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Journal of Nuclear Physics, Material Sciences, Radiation and Applications
Number of Followers: 6  

  This is an Open Access Journal Open Access journal
ISSN (Print) 2321-8649 - ISSN (Online) 2321-9289
Published by Chitkara University Homepage  [9 journals]
  • Phase Shift Analysis for Alpha-alpha Elastic Scattering using Phase
           Function Method for Gaussian Local Potential

    • Authors: Anil Khachi; O.S.K.S. Sastri, Lalit Kumar, Aditi Sharma
      Abstract: The phase shifts for α- α scattering have been modeled using a two parameter Gaussian local potential. The time independent Schrodinger equation (TISE) has been solved iteratively using Monte-Carlo approach till the S and D bound states of the numerical solution match with the experimental binding energy data in a variational sense. The obtained potential with best fit parameters is taken as input for determining the phase-shifts for the S channel using the non-linear first order differential equation of the phase function method (PFM). It is numerically solved using 5th order Runge-Kutta (RK-5) technique. To determine the phase shifts for the ℓ=2 and 4 scattering state i.e. D and G-channel, the inversion potential parameters have been determined using variational Monte-Carlo (VMC) approach to minimize the realtive mean square error w.r.t. the experimental data.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Heavy Particle Accompanied Fission of 284Og - A Statistical Model Study

    • Authors: S. Subramanian; S. Selvaraj
      Abstract: The structural characteristics of SHN can be investigated through the decay of SHN. In the present work ternary fission of SHN 284Og for two proton magic fixed third fragment 48Ca and 68Ni is studied at three different excitation energies 20, 35 and 50 MeV. Interestingly, 169Yb + 67Ni + 48Ca is having larger yield values and hence it is the most favoured way of fragmentation at intermediate excitation energy 35 MeV. It is observed that, asymmetric fission is favoured over symmetric fission at all the excitation for the third fragment 48Ca. Asymmetric fission is the most favoured with the fragment combination 148Sm + 68Ni + 68Ni for fixed A3 = 68Ni at all the excitations. Unlike the Ca third fragment, near symmetric fission is also favoured with 113Ag + 103Tc + 68Ni for A3 = 68Ni at all the three excitation energies.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Triton Scattering Phase-Shifts for S-wave using Morse Potential

    • Authors: Anil Khachi; Shikha Awasthi, O.S.K.S. Sastri, Lalit Kumar
      Abstract: In this paper, the phase-shifts for neutron-dueteron (n-d) scattering have been determined using the molecular Morse potential as theoretical model of interaction. The Triton (n-d) 2S1/2 ground state initially has been chosen as -7.61 MeV to determine the model parameters using variational Monte-Carlo technique in combination with matrix methods numerical approach to solving the time independent Schrodinger equation (TISE). The obtained potential is incorporated into the phase function equation, which is solved using Runge-Kutta (RK) 4,5 order technique, to calculate the phaseshifts at various lab energies below 15 MeV, for which experimental data is available. The results have been compared with those obtained using another molecular potential named Manning-Rosen (MR) and have been observed to fare better. Finally, the Triton ground state has been chosen as its binding energy (BE), given by -8.481795 MeV, as determined from experimental atomic mass evaluation data and the calculations are repeated. It has been found that these phase-shifts from BE data are slightly better matched with experimental ones as compared to those obtained using -7.61 MeV ground state for Triton (n-d two-body system) modeled using Morse potential.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Comparative Analysis of Woods-Saxon and Yukawa Model Nuclear Potentials

    • Authors: O.S.K.S. Sastri; Aditi Sharma, Swapna Gora, Richa Sharma
      Abstract: In this paper, we model the nuclear potential using Woods-Saxon and Yukawa interaction as the mean field in which each nucleon experiences a central force due to rest of the nucleons. The single particle energy states are obtained by solving the time independent Schrodinger wave equation using matrix diagonalization method with infinite spherical well wave-functions as the basis. The best fit model parameters are obtained by using variational Monte-Carlo algorithm wherein the relative mean-squared error, christened as chi-squared value, is minimized. The universal parameters obtained using Woods-Saxon potential are found to be matched with literature reported data resulting a chi-square value of 0.066 for neutron states and 0.069 for proton states whereas the chi-square value comes out to be 1.98 and 1.57 for neutron and proton states respectively by considering Yukawa potential. To further assess the performance of both the interaction potentials, the model parameters have been optimized for three different groups, light nuclei up to 16O - 56Ni, heavy nuclei 100Sn - 208Pb and all nuclei 16O - 208Pb. It is observed that Yukawa model performed reasonably well for light nuclei but did not give satisfactory results for the other two groups while Woods-Saxon potential gives satisfactory results for all magic nuclei across the periodic table.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Impact of Nuclear Deformation on Neutron Dripline Prediction: A Study of
           Mg Isotopes

    • Authors: Pankaj Kumar; Virender Thakur, Shashi K. Dhiman
      Abstract: We have employed the relativistic Hartree-Bogoliubov (RHB) model with density-dependent meson-exchange interaction and separable pairing to investigate neutron dripline mechanisms for heavy Mg isotopes. In the present study, 40Mg is predicted to be dripline nuclei. The calculations are carried out by taking axial deformation into account. An investigation of shape transition is also done for even-even 32-42Mg isotopes. Our prediction for neutron dripline for 40Mg is consistent with some recent studies.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Study of the Production Cross-Sections of the Neutron-rich 184Ta and 186Ta

