Thermoluminescence properties of irradiated chickpea and corn

A study was carried out to establish a detection method for irradiated chickpea and corn by thermoluminescence (TL) method. The leguminous were packed in polyethylene bags and then the packets were irradiated at room temperature at different doses by ⁶⁰Co gamma source at 1, 4, 8 and 10 kGy. Minerals extracted from the leguminous were deposited onto a clean aluminum disc and TL intensities of the minerals were measured by TL. It was observed that the extracted samples from both leguminous exhibit good TL Intensity and the TL intensity of glow curves of them increased proportionally to irradiation doses. The TL glow curve of both irradiated leguminous presents a single broad peak below 400 °C. The TL trapping parameters glow peaks were estimated by the additive dose (AD), T_m(E_a)-T_stop and computerized glow curve deconvolution (CGCD) methods. The fading characteristics of glow curves were also recorded up to 6 months.     

The thermoluminescent properties of lithium triborate (LiB3O5) activated by aluminium

In this paper, the thermoluminescence (TL) dosimetric characteristics of Al-doped LiB₃O₅ compounds are presented. The powder samples were prepared by the solid-state reaction method and the formation of the compounds were confirmed by an X-ray diffraction study. The TL studies of undoped and Al-doped LiB₃O₅ samples showed similar glow curve structures. They have three TL glow peaks at about 60, 130 and 200 °C after heating at a constant heating rate of 1 °C/s. Their comparative TL studies indicated that 5 wt% Al-doped LiB₃O₅ compound was approximately 240 times more sensitive than undoped compound. The TL emission spectra of Al-doped LiB₃O₅ showed a maximum band at around 520 nm. The main dosimetric characteristics, which are namely the TL dose response, TL sensitivity, fading, minimum detectable dose, reproducibility, precision of dose measurement and annealing procedure, indicated that Al-doped LiB₃O₅ sample, can be used in dosimetric applications. The trap parameters namely order of kinetics (b), activation energy (E) and frequency factor (s) associated with the glow peaks in beta irradiated undoped and Al-doped LiB₃O₅ samples were obtained by glow curve deconvolution (GCD) program.     

The thermoluminescence properties of natural CaF2 after β-irradiation

In this study, the thermoluminescence (TL) properties of natural CaF₂ were investigated after β-irradiation at room temperature (RT). The additive dose (AD), T_m(E_a)-T_stop, repeated initial rise (RIR), and computerized glow curve deconvolution (CGCD) methods were used to analyze the thermoluminescence (TL) glow peaks in natural CaF₂ after β-irradiation between 0.015 Gy and ≈2 kGy dose level. These methods were used to determine the number of peaks and kinetic parameters (kinetic orders b, activation energy E_a, and attempt-to-escape frequency s) associated with the thermoluminescence (TL) glow peaks of natural CaF₂. The E_a-T_stop and CGCD methods indicate that the glow curve of this material is the superposition of at least six glow peaks, which were dealt with as P1-P6, in the temperature range between room temperature (RT) and 400 °C. Dose variation experiments revealed that TL glow curve of natural CaF₂ has both first and general-order glow peaks. The dose responses and fading process, which are very useful in radiation dosimetry, of individual TL peaks of this material were also examined. In addition, the influence of heating rates on the response of dosimetric glow peaks of natural CaF₂ was studied. It was observed that the total area of glow peak and peak intensities of all glow peaks are continuously decreasing with increasing heating rate.     

Thermoluminescence of terbium-doped double fluorides

This paper presents the thermoluminescence (TL) characteristics of the double fluorides: K₂YF₅, K₂GdF₅ and K₂LuF₅ doped with Tb³⁺, which were studied in the temperature range from 30 to 400 °C. Materials which presented better response to the irradiation with beta particles and with ultraviolet radiation were: K₂YF₅:Tb (1 at.% Tb³⁺) and K₂LuF₅:Tb (1 at.% Tb³⁺); meanwhile, K₂YF₅:Tb at high concentrations (10 and 20 at.% Tb³⁺) as well as K₂LuF₅:Tb (1 at.% Tb³⁺) and K₂LuF₅:Tb (1 at.% Tb³⁺) presented good response to gamma radiation. The intensity of the thermoluminescent response induced in these materials by ionizing radiation has determined that their dosimetric characteristics should be studied further as this may allow the development of potentially useful TL materials for radiation dosimetry.     

