Measurements of the elastic scattering cross section of ${}^3\mathrm{He}$ and ${}^4\mathrm{He}$ are important in order to improve constraints on theoretical models of ${}^4\mathrm{He}({}^3\mathrm{He},\gamma ){}^7\mathrm{Be}$, a key reaction in Big Bang nucleosynthesis and solar neutrino production. The astrophysical $S$ factor for this reaction is a significant source of uncertainty in the standard-solar-model prediction of the ${}^7\mathrm{Be}$ and ${}^8\mathrm{B}$ solar neutrino fluxes. The elastic scattering measurements reported in the literature do not extend to low energies and lack proper uncertainty quantification. A new measurement of the ${}^4\mathrm{He}({}^3\mathrm{He},{}^3\mathrm{He}){}^4\mathrm{He}$ reaction has been made at center-of-mass energies $E_{\text{c.m.}}=0.38-3.13$ MeV using the Scattering of Nuclei in Inverse Kinematics (SONIK) scattering chamber: a windowless, extended gas target surrounded by an array of 30 collimated silicon charged particle detectors situated at TRIUMF. This is the first elastic scattering measurement of ${}^3\mathrm{He}+{}^4\mathrm{He}$ made below 500 keV and it has greater angular range and better precision than previous measurements. The elastic scattering data were analyzed using both $R$-matrix and halo effective field theory frameworks, and values of the $s$-wave scattering length and effective range were extracted. The resulting improvement in knowledge of the $s$-wave effective-range function at low energies reduces the overall uncertainty in $S_{34}$ at solar energies.

We present measurements of polarized neutron birefringence in transmission through nuclear-polarized ${}^{129}\mathrm{Xe}$ and ${}^{131}\mathrm{Xe}$ gas and determine the neutron incoherent scattering lengths $b_i{(}^{129}\mathrm{Xe})=-0.186\pm {\left(0.021\right)}_{\mathrm{stat}.}\pm {\left(0.004\right)}_{\mathrm{syst}.}\text{fm}$ and $b_i{(}^{131}\mathrm{Xe})=2.09\pm {\left(0.29\right)}_{\mathrm{stat}.}\pm {\left(0.12\right)}_{\mathrm{syst}.}\text{fm}$. These results determine the essential parameter needed for interpretation of spin-dependent neutron-scattering studies on polarized xenon ensembles with possible future applications ranging from tests of time-reversal violation to mode-entangled neutron scattering experiments on nuclear-polarized systems.

In this study, we determine the mass radius of ${}^4\mathrm{He}$, a very light nucleus, by examining the near-threshold $\varphi$-meson photoproduction data of the LEPS Collaboration. To assess the gravitational form factor of ${}^4\mathrm{He}$, we employ multiple models for the mass distribution, including Yukawa-type, exponential, Gaussian, and uniform functions. The mass radius of ${}^4\mathrm{He}$ is measured to be $1.70\pm 0.14$ fm, which is approximately equal to the charge radius of ${}^4\mathrm{He}$. Surprisingly, in contrast to the findings of the proton, no noticeable discrepancy between the charge radius and the mass radius is noted for the ${}^4\mathrm{He}$ nucleus. The proton and neutron distributions within ${}^4\mathrm{He}$ are likely to be identical, confirming its regular tetrahedral structure in a new way. We propose exploring the difference between charge and mass radii as a new approach to examine the nuclear structure.