    • Authors: Susshma N; Deepa Seetharaman, Gowrishankar Ramadurai
      Abstract: Synthesizing nuclei through reactions that produce a reasonable yield is important for the experimental study of neutron-rich nuclei. In this study, the cross-section values of 184Ta and 186Ta nuclei in various experiments were reviewed and analysed. The experimental data of (n, p), (p, x) and (n, α) reactions were compared to identify the best reaction to produce these nuclei for further study. Our study shows that (n, p) reactions on natural Tungsten targets are the most feasible reactions with a good yield of the neutron-rich Tantalum isotopes. New reactions have been proposed for the effective synthesis of 184Ta and 186Ta using tritium beams on Hafnium targets. The cross-section values of the proposed reactions were calculated by PACE4 software simulations.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Effect of Oriented Nuclei on the Competing Modes of α and One-Proton
           Radioactivities in the Vicinity of Z = 82 Shell Closure

    • Authors: Sarabjeet Kaur; BirBikram Singh, S. K. Patra
      Abstract: The purpose of the present work is to investigate the alpha (α) emission as competing mode of one proton emission using the preformed cluster decay model (PCM). PCM is based on the quantummechanical tunneling mechanism of penetration of the preformed fragments through a potential barrier, calculated within WKB approximation. To explore the competing aspects of α and one proton radioactivity, we have chosen emitters present immediately above and below the Z = 82 shell closure i.e. 177Tl and 185Bi by taking into account the effects of deformations (β2) and orientations of outgoing nuclei. The minimized values of fragmentation potential and maximized values of preformation probability (P0) for proton and alpha fragment demonstrated the crucial role played by even Z - even N daughter and shell closure effect of Z = 82 daughter, in 177Tl and 185Bi, respectively. The higher values of P0 of the one proton further reveal significance of nuclear structure in the proton radioactivity. From the comparison of proton and α decay, we see that the former is heavily dominating with larger values of P0 in comparison to the later. Theoretically calculated half-lives of one proton and α emission for spherical and deformed considerations have also been compared with available experimental data.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Recalculated Viola-Seaborg Coefficients for Partial Alpha Half-lives Based
           on AME2016

    • Authors: Lalit Kumar; Swapna Gora, Vikram Rana, Anil Khachi, O. S. K. S. Sastri
      Abstract: In this paper, the systematics for obtaining the Viola-Seaborg formula (VSF) for logarithmic partial alpha half-lives (Tα1/2) have been undertaken based on the NUBASE2016 evaluation. The constants Az and Bz in Geiger-Nuttal law for determination of Tα1/2 , are obtained using gs-gs transitions data, of even-even nuclei for two sets of nuclei with Z = 84 - 102 and Z = 86 - 98 with N > 126. The Viola-Seaborg co-efficients are determined for both the sets. The obtained parameters for both sets are tested on even-even nuclei for Z ranging from 104 - 118 and it is observed that first set parameters fare better. This formula for estimating α-decay half-lives of heavy nuclei can be extrapolated to predict those of super-heavy nuclei. The logarithmic half-lives Tα1/2 obtained for isotopes of Z = 121 and 122 using current modified VSF (AME2016) are compared with those obtained from theoretical considerations using Coulomb and proximity potential model (CPPM) and observed to be much larger. They are also much larger than those obtained from the previous coefficients based on AME2003 data.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Enhanced Fission Probability of Even-Z Fragments in the Decay of Hot and
           Rotating 210Rn* Compound System

    • Authors: Dalip Singh Verma; Kushmakshi
      Abstract: Mass and charge distribution of the cross-section for the fission fragments obtained in the decay of hot and rotating compound system formed in the reaction 48Ca + 162Dy → 210Rn* at an incident energy 139.6 MeV has been calculated using the dynamical cluster-decay model. Isotopic composition for each element belonging to the symmetric mass region has been obtained. The shell closure at N=50 for light and at Z=50 for heavy mass binary fragments gives a deep minima in the fragmentation potential at touching configuration and governs the fission partition of the compound system. The fission fragments of the symmetric mass region have their dominating presence along with strong odd-even staggering i.e., even-Z fission fragments are more probable than the odd ones, similar to the observed trends of the yield.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Comparative Analysis of 13,14C Induced Reactions on 232Th Target

    • Authors: Manpreet Kaur; BirBikram Singh, Manoj K. Sharma
      Abstract: We have investigated the pairing and magicity effect in context of a comparative study of 13,14C induced reactions on 232Th target at energies in the vicinity of Coulomb barrier. The fission distribution and related properties are explored in terms of the summed-up preformation probabilities. The barrierpenetrability is found to be higher for fragments emitted from 246Cm* formed in 14C+232Th reaction than those emitted in the fission of 245Cm*, leading to higher magnitude of cross-section for earlier case. The DCM calculated fusion-fission cross-sections using ΔR=0 fm are normalised to compare with the available experimental data. The calculations are done for spherical shape of fragments and it will be of further interest to explore the fission mass distribution after the inclusion of deformations.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • T-dependent RMF Model Applied to Ternary Fission Studies

