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In this contribution, we give a brief overview over the historical development of shell-model-related experimental and theoretical nuclear physics activities at KTH Royal Institute of Technology that benefited from the classic Kuo–Brown interaction and the fundamental insight of Kuo on the core polarization effect. [ABSTRACT FROM AUTHOR]

We investigated isospin splitting in low-energy dipole (LED) states of spherical nuclei such as 40Ca, 90Zr, 132Sn, 208Pb, and several N = 50 isotones using self-consistent Hartree–Fock plus random phase approximation calculations. Our analysis of isovector dipole (IVD) and isoscalar dipole (ISD) strengths, along with transition densities, reveals a clear energy-dependent relationship between IS and IV modes in 40Ca and 90Zr. For 208Pb and 132Sn, LED states show mixed IS + IV characteristics due to different neutron and proton shell structures. In N = 50 isotones, E 1 modes exhibit varying IS and IV properties with smooth transitions as neutron excess increases. Our results suggest that compressional ISD strengths could provide valuable insights into the slope parameter of the nuclear equation of state. The observed dependence on nuclear shell structures and neutron–proton correlations highlights the need for precise measurements and further research in nuclear physics. [ABSTRACT FROM AUTHOR]

Short-range effect on C2, C3, C4 and C5 form factors in the 90Zr atomic nucleus was scrutinized. The charge density of the 90Zr was as well as scrutinized via the 1- and 2-body parts of cluster expansion in collaboration with harmonic functions of single particle. To incorporate the short-range effect in the 2-body part of cluster expansion, the Jastrow formula was used. Here, the core-polarization and model space participations are what lead to the form factors in 90Zr. The transition density of core polarization was calculated using the Tassie form, relying on the charge density. The elements of one body density matrix were determined by performing shell model computations using the computer code OXBASH together with the N50J interaction. The oscillator parameter b and correlation parameter β were applied to the existing calculations, where b and β are autonomously produced for each distinct nucleus by matching between the predicted and actual elastic form factors. A single value for each of b and β must be given for computing the density, elastic and inelastic form factors for diverse states in 90Zr. This work provides confirmation that the short-range effect substantially dominates existing computations, where taking this effect into account appears to be crucial to creating an important modification to the predicated findings which eventually leads to a noteworthy interpretation of the data across all assumed momentum transfers. [ABSTRACT FROM AUTHOR]

In the present work, we aim to study collectivity in the Pb isotopes in the framework of nuclear shell model. We have performed shell-model calculations using KHH7B effective interaction. The model space of KHH7B interaction consists of 14 orbitals. We have reported results for even-even 196 - 206 Pb isotopes for spectra and electromagnetic properties. The shell model results for isomeric states are also reported. Our results will be useful to compare upcoming experimental data. [ABSTRACT FROM AUTHOR]

This paper addresses the challenges of solving the quantum many-body problem, particularly within nuclear physics, through the configuration interaction (CI) method. Large-scale shell model calculations often become computationally infeasible for systems with a large number of valence particles, requiring truncation techniques. We propose truncation methods for the nuclear shell model, in which angular momentum is conserved and rotational symmetry is restored. We introduce the monopole-interaction-based truncation and seniority truncation strategies, designed to reduce the dimension of the calculations. These truncations can be established by considering certain partitions based on their importance and selecting physically meaningful states. We examine these truncations for Sn, Xe, and Pb isotopes, demonstrating their effectiveness in overcoming computational limits. These truncations work well for systems with either a single type of valence nucleon or with both types. With these truncations, we are able to achieve good convergence for the energy at a very small portion of the total dimension. [ABSTRACT FROM AUTHOR]

Dry water (DW) is a relatively new type of fire extinguishing material with a nuclear shell structure. It is advantageous because it contains both dry powder and water mist—which are effective for extinguishing fires—and has extensive research prospects. DW contains a considerable amount of water, and research on the stability of its core shell structure is crucial. Different additives can also be incorporated into DW to improve its fire extinguishing efficiency. This study prepared six distinct DW samples, some of which had various additives. Optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to confirm the shapes and structures of these DW samples. The study determined the fundamental characteristics of the DW samples by examining their bulk densities and particle size distributions. Centrifugation tests and thermogravimetric analyses were conducted to examine the stability and water content of the DW samples. The study also performed a fire extinguishing experiment in a semiopen space to test the fire extinguishing effectiveness of the DW samples. The results revealed that the stability of DW samples was enhanced by gel additives and that their fire extinguishing efficiency could be improved by the various additives. [ABSTRACT FROM AUTHOR]

