Manufacturing polycrystalline pellets of natural quartz for applications in thermoluminescence dosimetry

Abstract

This paper describes the manufacturing process of quartz-pellets and shows their potential use as thermoluminescence dosimeters (TLD) for those applications where low-levels of ionising radiation are present. Two batches of cold-pressed pellets were produced and their resistance were evaluated by vibration tests and weight-loss measurements. The batch manufactured with 75 × 150 µm particles showed enough resistance to be employed as TLD. The dosimetric properties of the 310 °C peak appearing in the glow curves of these pellets were characterized together with commercial TLD-100 units using γ-and X-ray beams with different energies. The uncertainties related to reproducibility and stability of the TL signal were better than 10%. The sensitivity and the linearity of the TL response of quartz-pellets were better than that measured for TLD-100 for doses ranging from 0.5 to 200 mGy. The energy dependence of the quartz-pellets was higher than that of TLD-100 but it cannot be considered a restriction to their use in clinical procedures and industrial applications.

Effect of blue light bleaching in a high TL sensitivity natural quartz crystal

“…The quartz pellets were manufactured following the procedure employed by Carvalho Junior et al [11]. This procedure consisted of pressing a homogeneous mixture of quartz particles and flocculated PTFE (polytetrafluoroethylene) at room temperature using a die manufactured using stainless steel.…”

Efeito Da Compactação Mecânica Na Intensidade Termoluminescente Do Quartzo E Da Calcita

“…Os discos de quartzo foram obtidos com grãos na faixa granulométrica 75x150 µm, tendo vista que essa faixa de tamanho é bastante utilizada para a produção de dosímetros TL a base de silicatos (SOUZA et al, 2001;ROCHA et al, 2003;CARVALHO JR et al, 2012;CANGUSSU et al, 2020). Para obter discos coesos, o quartzo particulado foi misturado com Teflon ® na proporção 1:1 (25 mg de quartzo + 25 mg de Teflon ® ).…”

“…Por esse motivo ele não é utilizado para dosimetria TL dos raios X e , sendo as análises que envolvem o comportamento desse pico descartadas nesse estudo. O pico TL a 288 o C é mais estável, sendo relatada uma pequena redução na sua intensidade após decorridos 60 dias (CARVALHO JR et al, 2012). O surgimento dos picos TL acima de 200 °C está associado a presença de armadilhas de elétrons formadas por vacâncias de oxigênio e pelos centros de defeitos de alumínio, onde ocorre o fenômeno da recombinação de pares elétron-buraco (MCKEEVER, 1985).…”

“…Alguns estudos realizados no quartzo natural mostraram que os picos TL acima de 200 °C podem ocorrer em altas intensidades, mesmo para baixas doses, indicando seu possível uso como dosímetro TL (KHOURY et al, 2007;CARVALHO JR et al, 2012). Entretanto, sabe-se também que a intensidade dos picos TL do quartzo particulado são muito dependentes do tamanho dos grãos (CARVALHO JR et al, 2012).…”

A comparative study of particle size distribution using analysis of variance for sedimentation and laser diffraction methods

“…In addition to kaolinite, it was possible to verify the presence of muscovite mica as a contaminant present in compositions CAU100, CAU75, and CAU50, with characteristic peaks at 2θ 8.99° and 17.88°, corresponding to distances of 9.83 and 4.96 Å, respectively. The characteristic peaks of quartz with the highest intensities are located at 2θ positions of 26.78° and 21.02°, with interplanar distances of 3.32 and 4.22 Å [11,12]. Table II shows the chemical composition of the formulations under study, as determined using X-ray fluorescence spectroscopy.…”