    • Authors: C. Kokila; C. Karthika, M. Balasubramaniam
      Abstract: Ternary decay is comparatively a rare phenomenon. The yield distribution for the thermal neutroninduced fission of 236U was investigated within the Temperature-dependent Relativistic Mean Field (TRMF) approach and statistical theory. Binding energy obtained from TRMF for the ground state and at a specific temperature is used to evaluate the fragment excitation energy, which is needed to calculate the nuclear level density. Using the ternary convolution, the yield for α-accompanied fission of 236U* is calculated. Initial results are presented which shows a maximum yield for the fragment pair Tc + Ag +α. Further, the ternary pre-existence probability for the spontaneous fission of 236U was studied considering fixed third fragments of α,10Be and 14C using the area of the overlapping region. No significant change in the yield distribution was observed when fragment deformations are considered. However, the heavy group for the probable pair remains as 132Sn with a change in mass number of the lighter fragment.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Decay Analysis of 197Tl* Compound Nucleus Formed in 16O + 181Ta Reaction
           at above Barrier Energy Ec.m.~100 MeV

    • Authors: Gayatri Sarkar; Moumita Maiti, Amandeep Kaur, Manoj K. Sharma
      Abstract: The decay dynamics of 197Tl* compound nucleus has been studied within the framework of the dynamical cluster-decay model (DCM) at above barrier energy Ec.m. ≈ 100 MeV using quadrupole deformed configuration of decay fragments. The influence of various nuclear radius parameters on the decay path and mass distributions has been investigated by analysing the fragmentation potential and preformation probability. It is observed that 197Tl* nucleus exhibits the triple-humped mass distribution, independent of nuclear radius choice. The most preferred fission fragments of both fission modes (symmetric and asymmetric) are identified, which lie in the neighborhood of spherical and deformed magic shell closures. Moreover, the modification in the barrier characteristics, such as interaction barrier and interaction radius, is observed with the variation in the radius parameter of decaying fragments and influences the penetrability and fission cross-sections. Finally, the fission cross-sections are calculated for considered choices of nuclear radii, and the results are compared with the available experimental data.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Binary and Ternary Fragmentation Analysis of 252Cf Nucleus using Different
           Nuclear Radii

    • Authors: Nitin Sharma; Manoj K. Sharma
      Abstract: Pioneering study reveals that a radioactive nucleus may split into two or three fragments and the phenomena are known as binary fission and ternary fission respectively. In order to understand the nuclear stability and related structure aspects, it is of huge interest to explore the fragmentation behavior of a radioactive nucleus in binary and ternary decay modes. In view of this, Binary and ternary fission analysis of 252Cf nucleus is carried out using quantum mechanical fragmentation theory (QMFT). The nuclear potential and Coulomb potential are estimated using different versions of radius vector. The fragmentation structure is found to be independent to the choice of fragment radius for binary as well
      as ternary decay paths. The deformation effect is included up to quadrupole (β2) with optimum cold orientations and their influence is explored within binary splitting mode. Moreover, the most probable fission channels explore the role of magic shell effects in binary and ternary fission modes.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Role of Polar vs Non-polar Configurations in the Decay of 268Sg* Compound
           Nucleus Within the Skyrme Energy Density Formalism

    • Authors: Rajni; Kirandeep Sandhu, M. K. Sharma
      Abstract: The effect of polar and non-polar configurations is investigated in the decay of 268Sg* compound nucleus formed via spherical projectile (30Si) and prolate deformed target (238U) using the dynamical cluster decay model. The SSK and GSkI skyrme forces are used to investigate the impact of polar and nonpolar (equatorial) configurations on the preformation probability P0 and consequently on the fission cross-sections of 268Sg* nucleus. For non-polar configuration some secondary peaks corresponding to magic shells Z=28 and N=50 are observed, whose magnitude is significantly suppressed for the polar counterpart. The effect of polar and non-polar configurations is further analyzed in reference to barrier lowering parameter ΔVB. The calculated fission cross-section find adequate agreement with experimental data for chosen set of skyrme forces.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Texture One Zero Model Based on A4 Flavor Symmetry and its Implications to
           Neutrinoless Double Beta Decay

    • Authors: Rishu Verma; Monal Kashav, Ankush, Gazal Sharma, Surender Verma, B. C. Chauhan
      Abstract: Neutrinos are perhaps the most elusive particles in our Universe. Neutrino physics could be counted as a benchmark for various new theories in elementary particle physics and also for the better understanding of the evolution of the Universe. To complete the neutrino picture, the missing information whether it is about their mass or their nature that the neutrinos are Majorana particles could be provided by the observation of a process called neutrinoless double beta (0νββ) decay. Neutrinoless double beta decay is a hypothesised nuclear process in which two neutrons simultaneously decay into protons with no neutrino emission. In this paper we proposed a neutrino mass model based on A4 symmetry group and studied its implications to 0νββ decay. We obtained a lower limit on Mee for inverted hierarchy and which can be probed in 0νββ experiments like SuperNEMO and KamLAND-Zen.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Appearance / Disappearance of Magic Number in Light Nuclei

