Thermoluminescence properties of nanostructured calcium borate as a sensitive radiation dosimeter for high radiation doses

The crystalline calcium tetraborate (CaB4O7) nanoparticles were synthesized using a combination of facile co-precipitation and thermal treatment. The synthesized phosphor nanoparticles were found to possess a monoclinic nanostructure of particle size of about 8 nm. The thermoluminescence (TL) glow curve of the nanoparticles shows a single peak centred at about 150°C. The TL nanophosphor revealed an excellent dosimetric response with a respectable linearity in the dose range of 0.05 to 1000 Gy, which is wider than its counterparts prepared by non nanosynthesis methods. They exhibited good luminescence efficiency and wide range linearity, suggesting the present phosphor nanoparticles may be considered as a suitable candidate for the dosimetric applications

Thermoluminescence characteristics of copper activated calcium borate nanocrystals (CaB4O7:Cu)

The copper activated calcium tetraborate (CaB4O7:Cu) nanophosphor was synthesized by a combination of facile co-precipitation and thermal treatment methods for the first time. Thermoluminescence and dosimetric characteristics of the gamma irradiated CaB4O7:Cu nanophosphor was reported. The glow curves shows two well resolved TL peaks centered at about 120 °C and 260 °C. The copper concentration was varied from 1 to 3 mol% and it was found that the nanocrystalline CaB4O7:Cu with a dopant concentration of 2 mol% has the highest sensitivity among the other dopant concentrations. The results demonstrated that copper can enhance TL efficiency to 2.26 times more than that of un-doped nanocrystalline samples. Moreover, the dose response of the dosimetric peak at 260 °C follows a good linearity up to 3 kGy whereas the linearity of lower temperature peak at 120 °C extended up to 30 Gy. The linearity characteristic of the present nanophosphor suggests it as a candidate towards dosimetric applications

Characterization of fabricated optical fiber for food irradiation dosimetry

Food irradiation is a process carried out in order to improve hygienic quality and germination control, retarding sprouting, also enhancing physical attributes of the food product. In order to provide for food safety, radiation dosimetry in irradiated foods is required. In present studies use is made of germanium doped (Ge-doped) optical fibres of various form and dimensions. The fibres are irradiated using a gamma source irradiator (Gamma Cell 220 Excel), with doses from 1 kGy up to 10 kGy. For the particular Ge-doped optical fibres, investigation has been made of linearity with dose, reproducibility, and fading, intercomparisons being made. The fibres all exhibit TL yields that are linear with dose from 1 kGy up to 10 kGy, exceeding the dose range of all commercial high dose dosimeters used in the food irradiation industry. In respect of the flat fibre dosimeters, the mean reproducibility was found to be within 0.53% to 4.96%, also offering low signal loss (fading), within 13.41% (for fibres of cross-sectional dimensions 60 x 180 μm) to 20.12% (for fibres of cross-sectional dimensions 200 x 750μm), after 22 days of storage

Thermoluminescence studies of manganese doped calcium tetraborate (CaB4O7:Mn) nanocrystal synthesized by co-precipitation method

Manganese (Mn) doped bone-equivalent calcium tetraborate (CaB4O7) nanocrystals were synthesized using co-precipitation and thermal treatment techniques. The synthesized nanophosphors are found to possess the monoclinic structure and have the particle size about 9 nm. They showed good luminescence quantum efficiency and enough potential for radiation dose measurement in medical and industrial purposes. The variation of dopant concentrations was investigated from 0.1 to 2 mol% and it was found that the optimal concentration of 1.4 mol% Mn has the highest sensitivity among other concentrations. The results revealed that Mn enhance the thermoluminescence (TL) sensitivity about 80 times higher than the un-doped samples at 1 kGy and the TL response over a wide range of doses from 0.05 Gy to 2.0 kGy increased linearly with increasing the absorbed dose

Analyzing and sense making of human factors in the Malaysian radiation and nuclear emergency planning framework

