Journal of Nuclear Physics, Material Sciences, Radiation and Applications
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Phase Shift Analysis for Neutron-Alpha Elastic Scattering Using Phase Function Method with Local Gaussian Potential
Get PDFBackground: The nucleon-nucleus scattering has been studied using Gaussain potential withspin-orbit term of Thomas type to fit the experimental scattering phase shifts (SPS). Recently,Hulthen potential without spin-orbit term has been utilised for studying α–nucleon scattering with phase function method (PFM).Purpose: The main objectives of this paper are:1. To obtain the best possible interaction potentials that best describe the neutron-α elasticSPS in various channels.2. To compute the partial cross-sections for scattering p-states and the total cross-section forthe reaction.Methods: The local interaction potential is modeled using Gaussian function. The non-localspin orbit term is chosen to be proportional to derivative of local potential. The phase function method has been numerically solved using 5th order Runge-Kutta method to compute the SPS. The model parameters are varied in an iterative fashion to minimise the mean absolute percentage error (MAPE) w.r.t. the experimental SPS.Results:1. The SPS for S, P and D channels have been obtained with MAPE values less than 3%.2. The partial cross-sections for p 1/2 and p 3/2 have been plotted and the respective resonance energies and FWHM have been found to be in reasonable agreement with values in literature.3. The total cross-section for the reaction has been determined and found to be matching well with experimental findings.Conclusions: Gaussian potential with associated spin-orbit term has been shown to be areasonably good choice for explaining the n-α scattering reaction
Low Energy S-Wave Proton-Deuteron Scattering Phase-Shifts using Morse Potential
Get PDFBackground: Study of nucleon-nucleus interaction is important to understand the stabilityof nuclei. At small lab energies ≈ 1-10 MeV, the three body 3He system can be considered asa combination of proton and deuteron two body system. The two body system can be modeled by a local central potential along with Coulomb potential to obtain phase-shifts.Purpose: Molecular Morse potential has been successfully able to calculate scattering phaseshifts of neutron-Deuteron (3He). The main objective of this paper is to test if Morse potential proves to be a good interaction potential to study proton-Deuteron (3He) scattering as well. Methods: The phase function method is solved numerically using RK-5 method for determining the S-wave scattering phase shifts (SPS) for proton-deuteron (p-D) scattering as afunction of proton laboratory energy ranging from 1-10.4 MeV. The model paramters of Morse potential have been varied to obtain best mean absolute percentage error (MAPE) w.r.t. experimental data.Results: The calculated SPS are found to have MAPE less than 3 percent w.r.t experimental phase shifts. Partial scattering cross-section has been determined using the obtained SPS.Conclusions: Morse potential has been found to be successful in explaining interactionbetween proton and deuteron
Assignment of the spin and parity to the excited states of the (85-86)^Rb nuclei
Get PDFBackground: The isotopes of Rb (Z=37) are one proton away from semi-magic (Z=38) proton number and deficits the characteristic of a spherical nucleus. In the 85,86Rb nuclei, the γ-ray spectroscopy are already performed and given an indication of Magnetic Rotation (MR) which usually observed in nearly spherical nuclei. The angular correlation measurements were used to find the spin and parity of the states.Purpose: To confirm the spin and parity of the states in both the nuclei using Directional Correlation of Oriented (DCO) states ratio and polarization asymmetry (Δ) measurements.Methods: The excited states of the 85,86Rb nuclei were populated via the 76Ge(13C,p3n/p2n) reaction at a beam energy of 45 MeV. The γ-rays emitted from the excited states were detected using Indian National Gamma Array (INGA) spectrometer at the Tata Institute of Fundamental Research (TIFR), Mumbai India.Results: The values of the DCO states ratio and polarization asymmetry (Δ) were obtained and utilized to confirm the spin-parity of the states in the 85,86Rb nuclei. The polarization asymmetry (Δ) values were obtained for the first time using Compton-suppressed clover detectors.Conclusions: In 85Rb, the spin and parity of 3491.1-, 4135.4-, 4757.2- and 5419.3 keV levelsare confirmed and for the 5312.2-, 5611.8 and 6335.9 keV states, only the spin is established. The mul-tipolarity assignment of the 224.3-, 331.5-, 732.8-, 778.1-, 865.4-, 973.5-, 1002.4-,1427.5-, 1453.7-, 1598.2-, 1814.1- and 1881.5 keV γ-ray transitions allowed to confirm the spinand parity of most of the levels above the 6- isomer in 86Rb
Iscovector Giant Dipole Resonance in 175Lu Within the Linear Response Theory