    • Authors: C. Karthika; C. Kokila, M. Balasubramaniam
      Abstract: The shell structure of a nucleus is important to study their observed characteristic features. The classic magic numbers are successful in explaining the nuclear properties for nuclei lying near the stability line. The advent of radioactive ion beam facilities has permitted to examine nuclei in their extreme proton to neutron ratio. The light exotic nuclei were found to exhibit unique shell closure behaviour which is different from the medium mass nuclei near the stability line. The two nucleon separation energy difference systematics was used as a probe to study the magic character of light nuclei. New proton and neutron magic numbers were predicted among the available even Z isotopes and even N isotones. For certain systems, the classic magic numbers were found to be non-magic, while for some systems the magic property is retained even at the drip lines. The shell closure behaviour predicted is found to depend on the version of the mass table.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Effect of the Width of Gaussian Wave Packets on the Stability of the
           Nuclei

    • Authors: Supriya Goyal
      Abstract: The role of the range of interaction on the stability of the nuclei propagating with and without momentum dependent interactions is analyzed within the framework of Quantum Molecular Dynamics (QMD) model. A detailed study is carried out by taking different equations of state (i.e., static soft and hard and the momentum dependent soft and hard) for the selected nuclei from 12C to 197Au. Comparison is done by using the standard and the double width of the Gaussian wave packets. We find that the effect of the double width of the Gaussian wave packets on the stability of the initial stage nuclei cannot be neglected. The nuclei having double width do not emit free nucleons for a long period of time. Also, the ground state properties of all the nuclei are described well. In the low mass region, the obtained nuclei are less bound but stable. Heavy mass nuclei have proper binding energy and are stable.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Nonfactorizable Contribution to B-Meson Decays to s-Wave Mesons

    • Authors: Maninder Kaur; Supreet Pal Singh , R. C. Verma
      Abstract: Two-body weak decays of bottom mesons into two pseudoscalar and pseudoscalar and vector mesons, are examined under isospin analysis to study nonfactorizable contribution.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Neutron-Proton Scattering Phase Shifts in S-Channel using Phase Function
           Method for Various Two Term Potentials

    • Authors: Anil Khachi; Lalit Kumar, O. S. K. S. Sastri
      Abstract: The scattering phase shifts for n-p scattering have been modeled using various two term exponential type potentials such as Malfliet-Tjon, Manning-Rosen and Morse to study the phase shifts in the S-channels. As a first step, the model arameters for each of the potentials are determined by obtaining binding energy of the deuteron using matrix methods vis-a-vis Variational Monte-Carlo (VMC) technique to minimize the percentage error w.r.t. the experimental value. Then, the first order ODE as given by phase function method (PFM), is numerically solved using 5th order Runge-Kutta (RK-5) technique, by substituting the obtained potentials for calculating phase shifts for the bound 3S1 channel. Finally, the potential parameters are varied in least squares sense using VMC technique to obtain the scattering phase-shifts for each of the potentials in the 1S0 channel. The numerically obtained values are seen to be matching with those obtained using other analytical techniques and a comparative analysis with the experimental values up to 300 MeV is presented.
      PubDate: Tue, 31 Aug 2021 00:00:00 +053
       
  • Simultaneous Grafting of Poly(Acrylic Acid) and Poly(Ethylene Glycol) onto
           Chitosan using Gamma Radiation: Polymer Networks for Removal of Textile
           Dyes

    • Authors: M. D. P. Carreón-Castro; M. Caldera-Villalobos, B. Leal-Acevedo, A. M. Herrera-González
      Abstract: Chitosan is a bio-based polyelectrolyte with high potential for wastewater treatment. Chitosan can remove anionic dyes by adsorption but it has low performance in the removal of cationic dyes. In this work, we report the synthesis of chitosan-based graft-copolymers using gamma radiation. Acrylic acid and poly(ethylene glycol) were grafted successfully onto chitosan applying a radiation dose of 12 kGy at a dose rate of 8 kGyh-1. The grafted-copolymers have improved adsorptive properties for the removal of basic dyes reaching a maximum adsorption capacity higher than 300 mgg-1. The Lanmguir’s isotherm model described satisfactorily the interaction between the grafted copolymers and basic dyes. Freundlich’s isotherm model described the adsorption of anionic dye acid orange 52. The grafted copolymers removed successfully textile dyes from wastewater of the dyeing process. The best results were obtained in the removal of direct and basic dyes. Further, poly(ethylene glycol) grafted on the copolymer conferred better swelling behavior making easy the separation of the adsorbent after dye removal. The results showed that the adsorbent materials synthesized by radiochemical graftcopolymerization are more efficient than the beads, composite materials, and blends of chitosan.
      PubDate: Wed, 10 Feb 2021 15:30:36 +053
       
  • Hydrochemistry and Uranium Concentration in Brackish Groundwater from an
           Arid Zone, Chihuahua, Mexico

