Journal of Nuclear Physics, Material Sciences, Radiation and Applications
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Dependence on the Identification of the Scale Energy Parameter Q 2 in the Quark Distribution Functions for a DIS Production of Za
Get PDFWe discuss the Z-production in a DIS (Deep Inelastic Scattering) process e + p → e + Z + X using the Parton Model, within the context of the Standard Model. In contrast with deep inelastic eP-scattering (e + p → e + X), where the choice of Q2, as the transferred momentum squared, is unambiguous; whereas in the case of boson production , the transferred momentum squared, at quark level, depends on the reaction mechanism (where is the EW interaction taking place). We suggest a proposal based on kinematics of the process considered and the usual criterion for Q2 , which leads to a simple and practical prescription to calculate Z-production via ep-DIS. We also introduce different options in order o perform the convolution of the parton distribution functions (PDFs) and the scattering amplitude of he quark processes. Our aim in this work is to analyze and show how large could be the dependence of the total cross section rates on different possible prescriptions used for the identification of the scale energy parameter Q2 . We present results for the total cross section as a function of the total energy √s of the system ep, in the range 300 <√s ≤ 1300 Ge
Temperature Effects in the Composition of Metal Halide Perovskite thin Films
Get PDFMetal halide perovskites have shown to be a structure with great promise as an efficient photovoltaic, but at the same time it is affected by instability problems that degrade their performance. Degradation mechanisms vary with temperature, moisture, oxidation, and energy conversion during light exposure. We study performance loss due to temperature by probing diffusion of elemental composition across the thickness of films produced by spin coating and for temperatures ranging from 20 to 200°C. X-ray reflectivity was used to identify the electron density, composition, and quality of the films, aided with X-ray fluorescence and X-ray photoelectron spectroscopy studies to obtain information about degradation of the organic phase of the films
Gamma Dosimetry Using Some Dyes in Organic Solvents Solutions at 295 and 77 K
Get PDFThe aim of this work is to study the behavior under irradiation of different dyes (green malachite, methyl orange, red cresol, and bromothymol blue) in organic solvents (acetone and methanol) at different gamma doses and different temperatures to propose them as possible dosimeters for low-temperature applications. For this purpose, organic dissolutions were irradiated with gamma rays in the kiloGray (kGy) range at 77 and 295 K, and the color bleaching of the solutions was followed spectrophotometrically (UV-Vis range). The response curves at different temperatures show the linear range interval from 10 to 40 kGy with correlation coefficients of 0.999 and 0.998 for some systems. This is the main reason to continue carrying out studies that allow the proposal of these systems as chemical dosimeters
Clustering aspects in 20Ne Alpha-conjugate Nuclear System
Get PDFThe clustering aspects in alpha-conjugate nuclear system 20Ne has been investigated comparatively within microscopic and macroscopic approaches of relativistic mean field theory (RMFT) and quantum mechanical fragmentation theory (QMFT), respectively. For the ground state of 20Ne, the matter density distribution calculated within RMFT, depict the trigonal bipyramidal structure of 5α’s and within QMFT, the equivalent α+16O cluster configuration is highly preformed. For excited state corresponding to experimental available energy, the QMFT results show that in addition to α+16O clusters, other xα-type clusters (x is an integer) are also preformed but in addition np-xα type (n, p are neutron and proton, respectively) 10B clusters are having relatively more preformation probability, due to the decreased pairing strength in liquid drop energies at higher temperature. These results are in line with RMFT calculations for intrinsic excited state which show two equal sized fragments, probably 10B clusters
Dose Calibration and Track Diameter Distribution for 241Am-Be Neutron Source, Using CR-39 Nuclear Track Methodology
Get PDFIn neutron detection, the more common method is using electronic instrumentation associate with Bonner spheres, however, currently the Nuclear Tracks Methodology (NTM) is coming popular because of the simplicity, flexibility in size of the detector, no requirement for sophisticated instrumentation and installation, and low cost. In this work, a preliminary result of the dose calibration and track diameter distribution of Americium-Beryllium (241Am-Be) source using Nuclear Track Methodology is presented. As material detector, CR-39 polycarbonate, cut in 1.8 × 0.9 cm2 chips was chosen, and two step chemical etchings after neutron exposure was used to develop the tracks. The irradiations were made in environmental normal conditions, in the ORNL neutron calibration facilities. The CR-39 chips were placed in a phantom, with 3mm plastic (Lexan) sheet in between the source and detectorsto increase the proton generation. The total track density and track diameter distribution was performing in a Counting and Analysis Digital Image System (CADIS), developed at the Institute of Physics of the University of Mexico UNAM. The results are compared with a standard survey instrument and energy reference spectra of the International Atomic Energy Agency (IAEA)
Distinguishing Features of Radioactive Compound Nucleus Decays within the Dynamical Cluster-decay Model