The aim of this work is to explain how, starting from the orthogonality expression of two polynomials, we deduce the Schrödinger equation and the solution of the N-body problem including two-body correlations as well as the existence of shells. Generated by the behaviour of kinetic energy for a two-body interaction. The quantification of matters is obtained by the application of the weight function algorithm to the statement that two states are independents when their product integrated over the whole space is null leading to a two variables second order differential equation. The Nuclear Shell Model is a consequence of the kinetic energy behaviour for increasing number of nucleons in ground state. It leaves the mean field theory useless. [ABSTRACT FROM AUTHOR]

Experimental and theoretical studies of β electrons (electrons emitted in β-decay transitions) and their β-electron spectra have recently experienced a rapid expansion. These β spectral shapes have been used to study total β spectra of fission-product nuclei in the quest for explanation of the reactor-flux anomalies, and individual β transitions in search for β spectral shapes sensitive to the effective value of the weak axial coupling gA. In the former case the TAGS (total absorption gamma-ray spectroscopy) can be efficiently used to measure the total β spectral shapes and in the latter case dedicated measurements of the involved forbidden nonunique β transitions have been deployed. The fourth-forbidden nonunique decay transitions 113Cd(1/2+g.s → 113In(9/2+g.s and 115In(9/2+g.s 115Sn(1/2+g.s represent theoretically and experimentally much-studied cases where the total β spectra consist of these single transitions. In these particular cases the TAGS method could be used to assess the effective value of gA. In the present work we have identified five more interesting cases where a total β spectrum consists of a single transition. These spectra correspond to second-forbidden nonunique transitions and are gA and/or sNME dependent, where sNME denotes the so-called small relativistic vector nuclear matrix element. These studies have been performed using the nuclear shell model with well established effective Hamiltonians. With this we target to β transitions that would potentially be of high interest for the TAGS and present and future dedicated β -spectrum experiments. [ABSTRACT FROM AUTHOR]

Study of the nuclear structure of nuclides used for medical diagnosis using positron emission tomography (PET) is presented in this work. These nuclides are 11C, 13N, 15O and 18F, which are unstable by emitting β+ particles. They have half-lives of several minutes, which make them suitable radionuclides for PET. These radionuclides are produced through nuclear reactions using a cyclotron.  Studying the nuclear structure of these light nuclides is performed through the shell model. The full space of the p-shell model is used for the p-shell nuclei, and the full space of the sd-shell model for the sd-shell nucleus. The study includes calculations of magnetic moments and quadrupole electric moments. Calculations of form factors are presented to give predictions for future experimental studies. Protons and neutrons’ effective charges are used to include core-polarization effects. The single-particle states used in the calculations are those of the harmonic oscillator potential. Excellent agreement is obtained between the calculated observables and the available experimental data. [ABSTRACT FROM AUTHOR]

The study of nuclear isomer properties and the isomer applications is a current research focus of nuclear physics and nuclear astrophysics. Theoretical description of nuclear isomers, the surrounding states, and the interplay of them becomes an important issue. In this article, we present the projected shell model method for describing excited nuclear states in general, and for treating K-isomers in particular. With some examples, we emphasize how to apply the modern nuclear many-body technique to calculate K-isomers and normal excited states on an equal footing. [ABSTRACT FROM AUTHOR]

The nuclear shell model was used to investigate the bulk properties of lithium isotopes ( 6,7,8,9,11Li), i.e., the ground state density distributions and C0 and C2 components of charge form factors. The theoretical treatment was based on supposing that the Harmonic-oscillator (HO) potential governs the core nucleons while the valence nucleon(s) move through Hulthen potential. Such assumptions were applied for both stable and exotic lithium isotopes. The HO size parameters (bn and bp), the core radii (rc ) and the attenuation parameters (kn and kp) were fixed to recreate the available empirical size radii for lithium isotopes under study. [ABSTRACT FROM AUTHOR]