    • Authors: Renteria-Villalobos Marusia; Mendieta-Mendoza Aurora, Montero-Cabrera María Elena, Manjón-Collado Guillermo, Galván-Moreno José Antonio
      Abstract: In arid zones, the principal water supply is from groundwater, which can present high concentration of salts, heavy metals, and radioactive elements. The aim of the study was to determine isotopic uranium concentration in groundwater samples with high concentration of salts and its association with other chemical species. Samples were taken from wells with high salt content. The 238,234U radioisotope concentrations were determined by liquid scintillation and alpha-particle spectrometry. In addition, the physical-chemical parameters were recorded in situ; whereas the dissolved ions and elemental composition were measured by UV-Vis and X-ray fluorescence spectrophotometry, respectively. To obtain isotopic uranium concentrations, three radiochemistry procedures were carried out. An ANOVA test was performed to compare the results from procedures, as well as an analysis of Pearson correlation was used between parameters to obtain their associations. Statistically, the U isotopic concentrations did not show differences (p-value 0.82) between procedures. 238U and 234U showed mean concentrations of 6.7 mBq mL-1 and 16.6 mBq mL-1, respectively, with an Activity Ratioby up 7.2. The groundwater under study showed high concentration of TDS, calcium, sulphate, chloride, nitrate, and nitrite. Isotopic U concentrations tend to increase with NO3>Zn>Cl>Br>SO4>Cu>T>SDT>P; meanwhile their contents decrease with T>Cl->NO2>Fe. These findings help us to understand the uranium behavior in groundwater with high salt contents as well as the influence of agricultural supplies on chemical species presents in groundwater.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • GEANT4 Study of Proton–Body Interactions

    • Authors: J. A. López; S. S. Romero González, O. Hernández Rodríguez, J. Holmes, R. Alarcon
      Abstract: Proton therapy uses a beam of protons to destroy cancer cells. A problem of the method is the determination of what part of the body the protons are hitting during the irradiation. In a previous study we determine that by capturing the gamma rays produced during the irradiation one can determine the location of the proton-body interaction, in this work we investigate if by examining the gamma rays produced it is possible to determine the body part that produced the gamma rays by the proton collision. This study uses GEANT4 computer simulations of interactions of proton-tissue, protonbrain, proton-bone, etc., which produce gamma rays, to determine the characteristics of the gamma rays produced. We then analyze the characteristics of the gamma rays to find signatures that could be used to determine the source of the rays. In particular, we study the distribution of gamma ray energies, their full-width half-maximum, energy resolution, maximum height, and total number of counts. This study concludes that it is possible to use the gamma ray spectra to determine what body part produced it.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Optimization of the Position of the CR-39 Polycarbonate Sheet Inside the
           Solid State Track Detector “Measuring Device” Through Computational
           Fluid Dynamics Technique

    • Authors: A. Lima Flores; R. Palomino-Merino, V. M. Castaño, J. I. Golzarri, G. Espinosa
      Abstract: The “measuring device” is one of the most reliable, efficient and economic indoor radon dosimeters that exist. This device was developed by the Proyecto de Aplicaciones de la Dosimetría (PAD) at the Physics Institute of UNAM (IF-UNAM) and consists of a transparent rigid plastic cup, a CR-39 polycarbonate sheet and a standard size metal clip that is used to hold the polycarbonate in the center of the cup. The cup is wrapped and covered with a low-density polyurethane protector in order to prevent the detector from being irradiated by ionizing particles found in the environment. In this work, an analysis was carried out that allowed to understand how the radon concentration on the polycarbonate sheet varies when its height is changed with respect to the base of the plastic cup, in order to understand what position increase the probability of interaction between radon and the surface of the detector. For the development of this work, four computational simulations were performed with the technique called Computational Fluid Dynamics (CFD). The results shows that as the CR-39 is positioned more closed to the base of the cup, the probability of interaction of the radon and the detector increase. Based on these results it is concluded that, when there is a limit in the time in which a measuring device can be placed in the zone where it is desired to quantify indoor radon, it is recommended to collocated the CR-39 at 1 cm with respect to the base of the cup.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Charged Lepton Masses as a Possible CPV Source

    • Authors: O. Félix-Beltrán; J. E. Barradas-Guevara J. E. Barradas-Guevara, F. González-Canales
      Abstract: We realize a model-independent study of the so-called Tri-Bi-Maximal pattern of leptonic flavor mixing. Different charged lepton mass matrix textures are studied. In particular, we are interested in those textures with a minimum number of parameters and that are able to reproduce the current experimental data on neutrino oscillation. The textures studied here form an equivalent class with two texture zeros. We obtain a Tri-Bi-Maximal pattern deviation in terms of the charged leptons masses, leading to a reactor angle and three CP violation phases non-zero. These lastest are one CP violation phase Dirac-like and two phases Majorana-like. Also, we can test the phenomenological implications of the numerical values obtained for the mixing angles and CP violation phases, on the neutrinoless double beta decay, and in the present and upcoming experiments on long-base neutrino oscillation, such as T2K, NOvA, and DUNE.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Formic Acid Ionization and Fragmentation by Multiphoton Absorption

