Journal of Nuclear Physics, Material Sciences, Radiation and Applications
Not a member yet
238 research outputs found
Sort by
Radiolysis and Thermolysis of Cytosine: Importance in Chemical Evolution
Get PDFAn important aspect of chemical evolution is the study of the stability of organic molecules with biological significance in primitive conditions, especially in the presence of constant energy sources. An example of sets of biologically important organic compounds is nitrogenous bases. The presence of these compounds in prebiotic environments is very important in forming more complex systems, such as nucleic acids, in which nitrogenous bases are an essential component. The aim of the present work is to study the stability of cytosine, a pyrimidine base, in high-radiation fields or at high temperature and to evaluate its recovery. Our results show that the cytosine (1x10-4 M aqueous solution, oxygen-free) decomposed completely at a dose of 22 kGy, and 25% recovery was obtained with a dose of 7.4 kGy. The analysis of irradiated samples was followed by HPLC, HPLC-mass spectrometry and UV-VIS spectroscopy. The main product in both thermolysis and radiolysis was uracil, formed via a deamination reaction. Uracil is another nitrogenous base with biological significance
Nuclear Tracks Morphology Study Using Raman Methodology
Get PDFIn this work, a new methodology for rendering profiles of etched nuclear tracks is presented, using confocal micro-Raman spectrometry instrumentation. The precise profile of etched nuclear tracks with normal and/or angular incidence of the particle can be determined in few minutes, with a great visual and numerical resolution, that means a quantitative and qualitative simultaneous chemical and morphology characterization with the Raman technique. The Raman image routine is designed to acquire at each image pixel a complete Raman spectrum. This is a mapping of the functional groups that form the polymeric structure, which may be broken by the damage caused by the incident radiation and/or the etching process
Semi Empirical Formula For Neutrinoless Double Beta Decay
Get PDFA Semi empirical formula for both phase space factor and Nuclear Matrix Element (NME) is developed for neutrinoless double beta decay, and the formula is used to compute the neutrinoless double beta decay half lives. Thecomputed half lives for neutrinoless double beta decay are compared with the corresponding experimental values and with those predicted by QRPA model. The semi empirical formula predictions are found to be in good agreement with experimental data. The semi empirical formula is used to predict neutrinoless double beta decay of various isotopes Ca, Ge, Se, Zr, Mo, Pd, Cd, Sn, Te, Xe, Nd and Sm that exhibiting single beta decay. As our semi empirical formula predictions agree with the experimental data we hope that the present work will be useful for the future experiments
Shape Transition to a Rare Shape Phase of Prolate Non-collective in A=100 Isobars
Get PDFA theoretical investigation on the shape transitions with neutron number, temperature and spin for A = 100 isobars of Z = 42 to 50 is presented. A variety of shape transitions are observed while moving from neutron rich 100Mo to proton rich 100Sn with predominant triaxiality. Temperature and spin induced shape transitions are explored within the microscopic theoretical framework of statistical theory of hot rotating nuclei. Prolate non-collective – a rare shape phase is reported in this mass region on the proton rich side of the nuclear chart
Nanocomposites for Decontamination of Multicomponent Technogenic Dilutions
Get PDFEmploying model solutions we have tested a new technological method of neutralization of multi-metal containing effluences including low radioactive ones. The proposed approach seamlessly combines the positive properties of both physical chemical methods and nanotechnology using silica-magnetite nanocomposite SiO2/Fe3O4 that is synthesized directly in the man-caused polluted solution (the so-called method of direct sedimentation). The novelty of the method is the absorption of pollutants by the whole volume of synthesized nanoparticles in addition to the absorption of the particles’ surface. After separation of the solid and liquid phases, about 75% Cs, 93% Sr, 97% Cu and 99% Fe+2/ Fe+3 pass from the dispersion medium into a solid phase per one loop. The obtained SiO2/Fe3O4 nanocomposite heated to 1000 °C forms a small size glass phase, which is a reliable matrix for the long-term retention of radionuclides incorporated in the composite’s volume. Thus the approach will allow one to reduce the collected radioactive isotopes to a tiny volume, which means the decrease of land and funds needed to burial radioactive waste
NaI(Tl) Scintillator's Response Functions for Point-like and Distributed Gamma-ray Sources
Get PDFThe response functions of a NaI(Tl) detectors have been estimated using Monte Carlo methods. Response functions were calculated for monoenergetic photon sources (0.05 to 3 MeV). Responses were calculated for point-like sources and for sources distributed in Portland cement cylinders. Calculated responses were used to estimate the detector efficiency for point-like and distributed sources. Samples of cylindrical Portland cement were prepared and exposed to the photoneutron field produced by a 15 MV linac used for radiotherapy. Short half-life radioisotopes were induced and the activity was determined by measuring the pulse-height spectra with a NaI(Tl) g-ray spectrometer that was calibrated using point-like sources. Instead of doing corrections due to differences between the geometry, material and solid angle of point-like sources used for calibration, and the Portland cement cylinders, the detection efficiency was determined using the ratio between the efficiencies for the point-like and the distributed sources estimated with the Monte Carlo calculations, and the activity of the induced isotopes in cement was obtained
