibility and optical bleaching were studied with an OSL reader, pointing out the suitability of this glass for OSL dosimetry. With TL techniques, the photon energy dependence and saturation effects were evaluated, as well as the possibility of enhancing the neutron sensitivity of the dosimeters by producing them with boric acid enriched in 10B.
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