    • Authors: C. Cisneros; T. Bautista, C. F. Betancourt, E. Prieto, A. Guerrero, I. Álvarez
      Abstract: Multiphoton absorption is an intensity dependent nonlinear effect related to the excitation of virtual intermediate states. In the present work, multiphoton ionization and dissociation of the formic acid molecule (HCOOH) by the interaction with photons from 532 Nd: YAG laser at different intensities are discussed, using different carrier gases. The induced fragmentation-ionization patterns show up to 17 fragments and dissociation channels are proposed. Some evidence of small clusters formation and conformational memory from the ratio of the detected products, CO+ and CO2+, on the light of the available results, it is possible to conclude that they arise from trans and cis formic acid. Our results are compared with those obtained in other laboratories under different experimental conditions, some of them show only partial agreement and differences are discussed. Following the Keldysh description it is possible, from our experimental parameters, characterize our results, in the multiphoton absorption regime.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Determination of 234U and 238U Activities in Soil by Liquid Scintillation
           and High-Resolution Alpha Spectrometry

    • Authors: Montero-Cabrera María Elena; Caraveo-Castro Carmen del Rocío, Méndez-García Carmen Grisel, Mendieta-Mendoza Aurora, Rentería-Villalobos Marusia, Cabral-Lares Rocío Magaly
      Abstract: Uranium is a radioactive element with a special presence in the rocks, waters, sediments, soils, and plants at the state of Chihuahua. The activity ratio of 238U/234U is used to explain the uranium transport by surface water and its deposition in arid environments. In this work, the activity concentration of natural U isotopes is determined by PERALS liquid scintillation and high-resolution alpha spectrometry (AS, Canberra camera 7401VR) in the Environmental Radiological Surveillance Laboratory (LVRA) at CIMAV, Chihuahua. Uranium is extracted from soils through the scintillating liquid extractor URAEX for PERALS, with chemical recovery (CR) of 80 - 85 %, and through the ion exchange resin UTEVA + electrode position by the Hallstadius method, with CR of 85 - 90 %, for AS. The procedures of 234U and 238U activity concentration (AC) determination in soils were validated by their application to the certified reference material IAEA-375. The resulting values were in the reference range of the certified or informative values. Both procedures were applied to 6 representative soil samples, with AC of the same order of magnitude or greater, and similar CR and compatible results. Both procedures are satisfactory for the purposes of LVRA research and in general.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Structural Shielding Design of CT Facility using Monte Carlo Simulation

    • Authors: Ashwani Kumar Yadav; Basilia Quispe Huillcara, Pablo Víctor Cerón Ramírez, Modesto Antonio Sosa Aquino, Miguel Ángel Vallejo Hernández
      Abstract: Radiation application in medicine offers extraordinary benefits. But radiation is like a double-edged sword, it has both benefits and associated risks on the community in contact. To justify the safety of workers and members of the public, regulated use of radiation is assessed by the radiation protection protocols. The aim of this study is to design a Computed Tomography (CT) facility with a simplified model of CT scanner, whose shielding follows the guidelines of National Council on Radiation Protection and Measurements (NCRP) Report No. 147. To design the study model, Monte Carlo (MC) radiation transport code in MCNPX 2.6.0 was used for the simulation. Furthermore, MCNPX was used to measure the photon flux in a vicinity or the detector cell. To validate the functioning of the X-ray tube, the experimental results were compared with the X-ray Transition Energies Database of National Institute of Standards and Technology, U.S. Department of Commerce. The results obtained were within 0.60% of relative error. To confirm the functioning of shielding design, radiation protection quantity, air kerma was measured at several points outside, and inside of the CT room and they were under the radiation dose recommended by NCRP, which demonstrates that the shielding design was
      successful in blocking the radiation. The study can be used for an easy evaluation of any CT room within the framework of the model of the study.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Superficial Surface Treatment using Atmospheric Plasma on Recycled Nylon
           6,6

    • Authors: M. Rodríguez; E. Vázquez-Vélez, H. Martinez, A. Torres
      Abstract: Polymers currently represent materials that are cost-effective, while its recycled nature is significant in terms of environmental protection. However, the surface properties of polymers often do not meet the demands of wettability, adhesion, and friction, among others. Atmospheric plasma treatment on the surface of polymers improves its physical-chemistry properties. In this work, a recycled nylon coating was prepared by the spin coating technique and characterized by Fourier transform infrared spectroscopy and X-ray diffraction. This coating was treated by atmospheric plasma, and Raman spectroscopy was performed to analyze the signals related to different functional groups present in the coating surface after plasma treatment. The action of plasma on the surface morphology was observed by scanning electron microscopy. The contact angle results showed an improvement in surface wettability.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Simulation of Dose Estimations from Solar Protons: A PMMA-Bi2O3 Shielding
           Model for Space Exploration

