Radiological emergency dosimetry – The use of luminescent mineral fillers in polymer-based fabrics

Abstract

Mineral fillers are widely used in the manufacture of thermoplastics and they are commonly found in the fabrics used to form bags. We show that carbonate mineral filler grains incorporated within faux leather fabrics and the coatings applied to woven nylon fibre fabrics exhibit a bright thermoluminescence TL response to ionising radiation dose, similar to that of calcite, with a broad thermoluminescence (TL) peak at 100 °C. The fabrics tested are shown to be potentially suitable as a surrogate material for emergency dosimetry, exhibiting a linear TL response to dose between 0.1 and 10 Gy, and with a detection limit varying with fabric type from 4 to 400 mGy. The region of the TL glow curve selected for dose evaluation was between ca 100–200 °C, and this is restricted by the presence of a native signal associated with the 250 °C TL peak. The rate of fading observed varied with glow curve temperature, attributed to the presence of a distribution of trapping levels; following 24 h storage at room temperature the loss recorded for the optimal glow curve temperature region selected (160–162 °C) ranged from 30 to 80 %, according to fabric and filler type. However, the fading mechanism is predominantly thermal and its rate can be substantially reduced by storing irradiated materials below room temperature. The use of filler minerals incorporated in the manufacture of plastics provides the scope to exploit a much wider range of materials for application to emergency dosimetry.