Radiochemical Separation and Measurement by Mass Spectrometry with Magnetic Sector with Inductively Coupled Plasma source (ICP-SFMS) of Plutonium Isotopes in Soil Samples
Get PDFThe aim of this work is twofold: to optimize the radiochemical separation of Plutonium (Pu) from soil samples, and to measure the Pu concentration. Soil samples were prepared using acid digestion assisted by microwaves; then, Pu purification was carried out with Pu AG1X8 resin. Pu isotopes were measured using Mass Spectrometry with Magnetic Sector with Inductively Coupled Plasma source (ICP-SFMS). In order to reduce the interference due to the presence of 238UH+ in the samples a desolvation system (Apex) was used. The limit of detection (LOD) of Pu was determined. The efficiency of Pu recovery from soil samples varies from 70 to 93%
Investigation of the Saturation of Elemental Concentration in the Depth Profile of Low Energy Silver Ion Implants in Silicon
Get PDFFor the efficient absorption of light in a broad wavelength band, Si photovoltaic devices require a high concentration of metal atoms at a shallow depth up to a few 10s of nm in the Si substrates. Low energy (< 50 keV) implantation of Ag ions in Si is one of the most suitable synthesis steps to facilitate the formation of these metal nanoclusters at the shallow depths in Si. However, during the low energy implantation of the heavy ions, one of the unintended consequences is the sputtering of target atoms particularly if the target is made of lower Z materials such as Si. In this study, we have investigated the re-distribution of atoms in the target layers due to the surface sputtering effects from 50 keV Ag ion implantation in Si substrates. Initially, the implant profile was estimated with the widely used static simulation code, theStopping and Range of Ions in Matter (SRIM). However, it’s simulation routine lacks any consideration of the fluence dependent evolution of the target material. Therefore, we have explored the use of another ion-solid interaction code T-DYN, which considers the dynamic changes in the thickness and/or composition of the target material during the implantation process. For 50 keV Ag ion implantation in Si, the T-DYN simulation predicts the Ag ion depth profile reaches a maximum or saturation in the concentration at a critical ion fluence of ~7×1016 atoms/cm2, whereas for a more heavier element like Au, similar saturation in the concentration is predicted at a relatively lower fluence of ~4×1016 atoms/cm2. The depth profiles of the implanted Ag atoms extracted from experiments utilizing the Rutherford Backscattering Spectrometry and X-ray Photoelectron Spectroscopy characterization techniques show asymmetric distributions with the position of peak concentration depth gradually moving towards the Si surface with increasing implant ion fluence. Once the implantation ion fluence reached a critical value, the peak value of the elemental concentration is seen saturated similar to the predictions from T-DYN simulations
Emanation Study of Gas Radon on the Ancient Cuexcomate Geyser in Puebla City, Mexico
Get PDFRadon measurements were collected over a period of nine months in the area of the ancient Cuexcomate geyser, in Puebla City. For measuring radon, the passive method of nuclear tracks in solids was used, using polycarbonate CR-39 as radiation sensitive material. Radon concentrations varied in strong anti-correlation with the rainfall intensity. And are lower compared to other locations, in concordance with the stratigraphic composition, as travertine and deposits of volcanic origin, corresponding to the geyser chemical composition and the active environment in the north part of the Trans-Mexican Volcanic Belt with an andesitic and basalt composition
Using Green Fluorescent Protein to Correlate Temperature and Fluorescence Intensity into Bacterial Systems
Get PDFThe unique and stunning spectroscopic properties of Green Fluorescent Protein (GFP) from the jellyfish Aequorea victoria, not to mention of its remarkable structural stability, have made it one of the most widely studied and used molecular tool in medicine, biochemistry, and cell biology. Its high fluorescent quantum yield is due to its chromophore, structure responsible of emitting green visible light when excited at 395 nm. Although it is noteworthy that there is enormous available information of the wonderful luminescent properties of GFP, the fact is that there are features and properties unexplored yet, particulary about its capabilities as molecular reporter in several biological processes. In this work, we used recombinant DNA technology to express the protein in bacteria; prepared the bacterial system both in liquid and solid media, and assembled an experimental set to expose those media to a laser beam; thereby we excited the protein chromophore and used emission spectroscopy in order to observe variations in fluorescence when the bacterial system is exposed to different temperatures