The evolution of current Radiation and Nuclear Emergency Planning Framework (RANEPF) simulator emphasizes on the human factors to be analyzed and interpreted according to the stakeholder’s tacit and explicit knowledge. These human factor criteria are analyzed and interpreted according to the “sense making theory” and Disaster Emergency Response Management Information System (DERMIS) design premises. These criteria are corroborated by the statistical criteria. In recent findings, there were no differences of distributions among the stakeholders according to gender and organizational expertise. These criteria are incrementally accepted and agreed the research elements indicated in the respective emergency planning frameworks and simulator (i.e. 78.18 to 84.32, p-value <0.05). This paper suggested these human factors criteria in the associated analyses and theoretical perspectives to be further acomodated in the future simulator development. This development is in conjunction with the proposed hypothesis building of the process factors and responses diagram. We proposed that future work which implies the additional functionality of the simulator, as strategized, condensed and concise, comprehensive public disaster preparedness and intervention guidelines, to be a useful and efficient computer simulation

Facile synthesis of calcium borate nanoparticles and the annealing effect on their structure and size

Calcium borate nanoparticles have been synthesized by a thermal treatment method via facile co-precipitation. Differences of annealing temperature and annealing time and their effects on crystal structure, particle size, size distribution and thermal stability of nanoparticles were investigated. The formation of calcium borate compound was characterized by X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and Thermogravimetry (TGA). The XRD patterns revealed that the co-precipitated samples annealed at 700 °C for 3 h annealing time formed an amorphous structure and the transformation into a crystalline structure only occurred after 5 h annealing time. It was found that the samples annealed at 900 °C are mostly metaborate (CaB2O4) nanoparticles and tetraborate (CaB4O7) nanoparticles only observed at 970 °C, which was confirmed by FTIR. The TEM images indicated that with increasing the annealing time and temperature, the average particle size increases. TGA analysis confirmed the thermal stability of the annealed samples at higher temperatures

Thermoluminescent dosimetry properties of double doped calcium tetraborate (CaB4O7:Cu-Mn) nanophosphor exposed to gamma radiation

This study reports the dosimeteric properties of double Cu–Mn doped calcium tetraborate nanophosphor prepared by co-precipitation technique. The structure and the morphology of the synthesized nanocrystals were characterized by X-ray diffraction and transmission electron microscope. The presented XRD patterns showed the monoclinic structure and transmission electron microscopy revealed the formation of spherical shape nanoparticles with an average particle size of 8 nm. The results demonstrated that the synthesized calcium borate nanophosphor has the highest dosimetric sensitivity at combined concentration of 2% and 1%, copper and manganese molar ratio, respectively. TL glow curve of this material showed two well resolved peaks located at around 124 and 256 °C. The most striking dosimeteric feature of this nanomaterial is the linearity response, which has a long range of 0.05–3000 Gy for both temperature peaks

Germanium-doped optical fiber for real-time radiation dosimetry

Over the past three decades growing demand for individualized in vivo dosimetry and subsequent dose verification has led to the pursuit of newer, novel and economically feasible materials for dosimeters. These materials are to facilitate features such as real-time sensing and fast readouts. In this paper, purposely composed SiO2:Ge optical fiber is presented as a suitable candidate for dosimetry. The optical fiber is meant to take advantage of the RL/OSL technique, providing both online remote monitoring of dose rate, and fast readouts for absorbed dose. A laboratory-assembled OSL reader has been used to acquire the RL/OSL response to LINAC irradiations (6 MV photons). The notable RL characteristics observed include constant level of luminescence for the same dose rate (providing better consistency compared to TLD-500), and linearity of response in the radiotherapy range (1 Gy/min to 6 Gy/min). The OSL curve was found to conform to an exponential decay characteristic (illumination with low LED source). The Ge doping resulted in an effective atomic number, Zeff, of 13.5 (within the bone equivalent range). The SiO2:Ge optical fiber sensor, with efficient coupling, can be a viable solution for in vivo dosimetry, besides a broad range of applications

Thermoluminescence response of ge-doped optical fiber dosimeters with different core sizes

Thermoluminescence (TL) properties of five different core diameter of 6 mol% germanium (Ge) doped optical fibers have been investigated for the purpose of TL dosimetry. The optical fiber dosimeter TL properties is compared with commercially available TLD-100 chips (LiF:Mg,Ti). Samples were irradiated using Cobalt-60 standard radiation source ranging from 1Gy to 10 Gy. These fibers show good linear dose response up to 10 Gy. Highest core diameter of Ge doped optical fiber (core 100 μm) provides the best response among all fibers. We observe the larger core fiber show better response than smaller core fiber. The relative sensitivity of 100 μm core optical fiber is 0.26 ± 0.04 with respect to TLD-100 chip