Results 1 - 10 of 18146
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[en] This study explored the zinc-boro-vanadate (ZBV) glass reinforced with AgO to show radiation shielding competencies. A glass system with composition 20ZnO-55BO-(25-x)VO-xAgO, where x ranges from 0 to 10 with the steps of 2.5 mol%, was designed. Some physical and optical calculations were employed to figure out glass density (ρ), molar volume (V), oxygen molar volume (OMV), oxygen packing density (OPD), refractive index (n), dielectric constant (ϵ), and metalization criterion (M) for the glass system of ZBV0 to ZBV10. According to the findings, one can specify that the increasing content of AgO enhanced both the physical and optical features of the ZBV series. The glass density was increased from 3.3150 to 3.6930 g/cm, while the refractive index was raised from 3.0693 to 3.1216 with the insertion ratio of AgO from 0 to 10 mol%. The ZBV10 sample having the maximum AgO of 10 mol% ensured to improve physical and optical properties. The shielding properties of the examined glass samples were investigated to evaluate their ability for radiation protection purposes. The Monte Carlo N-Particle Transport Code 5 (MCNP-5) was utilized to assess the projected gamma photons' average track length on the investigated glass samples. Then, the linear attenuation coefficient (LAC), half-value layer (HVL), transmission factor (TF), and radiation protection efficiency (RPE) were calculated based on the simulated gamma photons' average track length. The obtained results showed that the highest LAC values increased from 71.999 to 91.979 cm. Moreover, the thicker HVL decreased from 9.869 to 9.332 cm, increasing the AgO insertion ratio between 0 and 10 mol%, respectively. The mentioned data confirmed that substitution of the VO by the AgO enhance the gamma-ray shielding capacity of the explored series of glass.
[en] Under the CRP D1.50.19 focusing on the optimization of remediation of radioactive contaminated agricultural land, one important objective is to update the existing decision support system DSS4NAFA to support data management during remediation activities in the aftermath of a nuclear emergency affecting food and agriculture. During remediation, the need exists for keeping an overview of the remediation activities and, in particular, where, when and how these activities are carried out. Further, it is imperative to keep track of the efficiency and effectiveness of remediation activities (e.g. reduction of soil and food contamination). At this moment the workflow for the remediation module is being developed in close collaboration with the CRP D1.50.19 research partners from across the world for addressing the above-mentioned needs for enhanced data management during remediation.
[en] The synthesis of CdTe nanocrystals (NCs) is performed by electrochemical deposition into prepared ion tracks in a a-SiOO/Si-n template. As a result, CdTe NCs are obtained in a wurtzite (WZ) crystal phase. The measurement of the current-voltage characteristics shows that the CdTe (WZ NC)/SiOO/Si system obtained in this way has n-type conductivity. Computer simulations using the CRYSTAL computer code show good agreement between experimental and calculated lattice parameters. The theoretical calculations also show that the crystal has a direct bandgap at the Γ point of the Brillouin zone. (© 2020 Wiley‐VCH GmbH)
[en] This paper presents the swift heavy ions irradiation effects in commercial Gd-doped YBCO (YGdBaCuO) coated conductors irradiated by 1.9 GeV Ta ions with a wide range of ion fluences. Both continuous latent tracks produced by incident ions and nonuniform inclusions induced during film manufacture can be observed from TEM images, proving the existence of mixed-pinning landscapes. Onset critical temperature T is almost unchanged (△T ≈ 0.5 K) when irradiated at optimal fluence of 5.0 × 10 ions/cm, whereas in-field critical current J increased to a factor of more than 2 over a wide range of magnetic field at 77 K. Moreover, the value of α in power-law regime has been reduced to 0.31, compared to 0.72 for pristine sample, indicating slower J decay with magnetic field after Ta ions irradiation. Peak value of J/J curve appears when external magnetic field is near matching field at which the density of vortice equal to ion fluence. Experimental results proving that latent tracks can further enhance in-field current-carrying capability of commercial YBCO coated conductors.