Neutrinoless double beta decay is a pivotal weak nuclear process that holds the potential to unveil the Majorana nature of neutrinos and predict their absolute masses. In this study, we delve into examining the impact of spin-dependent short-range correlations (SRCs) on the nuclear matrix elements (NMEs) for the light neutrino-exchange mechanism in neutrinoless double beta ( 0 ν β β ) decay of 48 Ca, employing an extensive interacting nuclear shell model. All computations are performed employing the effective shell model Hamiltonian GXPF1A, encompassing the entire f p model space through the closure approximation. Our investigation examines the NMEs' dependencies on factors such as the number of intermediate states, coupled spin-parity attributes of neutrons and protons, neutrino momentum, inter-nucleon separation, and closure energy. This scrutiny is performed with respect to both the conventional Jastrow-type approach of SRCs, employing various parameterizations, and the spin-dependent SRC paradigm. Our findings illuminate a discernible distinction in NMEs induced by spin-dependent SRCs, differing by approximately 10–20% from those computed through the conventional Jastrow-type SRCs, incorporating distinct parameterizations. [ABSTRACT FROM AUTHOR]

High-spin nuclear isomers in N ≈ Z nuclei between doubly magic 40 Ca and 56 Ni provide an excellent testing ground for the nuclear shell model and questions related to isospin symmetry breaking in the vicinity of the proton drip line. The purpose of the present study is to investigate the possibility of weak electromagnetic decay branches along the decay paths of the 6526-keV 10 + isomer in 54 Fe. The isomer was strongly populated by means of the fusion-evaporation reaction 24 Mg( 36 Ar, α 2 p ) 54 m Fe. The Gammasphere array was used to detect γ -ray cascades emitted from the isomeric state. By means of γ γ γ coincidences, weak non-yrast decay branches can be discriminated, with the isomer's half-life confirmed at T 1 / 2 = 363 (4) ns. The yrast 6 1 + → 2 1 +   E 4 cross-over transition was interrogated. The observations are compared with shell-model calculations. [ABSTRACT FROM AUTHOR]

The nuclear shell model is one of the prime many-body methods to study the structure of atomic nuclei, but it is hampered by an exponential scaling on the basis size as the number of particles increases. We present a shell-model quantum circuit design strategy to find nuclear ground states by exploiting an adaptive variational quantum eigensolver algorithm. Our circuit implementation is in excellent agreement with classical shell-model simulations for a dozen of light and medium-mass nuclei, including neon and calcium isotopes. We quantify the circuit depth, width and number of gates to encode realistic shell-model wavefunctions. Our strategy also addresses explicitly energy measurements and the required number of circuits to perform them. Our simulated circuits approach the benchmark results exponentially with a polynomial scaling in quantum resources for each nucleus. This work paves the way for quantum computing shell-model studies across the nuclear chart and our quantum resource quantification may be used in configuration-interaction calculations of other fermionic systems. [ABSTRACT FROM AUTHOR]

In this study, the energy levels, electromagnetic transition probability, and charge density distribution of the 18O nucleus were calculated using the NuShellX@MSU code within the sdpn-shell and using the effective USDEPN and WCPN interactions. The charge density distribution values were also reasonably consistent with existing experimental data. Comparing the theoretical and experimental results indicates that applying the nuclear shell model using the USDEPN and WCPN interactions is successful within the sdpn-shell. [ABSTRACT FROM AUTHOR]

The paper reviews the recent progress in the description of isospin-symmetry breaking within the nuclear shell model and applications to actual problems related to the structure and decay of exotic neutron-deficient nuclei and nuclei along the N = Z line, where N is the neutron number and Z the atomic number. The review recalls the fundamentals of the isospin formalism for two-nucleon and many-nucleon systems, including quantum numbers, the spectrum's structure and selection rules for weak and electromagnetic transitions; and at the end, summarizes experimental signatures of isospin-symmetry breaking effects, which motivated efforts towards the creation of a relevant theoretical framework to describe those phenomena. The main approaches to construct accurate isospin-nonconserving Hamiltonians within the shell model are briefly described and recent advances in the description of the structure and (isospin-forbidden) decay modes of neutron-deficient nuclei are highlighted. The paper reviews major implications of the developed theoretical tools to (i) the fundamental interaction studies on nuclear decays and (ii) the estimation of the rates of nuclear reactions that are important for nuclear astrophysics. The shell model is shown to be one of the most suitable approaches to describing isospin-symmetry breaking in nuclear states at low energies. Further efforts in extending and refining the description to larger model spaces, and in developing first-principle theories to deal with isospin-symmetry breaking in many-nucleon systems, seem to be indispensable steps towards our better understanding of nuclear properties in the precision era. [ABSTRACT FROM AUTHOR]