Investigation of the stability of the radiation sensitivity of TL peaks of quartz extracted from tiles

One of the most important mineral in dosimetric investigation is quartz, which is found abundantly in archaeological and geological materials. Although there are many studies about its thermoluminescence (TL) properties in the literature, it may exhibit different properties for each quartz mineral extracted from the different region of the world. In the present work, the stabilities and dose responses of glow peaks of quartz obtained from the tiles of Kubad Abad Palace in central Turkey were investigated after annealing at 500 and 600 °C for 1 h. The variation of radiation sensitivity of TL peaks of the quartz grains extracted from tiles are found to be more stable after annealing at 600 °C than 500 °C for 1 h. The TL dose responses of glow peaks of annealed and unannealed quartz samples were also studied up to approximately 3 kGy. It was observed that the pre-irradiation heat treatments affect the dose response behaviors of glow peaks.     

The effects of heating rate on the dose response characteristics of TLD-200, TLD-300 and TLD-400

In the given study; the effects of heating rates on the dose response characteristics of CaF₂:Dy (TLD-200), CaF₂:Tm (TLD-300) and CaF₂:Mn (TLD-400) crystals have been investigated using the dose dependence curve and dose response function f(D). It was observed from the dose response functions that the linearity and behaviour of the TL glow peaks of TLD-200 and TLD-400 are affected, but the TLD-300 is not affected from the heating rate.     

Thermal and structural properties of low-fluence irradiated graphite

The release of Wigner energy from graphite irradiated by fast neutrons at a TRIGA Mark II research reactor has been studied by differential scanning calorimetry and simultaneous differential scanning calorimetry / synchrotron powder X-ray diffraction between 25 and 725 °C at a heating rate of 10 °C min⁻¹. The graphite, having been subject to a fast-neutron fluence from 5.67 × 10²⁰ to 1.13 × 10²² n m⁻² at a fast-neutron flux (E > 0.1 MeV) of 7.88 × 10¹⁶ n m⁻² s⁻¹ and at temperatures not exceeding 100 °C, exhibits Wigner energies ranging from 1.2 to 21.8 J g⁻¹ and a Wigner energy accumulation rate of 1.9 × 10⁻²¹ J g⁻¹ n⁻¹ m². The differential-scanning-calorimeter curves exhibit, in addition to the well known peak at ∼200 °C, a pronounced fine structure consisting of additional peaks at ∼150, ∼230, and ∼280 °C. These peaks correspond to activation energies of 1.31, 1.47, 1.57, and 1.72 eV, respectively. Crystal structure of the samples is intact. The dependence of the c lattice parameter on temperature between 25 and 725 °C as determined by Rietveld refinement leads to the expected microscopic thermal expansion coefficient along the c axis of ∼26 × 10⁻⁶ °C⁻¹. At 200 °C, coinciding with the maximum in the differential-scanning-calorimeter curves, no measurable changes in the rate of thermal expansion have been detected - unlike its decrease previously seen in more highly irradiated graphite.     

Glass matrices for immobilizing nuclear waste containing molybdenum and phosphorus

Vitrification has been selected in France as the process for immobilizing high-level waste arising from spent fuel reprocessing. Some high-level solutions generated by reprocessing legacy fuel contain high molybdenum concentrations. Molybdenum is known to be sparingly soluble in conventional borosilicate glass, and work is in progress to find suitable glass formulations for such waste. The results of a basic study to identify borosilicate glasses composition zones of potential interest are discussed. A vast composition range was investigated by defining a fine mesh. The limits considered to delimit the range of the study were intentionally extended to identify formulations such as SiO₂-B₂O₃-Al₂O₃-Na₂O-P₂O₅ that are of interest for vitrifying molybdenum-rich waste. Observation of more than 50 tested mixtures revealed two composition zones of potential interest. One forms a homogeneous glass after melting at 1300 °C and rapid cooling; the other vitreous material comprises unconnected microbeads uniformly dispersed in a borosilicate glass.     

