ABSTRACT
Alpha-alumina is a useful thermoluminescence (TL) dosemeter. The knowledge of its behaviour under irradiation is thus of primary importance. The purpose of this paper is to characterise the radiation damage produced by swift krypton ions using various experimental methods, namely TL, optical absorption, fluorescence and electron paramagnetic resonance (EPR). After ion irradiation, the TL intensity is shown to decrease, whereas the optical absorption rises in the whole studied wavelength range. These two phenomena seem to be related to one another. Furthermore, optical absorption measurements highlight the appearance of new absorption bands probably owing to oxygen vacancies. Induced defects are also observed in the EPR spectra of irradiated pellets. They are likely related to electronic holes trapped on oxygen ions. The concentration of these defects increases with ion fluence and fluorescence measurements indicate that some pre-existing defects such as F2(2+) centres follow the same trend up to approximately 4.1 x 10(13) ions cm(-2).
Subject(s)
Aluminum Oxide/chemistry , Aluminum Oxide/radiation effects , Heavy Ions , Hot Temperature , Krypton , Thermoluminescent Dosimetry/methods , Dose-Response Relationship, Radiation , Materials Testing , Radiation Dosage , Thermoluminescent Dosimetry/instrumentationABSTRACT
The application of diamond to dosimetry is desirable because of its tissue equivalence, chemical inertness and small size, but this has not been commercially viable owing to the non-reproducible response of natural diamond. The chemical vapour deposition (CVD) of diamond permits controlled, reproducible and large-scale production of this material at potentially low cost. An investigation of some clinically relevant features like the depth-dose distribution as well as the absorbed dose profile, obtained using thermoluminescence (TL), is reported for several CVD diamond films. The TL characterisation presented here shows that CVD diamond films should be excellent TL-mode detectors in instances of radiotherapy and in vivo radiation dosimetry.
Subject(s)
Diamond/chemistry , Diamond/radiation effects , Radiotherapy Planning, Computer-Assisted/instrumentation , Thermoluminescent Dosimetry/instrumentation , Dose-Response Relationship, Radiation , Materials Testing , Radiation Dosage , Radiotherapy Planning, Computer-Assisted/methods , Reproducibility of Results , Sensitivity and Specificity , Thermoluminescent Dosimetry/methodsABSTRACT
The aim of this work is to calculate the absorbed dose to matter due to neutrons in the 5-150 MeV energy range. Materials involved in the calculations are Al2O3, CaSO4 and CaS, which may be used as dosemeters and have already been studied for their luminescent properties. The absorbed dose is assumed to be mainly due to the energy deposited by the recoils. Elastic reactions are treated with the ECIS code while for the non-elastic ones, a Monte Carlo code has been developed and allowed to follow the nucleus decay and to determine its characteristics (nature and energy). Finally, the calculations show that the absorbed dose is mainly due to non-elastic process and that above 20 MeV this dose decreases slightly with the neutron energy.
Subject(s)
Algorithms , Fast Neutrons , Linear Energy Transfer , Models, Chemical , Radiometry/instrumentation , Radiometry/methods , Absorption , Aluminum Oxide/radiation effects , Calcium Compounds/radiation effects , Calcium Sulfate/radiation effects , Computer Simulation , Computer-Aided Design , Equipment Design/methods , Radiation Dosage , Reproducibility of Results , Sensitivity and Specificity , Sulfides/radiation effectsABSTRACT
The TL glow curves of Al2O3:C crystals have been investigated as a function of the irradiation temperature. The nature of the observed TL peaks has been studied by optical annealing. The filling of traps was found strongly dependent on the irradiation temperature in the case of UV exposure, which has been explained by the temperature dependence of the photoionisation of F centres. This latter phenomenon could have a part in the luminescence quenching and UV bleaching of F centres.
Subject(s)
Aluminum Oxide/radiation effects , Thermoluminescent Dosimetry/methods , Aluminum Oxide/chemistry , Carbon/chemistry , Models, Theoretical , Radiochemistry , Temperature , Thermoluminescent Dosimetry/statistics & numerical data , Ultraviolet RaysABSTRACT
Miniature LiF:Mg,Ti (MTS-N) pellets, specially designed for dosimetry in proton radiotherapy, were studied in the 85-550 K temperature range. TL glow curves for differently Mg- or Ti-doped detectors were recorded, showing the preponderant influence of Mg concentration on the intensity of peak 5. The presence of a three-peak complex was also confirmed near 140 K; spectral emission of this peak consists of two bands whose maxima occur at 290 and 420 nm. TSEE glow curves above 300 K similar to those of TL were observed. The behaviour of TSEE and TL peak 5 following an X ray exposure from 33 to 500 Gy was studied: its intensity is a linear function of air kerma in both cases.
Subject(s)
Fluorides/radiation effects , Lithium Compounds/radiation effects , Thermoluminescent Dosimetry/methods , Fluorides/chemistry , Hot Temperature , Humans , Lithium Compounds/chemistry , Magnesium/chemistry , Proton Therapy , Radiochemistry , Radiotherapy Dosage , Spectrophotometry , Thermoluminescent Dosimetry/statistics & numerical data , Titanium/chemistry , X-RaysABSTRACT
An investigation of the thermoluminescence (TL) properties of high pressure, high temperature (HPHT) synthetic diamond crystals grown under diluted nickel or cobalt as solvent catalysts is reported. After a study of TL properties of 6 different samples, it is shown that a crystal grown with Ni+2%Ti and annealed at 2100 K presents an intense glow peak at around 490 K. This peak is characterised by a broad emission band centred at 530 nm (2.34 eV). This crystal presents a significant, reproducible and linear TL response relative to the absorbed dose up to an X ray air kerma of 10 Gy. All these features make this material suitable for ionising radiation dosimetry. A similar study is made on another crystal grown from pure Co, and a comparative review of the results does show that for dosimetry work, Ni-containing diamonds are more appropriate than those grown from Co catalyst.
Subject(s)
Diamond/radiation effects , Thermoluminescent Dosimetry/methods , Cobalt/chemistry , Crystallization , Diamond/chemistry , Hot Temperature , Luminescent Measurements , Nickel/chemistry , Pressure , Radiochemistry , Spectrophotometry , X-RaysABSTRACT
The luminescent properties of cerium doped calcium sulphate are studied: fluorescence and excitation spectra, optical absorption and thermoluminescence (TSL). It is known that, in rare earth doped CaSO4, only cerium induces a strong 400 degrees C TSL peak. In CaSO4:0.2%Ce samples synthesised under oxidising conditions, the recovery step of Ce3+ fluorescence is correlated with the 400 degrees C TSL peak readout, as mentioned by Nair er al. Our results indicate that an oxidation of Ce3+ ion does occur under X-irradiation (Ce3+ --> Ce4+), followed by a complete return to the trivalent state after thermal annealing at about 500 degrees C; our results confirm the hypothesis of Nair et al that Ce3+ ions are oxidised by ionising irradiation. So, a pure redox reaction seems the most probable for the 400 degrees C TSL peak of CaSO4:Ce. Moreover, the use of the 400 degrees C TSL peak for high temperature dosimetry applications is discussed.