The ground state density distributions and electron scattering Coulomb form factors of Helium (4,6,8He) and Phosphorate (27,31P) isotopes are investigated in the framework of nuclear shell model. For stable (4He) and (31P) nuclei, the core and valence parts are studied through Harmonic-oscillator (HO) and Hulthen potentials. Correspondingly, for exotic (6,8He) and (27P) nuclei, the HO potential is applied to the core parts only, while the Hulthen potential is applied to valence parts. The parameters for HO and Hulthen are chosen to reproduce the available experimental size radii for all nuclei under study. Finally, the CO component of electron scattering charge form factors are also investigated. Unfortunately, there is no analytic solution to the Hulthen potential except for the states which are harnessed to the current calculation. [ABSTRACT FROM AUTHOR]

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• CoFe 2 O 4 @BaTiO 3 multiferroic fluids were prepared by ball milling method. • HRTEM images confirm the formation of the nuclear shell structure. • When the surfactant is 3-aminopropyltriethoxysilane, the magnetoelectric coupling coefficient is18.07 V/(cm-Oe). In this paper, CoFe 2 O 4 and CoFe 2 O 4 @BaTiO 3 (CFO@BTO) particles were prepared by hydrothermal method and sol-gel method, and the CFO@BTO multiferroic fluids with different surfactants were prepared by ball milling method, respectively. The stability, electric properties, and magnetoelectric coupling properties were investigated. From the XRD experimental results, the pure phase CFO@BTO composite particles were successfully prepared, and the HETEM images verified the core-shell structure. When the surfactant was 3-aminopropyltriethoxysilane, it had a good stability with a sedimentation rate of 4.6 % after 48 h From the dielectric constant as a function of frequency, the average value of the dielectric constant was 4.41. The saturated polarization strength was 8.33 nC/cm2 and the residual polarization strength was 0.91 nC/cm2 as shown in the hysteresis loop. In addition, it had a larger magnetodielectric coefficient (1.54 %) and magnetoelectric coupling coefficient (18.07 V/(cm·Oe)), which provide ideas to further enhance the magnetoelectric coupling effect. [Display omitted] [ABSTRACT FROM AUTHOR]

We evaluate all nuclear matrix elements (NMEs) up to next-to-next-to leading order (N2LO) in chiral effective field theory (χ EFT) for the neutrinoless double-beta (0 ν β β) decay of the nuclei most relevant for experiments, including 76Ge, 100Mo, and 136Xe. We use the proton-neutron quasiparticle random-phase approximation (pnQRPA) and the nuclear shell model to calculate the N2LO NMEs from very low-momentum (ultrasoft) neutrinos and from loop diagrams usually neglected in 0 ν β β studies. Our results indicate that the overall N2LO contribution is centered around − (5 - 10) % for the shell model and + (10 - 15) % for the pnQRPA, with sizable uncertainties due to the scale dependence of the ultrasoft NMEs and the short-range nature of the loop NMEs. The sign discrepancy between many-body methods is common to all studied nuclei and points to the different behavior of the intermediate states of the 0 ν β β decay. Within uncertainties, our results for the ultrasoft NME are of similar size as contributions usually referred to as "beyond the closure approximation". [ABSTRACT FROM AUTHOR]

We investigate the experimental feasibility of detecting second-order double-magnetic dipole (γγ - M 1 M 1) decays from double isobaric analog states (DIAS), which have recently been found to be strongly correlated with the nuclear matrix elements of neutrinoless ββ decay. Using the nuclear shell model, we compute theoretical branching ratios for γγ - M 1 M 1 decays and compare them with other competing processes, such as single- γ decay and proton emission, which represent the dominant decay channels. We also estimate the potential competition from internal conversion and internal pair creation, which can influence the decay dynamics. Additionally, we propose an experimental strategy based on using LaBr 3 scintillators to identify γγ - M 1 M 1 transitions from the DIAS amidst the background of the competing processes. Our approach emphasizes the challenges of isolating the rare γγ - M 1 M 1 decay and suggests ways to enhance the experimental detection sensitivity. Our simulations suggest that it may be possible to access experimentally γγ - M 1 M 1 decays from DIAS, shedding light on the neutrinoless ββ decay nuclear matrix elements. [ABSTRACT FROM AUTHOR]

