Thermoluminescent characteristics of mineral samples acquired as jade

Valério

Caldas

2007

In this work a preliminary study of the thermoluminescent (TL) dosimetric properties of the Brazilian actinolite:Ca 2 (Mg,Fe) 5 (Si 8 O 22 )(OH) 2 (silicate of the Jade family) was undertaken for gamma high-doses. Actinolite occurs in several regions in the world. In this work actinolite in the form of rude mineral from Governador Valadares, Minas Gerais, Brazil, was studied. The natural actinolite samples were powdered, and the selected grains were mixed with Teflon in the proportion 2 (Teflon):1(Actinolite). The mixture was pressed and sintered for production of pellets of composites Actinolite -Teflon. The glow curves present two peaks at 125°C and 210°C. The TL response reproducibility presents a maximum variation coefficient of 4.8%. The calibration curve is linear between 0.5Gy and 1kGy for pellets irradiated with gamma radiation ( 60 Co) and between 0.5Gy and 10Gy for pellets irradiated with X-rays (33keV). The TL response presents an energy dependence of 26% for X-rays between 27 and 41keV. 1 Introduction The continuous use of ionizing radiations in processes associated to medical, industrial, agriculture and research applications has motivated the development of new thermoluminescent materials applied to high-dose dosimetry. Solid-state techniques based on thermoluminescence (TL) dosimetry are relatively inexpensive methods.Developments of silica-based materials suitable for thermoluminescence dosimetry (TLD) have been studied by several authors. Many materials as fluorides, borates, oxides, sulphates and silicates present thermoluminescent properties [1]. McLaughlin et al. [2] described the main kinds of high-dose dosimeters, discussing their advantages and disadvantages; however, they need to combine characteristics that limit their use in the radiation dosimetry [3]. Additionally, most of the current detectors present high cost. The silicates represent 92% of the whole percentage volume of the minerals of the earth crust [4], and therefore there is a wide field of studies of new materials for radiation dosimetry. The dosimetric properties of Jade were already studied using the thermoluminescent technique, showing its potential use for high-dose dosimetry [5].Recently, TL properties of manufactured composites with a mixture of Topaz-Teflon have been studied with the aim of developing a new solid-state dosimeter [6]. The objective of this work was to study the dosimetric properties of actinolite:Ca 2 (Mg,Fe) 5 (Si 8 O 22 )(OH) 2, a Brazilian silicate of the Jade family, for gamma high-doses.

Section: Energy Dependencesupporting

confidence: 89%

mentioning

confidence: 99%

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Thermoluminescent characteristics of Actinolite‐Teflon composites for gamma high‐doses

Valério

Caldas

2007

“…The saturation effect displayed by glow-peaks in many of the available TL dosimeters at high doses is however a serious limitanting factor against the acceptance of this technique in both high-dose measurements and accident dosimetry [4,6]. Recently commercial glasses [4,5], sand [6], topaz [7] and jade [8] have been studied using the thermoluminescent technique, and the results showed potential applications for high-dose dosimetry.…”

mentioning

confidence: 99%

“…Though dosimeters prepared with natural minerals like topaz or jade mixed with Teflon could be used at high-dose measurements they do not present linear TL behavior to doses higher than 1 kGy [7,8].…”

mentioning

confidence: 99%

Dosimetric characterization of wollastonite‐teflon composites

Souza

Oliveira

et al. 2007

In this work, the thermoluminescent properties of pellets containing powdered Wollastonite embedded in Teflon were studied. The preliminary results using gamma rays from a 60 Co source showed linearity at the calibration curve between 0.5 Gy and 10 Gy. The main TL peaks are located at 125, 200 and 245 °C. The repeatibility of TL response presented a maximum coefficient of variation of 6.3%. The material can be used in successive irradiation-reading-annealing cycles without an appreciable change in its sensitivity. The calibration curve for a gamma source ( 60 Co) up to 20 kGy and the minimum detection limits were obtained. The results show that these Wollastonite-Teflon pellets present possibilities for use as TL dosimeters.

Defects induced in bioglass by gamma radiation for dosimetric purposes

Costa

Giehl

et al. 2007

Some dosimetric properties of the glass system 50P 2 O 5 •30-40CaO•20-10Na 2 O mol% were studied applying the thermoluminescence technique.. The glass samples were powdered, and were pressed with Teflon™ in the proportion 1:2 to produce pellets. The glow curves of the pellets presented three peaks at 130 °C, 215 °C and 270 °C, respectively. The TL response reproducibility presented a maximum coefficient of variation lower than 10%. The calibration curve is linear between 1.0 Gy and 1 kGy. Minimum detection limits were also determined. The gamma radiation dose response and the thermal stability of the materials were studied with the purpose to establish the best conditions of the present bioglass system for use in gamma ray TL dosimetry.