Neutron-gamma mixed field measurements by means of MCP-TLD600 dosimeter pair

In this paper, we compared the TL response of three types of thermoluminescence dosimeters, TLD600 (⁶LiF:Mg,Ti), TLD700 (⁷LiF:Mg,Ti) and MCP (LiF:Mg,Cu,P) after exposure to a n-γ mixed field in the fluence range of radiotherapeutic applications. Since a dosimeter pair is required to discriminate the two components of the mixed field, we analyzed the ability of each dosimeter pair to provide the fluence value in the mixed field. At this aim we performed a ⁶⁰Co-γ calibration and a neutron calibration for all three dosimeter types. Finally, a blind test was performed in order to analyze the accuracy of each dosimeter pair and we found that in this mixed field the fluence value obtained through the TLD600-MCP pair is as accurate as the value obtained through the most common TLD600-TLD700 pair.     

Peak shape methods for general order thermoluminescence glow-peaks: A reappraisal

This paper presents a reappraisal of the well known peak shape expressions for calculating the activation energy E in a thermoluminescence (TL) glow-peak. This study leads to new insights as to the meaning of the coefficients used in the original equations. The reappraisal leads to new equations for the coefficients of the peak shape expressions which contain the general order parameter b, instead of the experimentally determined geometrical shape factor which is used in the original equations. Previously only the coefficients for first and second order kinetics were determined on the basis of existing theory and the coefficients for intermediate kinetics order were determined empirically using a linear interpolation-extrapolation method. In the present work the improved peak shape coefficients are evaluated in analytical form as a function of the kinetic order b, by using the general order kinetics expression for the TL intensity. The intrinsic errors in the newly derived expressions for E are evaluated and their relevance to experimental work is discussed in detail. A method for a further improvement of the accuracy of the peak shape methods is suggested.     

UV curing of nanoparticle reinforced acrylates

To improve the surface hardness of radiation cured acrylate coatings, both silica nanoparticles and alumina particles with a few microns in size have been embedded into acrylate formulations. Regular mixing of nanoparticles into acrylate formulations, however, leads to highly viscous solutions inappropriate for coating procedures. The incompatibility of inorganic fillers and organic polymers can be avoided by surface modification of nanoparticles using trialkoxysilanes, which provide an interface between the two dissimilar materials. Nanoparticles modified by methacryloxypropyltrimethoxysilane (MEMO) and vinyltrimethoxysilane (VTMO), both having polymerisation-active groups, may be crosslinked with the acrylate resin. UV curing of the nanocomposites revealed an unexpected lower reactivity of the vinyl groups of VTMO modified silica compared to MEMO grafted on silica. For VTMO modification, DFT calculations showed a decrease of Mulliken atomic charge for the olefinic carbons pointing to a lower reactivity. For UV cured nano/microhybrid composites, a significant improvement of abrasion resistance was obtained.     

Electronic excitations induced modifications of structural and optical properties of ZnO-porous silicon nanocomposites

The influence of swift heavy ion (SHI) irradiation on structural and photoluminescence (PL) properties of ZnO nanocrystallites deposited into porous silicon (PS) templates by the sol-gel process was studied. The ZnO/PS nanocomposites were irradiated using 120 MeV Au ions at different fluences varying from 1 × 10¹² to 1 × 10¹³ ions/cm². The intensity of the X-ray diffraction peaks is suppressed at the high fluence, without evolution of any new peak. The PL emission from PS around 700 nm is found to decrease with increase in ion fluence, while the PL emission from deep level defects of ZnO nanocrystallites is increased with ion fluence. At the highest fluence, the observation of drastic increase in PL emission due to donor/acceptor defects in the region 400-600 nm and suppressions of XRD peaks could be attributed to the defects induced structural modifications of ZnO nanocrystallites.     