    • Authors: L. Sajo-Bohus; J. A. López, M. Castro-Colin
      Abstract: Adverse effects of long-term exposure to galactic cosmic radiation (GCR) pose a non negligible obstacle for future space exploration programs; the high-LET-particle-rich environment has an adverse effect on human health. Concomitant to GCR we have as well solar particle radiation. Long term space exploration will rely on adequate and highly efficient shielding materials that will reduce exposure of both biosystems and electronic equipment to GCR and solar particles. The shield must attenuate efficiently heavy GCR ions, by breaking them up into less-damaging fragments and secondary radiation: biologically damaging energetic neutrons and highly charged and energetic HZE- particles. An approach to this problem is the development of shielding compounds. Shielding materials should address the conditions of different aspects of a given mission, e.g. time duration and travel path. The Monte Carlo method (GEANT4) is here employed to estimate the effects of a shielding material based on the recently developed Bi2O3-based compound (Cao et al., 2020). In the present study GEANT4 code is used to make estimations of attenuation of solar protons. The objective is to provide some insight about the effect of the new composite shield that has an intrinsic capability for dose reduction.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Changes of the Neutron Flux of the Nuclear Reactor Triga Mark III Since
           the Conversion from High to Low 235U Enrichment

    • Authors: C. Vázquez-López; O. Del Ángel-Gómez, R. Raya-Arredondo, S. S. Cruz-Galindo, J. I. Golzarri-Moreno, G. Espinosa
      Abstract: The neutron flux of the Triga Mark III research reactor was studied using nuclear track detectors. The facility of the National Institute for Nuclear Research (ININ), operates with a new core load of 85 LEU 30/20 (Low Enriched Uranium) fuel elements. The reactor provides a neutron flux around 2 × 1012 n cm-2s-1 at the irradiation channel. In this channel, CR-39 (allyl diglycol policarbonate) Landauer® detectors were exposed to neutrons; the detectors were covered with a 3 mm acrylic sheet for (n, p) reaction. Results show a linear response between the reactor power in the range 0.1 - 7 kW, and the average nuclear track density with data reproducibility and relatively low uncertainty (±5%). The method is a simple technique, fast and reliable procedure to monitor the research reactor operating power levels.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Radon Dose Determination and Radiological Risk in Some Mexican Caves with
           CR-39 Detectors

    • Authors: A. Chavarria; J. I. Golzarri, G. Espinosa
      Abstract: Radon (222Rn) is a radioactive gas, from the 238U decay chain, that contributes in large part of the natural radiation dose to which humans are exposed. Radon is the second cause of lung cancer after tobacco. The US-EPA considers a concentration of 148 Bq/m3 for homes and 400 Bq/m3 for workplaces as the reference level. Caves are closed spaces where 222Rn, which emanates from the surrounding minerals and rocks, can accumulate and reaches large concentrations that can represent a health risk for the guides, speleologists and visitors who spend time in these spaces. This work uses the previously recorded radon concentrations in 8 caves in Mexico and calculates the average dose range and the average annual dose for each of them with the “Wise” public domain program (http://www.wise-uranium.org/rdcrn.html) to determine the level of radiological risk with 2,000 1,000 and 500 working hours per year. Karmidas cave had the highest average 222Rn concentration with 27,633.3 Bq/m3 and for 2,000 working hours per year an average annual dose rate of 347.1 mSv/y. Los Riscos cave had the lowest average concentration with 384.7 Bq/m3 and for 2,000 working hours per year an average annual dose rate of 4.832 mSv/y. These results show that all the caves studied present values,
      with 2,000 working hours per year, that exceed 3 mSv/y for workplaces and must be considered by the people who work in these places. A casual tourist visiting the caves does not present any radiological risk, while guides and speleologists should consider it.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Wear Behavior of a Ni/Co Bilayer Coating by Physical Vapor Deposition on
           AISI 1045 Steel

    • Authors: E. Pardo L; S. E. Rodil, B. Campillo, I. Dominguez, J. G. González-Rodriguez, H. Martinez
      Abstract: Coatings by physical vapor deposition (PVD) have become highly relevant due to their wide range of applications and the rapid rate of coating formation. In this work, AISI steel 1045 was coated with two layers, Ni and Co using the PVD technique. Each coating was deposited with a thickness of 1 μm. After applying the coatings, a post-treatment was applied in an AC plasma reactor using a boron nitride blank in an Ar atmosphere at a pressure of 3 Torr, 0.3 A, and 460 V at 4, 8, and 12h. The post-treatment was characterized by optical emission spectroscopy (OES) in a range of 200-1100 nm. The main species observed by OES were Ar+, N2, N2+, and B+. The coatings on 1045 steel and posttreatment were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Also, were subjected to tribological tests to analyze wear resistance, using the Pin-on-Disk technique. The coatings on steel 1045 present remarkably better wear properties than the uncoated 1045 steel, being the sample post-treated at 4h that showed a lower wear rate.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Study through Geant4, for Time Resolution characterization of different
           detectors arrays coupled with two SiPMs, as a function of: the
           scintillator plastic material, its volumetric dimensions and the location
           of the radiation emission source