We report experimental data for excited states of ${}^{72,74}\mathrm{Se}$ obtained from proton removal from ${}^{73,75}\mathrm{Br}$ secondary beams on a proton target. The experiments were performed with the Ursinus-NSCL liquid hydrogen target and the combined $\mathrm{GRETINA}+\mathrm{S}800$ setup at the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory at Michigan State University. Within uncertainties, the inclusive cross sections for proton removal from ${}^{73,75}\mathrm{Br}$ on a proton target are identical suggesting that the same single-particle orbitals contribute to the proton-removal reaction. In addition, details of the partial cross section fragmentation are discussed. The data might suggest that $l=1,2,3$, and 4 angular momentum transfers are important to understand the population of excited states of ${}^{72,74}\mathrm{Se}$ in proton removal. Available data for excited states of ${}^{74}\mathrm{Ge}$ populated through the ${}^{75}\mathrm{As}{(d,{}^3\mathrm{He})}^{74}\mathrm{Ge}$ proton-removal reaction in normal kinematics suggest indeed that the $fp$ and $sd$ shell as well as the $1g_{9/2}$ orbital contribute. A comparison to data available for odd-$A$ nuclei supports that the bulk of the spectroscopic strengths could be found at lower energies in the even-even Se isotopes than in, for instance, the even-even Ge isotopes. In addition, the population of high-$J$ states seems to indicate that multistep processes contribute to proton-removal reactions at intermediate energies in these collective nuclei.

We investigate the formation of a pocket structure in the $\alpha$-nucleus potential based on the dynamic double-folding potential model. We improve the model with the density-dependent Migdal nucleon-nucleon (NN) interaction and combine it with the nuclear medium effect. The improved potential naturally generates a pocket structure at the nuclear surface, which physically agrees with the characteristics suggested by the microscopic many-body calculations. The result reveals that the formation of the pocket structure is due to the strong Pauli repulsion caused by the variation of the NN interaction when the $\alpha$ cluster and the daughter nucleus have large density overlaps. The existence of the nuclear medium effect is essential to the physical self-consistency of the pocket position. These findings highlight the importance of the medium effect on the NN interaction and provide solid theoretical support for the understanding that $\alpha$ clustering occurs at the surface of heavy nuclei.

We probe the existence of the ${}_{{\mathrm{\Lambda }}_c}{}^3\mathrm{H}$ where the $N{\mathrm{\Lambda }}_c$ potentials are derived from the quark-delocalization color-screening model (QDCSM). The $N{\mathrm{\Lambda }}_c$ system is studied and the $N{\mathrm{\Lambda }}_c$ scattering length as well so the effective ranges are obtained in the QDCSM. We construct effective Gaussian-type $N{\mathrm{\Lambda }}_c$ potentials which reproduce the $N{\mathrm{\Lambda }}_c$ scattering data given by the QDCSM. By solving the $NN{\mathrm{\Lambda }}_c$ three-body Schrödinger equation with the Gaussian expansion method, we calculate the energies of the ${}_{{\mathrm{\Lambda }}_c}{}^3\mathrm{H}$ with isospin $I=0$, $J^P=1/2^{+}$ and $I=0$, $J^P=3/2^{+}$ under different color screening parameter $\mu$. The $J^P=1/2^{+}$ and $J^P=3/2^{+}$ states are both bound when the color screening parameter $\mu$ is set to 1.0 ${\mathrm{fm}}^{-2}$ or 1.2 ${\mathrm{fm}}^{-2}$, where the $J^P=1/2^{+}$ state is bound by 0.08–0.85 MeV and the $J^P=3/2^{+}$ state is bound by 0.15–1.31 MeV with respect to the deuteron-${\mathrm{\Lambda }}_c$ threshold.

For the first time, we approach in this work the problem of the renormalization of the Gamow-Teller decay operator for nuclear shell-model calculations by way of many-body perturbation theory, starting from a nuclear Hamiltonian and electroweak currents derived consistently by way of the chiral perturbation theory. These are the inputs we need to construct microscopically the effective shell-model Hamiltonians and decay operators. The goal is to assess the role of both electroweak currents and many-body correlations as the origins of the well-known problem of the quenching of the axial coupling constant $g_A$. To this end, the calculation of observables related to the Gamow-Teller transitions has been performed for several nuclear systems outside the ${}^{40}\mathrm{Ca}$ and ${}^{56}\mathrm{Ni}$ closed cores and compared with the available data.