Get PDFWe investigate the isovector giant dipole resonance (IVGDR) in a well-deformed odd-even 175Lu within a microscopic approach for giant dipole resonance (GDR) where the linear response by the nuclear density to the dipole radiation is represented through the single-particle wavefunctions calculated with a triaxial Woods-Saxon (WS) potential. The nuclear shape is obtained using the same WS potential in a microscopic-macroscopic approach. The results for the photo-absorption cross-section are compared with the experimental data and show a splitting of GDR strength into K=0 and K=1 components due to large quadrupole deformation. The splitting of the GDR peak is consistent with the experimental data
Theoretical Investigation of α-decay Chains of Fm-isotopes
Get PDFBackground: The theoretical and experimental investigations of decay properties of heavy and superheavy nuclei are crucial to explore the nuclear structure and reaction dynamics.
Purpose: The aim of this study is to probe the α-decay properties of 243Fm and 245Fm isotopic chains using relativistic mean-field (RMF) approach within the framework of preformed cluster-decay model (PCM).
Methods: The RMF densities are folded with the relativistic R3Y NN potential to deduce the nuclear interaction potential between the α particle and daughter nucleus. The penetration probability is calculated within the WKB approximation.
Results: The α-decay half-lives of even-odd 243Fm and 245Fm isotopes and their daughter nuclei are obtained from the preformed cluster-decay model. These theoretically calculated half-lives are found to be in good agreement with the recent experimental measurements.
Conclusions: The novel result here is the applicability of the scaling factor within the PCM as a signature for shell/sub-shell closures in α-decay studies. As such, we have also demonstrated that N=137, 139 and Z=94 corresponding to 231,233Pu could be shell/sub-shell closures. The least T1/2 is found at 243,245Fm which indicate their individual stability and α-decay as their most probable decay mode
Systematic of Signature Splitting in Ce Nuclei
Get PDFThe signature splitting and signature inversion in rotational bands belonging to configurations in even-even deformed 132,134,136Ce nuclei have been studied. These Ce isotopes are interesting candidates to probe for signature of triaxiality. The energy staggering index S(I) is found nearly constant for band 4 and 5 132Ce. similarly, S(I) is also found nearly constant as a function of spin 134 Ce. The observed signature splitting in these two nuclei does not support low K (projection on symmetry axis) value for these bands on the other hand, high K value is not expected for and / orbitals at Z=58. Hence, this low and constant signature splitting is only possible due to triaxiality. However, in 136Ce favored and unfavored partner bands (B1 and B2) Shows normal signature splitting and indicate axially symmetric shape for 136Ce
Heavy cluster radioactivity and decay mode of Superheavy element 306^120
No full textBackground: Many theoretical studies and experimental attempts are conducted to synthesize SHN with Z =120 being an element with a proton magic number. The prediction of the island of stability also encourages scientists to search for the existence of super heavy nuclei near Z=120.Purpose: Main aim of our work is to predict all heavy cluster emissions from superheavy nuclei (SHN) 306120. Methods: Modified Generalized Liquid drop model (MGLDM) with Q value dependent pre-formation factor [Phys. Rev. C, 99, 064604 (2019)] is the theoretical model used to calculate the alpha and cluster decay half-life of SHN 306120. The spontaneous fission half-life is predicted using the shell effect and mass inertia dependent formula by our group [Phys. Rev. C, 104, 024617 (2021)].Results: We investigate all cluster emissions from 306120, and the fragment combination 123Cd (Z=48) leading to 183Hf daughter nucleus is predicted to be a probable heavy cluster decay with halflives comparable with alpha decay half-lives. The heavy cluster 137Xe (N=83) with 169Dy daughter nucleus is predicted to be the most probable cluster decay with the least half-life among all fragment combinations. Thus, our study shows the role of the magic number of proton and neutron in cluster decay. We also predict that the superheavy element 306120 decays by 4 alpha chains followed by spontaneous fission.Conclusions: The predicted half-life in the case of alpha decay and heavy cluster emission from SHN 306120 are within experimental limits and we hope that our predictions will guide future experiments
Application of R-Matrix and Lagrange-Mesh Methods to Nuclear Transfer Reactions
Get PDFBackground: Nuclear transfer reactions are a useful tool to study the structure of a nucleus. For reactions involving weekly bound nuclei, breakup effects can play significant role and theoretical calculations can be computational expensive in such cases.
