Hyper pure quartz as a promising material for retrospective and radiation processing dosimetry using ESR technique

Samples of highly purified naturally occurring silicon dioxide (SiO2) commercially named clear fused quartz (CFQ), both in bulk and in powder form were exposed to 4 and 8 MeV electrons from a linear accelerator (radiotherapy unit) at doses between 0.5 and 60 Gy (minimum and maximum attainable dose, respectively). After irradiation, the samples were subjected to electron spin resonance (ESR) analysis readout to test their use as a mean of measuring absorbed doses in the samples. A good linearity between the absorbed dose (from 2 Gy up to the maximum dose applied of 60 Gy) and the ESR intensity of the samples was observed while a poor linearity at low doses (between the absorbed dose from 0.5 to 10 Gy and the ESR intensity) is seen. The background intensity in the case of the powder was higher than for the cylindrical samples and the ESR intensity was also lower in the former case, which gave rise to a dose curve response with a lower slope for the powders. No energy dependence was apparent for electrons of 4 and 8 MeV energy. The thermal fading of CFQ at room temperature showed a relatively sharp decay of ∼30% over a period of 10 days after which the decay rate was negligible for a measured period of 80 days. The results in this study plus the previous work done (gamma irradiation of the samples) by the authors suggest that the materials could, by using the ESR technique, be a suitable candidate for alternative dose measurements in radiation processing and retrospective dosimetry.