A direct measurement of the ground-state-to-ground-state electron-capture decay Q value of 95Tc has been performed utilizing the double Penning trap mass spectrometer JYFLTRAP. The Q value was determined to be 1695.92(13) keV by taking advantage of the high resolving power of the phase-imaging ion-cyclotron-resonance technique to resolve the low-lying isomeric state of 95Tc (excitation energy of 38.910(40) keV) from the ground state. The mass excess of 95Tc was measured to be −86015.95(18) keV/c2, exhibiting a precision of about 28 times higher and in agreement with the value from the newest Atomic Mass Evaluation (AME2020). Combined with the nuclear energy-level data for the decay-daughter 95Mo, two potential ultra-low Q -value transitions are identified for future long-term neutrino-mass determination experiments. The atomic self-consistent many-electron Dirac–Hartree–Fock–Slater method and the nuclear shell model have been used to predict the partial half-lives and energy-release distributions for the two transitions. The dominant correction terms related to those processes are considered, including the exchange and overlap corrections, and the shake-up and shake-off effects. The normalized distribution of the released energy in the electron-capture decay of 95Tc to excited states of 95Mo is compared to that of 163Ho currently being used for electron-neutrino-mass determination. [ABSTRACT FROM AUTHOR]

A new algorithm to solve numerically the evolution of empirical shell models of polarizable systems is presented. It employs constrained molecular dynamics to satisfy exactly, at each time step, the crucial condition that the gradient of the potential with respect to the shell degrees of freedom is null. The algorithm is efficient, stable, and, contrary to the available alternatives, it is symplectic and time reversible. A proof-of-principle calculation on a polarizable model for NaCl is presented to illustrate its properties in comparison with the current method, which employs a conjugate-gradient procedure to enforce the null gradient condition. The proposed algorithm is applicable to other cases where a minimum condition on a function of an auxiliary set of driven dynamical variables must be satisfied. [ABSTRACT FROM AUTHOR]

In this paper we present an extension of our nucleosynthesis parameter study within the classical neutrino-driven wind scenario of core-collapse supernovae (ccSNe). The principal aim of this decade-old study was to shine light on the production of the historical 'p-only' isotopes of the light trans-Fe elements in the Solar System (S.S.). One of our earliest key findings was the co-production of neighbouring classical 's-only' and 'r-only' isotopes between Zn (Z = 30) and Ru (Z = 44), alongside the synthesis of light p-isotopes, under similar conditions of a moderately neutron-rich, low-entropy, charged-particle component of Type II SNe wind ejecta. We begin this analysis by expressing the need for nuclear-structure input from detailed spectroscopic experiments and microscopic models in the relevant shape-transition mass region between N = 50 and N = 60. Then, we focus on the unique nucleosynthetic origin of the anomalous isotopic compositions of Zr (Z = 40), Mo (Z = 42) and Ru (Z = 44) in presolar silicon carbide X-grains. In contrast to the interpretation of other studies, we show that these grains do not reflect the signature of a 'clean' stellar scenario but are mixtures of an exotic rapid (r-process like) nucleosynthesis component and different fractions of S.S. material. Thus, the synthesis of these light isotopes through a 'primary' production mode provides further means to revise the abundance estimates of the light trans-Fe elements in the S.S., reducing our dependence on still favoured 'secondary' scenarios like Type Ia SNe or neutron-bursts in exploding massive stars. [ABSTRACT FROM AUTHOR]

Studies of weak interaction in nuclei are important tools for testing different aspects of the fundamental symmetries of the Standard Model. Neutrinoless double beta decay offers an unique venue of investigating the possibility that neutrinos are Majorana fermions and that the lepton number conservation law is violated. Here, I use a shell model approach to calculate the nuclear matrix elements needed to extract the lepton-number-violating parameters of a few nuclei of experimental interest from the latest experimental lower limits of neutrinoless double beta decay half-lives. The analysis presented here could reveal valuable information regarding the dominant neutrinoless double beta decay mechanism if experimental half-life data become available for different isotopes. A complementary shell model analysis of the two-neutrino double beta decay nuclear matrix elements and half-lives is also presented. [ABSTRACT FROM AUTHOR]

