Paper TL BEHAVIOR OF TOPAZ-GLASS COMPOSITE IN VARIOUS IRRADIATION FIELDS M. Sardar,* D.N. Souza,† M. Tufail,‡ Linda V.E. Caldas,§ P.L. Antonio,§ and A.B. Carvalho, Jr** AbstractVTopaz is a natural hard silicate mineral that has the potential to be used as a thermoluminescent dosimeter (TLD). It is difficult to manufacture chips of topaz and problematic to use its powder as TLDs. Topaz-glass composite (in the form of pellets) can be made easily and applied for radiation dosimetry. To produce pellets of topaz-glass composite in 2:1 wt (%), topaz powder was combined with commercial glass. The pellets with 6 mm diameter and 1 mm thickness were sintered in a furnace at 900-C for 1 h. The composite pellets were irradiated with x-ray and gamma photons and alpha and beta particles. The pellets yielded two peaks in the glow curve; Peak 1 at temper- ature range 150Y160-C and Peak 2 at 250Y260-C. The intensity of Peak 2 rose linearly with the increase in absorbed dose. The intensity of Peak 2 was comparable with peaks for photons and beta irradiation but relatively low for alpha exposure. The re- producibility of the intensity of Peak 2 was within 5Y8%. Two months after irradiation of the pellets, the fading of the intensity of Peak 2 was found to be about 7%. The topaz-glass composite can be used effectively and efficiently for dosimetry of alpha, beta, and gamma radiation. Health Phys. 105(2):150Y155; 2013 Key words: detector, thermoluminescent; dosimetry; dosimetry, calibration; dosimetry, personnel INTRODUCTION TOPAZ IS a natural silicate mineral with chemical formula Al 2 SiO 4 (F, OH) 2 . It exists worldwide in a variety of colors depending on its geological origin. In Pakistan, topaz is found in the northern parts of the country and in the Himalayas (Anthony et al. 1995). After the discovery of the thermoluminescence (TL) of topaz by Nishita et al. (1974), many researchers have studied the TL features of topaz. Moss and McKlveen (1978) observed that topaz from the Utah Mountains in the United States (US) can be used easily for the measurement of gamma absorbed dose up to 10 5 Gy. Azorin et al. (1982) found a linear response between 10 j2 Y10 3 Gy for topaz. Lima et al. (1986) investigated whether the TL features of topaz from Governador, Minas Gerais, in Brazil were suitable for radiation dosimetry. Souza et al. (1995) found that topaz from Brazil is suitable for dosimetric applica- tions. Souza et al. (2000) concluded that colorless topaz from Minas Gerais in Brazil is a promising material for personal dosimetry in radiotherapy; they also suggested the application of topaz for radiation dosimetry during and after the occurrence of nuclear accidents. The shape, number of peaks, and peak intensities of the TL glow curve depend on the geologic origin of the topaz (Souza et al. 2000); therefore, assessment of the TL features of topaz of a particular origin is necessary. Sardar and Tufail (2011, 2012) worked on the TL properties of topaz from Skardu, Pakistan, and concluded that topaz is a suitable material for dosimetric applications. Topaz, being hard (8 out of 10 on the Mohs scale), requires a cutting tool harder than itself, and it takes a long time to make chips of topaz with precise dimensions. It is relatively easy to make powder of topaz, but its handling for personal dosimetry is not an easy task. An alternative solution is to make a suitable composite and form pellets. The objective of the present study was to investigate the TL behavior of topaz-glass composite in various irra- diation fields. To make the composite, topaz was obtained from the Sabser, Yono, and Nyit mines near Skardu in northern Pakistan, and the glass was obtained from a local market of Sergipe in Brazil. Some TL features of this composite were evaluated after exposure to photons (x-ray and gamma) and particles (beta and alpha). This is the first study to assess the TL features of topaz from Pakistan using glass composite. 150 www.health-physics.com *Pakistan Institute of Engineering and Applied Sciences, Nilore, Islamabad 45650, Pakistan; †Departamento de Fı ´sica, Universidade Federal de Sergipe, Brazil; ‡Riphah International University, Islamabad, Pakistan; §Instituto de Pesquisas Energe ´ticas e Nucleares, IPEN/CNEN, Sa ˜o Paulo, Brazil; **Departamento de Energia Nuclear, Universidade Federal de Pernambuco, Brazil. The authors declare no conflicts of interest. For correspondence contact: M. Sardar, Pakistan Institute of En- gineering and Applied Sciences, Nilore, Islamabad 45650, Pakistan, or email at phd0913@pieas.edu.pk. (Manuscript accepted 12 February 2013) 0017-9078/13/0 Copyright * 2013 Health Physics Society DOI: 10.1097/HP.0b013e31828cf924 Copyright © 2013 Health Physics Society. Unauthorized reproduction of this article is prohibited.