RESUMEN
In this work, an absolute method to calibrate an α-spectrometer is proposed taking into account the Source-to-Detector, and lateral distances due to eccentric source distribution. An analytical formula to calibrate an α-spectrometer is derived and the Simpson's integration method was utilized to solve these equations in its integral form numerically using a written C computer code. The general Monte Carlo N-particle code, MCNP as well as experimental measurements for some standard α-emitters are used to benchmark the proposed method. An agreement was found between the efficiency results calculated by MC and the proposed method with a maximum relative difference of about 0.5%. While, experimental measurement of α-emitters activity employing the proposed method differs by about 1.65% from the certified values. Accounting for the man made error allows to accurately quantify the assayed sample. Therefore, the inaccuracy in the efficiency results due to non-accurate inputs pertained to the source, and detector radii, Source-Detector distances, and eccentric source distribution are investigated in the Source-to-Detector distance range of (4 to 44 mm). The results show that a difference of ±1% in the detector radius, and Source-to-Detector distance than the normal values yields a relative difference of about ±2%, while a difference of ±50% in the source radius or source lateral distance from detector symmetry axis could only yields inaccuracy of less than ±3% in the efficiency results.
RESUMEN
Heavy-oil fly ash (HOFA) is a graphitic carbon powder extracted in vast amounts as a waste material from burning crude oil in power plants. This HOFA has attractive structural properties besides its high amount of pure carbon (â¼90 wt %). This powder exists in spherical, highly porous micron-sized particles, which implies its great potential as a mechanical reinforcement for different polymers. In this work, HOFA has been utilized to enhance the mechanical properties of epoxy flooring at HOFA weight fractions of 0, 1, 1.6, and 3.2 wt %. The obtained results revealed that the prepared epoxy-flooring/HOFA composites at a HOFA content of 1.6 wt % showed significant mechanical improvements compared with the pristine polymer. The tensile strength and Young's module values were enhanced by â¼17 and 11%, respectively. Furthermore, the neutron-shielding performance was investigated. The composite with 1.6 wt % showed better neutron attenuation and lower transmittance than the pristine epoxy. The chemical resistance was also extensively studied against sodium hydroxide, nitric acid, and sulfuric acid. The changes in morphology, chemical elements, mass, volume, and molecular structures were investigated rigorously for pristine epoxy and its composite with HOFA at 1.6 wt %. After exposure to these chemicals for 21 days, the tested properties of the epoxy-flooring/HOFA composite showed better chemical resistance than that of the pristine epoxy. Where the epoxy-flooring/HOFA composite showed a surface with low cracks and blistering, it showed lesser changes in mass and volume and fewer molecular structure changes. These results indicated that it is possible to use this multifunctional composite for several applications, including the petrochemical industry, radiation shielding, construction, and automobiles.
RESUMEN
In the present work, a thermal treatment technique is applied for the synthesis of CexSn1-xO2 nanoparticles. Using this method has developed understanding of how lower and higher precursor values affect the morphology, structure, and optical properties of CexSn1-xO2 nanoparticles. CexSn1-xO2 nanoparticle synthesis involves a reaction between cerium and tin sources, namely, cerium nitrate hexahydrate and tin (II) chloride dihydrate, respectively, and the capping agent, polyvinylpyrrolidone (PVP). The findings indicate that lower x values yield smaller particle size with a higher energy band gap, while higher x values yield a larger particle size with a smaller energy band gap. Thus, products with lower x values may be suitable for antibacterial activity applications as smaller particles can diffuse through the cell wall faster, while products with higher x values may be suitable for solar cell energy applications as more electrons can be generated at larger particle sizes. The synthesized samples were profiled via a number of methods, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). As revealed by the XRD pattern analysis, the CexSn1-xO2 nanoparticles formed after calcination reflect the cubic fluorite structure and cassiterite-type tetragonal structure of CexSn1-xO2 nanoparticles. Meanwhile, using FT-IR analysis, Ce-O and Sn-O were confirmed as the primary bonds of ready CexSn1-xO2 nanoparticle samples, whilst TEM analysis highlighted that the average particle size was in the range 6-21 nm as the precursor concentration (Ce(NO3)3·6H2O) increased from 0.00 to 1.00. Moreover, the diffuse UV-visible reflectance spectra used to determine the optical band gap based on the Kubelka-Munk equation showed that an increase in x value has caused a decrease in the energy band gap and vice versa.
RESUMEN
The aim of this study is to characterise the neutron flux generated directly behind targets used in medical cyclotrons. The characterisation process aims at determining the feasibility of using the generated neutrons for research purposes in neutron activation analysis. The study was performed by activating gold foils placed directly behind the cyclotron targets. The thermal and epithermal neutron flux were found to be 4.5E+05 ± 8.78E+04 neutrons cm-2 s-1 and 2.13E+06 ± 8.59E+04 neutrons cm-2 s-1, respectively. The flux value is the same order of magnitude listed in the manual produced by the cyclotron manufacturer. The results are encouraging and show high potential for using the cyclotron facility as a thermal neutron source for research purposes. However, it is important radiation protection procedures be followed to ensure the safety of researchers due to the high gamma dose rate measured directly behind the target at 2.46 Sv/h using an OSL chip during the beam on time.