Low-lying dipole states in the singly closed-shell nucleus ${}^{58}\mathrm{Ni}$ were studied via nuclear resonance fluorescence experiments using a quasimonoenergetic, linearly polarized photon beam. The parity quantum numbers of the dipole states were determined by the intensity asymmetry of resonantly scattered $\gamma$ rays with respect to the polarization plane of the incident photon beam. The electric and magnetic dipole ($E1$ and $M1$) strengths at excitation energies between 5.9 and 9.8 MeV were obtained based on dipole strengths taken from literature. The $E1$ and $M1$ strength distributions were compared with large-scale shell-model predictions in the $fp$ shell using the SDPFSDG-MU interaction.

The nonaxial octupole shape in some nuclei with $N=184$, namely, ${}^{284}\mathrm{Fm}$, ${}^{286}\mathrm{No}$, ${}^{288}\mathrm{Rf}$, and ${}^{290}\mathrm{Sg}$, is investigated using covariant density functional theories. Employing the density-dependent point-coupling covariant density functional theory with the parameter set DD-PC1 in the particle-hole channel, it is found that the ground states of ${}^{284}\mathrm{Fm}$, ${}^{286}\mathrm{No}$, ${}^{288}\mathrm{Rf}$, and ${}^{290}\mathrm{Sg}$ have pure nonaxial octupole shapes with deformation parameters ${\beta }_{31}\approx 0.08$ and ${\beta }_{33}\approx -0.01$ to $-0.03$. The energy gain due to the ${\beta }_{31}$ and ${\beta }_{33}$ distortion is $\approx 1$ MeV. The occurrence of the nonaxial octupole correlations is mainly from the proton orbitals $1i_{13/2}$ and $2f_{7/2}$, which are close to the proton Fermi surface. The dependence of the nonaxial octupole effects on the form of the energy density functional and on the parameter set is also studied.

In this paper we study the mass relation of mirror nuclei with our focus on pairing and shell effects in the Coulomb energy. We present an accurate mass formula for neutron-deficient nuclei with mass number $A>20$ that achieves a root-mean square deviation (RMSD) of 70 keV when compared to experimental data from AME2020, and the RMSD further diminishes to 49 keV when excluding five nuclei with experimental uncertainties larger than 100 keV. Based on the mass formula, we predict 174 atomic masses near the proton drip line with $20<A<115$, and tabulate the results in the Supplemental Material of this paper.

High-spin states in ${}^{59}\mathrm{Co}$ $(Z=27)$, ${}^{59}\mathrm{Ni}$ $(Z=28)$, and ${}^{61}\mathrm{Co}$ have been populated by the fusion evaporation reactions, ${}^{48}\mathrm{Ti}({}^{14}\mathrm{C},p2n){}^{59}\mathrm{Co}$, ${}^{48}\mathrm{Ti}({}^{14}\mathrm{C},3n){}^{59}\mathrm{Ni}$, and ${}^{50}\mathrm{Ti}({}^{14}\mathrm{C},p2n){}^{61}\mathrm{Co}$. The 9 MV tandem accelerator at the John D. Fox Laboratory, Florida State University (FSU) was used to accelerate the ${}^{14}\mathrm{C}$ beam and the deexciting $\gamma$ rays were detected by the FSU detector array consisting of six high-purity germanium (HPGe) clover detectors and three single crystals. Directional correlation of the $\gamma$ rays deexciting oriented states (DCO ratios) and polarization asymmetry measurements helped to establish spin and parities of the excited states whenever possible. The level scheme of ${}^{59}\mathrm{Co}$ has been expanded with the inclusion of positive-parity states up to $31/2^{+}$ at around 11 MeV. The ${}^{59}\mathrm{Ni}$ positive-parity states known from previous study were verified with modifications to some of the spins and parities. On the other hand, the negative-parity states were extended to 31/2 at an excitation energy of 12 MeV. No new transition was observed for ${}^{61}\mathrm{Co}$, but one of the major bands has been reassigned as consisting of positive-parity states by reason of this study. Excitations observed within the $f_{7/2}$, $p_{3/2}$, $f_{5/2}$, and $p_{1/2}$ orbitals, and also across the $N=40$ subshell closure into the $g_{9/2}$ orbital was established by comparison with large-scale shell-model calculations for the three nuclei studied.

