title: A COMPARATIVE STUDY OF THE DOSIMETRIC FEATURES OF α-Al2O3:C,Mg AND α-Al2O3:C.
abstract: A comparative study of the dosimetric features of α-Al2O3:C,Mg and α-Al2O3:C relevant to thermoluminescence dosimetry is reported. A glow curve of α-Al2O3:C,Mg measured at 1°C/s after beta irradiation to 1 Gy shows two subsidiary peaks at 42°C (labelled as I) and 72°C (II) and the main peak at 161°C (III) whereas a glow curve of α-Al2O3:C measured under the same conditions shows the main peak at 178°C (II') and a lower intensity peak at 48°C (I'). Apart from these ones, there are several other peaks at temperatures beyond that of the main peak in both α-Al2O3:C,Mg and α-Al2O3:C. However, the latter are not included in this study. We report a comparative quantitative analysis of dose response and fading of peaks I, II and III of α-Al2O3:C,Mg and peaks I' and II' of α-Al2O3:C. Analysis shows that the dose response of peaks I and III is sublinear within 1-10 Gy whereas that of peak II is superlinear within 1-4 Gy followed by a sublinear region within 4-10 Gy. In comparison, the dose response of peak I' is superlinear within 1-4 Gy followed by a sublinear region within 4-10 Gy whereas that of peak II' is sublinear within 1-4 Gy followed by a superlinear region within 4-10 Gy. As regards to fading corresponding to 1 Gy, peak I is very unstable and fades within 300 s, peak II is more stable and takes up to 43200 s to fade. In comparison, peak III fades down to 30% of its initial intensity within 2400 s. Interestingly, between 2400 and 800 s, the intensity fades by 17% only. Regarding fading in α-Al2O3:C, peak I' fades within 600 s whereas peak II' shows an inverse fading behaviour up to 64800 s. The rate of fading for peaks I, II and III in α-Al2O3:C,Mg was found to decrease with increase in dose. However, no such behaviour was observed in α-Al2O3:C. The fading in both samples is discussed on the basis of a charge hopping mechanism.
authors.affiliation: Department of Physics and Electronics, Rhodes University, P O Box 94, Grahamstown 6140, South Africa.
authors.forename: J M
authors.initials: JM
authors.lastname: Kalita
authors.affiliation: Department of Physics and Electronics, Rhodes University, P O Box 94, Grahamstown 6140, South Africa.
authors.forename: M L
authors.initials: ML
authors.lastname: Chithambo
mesh_terms: D000537:Aluminum Oxide / Q000737:chemistry* / Q000528:radiation effects*; D002244:Carbon / Q000737:chemistry* / Q000528:radiation effects*; D008027:Light; D008274:Magnesium / Q000737:chemistry* / Q000528:radiation effects*; D008422:Materials Testing; D008956:Models, Chemical; D011829:Radiation Dosage; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation*
chemical_list: D002244:Carbon; D008274:Magnesium; D000537:Aluminum Oxide