The thermoluminescence kinetic parameters of Ge-doped flat fibre have been investigated comprehensively using the computerized glow curve deconvolution analysis. The Ge-doped flat fibre was irradiated to 6 MV and 10 MV photon beam with dose ranging from 100 cGy to 300 cGy. Analysis was done using WinGCF software on the dependence of the glow curve intensity on dose delivered and the determination of the trap parameters. Ge-doped flat fibre was found to be linear over the entire dose range explored for both 6 MV and 10 MV irradiations with r2 value of 0.9955 and 0.9933 respectively. The glow curve consists of five individual glow peaks. The peak height increases with increasing irradiation dose. The first peak (P1) is a dominant individual peak for low temperature peak (LTP) with the maximum temperature ranging from 167.4°C to 179.0°C for both beams studied. Meanwhile, peak (P4) is a dominant individual glow curve for high temperature peak (HTP) with maximum temperature for 6 MV and 10 MV and is observed between 264.5°C to 279.4°C. Peak 1 has the lowest activation energy which is less than 0.72 eV while peak 2 shows the highest activation energy (1.3 eV < Ea < 2.1 eV) which indicates the deepest electrons trap. The results showed that the peak integral will increases as the dose increases. The Ge-doped flat fibre demonstrated the second-order kinetic peak behavior by exhibiting the symmetric shape of the glow curve with high temperature half of the curve slightly broader than the low temperature half, which suggests the possibility of electron retrapping.
The thermoluminescence (TL) glow curves and kinetics parameters of Thulium (Tm) doped silica cylindrical fibers (CF) are presented. A linear accelerator (LINAC) was used to deliver high-energy radiation of 21MeV electrons and 10MV photons. The CFs were irradiated in the dose range of 0.2-10Gy. The experimental glow curve data was reconstructed by using WinREMS. The WinGCF software was used for the kinetic parameters evaluation. The TL sensitivity of Tm-doped silica CF is about 2 times higher as compared to pure silica CF. Tm-doped silica CF seems to be more sensitive to 21MeV electrons than to 10MV photons. Surprisingly, no supralinearity was displayed and a sub-linear response of Tm-doped silica CF was observed within the analyzed dose range for both 21MeV electrons and 10MV photons. The Tm-doped silica CF glow curve consists of 5 individual glow peaks. The Ea of peak 4 and peak 5 was highly dependent on dose when irradiated with photons. We also noticed that the electron radiation (21MeV) caused a shift of glow peak by 7-13°C to the higher temperature region compared with photons radiation (10MV). Our Tm-doped fibers seem to give high TL response after 21MeV electrons, which gives around 2 times higher peak integral as compared with 10MV photon radiation. We concluded that peak 4 is the first-order kinetic peak and can be used as the main dosimetric peak of Tm-doped silica CF.
In regard to thermoluminescence (TL) applied to dosimetry, in recent times a number of researchers have explored the role of optical fibers for radiation detection and measurement. Many of the studies have focused on the specific dopant concentration, the type of dopant and the fiber core diameter, all key dependencies in producing significant increase in the sensitivity of such fibers. At doses of less than 1 Gy none of these investigations have addressed the relationship between dose response and TL glow peak behavior of erbium (Er)-doped silica cylindrical fibers (CF). For x-rays obtained at accelerating potentials from 70 to 130 kVp, delivering doses of between 0.1 and 0.7 Gy, present study explores the issue of dose response, special attention being paid to determination of the kinetic parameters and dosimetric peak properties of Er-doped CF. The effect of dose response on the kinetic parameters of the glow peak has been compared against other fiber types, revealing previously misunderstood connections between kinetic parameters and radiation dose. Within the investigated dose range there was an absence of supralinearity of response of the Er-doped silica CF, instead sub-linear response being observed. Detailed examination of glow peak response and kinetic parameters has thus been shown to shed new light of the rarely acknowledged issue of the limitation of TL kinetic model and sub-linear dose response of Er-doped silica CF.