We investigate the quantum equation of motion (qEOM), a hybrid quantum-classical algorithm for computing excitation properties of a fermionic many-body system, with a particular emphasis on the strong-coupling regime. The method is designed as a stepping stone towards building more accurate solutions for strongly coupled fermionic systems, such as medium-heavy nuclei, using quantum algorithms to surpass the current barrier in classical computation. Approximations of increasing accuracy to the exact solution of the Lipkin-Meshkov-Glick Hamiltonian with $N=8$ particles are studied on digital simulators and IBM quantum devices. Improved accuracy is achieved by applying operators of growing complexity to generate excitations above the correlated ground state, which is determined by the variational quantum eigensolver. We demonstrate explicitly that the qEOM exhibits a quantum benefit due to the independence of the number of required quantum measurements from the configuration complexity. Postprocessing examination shows that quantum device errors are amplified by increasing configuration complexity and coupling strength. A detailed error analysis is presented, and error mitigation based on zero noise extrapolation is implemented.

The importance of studying the ${}^{16}\mathrm{O}(n,\alpha )$ reaction is motivated by multiple nuclear applications which rely on an accurate nuclear reaction data library for oxygen. Discrepancies between past experimental data on the ${}^{16}\mathrm{O}(n,\alpha ){}^{13}\mathrm{C}$ reaction and its time-reverse ${}^{13}\mathrm{C}(\alpha ,n){}^{16}\mathrm{O}$ reaction have led to various different nuclear data evaluations. We have measured ${}^{16}\mathrm{O}(n,\alpha )$ reaction cross sections using the LENZ instrument with the unmoderated white neutron source at LANSCE. Results from 2016/2017 data are discussed and used to benchmark the mcnp and geant simulations of the LENZ experimental setup. We report partial differential cross sections of ${}^{16}\mathrm{O}(n,{\alpha }_0)$ at $E_n=3.8–15$ MeV and ${}^{16}\mathrm{O}(n,{\alpha }_1+{\alpha }_2+{\alpha }_3)$ at $E_n=9–15$ MeV, based on the new measurement in 2021. The resonances that we observed are in good agreement with the levels in ${}^{17}\mathrm{O}$ that were previously measured. The LENZ cross sections are in better agreement with the ENDF/B-VIII.0 evaluation than the with reduced cross section found in ENDF/B-VII.1 up to 6 MeV. However, the current results for ${}^{16}\mathrm{O}(n,{\alpha }_0){}^{13}\mathrm{C}_{\mathrm{g}.\mathrm{s}.}$ appear to be in the best agreement over the entire energy range with that of JENDL/AN-2005 (ENDF/B-VI.0).

Approximating the angular momentum dependence of the reaction probability at a given bombarding energy by shifting it by the centrifugal energy and using the analytical formula for the elastic scattering probability, new analytical formulas for heavy-ion reaction cross sections and the universal reaction function are derived. It has been found that these new formulas describe the experimental data well and can be used for the analysis and predictions of heavy-ion reaction cross sections.

Axions coupled to nucleons might be copiously emitted from core-collapse supernovae (SNe). If the axion-nucleon coupling is strong enough, then axions would be emitted from the SN as a burst and, reaching Earth, may excite the oxygen nuclei in water Čherenkov detectors (${}^{16}\mathrm{O}+a\to {}^{16}\mathrm{O}^{*}$). This process will be followed by decay(s) of the excited state resulting in an emission of photons and thus providing a possibility for a direct detection of axions from a galactic SN in large underground neutrino Čherenkov detectors. Motivated by this possibility, we present an updated calculation of axion-oxygen cross section obtained by using self-consistent continuum random-phase approximation. We calculate the branching ratio of the oxygen nucleus deexcitation into $\gamma$ rays, neutrons, protons, and $\alpha$ particles and also consider photon emission from secondary nuclei to compute a total $\gamma$ spectrum created when axions excite ${}^{16}\mathrm{O}$. These results are used to revisit the detectability of axions from SN 1987A in Kamiokande-II.

