New calculations concerning the fading of thermoluminescent materials

“…Temperature-dependent kinetics of decay were experimentally investigated by isothermal annealing, which allows the assessment of halflife, t./2, and activation energy, Ea (eV). The processes of decay are classically described by first or second order equations (Furetta 1988). The first order (Arrhenius) law can be written:…”

Section: Stability Of the Radiation-induced Defectsmentioning

confidence: 99%

Nature and Stability of Radiation-Induced Defects in Natural Kaolinites: New Results and a Reappraisal of Published Works

Clozel

Allard

Müller

1994

Clays and clay miner.

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Abstract--A new appraisal of radiation-induced defects (RID) in natural kaolinite, i.e., positive trapped holes on oxygen atoms, has been undertaken using Q-band EPR spectra, recorded at 93 K, of irradiated annealed and oriented kaolinite samples originating from various environments. Three different centers were identified. Two of the centers, A-and A'-centers, are trapped holes on oxygen from Si-O bonds. They have a distinct signature and orthogonal orientation, i.e., perpendicular and parallel to the (ab) plane, respectively. The third center, the B-center, is a hole trapped on the oxygen bonding A1 in adjacent octahedral positions (Alv~-O--Alw bridge). This confirmed some previous assignments from the literature, some others are no longer considered as valid.A least squares fitting procedure is proposed to assess the RID concentration in any kaolinite. It allows a quantitative approach of the thermal stability of RID. Isochronal annealing shows that the thermal stability of the centers decreases in the order A, A', B over the temperature range 0-450~ (1) B-center is completely annealed above 300~ (2) A'-center can be annealed by heating at 400~ for more than two hours; (3) A-center is stable up to 450~ The activation energy and the magnitude of the mean halflife for A-center is evaluated through isothermal annealing at 350, 375 and 400*(2, with Ea = 2.0 eV + 0.2, and tv, > l0 ~2 years at 300 K. The stability of A-center seems to decrease with increasing crystalline disorder. Nevertheless, it is high enough for radiation dosimetry using kaolinites from any environment on the Earth's surface.

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“…This phenomena has been theoretically studied by several authors [1][2][3][4][5][6], but no practical expressions have been given up to now.…”

Section: Introductionmentioning

confidence: 95%

Simulation of competing irradiation and fading effects in thermoluminescence dosimetry

Kitis

Furetta

2005

Radiation Effects and Defects in Solids

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The aim of this article is to give some useful expressions for fading correction in practical situations as they can be encountered in radiation protection dosimetry monitoring, i.e. personal, environmental and clinical dosimetry. They are obtained considering the general case in which, for both first and second-order kinetics, during the experimental period of time two effects are in competition between them: one is the trapping rate due to the irradiation, the second is the detrapping rate which takes place at the same time, owing to thermal fading. Various practical situations are taken into consideration.

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New calculations concerning the fading of thermoluminescent materials

Cited by 11 publications

References 3 publications

The thermal stability of radiation-induced defects in illite

The thermal stability of radiation-induced defects in illite

Nature and Stability of Radiation-Induced Defects in Natural Kaolinites: New Results and a Reappraisal of Published Works

Simulation of competing irradiation and fading effects in thermoluminescence dosimetry

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