Journal of Nuclear Physics, Material Sciences, Radiation and Applications
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A Hartree-Fock-Bogoliubov Study on the Pairing Correlations of the Isotopes of Cobalt
Get PDFBackground: The phenomena of nucleon pairing could be outlined from the Bethe-Weizäcker semi-empirical formula, from which the nuclear properties, viz. the binding energy, stability, shape etc. could be clearly sketched. Though the pairing correlation seems to be a small correction to the binding energy term, it plays a determinative role in defining the structure of nuclear systems. The addition to the binding energy in turn affects the position of the isotope on the dripline and hence increases the stability.
Purpose: To study the effects of pairing on the ground state properties of the isotopes of Cobalt.
Methods: We use Hartree-Fock-Bogoliubov (HFB) theory for the study. The general wave functions for the HFB approach are determined from variational principle. The eigen functions for the Hamiltonian are connected with the particle operators through the Bogoliubov transformations. The Hartree-Fock energy is obtained through the minimization of the variational parameter and the HFB equation is solved by iterative diagonalization by restoring the particle number symmetry.
Results: The HFB analysis substantiates the effect of pairing correlation on binding energies, neutron and proton pairing energies, neutron and proton pairing gaps and one- and two-neutron separation energies of the Cobalt isotopes. The binding energies and one and two-neutron separation energies match with the experimental values and for pairing energies and pairing gaps, the regions where pairing is significant and the effects of shell closure at the vicinity of magic configuration of neutrons could be recognized.
Conclusion: The Hartree-Fock-Bogoliubov calculations of the effects of pairing could be used as an efficient tool to study the nuclear structure. It can be ascertained that pairing plays an important role in determining the ground state properties of atomic nuclei
Radii of Thorium Nuclides Lying in Between the Drip Lines
Get PDFBackground: Nuclear rms radii give information about the nuclear structure, nuclear shape, deformation etc. Microscopic methods are widely used for the study of nuclear structure properties. Hartree-Fock method with an effective interaction of Skyrme force is used for studying the nuclear structure properties.Purpose: To calculate the rms radii of proton and neutron for thorium nuclei, lying between the drip lines, by using the microscopic mean field theory. The nuclear rms radii data is useful for identifying the shape variation of thorium nuclei, from proton drip line to neutron drip line. It also helps to identify the trends in nuclear radii variation as we move towards the drip line. This nuclear data will be useful in designing experiments in future and also in understanding the behaviour of complex nuclei. Microscopic study of thorium nuclei is also important in the astrophysical environments.Methods: This study is based on the Skyrme interacting potential in the Hartree-Fock mean field theory. Iterative diagonalization method with the help of a computational code is used for solving the Hartree-Fock equation.Results: We have calculated the rms radii of neutron, proton and their total with SV, SLY4 and UDF2 parametrization of the Skyrme force. Neutron rms radii, proton rms radii and total rms radii of thorium nuclei are found to increase with neutron number. UDF2 parametrization shows an oscillatory nature in the rms radii. This may be due to the shape change of thorium nuclei when adding neutrons.Conclusions: The rms radii of thorium nuclei are found to increase with neutron number. The Skyrme force with UDF2 parametrization is the most suitable one for the structure studies of thorium nuclei
Investigation for Suitable Target-Projectile combination for Fusion from the Isotopes of Ti and Nd using Intrinsic Fusion and Fission Barriers Analysis
Get PDFBackground: A configuration is most suitable for the fusion if it corresponds to a minimum intrinsic fusion barrier and maximum fission barrier.Purpose: To find a suitable target-projectile combination from the isotopes of Ti and Nd by analyzing the intrinsic fusion and fission barriers theoretically by including the deformations up to hexadecapole order.Methods: The fragmentation theory has been used for the calculations. Results: The intrinsic fusion barrier is minimum and fission barrier is maximum for the targetprojectile combination: 43Ti+150Nd in belly-belly configuration, and the inclusion of deformation of higher order leads to the decrease of fission barrier for the prolate shaped cases and compactness for most of the cases.Conclusions: The most suitable target-projectile combination from the isotopes of Ti and Nd for the fusion is 43Ti+150Nd
Study of negative parity Bands in 136 Ce
Get PDFBackground: The band structures of Ce(Z=58) nuclei with A~135 were studied extensively with the physics interest such as triaxiality and rotation like-sequence i.e. shears mechanism etc. The level structures of 136Ce, with 58 protons and 78 neutrons, were predicted to arise from the interaction between valence proton particles above the Z = 50 major shell and four neutron holes in the N = 82 major shell. The γ-ray spectroscopy of 136Ce was performed here for experimental investigations.Purpose: Study the states of two negative parity bands B1 and B2 with band head Iπ = 5- andIπ = 6- with level energy 1979 keV and 2425 keV respectively.