[en] LiF:Mg,Ti detectors show relative efficiency η for heavy charged particles significantly lower than one. It was for a long time not recognised that η varies also for electron energies and, as a consequence for photons. For LiF:Mg,Cu,P detectors measured photon energy response was named 'anomalous' because it differed significantly from the ratio of photon absorption coefficients. The decrease of η was explained as a microdosimetric effect due to local saturation of trapping centres around the electron track. For TLD-100 it was noticed by Horowitz that the measured photon energy response disagrees with the ratio of absorption coefficient by about 10%. It was demonstrated that a fraction of the TL signal in LiF:Mg,Ti is generated in the supralinear dose-response range, due to the high local doses generated by photon-induced tracks. Prediction of TL efficiency is particularly important in space dosimetry and in dosimetry of therapeutic beams like protons or carbon ions. (authors)
[en] Quantitative mechanistic modeling of the biological effects of ionizing radiation has a long rich history. Initially, it was dominated by target theory, which quantifies damage caused by traversal of cellular targets like DNA by ionizing tracks. The discovery that mutagenesis, death and/or altered behavior sometimes occur in cells that were not themselves traversed by any radiation tracks but merely interacted with traversed cells was initially seen as surprising. As more evidence of such 'non-targeted' or 'bystander' effects accumulated, the importance of their contribution to radiation-induced damage became more recognized. Understanding and modeling these processes is important for quantifying and predicting radiation-induced health risks. Here we review the variety of mechanistic mathematical models of non-targeted effects that emerged over the past 2-3 decades. This review is not intended to be exhaustive, but focuses on the main assumptions and approaches shared or distinct between models, and on identifying areas for future research. (authors)
[en] The most used passive detectors for Radon measurement are the CR39s, both for the good stability of the material and for the practicality of use. But, commercial reading systems are expensive and not always fast. The aim of the present work was the development of a method for a rapid, efficient and economic evaluation of the result of the indoor Radon measurement performed with CR39 detectors. The analysis and acquisition of detector images were performed using a photo scanner and the free ImageJ software. Several groups of CR-39 detectors were exposed, developed and analysed. Calibration curve was obtained in a wide range of exposure values (200-12 000 kBq.h.m-3) to allow the procedure to be applied in all possible measurement environments. Furthermore, a statistical study was carried out on the shape and size of nuclear tracks after chemical development. The dependence of the track size on Radon exposure was effective in showing the trace saturation effect as well. (authors)
[en] New physics opportunities are opening up by the Advanced Gamma Tracking Array, AGATA, as it evolves to the full 4π instrument. AGATA is a high-resolution γ-ray spectrometer, solely built from highly segmented high-purity Ge detectors, capable of measuring γ rays from a few tens of keV to beyond 10 MeV, with unprecedented efficiency, excellent position resolution for individual γ-ray interactions, and very high count-rate capability. As a travelling detector AGATA will be employed at all major current and near-future European research facilities delivering stable and radioactive ion beams.
[en] Radon and thoron are natural radioactive gases that tend to accumulate in the indoor environment and one of their major health implications is the ability to cause lung cancer. Present study comprises the quantification of radon and thoron activity concentrations and measurement of gamma exposure rates in different types of dwellings from the endosulfan-affected area, Panathady, Kasaragod district, Kerala. It is observed that, residents of this area were more prone to various diseases and health problems including cancer. The LR-115 type II solid state nuclear track detectors with single entry pin-hole based dosemeters have been used for the measurement of 222Radon and 220Rn activity concentrations. The assessment of radiological parameters such as annual effective doses and excess lifetime cancer risk has also been done in order to understand the dose level and the associated risk. The estimated values have been compared with the limit recommended by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and International Commission on Radiological Protection (ICRP). The average indoor radon and thoron activity concentrations observed in these dwellings were 134 ± 30 and 111 ± 28 Bq m-3, respectively. The estimated activity concentrations, effective doses, etc. are found to be within the recommended level by the UNSCEAR or ICRP. (authors)