We modified the Hfs92 code of the GRASP package in order to describe the magnetic octupole hyperfine interaction. To illustrate the utility of the modified code, we carried out state-of-the-art calculations of the electronic factors of the magnetic octupole hyperfine interaction constants for levels in the ground configuration of the Bi atom. The nuclear magnetic octupole moment of the 209 Bi isotope was extracted by combining old measurements of the hyperfine structures of 6 p 3 4 S 3 / 2 o [Hull, R.; Brink, G. Phys. Rev. A1970, 1, 685] and 2 P 3 / 2 o [Landman, D.A.; Lurio, A. Phys. Rev. A1970, 1, 1330] using the atomic-beam magnetic-resonance technique with our theoretical electronic factors. The present extracted octupole moment was consistent with all the available values but the one obtained in the single-particle nuclear shell model approximation. This observation supports the previous finding that nuclear many-body effects, such as the core polarization, significantly contribute to the nuclear magnetic octupole moment in the case of 209 Bi. [ABSTRACT FROM AUTHOR]

The total and individual multipole moments of magnetic electron scattering form factors in 41 Ca have been investigated using a widely successful model which is the nuclear shell model configurations keeping in mind of 1f7⁄2 subshell as an L-S shell and Millinar, Baymann, Zamick as L-S shell (F7MBZ) to give the model space wave vector. Also, harmonic oscillator wave functions have been used as wave function of a single particle in 1f7⁄2 shell. Nucleus 40Ca as core closed and Core polarization effects have been used as a corrective with first order correction concept to basic computation of L-S shell and the excitement energy has been implemented with 2ћω. The core polarizability effect has been utilized to incorporate the rejected space (core + higher arrangement) via L-S shell with a realism interaction of effective M3Y P2 interaction to connect the model space particles in motion with the spouse (p-h). The two body M3Y interactions have been utilized as an interaction residue to calculate the core polarizability matrix elements. Finally, the theoretical result of the form factor has been compared with the experimental results. [ABSTRACT FROM AUTHOR]

A method for optimizing machine learning hyperparameters in the problem of extrapolation of quantum-mechanical variational calculations is proposed. The method allows us to obtain optimal values of hyperparameters for artificial neural networks. It is shown that deviations of hyperparameters from optimal values worsen the accuracy of predictions. [ABSTRACT FROM AUTHOR]

Level density ρ (E , Q) is derived within the micro-macroscopic approximation (MMA) for a system of strongly interacting Fermi particles with the energy E and additional integrals of motion Q, in line with several topics of the universal and fruitful activity of A. S. Davydov. Within the extended Thomas Fermi and semiclassical periodic orbit theory beyond the Fermi-gas saddle-point method, we obtain ρ ∝ I ν (S) / S ν , where Iν (S) is the modified Bessel function of the entropy S. For small shell-structure contribution, one finds ν = κ/2 + 1, where κ is the number of additional integrals of motion. This integer number is a dimension of Q, Q = {N, Z, ...} for the case of two-component atomic nuclei, where N and Z are the numbers of neutrons and protons, respectively. For much larger shell structure contributions, one obtains ν = κ /2 + 2. The MMA level density ρ reaches the well-known Fermi gas asymptote for large excitation energies and the finite micro-canonical combinatoric limit for low excitation energies. The additional integrals of motion can also be the projection of the angular momentum of a nuclear system for nuclear rotations of deformed nuclei, number of excitons for collective dynamics, and so on. Fitting the MMA total level density ρ(E, Q) for a set of the integrals of motion Q = {N, Z}, to experimental data on a long nuclear isotope chain for low excitation energies, one obtains the results for the inverse level-density parameter K, which differs significantly from those of neutron resonances due to shell, isotopic asymmetry, and pairing effects. [ABSTRACT FROM AUTHOR]

This is a fitting memory for our late friend and colleague Aldo Covello. For many years, he was our host in the series of Spring Seminars which he organized. In these conferences, the shell model was a central subject which was taken very seriously. This paper is written after 70 years of successful shell model calculations of nuclear energies and also various transitions. The beta decay of 14 C has been an enigma. The history and present situation are described. The importance check of any theory to yield the strength of the mirror transition of 14 O is pointed out. [ABSTRACT FROM AUTHOR]

Nuclear shell model is a powerful approach to investigate nuclear structure microscopically. However, the computational cost of shell-model calculations becomes huge in medium-heavy nuclei. I briefly review the theoretical framework and the code developments of the conventional Lanczos diagonalization method for shell-model calculations. In order to go beyond the conventional diagonalization method, the Monte Carlo shell model and the quasiparticle-vacua shell model were introduced. I present some benchmark examples of these models. [ABSTRACT FROM AUTHOR]

