Assignment of the spin and parity to the excited states of the (85-86)^Rb nuclei

Background: 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

Revisiting Macro-microscopic Mass Formula using Atomic Mass Evaluation-2020 Data

Background: 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

3He-α Elastic Scattering Phase Shifts in Various Channels Using Phase Function Method with Morse Potential

Background: 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

Heavy cluster radioactivity and decay mode of Superheavy element 306^120

Background: 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

Systematic of Signature Splitting in Ce Nuclei

The 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

Theoretical Investigation of α-decay Chains of Fm-isotopes

Background: 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

Application of R-Matrix and Lagrange-Mesh Methods to Nuclear Transfer Reactions

Background: 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

Iscovector Giant Dipole Resonance in 175Lu Within the Linear Response Theory

We 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

Systematic Compilation/Evaluation of Reduced B(E3) Transition Probabilities and Configurations of Octupole (∆I=3) Isomers in Mass A~200 Region

Background: 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

Investigation for Suitable Target-Projectile combination for Fusion from the Isotopes of Ti and Nd using Intrinsic Fusion and Fission Barriers Analysis

Background: 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