Static properties and moisture content properties of polyester fabrics modified by plasma treatment and chemical finishing

Low temperature plasma treatment has been conducted in textile industry and has some success in the dyeing and finishing processes. In this paper, an attempt was made to apply low temperature plasma treatment to improve the anti-static property of polyester fabric. The polyester fabrics were treated under different conditions using low temperature plasma. An Orthogonal Array Testing Strategy was employed to determine the optimum treatment condition. After low temperature plasma treatment, the polyester fabrics were evaluated with different characterisation methods. Under the observation of scanning electron microscope, the surface structure of low temperature plasma-treated polyester fabric was seriously altered. This provided more capacity for polyester to capture moisture and hence increase the dissipation of static charges. The relationship between moisture content and half-life decay time for static charges was studied and the results showed that the increment of moisture content would result in shortening the time for the dissipation of static charges. Moreover, there was a great improvement in the anti-static property of the low temperature plasma-treated polyester fabric after comparing with that of the polyester fabric treated with commercial anti-static finishing agent.     

Rheological study of polypropylene irradiated with polyfunctional monomers

The aim of this paper is to investigate the rheological properties of polypropylene (PP) modified by ionization radiation (gamma rays) in the presence of two different monomers. The samples were mixed in a twin-screw extruder with ethylene glycol dimethacrylate (EGDMA) or trimethylolpropane trimethacrylate (TMPTMA) with concentration in the range of 0.5-5.0 mmol. After that, they were irradiated with 20 kGy dose of gamma radiation. The structural modification of polypropylene was analyzed in the melt state by measuring melt flow rate (MFR), η* (complex viscosity) and G′ (storage modulus) in the angular frequency range of 10⁻¹ to 3 × 10² rad s⁻¹. From the oscillatory rheology data, one could obtain the values of η₀ (zero shear viscosity) that would be related to the molar mass. All results were discussed with respect to the crosslinking and degradation process that occur in the post-reactor treatment to produce controlled rheology polypropylene.The resulting polymeric materials were submitted the cytotoxicity in vitro test by neutral red uptake methodology with NCTC L 929 cell line from American Type Culture Collection bank. All modified PP samples presented no cytotoxicity.     

Physical properties of an alumino-silicate waste form for cesium and strontium

Nuclear fuel reprocessing will be required to sustain nuclear power as a baseload energy supplier for the world. New reprocessing schemes offer an opportunity to develop a better strategy for recycling elements in the fuel and preparing stable waste forms. Advanced strategies could create a waste stream of cesium, strontium, rubidium, and barium. Some physical properties of a waste form containing these elements sintered into bentonite clay were evaluated. We prepared samples loaded to 27% by mass to a density of approximately 3 g/cm³. Sintering temperatures of up to 1000 °C did not result in volatility of cesium. Instead, the crystallinity noticeably increased in the waste form as temperatures increased from 600 to 1000 °C. Assemblages of silicates were formed. Significant water evolved at approximately 600 °C but no other gases were generated at higher temperatures.     

Effect of gamma irradiation on the properties of tyre cords

Gamma irradiation of high tenacity Nylon 6.6 (Ny 66) and polyester (PET) tyre cords was investigated. The untreated and treated tyre cords with different twist levels were irradiated at different dose rates in air. The effects of irradiation on both Ny 66 and PET cords were not found to be depending on the twist levels of the cords. The changes in the mechanical and thermal properties with absorbed dose at two different dose rates were measured. The mechanical properties were observed to deteriorate with increasing dose for Ny 66 cords, whereas remained almost unchanged for PET cords both in greige and dipped forms. Hot shrinkage value for the greige Ny 66 cords was found to be improved, i.e. decreased. This decrease was much lower for greige PET than Ny 66 cords. It is concluded that PET cord has higher radiation resistance than Ny 66 cord and the effects of high energy irradiation on tyre cords have to be taken into consideration during tyre design if pre-vulcanization with high energy radiation is to be applied.     

