NUKLEONIKA 2009, 54(1):39-43

 


DOSIMETRIC PROPERTIES OF GAMMA- AND ELECTRON-IRRADIATED COMMERCIAL WINDOW GLASSES



Piergiorgio Fuochi1, Ugo Corda1, Marco Lavalle1, András Kovács2, Marika Baranyai2, Arbi Mejri3, Khaled Farah3

1 ISOF-CNR, 101 P. Gobetti Str., 40129 Bologna, Italy
2 Institute of Isotopes, HAS, P. O. Box 77, H-1525 Budapest, Hungary
3 Laboratoire de Radiotraitement, CNSTN, 2020 Sidi-Thabet, Tunisia

Two different types of window glasses have been investigated as possible routine dosimeters in the range of 1–50 kGy. Glass samples were irradiated with 3.4 MeV and
8.4 MeV electron beams and the results compared with those obtained by 60Co gamma irradiation. Due to the strong optical absorption at wavelengths < 310 nm, even at low doses, optical measurements were limited to the range 320–700 nm. In both types of glasses, irradiation induced two absorption bands around 410 and 600 nm the intensities of which are proportional to dose; the 600 nm band being less sensitive to radiation. These bands have been attributed to non bridging oxygen hole centres existing in two different configurations. Because of the rapid fading of the optical absorbance observed at room temperature immediately after irradiation (> 15% in two days), the samples underwent a post-irradiation thermal treatment (150°C for 20 min) to improve the stability of absorbance. The fading characteristics of the irradiated and thermally treated glasses, kept in the dark at room temperature, were studied for several weeks. A fast decay, whose intensity depends on the type and energy of the ionizing radiation, was observed for few days after irradiation and thermal treatment, followed by a much slower decay. The results show that this kind of material could be used as routine dosimeters within a certain dose range, as long as proper calibrations are made for each batch of glass and the appropriate precautions are taken when doing calibration and performing routine dosimetry.

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