    • Authors: C. H. Zepeda Fernández; Hernández Aguilar Javier Efrén, E. Moreno-Barbosa
      Abstract: The high time resolution detectors are relevant in those experiments or simulations were the particles to detect, have a very short time of flight (TOF), and due this it´s required that the detections times are ranged between ns. & ps.
      Using Geant4 software, it was made thirty simulations of coupled detectors to plastic scintillators with two silicon photomultipliers (SiPMs) located on the scintillator’s central sides. To characterize the time resolution, it was required to quantify the optical photons that reach the Score in a certain time, which are generated by muons on the surface of the plastic scintillator. Different configurations of muon beams were simulated at energy of 1 GeV, to interact with the configuration of the scintillator material of its corresponding arrangement. The simulations were made varying three parameters: the scintillator material “BC404 & BC422”, its size, and the location of the radiation source. Fifteen simulations correspond to BC404 material & fifteen simulations to BC422 material respectively. The first five simulations consisted in varying the scintillator’s volumetric size and collocate the muons beam guided randomly distributed over it, the next five simulations differentiate from setting up a directly centered beam, and the last five simulations for guide the beam on the left lower corner of each scintillator.
      The best time resolution achieved was σ= 8.67 +/− 0.26 ps., reported by the detector with BC422 scintillator material which has a volume of 20x20x3 mm3.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Receptor Binding Domain (RBD) Structural Susceptibility in the SARS-CoV-2
           Virus Spike Protein Exposed to a Pulsed Electric Field

    • Authors: D. Osorio-González; V. J. Muñiz-Orozco, C. P. González, M. Fuentes-Acosta, J. Mulia-Rodríguez, L. A. Mandujano-Rosas
      Abstract: SARS-CoV-2 is responsible for causing the Coronavirus disease 2019 (COVID-19) pandemic, which has so far infected more than thirty million people and caused almost a million deaths. For this reason, it has been a priority to stop the transmission of the outbreak through preventive measures, such as surface disinfection, and to establish bases for the design of an effective disinfection technique without chemical components. In this study, we performed in silico analysis to identify the conformational alterations of the SARS-CoV-2 Spike Receptor Binding Domain (RBD) caused by the effect of a pulsed electric field at two different intensities. We found that both stimuli, especially the one with the highest angular frequency and amplitude, modified the electrical charge distribution in the RBD surface and the number of hydrogen bonds. Moreover, the secondary structure was significantly affected, with a decrease of the structured regions, particularly the regions with residues involved in recognizing and interacting with the receptor ACE2. Since many regions suffered conformational changes, we calculated RMSF and ΔRMSF to identify the regions and residues with larger fluctuations and higher flexibility. We found that regions conformed by 353-372, 453-464, and 470-490 amino acid residues fluctuate the most, where the first is considered a therapeutic target, and the last has already
      been characterized for its flexibility. Our results indicate that a pulsed electric field can cause loss of stability in the Spike-RBD, and we were able to identify the vulnerable sites to be used as a starting point for the development of viral inhibition or inactivation mechanisms.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Gamma Irradiation of Aqueos Solution of L-Aspartic Acid, L-Aspartic Acid
           in Solid State, and L-Aspartic Acid Adsorbed into Na-Montmorillonite: Its
           Relevance in Chemistry Prebiotic

    • Authors: A. Meléndez-López; M. F. García-Hurtado, J. Cruz-Castañeda, A. Negrón-Mendoza, S. Ramos-Bernal, A. Heredia
      Abstract: Aspartic acid is an amino acid present in the modern proteins, however, is considered a primitive amino acid hence its importance in prebiotic chemistry experiments studies. In some works of prebiotic chemistry have been studied the synthesis and the stability of organic matter under high energy sources, and the role of clays has been highlighted due to clays that can affect the reaction mechanisms in the radiolytic processes. The present work is focused on the study of the role of Namontmorillonite in the gamma radiolysis processes of L-aspartic acid. Gamma radiolysis processes were carried out in three different systems a) L-aspartic acid in aqueous solution; b) L-aspartic acid in solid-state; and c) L-aspartic acid adsorbed into Na-montmorillonite. L-aspartic acid was analyzed by high-performance liquid chromatography−electrospray ionization−mass spectrometry (HPLCESI-MS). The results showed that the decomposition of L-aspartic acid considerably decreased in the presence of clay thus highlighting the protector role of clays and favors the stability of organic matter even under the possible high energy conditions of primitive environments. The principal product of
      gamma radiolysis of L-aspartic acid was succinic acid produced by deamination reaction. On the other hand, when aspartic acid was irradiated in solid-state the main product was the L-aspartic acid dimer. Both radiolysis products are important for chemical evolution processes for L-aspartic acid in primitive environments.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
  • Surface modification of polyethylene terephthalate (PET) by corona
           discharge plasma

    • Authors: O. Flores; B. Campillo, F. Castillo, H. Martínez, J. Colín
      Abstract: Surface modification of polyethylene terephthalate (PET) was studied by corona discharge plasma at different exposure times using air as working gas. The modification of the surface properties are characterized, those are morphology and wettability. Corona plasma treatment was found to modify the PET surface in both morphology and wettability. The corona discharge at atmospheric pressure is a heterogeneous with multiple current pulses, which generates an asymmetric pattern of erosion on the PET surface. The corona discharge treatment erodes the surface and therefore modifies the surface morphology. The roughness of the PET surface increases in the impact point of the corona discharge on the PET surface. An increase in the wettability of PET was also observed after corona discharge treatment at atmospheric pressure.
      PubDate: Wed, 10 Feb 2021 00:00:00 +053
       
 
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