A review of recent advances in the study of the energy splitting between excited isobaric analogue states is presented. Some of the experimental developments, and new approaches, associated with spectroscopy of the most proton-rich members of isobaric multiplets, are discussed. The review focuses on the immense impact of the shell-model in the analysis of energy differences and their interpretation in terms of nuclear structure phenomena. [ABSTRACT FROM AUTHOR]

In the present work, we have predicted the half-lives for the β − decay for higher forbidden unique transitions in the mass range of nuclei from A = 40-138. For these transitions, the experimental data for half-lives are not available except for a few cases. The calculations for half-lives are performed within the framework of the nuclear shell model (SM). We have used the effective interactions sdpf-mu, gxpf1a, gwbxg, G-matrix, snet, sn100pn, and jj56pnb to perform the SM calculations in different mass regions. A comprehensive discussion has been made between the SM predicted half-lives and the scaled half-lives from proton-neutron quasiparticle random-phase approximation (pnQRPA). The results of the present study will be useful to plan new experiments to measure half-lives for these higher forbidden unique β − transitions. [ABSTRACT FROM AUTHOR]

Our study employs the nuclear shell model to systematically compute the half-lives of β -decay for nuclei in the mass range of A = 18 − 39 , encompassing the majority of s d shell nuclei. This analysis utilizes the USDB and SDNN Hamiltonians. The theoretical outcomes contain calculations of various parameters such as Q -values, half-lives, excitation energy, log f t values, and branching ratios. We explore these results with axial–vector coupling constant for weak interactions, denoted as g A (= 1. 27) , and κ value (= 6289). We perform calculations of Gamow Teller matrix elements for 116 decay processes to calculate the quenching factor; we found a quenching factor of q = 0. 794 ± 0. 05 for the USDB interaction and q = 0. 815 ± 0. 04 for the SDNN interaction. We have also calculated superallowed transitions 0 + → 0 + for seven nuclei. Further, we have also included the electron capture phase space factor for the required nuclei to calculate the half-lives. This inclusion leads to small contribution in results, particularly for nuclei where electron capture (EC) plays a significant role. The overall results are in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The Nuclear Structure 2024 conference, hosted by the Physics Division of Argonne National Laboratory, celebrated the 75th anniversary of defining the nuclear shell model by Hans Jensen and Maria Goeppert Mayer. Approximately 160 attendees from over 30 institutions and 14 countries participated in the event, which featured 63 talks covering various topics related to nuclear structure. The conference also included social activities and was sponsored by CAEN, Kontron, Skutek, XIA, and Mirion. The next edition of the conference will be hosted by Simon Fraser University and TRIUMF in Vancouver, Canada. [Extracted from the article]

In this work, we calculate the spin structure functions for spin-dependent elastic and inelastic WIMP scattering off 119 Sn and 121 Sb. Estimates for detection rates are also given. 119 Sn and 121 Sb are amenable to nuclear structure calculations using the nuclear shell model (NSM). With the possible exception of 201 Hg, they are the only such nuclei still unexplored theoretically for their potential of inelastic WIMP scattering to a very low excited state. The present calculations were conducted using a state-of-the-art WIMP–nucleus scattering formalism, and the available effective NSM two-body interactions describe the spectroscopic properties of these nuclei reasonably well. Structure functions were found to be high for both nuclei in the case of elastic scattering. Elastic scattering dominated at the zero momentum transfer limit. Detection rate calculations indicated that inelastic scattering was relevant for both nuclei, even surpassing elastic rates for some recoil energies. [ABSTRACT FROM AUTHOR]

In recent years, shell model studies have significantly contributed in improving the nuclear input, required in simulations of the dynamics of astrophysical objects and their associated nucleosynthesis. This review highlights a few examples such as electron capture rates and neutrino-nucleus cross sections, important for the evolution and nucleosynthesis of supernovae. For simulations of rapid neutron-capture (r-process) nucleosynthesis, shell model studies have contributed to an improved understanding of half lives of neutron-rich nuclei with magic neutron numbers and of the nuclear level densities and γ -strength functions that are both relevant for neutron capture rates. [ABSTRACT FROM AUTHOR]

