Search results for "DOSIMETRY"
showing 10 items of 297 documents
A novel radiation exposure control apparatus for microwave assisted chemical reactions
2004
AbstractA radiation exposure control apparatus is used for microwave (2.45 GHz) treatment of chemical reactions in controlled and reproducible conditions. A spectrophotometer has been interfaced with the microwave set-up in order to monitor the reaction evolution in situ. Both numerical and experimental dosimetries are carried out in order to evaluate the field distribution within the sample. Finally, particular working conditions are suggested.
Dosimetry in mixed gamma–neutron radiation fields and energy compensation filters for CaF2:Tm TL detectors
2008
Abstract Strong fields of thermal and epithermal neutrons as used for Boron Neutron Capture Therapy (BNCT) show a relatively small gamma dose. However, for accurate dose estimation, both the neutron as well as the gamma component has to be considered. Different approaches have been studied with various thermoluminescence detectors (TLDs). As a result, CaF2:Tm detectors (TLD-300) are attributed to be most insensitive to thermal neutrons but not tissue-equivalent. In this paper we focus on the measurement of the gamma dose with TLD-300 in mixed irradiation fields. To overcome the disadvantage of being not tissue-equivalent, a study on energy compensation filters was performed. The paper compr…
Pulsed EPR analysis of tooth enamel samples exposed to UV and gamma-radiations
2011
Abstract The electron paramagnetic resonance (EPR) spectroscopy is widely applied for retrospective dosimetric purposes by means of quantitative detection of radicals in tooth enamel and bone samples. In this work we report a study by cw and pulsed EPR on two samples of human tooth enamel respectively irradiated by UV (254 nm) and γ-exposed. The continuous wave (cw) EPR spectra have shown the usual presence in both samples of two types of CO 2 − radicals, with axial and orthorombic g tensors. We have obtained the electron spin echo detected EPR (ED-EPR) spectra at 80 K of the two samples, and we have shown that they are suitable to mark the difference between the effects produced by the dif…
Thermoluminescence properties of AlN ceramics
1998
Abstract The paper describes thermoluminescence (TL) properties of AlN:Y 2 O 3 ceramics irradiated with ionising radiation. A high TL sensitivity of AlN:Y 2 O 3 ceramics to radiation encouraged a study of the AlN ceramics for application as a dosimetric material. The paper presents experimental data on: glow curve, emission spectrum, dose response, energy dependence, influence of heating rate and fading rate. The measured TL characteristics were compared with those of well-known, widely used TLDs, i.e. LiF:Mg,Ti, LiF:Mg,Cu,P and Al 2 O 3 :C. It is concluded that AlN:Y 2 O 3 ceramics showing a radiation sensitivity which is approximately 50 times greater than that of LiF:Mg,Ti is an interest…
Stimulated luminescence of AlN ceramics induced by ultraviolet radiation
2001
Abstract Properties of thermally stimulated luminescence (TL) and optically stimulated luminescence (OSL) of the ceramic material AlN-Y 2 O 3 have been studied after exposure to ultraviolet radiation (UVR). The dosemeter material Al 2 O 3 : C has been used for comparative measurements. The spectral sensitivity of the samples has been studied and compared with spectral effectiveness of the UVR-induced biological processes. It has been shown that a very high yield and linear dose response characterise the UVR-induced TL from AlN-Y 2 O 3 . Although lower than the TL, the OSL signal from UV-exposed AlN-Y 2 O 3 is still higher than that of Al 2 O 3 : C in a broad spectral region. The possibilit…
Watch glasses exposed to 6 MV photons and 10 MeV electrons analysed by means of ESR technique: A preliminary study
2011
Abstract In this work we report a case study of the ESR response of watch glasses exposed to 6 MV photons and to 10 MeV electrons. The choice of watch glasses is justified by the fact that watch glasses are very close to the exposed individual. For both types of radiation beams, the absorbed doses belong to the range between 1 and 20 Gy. The samples have been irradiated in water-equivalent plastic phantom with a linear accelerator used for radiotherapy. After exposure watch glass samples have been cut in small strip-shaped pieces with suitable size to be put into the quartz tube for ESR measurements. The signal induced by radiation (RIS) lies in the g ∼ 2 region and must be discriminated fr…
A practical and transferable methodology for dose estimation in irradiated spices, based on thermoluminescence dosimetry
2008
Abstract The thermoluminescence technique is recommended by the European Committee for Standardization for the detection of irradiated food containing silicates as contaminants. In this work, the applicability of the thermoluminescence technique as a quantitative method to assess the original dose in irradiated oregano was studied; the additive-dose method was used, with reirradiation doses up to 600 Gy. The proposed new procedure allows to clearly discriminate irradiated from unirradiated samples, even after one year storage, and it gives an acceptable estimation of the original dose; the overall modified procedure requires only one day to be completed.
Optical and magnetic resonance spectroscopy of stimulated recombination processes in defect studies
2004
Optical and magnetic resonance spectroscopy is widely used in the investigation of radiation-induced processes in wide-gap solids. This paper discusses the present understanding of applications of the experimental methods of optical and thermoactivation spectroscopy in the research of new materials, for applications in radiation dosimetry and digital imaging and in the basic research into the fundamental physics and chemistry of radiation. The advantages of the simultaneous use of optical and magnetic resonance techniques for the investigation of stimulated processes are considered.
Determination of the irradiation field at the research reactor TRIGA Mainz for BNCT.
2009
For the application of the BNCT for the excorporal treatment of organs at the TRIGA Mainz, the basic characteristics of the radiation field in the thermal column as beam geometry, neutron and gamma ray energies, angular distributions, neutron flux, as well as absorbed gamma and neutron doses must be determined in a reproducible way. To determine the mixed irradiation field thermoluminescence detectors (TLD) made of CaF(2):Tm with a newly developed energy-compensation filter system and LiF:Mg,Ti materials with different (6)Li concentrations and different thicknesses as well as thin gold foils were used.
Trap Spectroscopy by the Glow Rate Technique using Bleaching of Colour Centres
2002
An application of the glow rate technique (GRT) for analysis of the parameters of thermostimulated decay of colour centres is presented using the data on the decay of radiation defects in LiBaF 3 :Fe crystals created by X rays at 300 K. The GRT offers a procedure for evaluation of the mean activation energy as a function of temperature in the case of arbitrary thermostimulated relaxation kinetics represented by the trap distribution function. The experimental procedure involves at least two subsequent measurements of thermostimulated decay kinetics at different heating rates. It is shown that the decay of the F type centres is governed by interaction of mobile anion vacancies with F A and F…