Preparation of composites of topaz embedded in glass matrix for applications in solid state thermoluminescence dosimetry C.M.S. de Magalh~ aes a , Z.S. Macedo a , M.E.G. Valerio a , A.C. Hernandes b , D.N. Souza c, * a Departamento de F  ısica, Universidade Federal de Sergipe, S~ ao Crist ov~ ao, SE 49100-000, Brazil b Instituto de F  ısica de S~ ao Carlos, Grupo Crescimento de Cristais e Materiais Cer^ amicos, Universidade de S~ ao Paulo, S~ ao Carlos, SP, Brazil c Depto. de Educac ß~ ao, Universidade Federal de Sergipe, CECH, S~ ao Crist ov~ ao, SE 49100-000, Brazil Abstract NaturalcolourlessBraziliantopazwascombinedwithcommercialsilicaglasstoproducecompositesoftopaz–glass for application in dosimetry. The preparation of the composites involved the following steps: (i) the glass and the natural topaz were milled; (ii) the glass and the microcrystals were mixed in specific proportions; (iii) pellets were prepared by uniaxial pressing and (iv) the pellets were sintered to produce the ceramics. Dosimetric performance was tested for c-rays ( 137 Cs and 60 Co), X-rays (6 MV) and b-rays ( 90 Sr/ 90 Y) radiation fields. The topaz–glass composite presentedaTLresponseinalargedoseinterval,reducedsensibilitytovisiblelight,slowfadingoftheTLglowcurves, possibility of successive uses and a simple pre-irradiation annealing at 400 °Cfor1h. Ó 2004 Elsevier B.V. All rights reserved. Keywords: Topaz; Composite; TL 1. Introduction The thermoluminescent (TL) properties of to- paz from different sources have been studied since 1978 [1] and in 1995 we presented the first results about the TL properties of the Brazilian topaz, employed in the present work [2]. Since then, the dosimetric properties of this mineral have been studiedbyourgroupandalsobyotherresearchers [3–9]. In 2001 we presented the first results about the manufactured composites with a mix of topaz and Teflon [3]. Topaz–Teflon composites showed some suitable characteristics as a dosimeter, such as large linearity range of dose response, good homogeneity, acceptable reproducibility and slow fading of the TL glow curves. For high doses, this composite can be used in successive irradiation– reading–annealing cycles without changing their sensibility. However, there is a limitation for the use of topaz–Teflon composite because Teflon volatilizes at temperatures higher than 300 °Cand it was observed in previous works [8,9] that the topaz TL peak used in dosimetry occurs in the * Corresponding author. Tel.: +55-79-212-6636/6725; fax: +55-79-212-6807. E-mail address: dnsouza@fisica.ufs.br (D.N. Souza). 0168-583X/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.nimb.2003.12.064 Nuclear Instruments and Methods in Physics Research B 218 (2004) 277–282 www.elsevier.com/locate/nimb