Applications of configuration-mixing methods for nuclei near the proton and neutron drip lines are discussed. A short review of magic numbers is presented. Prospects for advances in the regions of four new "outposts" are highlighted: 28 O, 42 Si, 60 Ca and 78 Ni. Topics include shell gaps, single-particle properties, islands of inversion, collectivity, neutron decay, neutron halos, two-proton decay, effective charge, and quenching in knockout reactions. [ABSTRACT FROM AUTHOR]

In this study, inelastic and elastic form factors for the low-lying excited states of 10B nucleus were calculated utilizing the nuclear shell model theory. We employed a large-basis psd model space with psdmwk interaction and the harmonic oscillator potential in the form factors calculation. The calculated results with the effective charge are in acceptable agreement with experimental results. [ABSTRACT FROM AUTHOR]

In the current study, 92Nb and 92Mo isotopes have been determined for calculating energy levels and electric quadrupole transition probabilities. Two interactions that have been applied in this study are surface delta and modified surface delta interactions. The calculations have been achieved by using appropriate effective charges for proton and neutron as well as parameter length of harmonic potential. Computed results have been compared with the experimental values. After this comparison, energy and the transition probability values have a good agreement with the experimental values, also there are values of the total angular momentum and parity are determined and confirmed for some of the experimental energies, undetermined and unconfirmed experimentally. Theoretically, new values of quadrupole electric transition probabilities have been explored which have not been known in the experimental data. [ABSTRACT FROM AUTHOR]

The possibility of detection of 5.5 MeV and 14.4 keV solar axions by observing axion-induced nuclear and atomic transitions is investigated. The presence of nuclear transitions between spin orbit partners can be manifested by the subsequent deexcitation via gamma ray emissions. The transition rates can also be studied in the context of radiative axion absorption by a nucleus. The elementary interaction is obtained in the context of the axion-quark couplings predicted by existing axion models. Then, these couplings will be transformed to the nucleon level utilizing reasonable existing models, which lead to effective transition operators. Using these operators, we calculate the needed nuclear matrix elements employing wave functions obtained in the context of the nuclear shell model. With these ingredients, we discuss possibilities of experimental observation of the axion-induced nuclear gamma rays. In the second part, we will examine the axion-induced production of X-rays (axion-photon conversion) or ionization from deeply bound electron orbits. In this case, the axion electron coupling is predicted by existing axion models; no renormalization is needed. The experimental signal is the observation of directly produced electrons and/or the emission of hard X-rays and Auger electrons, following the deexcitation of the final atom. Critical discussion is made on the experimental feasibility of detecting the solar axions by using multiton scale NaI detectors. [ABSTRACT FROM AUTHOR]

Some emerging concepts of nuclear structure are overviewed. (i) Background: the many-body quantum structure of atomic nucleus, a complex system comprising protons and neutrons (called nucleons collectively), has been studied largely based on the idea of the quantum liquid (à la Landau), where nucleons are quasiparticles moving in a (mean) potential well, with weak "residual" interactions between nucleons. The potential is rigid in general, although it can be anisotropic. While this view was a good starting point, it is time to look into kaleidoscopic aspects of the nuclear structure brought in by underlying dynamics and nuclear forces. (ii) Methods: exotic features as well as classical issues are investigated from fresh viewpoints based on the shell model and nucleon–nucleon interactions. The 70-year progress of the shell–model approach, including effective nucleon–nucleon interactions, enables us to do this. (iii) Results: we go beyond the picture of the solid potential well by activating the monopole interactions of the nuclear forces. This produces notable consequences in key features such as the shell/magic structure, the shape deformation, the dripline, etc. These consequences are understood with emerging concepts such as shell evolution (including type-II), T-plot, self-organization (for collective bands), triaxial-shape dominance, new dripline mechanism, etc. The resulting predictions and analyses agree with experiment. (iv) Conclusion: atomic nuclei are surprisingly richer objects than initially thought. [ABSTRACT FROM AUTHOR]

Nuclear mass is a key property of atomic nuclei. The accurate determination of nuclear masses provides information for the nuclear shell structure and nuclear deformations. The FRS Ion Catcher experimental setup at GSI, Darmstadt was used to perform mass measurements of 252Cf fragments using a multiple-reflection time-of-flight mass spectrometer. The reported results are compared to previous measurements and their implication in the estimation of two-neutron separation energy is discussed. [ABSTRACT FROM AUTHOR]