Radiative decay of the subthreshold $1_1^{-}$ and $2_1^{+}$ states of ${}^{16}\mathrm{O}$ is studied in cluster effective field theory. The wave function normalization factors for initial and final states of the radiative decay amplitudes are deduced by using the phase shift data of elastic $\alpha \text{−}{}^{12}\mathrm{C}$ scattering for $l=0,1,2$, which are related to the asymptotic normalization coefficients of $0_1^{+},$ $1_1^{-},$ $2_1^{+}$ states of ${}^{16}\mathrm{O}$ for the two-body $\alpha \text{−}{}^{12}\mathrm{C}$ channel; then only one unfixed parameter remains in each of the radiative decay amplitudes. I fit the parameters to the experimental radiative decay rates and apply the fitted parameters to the study of radiative $\alpha$ capture on ${}^{12}\mathrm{C},$ ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$. The order of magnitude of astrophysical $S$ factors of $E1$ and $E2$ transitions of ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ is reproduced compared to the experimental data, and I discuss an improvement in the calculation of $S$ factors of ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$.

An infinity of extensions of the Siegert transformation exist in the Coulomb gauge. All resulting transition multipoles of the electric field are identical at the long-wavelength approximation but differ beyond. In the particular case of isospin forbidden electric dipole transitions, they introduce an ambiguity about the form of the transition operator. Various expressions of the electric dipole operator are presented and compared, without and with Siegert transformation. Their influence on calculations of radiative capture reactions of isospin-zero nuclei is discussed.

The particle-induced deexcitations of the 9.64 MeV, $3_1^{-}$ and 9.87 MeV, $2_2^{+}$ resonances of ${}^{12}\mathrm{C}$ increase the ${}^{12}\mathrm{C}$ production rate in a very hot and dense stellar environment. The enhancements in ${}^{12}\mathrm{C}$ production in such environments were estimated for a particle ($n, p$, and $\alpha$) density of ${10}^6\mathrm{g}/{\mathrm{cm}}^3$ in the temperature range of $T_9=0.1$ to 10. Enhancement due to neutron-induced deexcitation was found to be the maximum. The net ${}^{12}\mathrm{C}$ production rate due to the combined contributions from 7.65 (Hoyle state), 9.64, and 9.87 MeV states is much higher compared to the rate adopted by NACRE compilation. In case of a typical collapsing massive star with temperature dependent densities, for any of the $3_1^{-}$ or $2_2^{+}$ resonances, the enhancement factor due to $n, p$, and $\alpha$-induced deexcitations together can be as high as 600.

We have used an ab initio Gamow shell model to study the isospin symmetry breaking in the $A=16$ mirror nuclei of ${}^{16}\mathrm{F}, {}^{16}\mathrm{N}, {}^{16}\mathrm{Ne}$, and ${}^{16}\mathrm{C}$. Starting from a chiral interaction with two-nucleon force (2NF) at ${\mathrm{N}}^3\mathrm{LO}$ and three-nucleon force (3NF) at ${\mathrm{N}}^2\mathrm{LO}$, a complex-momentum psd-shell Hamiltonian was constructed by employing the many-body perturbation theory in the Gamow Hartree-Fock basis which includes bound, resonant, and continuum states self-consistently. Such an elaborated ab initio Gamow shell model with both continuum coupling and 3NF included can properly treat the many-body correlations of weakly bound and unbound nuclei. The mirror partners of ${}^{16}\mathrm{F}$ and ${}^{16}\mathrm{N}$ exhibit different level orders in their excitation spectra, which can be well explained by the inclusion of 3NF in the calculation. The isospin asymmetry between the mirror partners ${}^{16}\mathrm{Ne}$ and ${}^{16}\mathrm{C}$ was studied in detail by insight into their configuration structures. The interplay between 3NF and the continuum coupling is discussed in the weakly bound and unbound nuclear states.