Methods: The excited states of 136Ce are populated via the 124Sn(16O, 4n ) 136Ce fusion evaporation reaction at Ebeam = 90 MeV. The emitted γ-rays from the excited nuclei were detected using the Indian National Gamma Array (INGA) spectrometer at IUAC, New Delhi India.Results: States of two negative parity bands, with band-head Iπ = 5- state at 1979 keV and Iπ = 6- state at 2425 keV have been studied in the present work. The placement of γ-ray transitions of negative parity band B1 has been changed from the earlier reported work and hence the level energy of this band revised and the systematics study of negative parity bands of isotones with N=78, the 136Ce, 134Ba, 138Nd has been carried out.Conclusions: The 806.3 keV γ-ray is found altered with the placement of 971 keV γ-ray transition in the earlier reported work and a 1015.2 keV γ-ray transition is placed in the place of the previously reported 1013 keV γ-ray transition above Iπ = 11- state in band B1. Previously, B1 and B2 bands were predicted as signature partner bands associated with two-quasiparticle, ν[h11/2⊗s1/2/d3/2] configuration. The present work does not support these bands as signature partner bands. Present results are discussed in view of systematics
Revisiting Macro-microscopic Mass Formula using Atomic Mass Evaluation-2020 Data
Get PDFBackground: The macro-microscopic model has been succesful in nuclear mass predictionsand in obtaining various other properties of nuclear and nucleon matter. The present statusof generalised liquid drop model (GLDM) has been based on atomic mass evaluation (AME)-2003 data.Purpose: In this work, the co-efficients of most efficient mass formulae from Royer et.al.,have been re-optimised for 2451 selected nuclei from AME-2020 data.Methods: The root mean squared deviation (RMS) is minimized to optimize seven modelparameters that correspond to various terms in the nuclear binding energy that come inpowers of mass number A and square of relative neutron excess I = N −Z/A .Results: The RMS between the theoretical and experimental binding energies has beenobtained as 0.65 using both the formulae.Conclusions: The best possible formula for nuclear binding energy has been obtained usingAME-2020 data and it needs to be seen how this would effect the various nuclear propertiesand predictions
Evaluation of Natural Radioactivity Levels and Exhalation rate of 222Rn and 220Rn in the Soil Samples from the Kuthiran Hills, Kerala, India
Get PDFBackground: Exposure to radon and its decay products is one of the important contributors of radiation doses to human population. Radon exhalation study is important for understanding the contribution of the soil towards the total radioactivity concentration found inside the dwellings.
Purpose: The aim of the present study is to investigate the radioactivity levels and radium and radon exhalation rates in soil samples collected from Kuthiran hills and nearby places in Thrissur district, Kerala state, India. On the basis of this data, radiological health hazard parameters are also evaluated.
Methods: About 18 soil samples were collected from the study location. The radium, thorium and potassium activity concentrations were analyzed by HPGe gamma ray spectrometer. The “can technique” using LR-115 type II plastic track detectors have been used for the measurement of radon exhalation rate in soil samples.
Results: The mean values of activity concentrations of 226Ra, 232Th and 40K were 64.60 Bqkg-1, 109.03 Bqkg-1and 972.67 Bqkg-1 respectively. The mean value of radon mass exhalation rate is 9.19 mBqkg-1h-1 and thoron surface exhalation rate is and 237.9 mBqm-2s-1. The radium equivalent activity concentration of all the soil samples was below the level of 370 Bqkg-1, recommended for building materials, by OECD 1979 (Organization for Economic Cooperation and Development).
Conclusions: The results show that the study area is safe, as far as the health hazard effects of radium and radon exhalation rate are concerned. This data will be helpful in establishing new regulations and safety limits, related to the radiation dose and radon activity in Kuthiran hills
Systematic Compilation/Evaluation of Reduced B(E3) Transition Probabilities and Configurations of Octupole (∆I=3) Isomers in Mass A~200 Region
No full textBackground: Strong octupole correlations are observed in mass region giving rise to a number of isomeric states decaying via type of transition involving interacting orbitals. Theoretically, the and neutron orbitals or the and proton orbitals are predicted to be involved in these enhanced decays.
Purpose: This work reports on the systematics of reduced transition probabilities and configurations of octupole isomers in order to compare them based on their structures such as even-even, even-odd, odd-even and odd-odd.
Methods: The data for a total of isomers is collected from the ENSDF/XUNDL Database of NNDC. The reduced transition probabilities are evaluated and compiled using the available data on half-life and branching ratios of the isomeric states having pure decay. In about cases, we have also evaluated the half-lives to get their adopted value to obtain the transition probability by RULER program.
Results: A systematic variation in the reduced transition strength is discussed as a function of neutron and proton number to see the contribution/effect from the core particles. An enhancement is observed experimentally for the isomeric states involving the and neutron orbitals or the and proton orbitals
Conclusions: The enhanced transitions rates are observed in nuclei having configurations with octupole effects
3He-α Elastic Scattering Phase Shifts in Various Channels Using Phase Function Method with Morse Potential
Get PDFBackground: Typically 3He-α reaction has been modeled using Gaussian and Hulthen potentials without incorporating the non-local spin-orbit interaction.Purpose: To obtain the scattering phase shifts (SPS) for α-3He radiative capture reaction for partial waves with total angular momentum J = 1/2, 3/2, 5/2, 7/2 having negative parities and J = 1/2 with positive parity, using Morse potential as the model of interaction along with the associated spin-orbit term.Methods: Phase function method is employed for determining phase shifts in an iterative fashion, by making changes to model parameters, to ensure minimisation of mean absolute percentage error (MAPE) w.r.t. the experimental SPS. Results: SPS have been obtained for 1/2+, 1/2-, 3/2-, 5/2- and 7/2- with MAPE values of 3.2, 1.0, 0.8, 17.6 and 6.5 respectively. The corresponding interaction potentials and partial cross-sections have been plotted. The resonance frequencies for the 5/2- and 7/2- scattering states are closely matching with experimental ones.Conclusions: The interaction potentials for different ℓ-channels of 7Be have been constructed by considering Morse potential and spin-orbit terms by considering experimental scattering phase shifts for 3He-alpha reaction
Structural Shielding Design of CT Facility using Monte Carlo Simulation
Get PDFRadiation 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 wassuccessful 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
Wear Behavior of a Ni/Co Bilayer Coating by Physical Vapor Deposition on AISI 1045 Steel
Get PDFCoatings 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