Glow Peak Analysis Of Pure And Ge-Doped Silica Flat Fiber At Ultra High Dose Electrons
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Date
2015-07
Authors
Ariffin, Alawiah
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Abstract
Silica flat fiber (FF) is being proposed as the basis for a novel radiation sensor of the
thermoluminescence (TL) produced. The TL performance of the FFs and its
respective glow curves were studied using a linear accelerator (LINAC) delivering
doses of clinical radiotherapy within the range of 0.2-10.0 Gy. An electron
accelerator (Alurtron®) was used to deliver the ultra-high dose. The TL dose
response, dopant effect, heating rate effect and kinetic parameters of the
deconvoluted glow peaks were investigated. The glow curve of FFs shifted to the
higher temperature region as the heating rate increases. The kinetic parameters show
dependence on the heating rate for both doped and un-doped FFs. It is found that the
Burlin Cavity Theory (BCT) fit model can be used to predict the energy response of
FF, accurately. Increasing the dopant concentration between 0 and 6 wt % Ge in FFs,
increases the linearity index, f D by 2.0. These remarkable findings showed the
effect of dopant quenching in FF as the Ge dopant concentration was increased up to
8 wt%. The TL sensitivity of 6 wt% Ge doped FF was found to be 3.5 higher as
compared to pure silica FF. Also noted, all peaks tend to show the first-order
kinetics behavior within the linear dose range of 0.1 - 10 Gy. The maximum
supralinearity of FFs found to be at ~30 kGy. No saturation occurred at f(D)max and
further increases of dose up to 1 MGy, exhibits a significant decrease in f(D). The TL
kinetic model can be used to explain the TL glow peak before the critical dose limit
was achieved whereas none of TL model can explain the strange changes in TL glow
peak at doses > 10 kGy up to 1 MGy. Overall results indicate that the silica FFs
have a considerable potential as radiation sensors in ultra-high dose electrons.
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Physics (General)