Purpose: To utilize the Lagrange-mesh and R-matrix methods for nuclear transfer reactions.
Methods: We use the adiabatic distorted wave approximation (ADWA) method which can approximately treats the breakup effects in a simpler manner. In our approach, we apply the R-matrix method combining it with the Lagrange-mesh method, which is known to provide the fast and accurate computations.
Results: As a test case, we calculate the angular distribution of the cross sections for the 54Fe(d,p)55Fe reaction, where deuteron breakup effects play important role.
Conclusions: We show that these methods work well in the ADWA framework, and we look forward to applying these methods in coupled channel calculations
Charge Radius And Neutron Skin Thickness Of Platinum And Osmium Isotopes Near The Nuclear Drip Lines
Get PDFBackground: The density distributions of exotic nuclei are different from that of stable nuclei. For stable nuclei, charge radii can be obtained through electron scattering experiments. The excessive neutrons in neutron-rich nuclei make a decoupling of neutron and proton distribution and as a result nuclear skin structures are appeared.Purpose: The charge radius and the way by which nucleons are distributed can provide information about size, surface thickness and shell structure of nuclei. The information collected from such nuclei can be used for astrophysical studies to understand the origin of heavy elements.
Methods: In the present study, we have made an attempt to investigate the charge radii, rms radii and skin thickness of Pt and Os isotopes. Here, the calculations were made by using the HFB solver which utilizes HO single-particle basis and iteratively diagonalizes the HFB Hamiltonian based on the Skyrme forces.Results: Here we can observe an increase in charge radius, rms radius and skin thickness with neutron number. The charge radii calculated are in good agreement with the experimental data and predictions of RCHB model. A linear dependence of skin thickness on neutron number is observed with the change in slope is noticed around N =126.Conclusion: Using HFB theory, we have analyzed the charge radius and neutron skin thickness of Pt and Os isotopes. The drip line nuclei have larger charge radius in comparison to the stable nuclei. The redistribution of the nucleons due to addition of neutrons leads to the gradual increase in neutron skin. The sudden increase of skin thickness may be due to the extra stability and shell closure around the magic number
Deformation Effect on Proton Bubble Structure in N = 28 Isotones
Get PDFPurpose: To study the effect of nuclear deformation on proton bubble structure of N = 28 isotones and and compare it with the spherical limits. The reduction of depletion fraction due to deformation can be explained by studying the relative differences in the central densities.Methods: In this work, we have employed relativistic Hartree-Bogoliubov (RHB) model withdensity-dependent meson-exchange (DD-ME2) interaction and separable pairing interaction. We have performed axially constrained calculations to investigate the deformed proton bubble structure in 40Mg, 42Si, 44S, and 46Ar, isotones of N = 28 shell closure.Results: We have observed that the nuclear deformation play againsts the formation of bubble structure. In the spherical limits, the isotones of N = 28 shell closure have pronounced bubble structure with large value of depletion fraction. But, the increase in deformation leads to the disappearance of bubble structure. The internal densities in deformed nuclei are found to increase with deformation which can be related to the decrease in depletion fraction.Conclusion: By using RHB model, we have investigated the ground state and proton bubble structure of N = 28 isotones. In 44S, and 46Ar, the 2s1/21d3/2 states get inverted due to the weakning of spin-orbit strength. Due to strong dynamical correlations, arising from deformation, the central depletion of proton density is greatly affected in these isotones. The decrease in depletion fraction can be related to increase in the internal density due to deformatio