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1.
Radiat Prot Dosimetry ; 200(10): 919-937, 2024 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-38851183

RESUMO

The features of the glow curves of LiF:Mg,Ti are dependent on many parameters of irradiation, storage, ionisation density and readout. These are presented herein with emphasis on their complexity. Successful applications require some understanding of the great diversity of the glow curves. Glow curve analysis/deconvolution in order to better understand the mechanisms is a 'tricky business' even with Tm-Tstop analysis. In the theoretical framework of spatially correlated trapping and luminescent centres, a mechanism is described which simulates the behaviour of composite peak 5 at different cooling rates and following photon bleaching at 3.65 eV.


Assuntos
Fluoretos , Compostos de Lítio , Magnésio , Dosimetria Termoluminescente , Titânio , Compostos de Lítio/química , Magnésio/química , Fluoretos/efeitos da radiação , Fluoretos/química , Dosimetria Termoluminescente/instrumentação , Dosimetria Termoluminescente/métodos , Titânio/química , Luminescência , Fótons
2.
Radiat Prot Dosimetry ; 200(4): 423-427, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38195760

RESUMO

The effect of natural rapid cooling and oven slow cooling on the precision of thermoluminescence measurements of LiF:Mg,Ti is investigated. Three separate series of measurements resulted in average precisions of 5.1 and 5.0%, respectively. However, the highest precision of 1.7% (1 SD) was achieved for an oven-cooled material.


Assuntos
Compostos de Lítio , Dosimetria Termoluminescente , Dosimetria Termoluminescente/métodos , Fluoretos , Titânio , Desenho de Equipamento
3.
Radiat Prot Dosimetry ; 198(4): 222-228, 2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-35313343

RESUMO

An experimental investigation into the possibility of dose-rate effects and wall scatter in the thermoluminescent response of LiF:Mg,Ti (TLD-100) was carried out. The investigation was motivated by theoretical simulations predicting the possible presence of dose-rate effects coupled with the lack of detailed experimental studies. The dose rate was varied by changing the source to sample distance, by the use of attenuators, sources of 137Cs of various activities, filtration and the construction of identical geometrical irradiators of Teflon and stainless steel. Four levels of dose in the linear dose response region were studied at 10-2 Gy, 1.5 × 10-2 Gy, 0.1 Gy and 0.5 Gy to avoid complications in interpretation due to supralinearity above 1 Gy. At the dose of 1.5 × 10-2 Gy, the dose rate was varied by five orders of magnitude from 4.9 × 10-3 Gy s-1 to 4.9 × 10-8 Gy s-1. At the other levels of dose, a one to two orders of magnitude in dose rate was achieved. Within the measurement uncertainty of 5-10%, no dose-rate effects were observed in any of the experimental measurements and no changes in the shape of the glow curve were observed. The maximum wall scatter effect (Teflon to stainless steel) was measured at ~8% within the experimental uncertainty and well below expectations. The results are encouraging with respect to the accurate and reproducible use of LiF:Mg,Ti under various experimental conditions of irradiation.


Assuntos
Compostos de Lítio , Dosimetria Termoluminescente , Radioisótopos de Césio , Fluoretos/efeitos da radiação , Compostos de Lítio/efeitos da radiação , Dosimetria Termoluminescente/métodos
4.
Radiat Prot Dosimetry ; 196(1-2): 53-59, 2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34463339

RESUMO

The cooling rate to room temperature following the 400°C pre-irradiation anneal is known to affect the thermoluminescent properties of LiF:Mg,Ti (TLD-100) as a result of migration and clustering of defects during the cooling down process. In this investigation the dose response over an extended dose range from 0.01 to 7000 Gy in both naturally cooled and the much slower furnace-cooled samples has been measured. Glow curve deconvolution based on first-order kinetics is employed to extract the dose response of the various glow peaks. Of especial interest is the behaviour of glow peaks 4, 5a and 5 as a function of dose. The idea is to modify the supralinear dose response of peak 5 from 1 to 30 Gy to a linear behaviour. This dose range is important for clinical therapy and a linear dose response is of substantial advantage leading to both improved accuracy and precision.


Assuntos
Compostos de Lítio , Dosimetria Termoluminescente , Desenho de Equipamento , Fluoretos , Doses de Radiação
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