X-ray photoelectron and Raman spectroscopic studies of MeV proton irradiated graphite

Poly-crystalline graphite samples were irradiated using 2.25 MeV H⁺ ions with a fluence of 2 × 10¹⁷ ions/cm². Magnetic ordering in highly oriented pyrolytic graphite samples have been reported earlier under the similar irradiation conditions [Esquinazi et al., Phys. Rev. Lett. 91 (2003) 227201]. In that study, the authors attribute the observed irradiation induced magnetic ordering to the formation of a mixed sp²-sp³ hybridized carbon atoms. In the present study, we report the X-ray photoelectron and Raman spectroscopic studies on pristine and irradiated samples. Irradiated samples are found to show an increased number of sp³ hybridized carbon atoms. However, the Raman spectrum, specially the second order data, do indicate that the nature of the graphene lattice structure has been preserved in the irradiated samples. The mechanisms for the irradiation induced enhancement in sp³ hybridization are discussed.     

Electron beam irradiation effects on the mechanical, thermal and surface properties of a fluoroelastomer

Fluoroelastomer can be used as a sealing material for different purposes. The aim of this work is the evaluation of the effects of the ionizing radiation of an electron beam (EB) on the mechanical, thermal and surface properties of a commercial fluoroelastomer containing carbon black and inorganic fillers. The material was irradiated with overall doses between 10 and 250 kGy. Tensile strength (stress and strain at break), hardness (Shore A) and compression set were evaluated. Thermal behavior was evaluated by thermogravimetric analysis and differential scanning calorimetry. Surface modifications were inspected using scanning electron microscopy (SEM) and optical microscopy. The experiments have shown that EB irradiation promotes beneficial changes in the fluoroelastomer tensile strength behavior while compression set remain constant and the glass transition temperature increases. The SEM micrographs have shown compactness in the irradiated samples, although optical observations showed no surface morphology changes.     

Optical analysis of gel dosimeters: Comparison of Fricke and normoxic polymer gels

The dosimetry method based on optical analysis of gel layers has been experienced utilising both Fricke and polymer (normoxic) gels. The aim of the work was that of investigating the potentiality of a normoxic polymer gel and of performing a further verification of the reliability of Fricke gel dosimeters. Optical absorbance was measured, both with a spectrophotometer and by imaging light transmittance detected with a CCD camera. The results of the study of sensitivity, linearity of the response and reproducibility of the polymer gel dosimeter have shown acceptable performances, except for doses below 2 Gy. The linearity range extends up to 20 Gy. On the other side, dose images and profiles have shown noticeable differences when compared to those calculated or measured with ionisation chambers or Fricke gel dosimeters. Such Fricke dosimeters have given further confirmation of their reliability.     

Analysis of radon, uranium 238 and thorium 232 in potable waters: Dose to adult members of the Moroccan urban population

Uranium (²³⁸U) and thorium (²³²Th) concentrations as well as radon (²²²Rn) and thoron (²²⁰Rn) alpha-activities per unit volume have been measured inside various potable water samples collected from nineteen cities in Morocco by using CR-39 and LR-115 type II solid state nuclear track detectors (SSNTDs). Measured radon alpha-activities ranged from (0.37 ± 0.02) Bq l⁻¹ to (13.6 ± 1.10) Bq l⁻¹ for the potable water samples studied. Alpha-activities due to radon from the ingestion of the studied potable water samples were determined in different compartments of the gastrointestinal system by using the ICRP compartmental model for radon. Annual committed equivalent doses due to radon were evaluated in the gastrointestinal compartments from the ingestion of the potable water samples studied. The influence of the target tissue mass, radon intake and alpha-activity integral due to radon on the annual committed equivalent doses in the gastrointestinal compartments was investigated.