Get PDFIn this paper, we are interested to study the distinguishing features of the decaying radioactive compound nuclei 246Bk* and 220Th*, using the Dynamical Cluster-decay Model (DCM) with deformation β and non-coplanar degree-of-freedom Φ. 246Bk* and 220Th* have so-far been studied within the DCM, using quadrupole deformations (β2i), “optimum” orientations (θopt) of the two nuclei lying in the same plane (Φ=0o), which shows that there is a non-compound nucleus (nCN) content in the observed data. The first turning point Ra (equivalently, the neck-length ∆R in Ra=R1+R2+∆R), which fixes both the preformation and penetration paths, is used to best fit the measured evaporation residue (ER) and fusion-fission (ff) cross sections, σER, σff, respectively, in 220Th* and 246Bk*, formed via different entrance channels. In this work, we subsequently add higher multipole deformations, the octupole and hexadecupole (β3i, β4i), `compact’ orientations θci and Φ≠00, and look for their effects on the nCN contribution predicted by the DCM calculations referenced above
X-Ray Fluorescence Analysis of Ground Coffee
Get PDFCoffee is becoming one of the most popular beverages in Mexico. In the present work, X-ray Fluorescence (XRF) was used to determine the contents of several elements (with atomic numbers between 11 and 38) in 11 samples of commercial ground coffee, comparing with another one of soluble coffee and two of used ground coffee. Samples were dried at room temperature and pelletized. XRF analyses were carried out using a spectrometer based on an Rh X-ray tube, registering the characteristic x-rays with a Silicon Drift Detector. The system detection calibration and accuracy check was performed through the analysis of NIST certified reference materials 1547 (peach leaves), 1570a (spinach leaves), 1573a (tomato leaves), and 1571 (orchid leaves). As a general rule, the elemental concentrations measured are similar in all samples of coffee, in values not exceeding toxic levels. However, the differences among the elemental concentrations are shown
Radiolysis of Nucleosides: Study of Sedimentary Microenvironment Models for the Protection of Bio-Organic Molecules on Early Earth
Get PDFNucleic acid bases and their derivatives are important compounds in biological systems. Many efforts have been made to demonstrate the possible prebiotic origin of these molecules, but the abiotic synthesis of these compounds has proved to be very difficult in that conditions. So, if their synthesis actually took place, a study of their stability in prebiotic conditions is quite relevant in chemical evolution studies. In this work, it has been examined and compared the influence of Sodium Montmorillonite on the chemical transformations undergone by two nucleosides (guanosine –purinic– and uridine, –pyrimidinic–) when subjected to conditions simulating the primitive Earth during the period of chemical evolution. The experiments prove the concentration capacity and protective role against external sources of ionizing radiation (specifically γ-ray) that clays can provide to these specific compounds adsorbed on them. By using X-ray diffraction, UV-vis spectrophotometry and HPLC for the analysis, it was found that purinic nucleosides (more than pyrimidinic) are quickly adsorbed on clay at low pH values, and the temperature of mineral desiccation applied after adsorption promotes their decomposition into their corresponding nitrogenous bases. In both, purinic and pyrimidinic, desorption occurs in neutral or slightly basic aqueous solutions, and both are protected by clay. Pyrimidinic nucleosides show more resistance to heat, but less resistance towards ionizing radiation, even when adsorbed in clay
Radon Exhalation from Industrial Residues as Suitable Additives for Building Materials
Get PDFRadon exhalation from phosphogypsum (PG) and red mud (RM) samples are of environmental concern. The study is oriented to evaluate by different nuclear techniques, industrial materials cumulated in sites at Morón (PG) and Puerto Ordaz (RM) in Venezuela. RM samples and industrial by products are assessed for its potential use as additives in building materials regarding its radiological health risk. Radioactive matter concentration in RM is up to 11.6 kBq.kg-1. Radon concentration range for RM dry powder is between DL and 2.5 kBq.m-³ and for PG is between 105-340 Bq.m-³. Results indicate that industrial by product before it can be used as additive; require remedial actions to lower the environmental impact. Experimental values are compared with locally available cement, bricks and gypsum building materials
Radio-Optically- and Thermally Stimulated Luminescence of Zn(BO2)2:Tb3+ exposed to Ionizing Radiation
Get PDFThe optical absorption of zinc tetraborate at different concentrations of the terbium impurity (0, 0.5, 1, 2, 4, 8 mol%) was analyzed. The radioluminescence (RL) emission spectra was obtained after beta irradiation of a 90Sr/90Y source. The RL spectrum showed the characteristics bands of Tb3+ with two main emissions at 489 nm and 546 nm which corresponding to the5D4→7F6 and 5D4→7F5 transitions respectively in this ion. The OSL and TL characteristics have been analyzed. The stimulation blue light (497 nm) of a diode laser at 500 mA was used to bleach the thermoluminescent (TL) signals obtained with 5Gy of 60Co source. The two main glow peaks (79 and 161 °C) are sensitives under 497 nm stimulation, and they were shifted to higher temperature values and faded their TL intensities. Similar behavior of TL glow curves before and after OSL stimulation with blue light was observed when the samples were exposed to 30 Gy gamma dose of 137Cs irradiator. The OSL signal response was linear with the dose range of 1-10 Gy and increased their response up to 200 Gy gamma dose. The OSL shows a bleaching sensitive shallow traps and diminishing the intensity of the TL glow curves remaining a complex traps distribution. The RL, TL and OSL properties were investigated in Zn(BO2)2:Tb3+ phosphor