Within the framework of the modified potential cluster model with forbidden states, the ${}^{13}\mathrm{N}(p,\gamma ){}^{14}\mathrm{O}$ reaction rate and the astrophysical $S$ factor are considered. It is shown that the first $p^{13}$ N resonance determines the $S$ factor and contributions of the $M1$ and $E2$ transitions are negligible at energies $E<1\mathrm{MeV}$, but are significant at high energies. The $S$ factor strongly depends on the ${}^{3}S_1$ resonance parameters. The influence of the width of the ${}^{3}S_1$ resonance on the $S$ factor is demonstrated. The reaction rate is calculated and an analytical approximation for the reaction rate is proposed. A comparison of our calculation with existing data is addressed. Results of our calculations for the ${}^{13}\mathrm{N}(p,\gamma ){}^{14}\mathrm{O}$ reaction rate provide the contribution to the steadily improving reaction-rate database libraries. Our calculations of the ${}^{13}\mathrm{N}(p,\gamma ){}^{14}\mathrm{O}$ reaction rate along with results for the rates of the ${}^{14}\mathrm{N}(p,\gamma ){}^{15}\mathrm{O}$ and ${}^{12}\mathrm{C}(p,\gamma ){}^{13}\mathrm{N}$ processes provide the temperature range $0.13<T_9<0.97$ for the conversion of the carbon-nitrogen-oxygen (CNO) cycle to the hot CNO cycle. Our results demonstrate that, at the early stages of a nova explosion at temperatures of about $0.1T_9$ and at late stages of evolution of supermassive stars at temperatures of about $1.0T_9$, the ignition of the hot CNO cycle could occur at much lower densities of a stellar medium.

A new $\alpha$-cluster linear chain is theoretically investigated in ${}^{16}\mathrm{C}$. By using the antisymmetrized molecular dynamics, we show that a ${(1/2_{\sigma }^{-})}^2{(1/2_{\sigma }^{+})}^2$ linear-chain configuration exists with extreme deformation. It is compared with a 27.2 MeV state observed by a recent cluster-decay experiment ${}^2\mathrm{H}({}^{16}\mathrm{C},{}^4\mathrm{He}+{}^{12}\mathrm{Be}$ or ${}^6\mathrm{He}+{}^{10}\mathrm{Be}){}^2\mathrm{H}$. We show that a decay pattern of this new linear-chain configuration—it dominantly decays into the ${}^6\mathrm{He}+{}^{10}\mathrm{Be}\left(0_2^{+}\right)$ channel—is in good agreement with the observed data.

We report a comprehensive study of ${}^{10–14}\mathrm{B}$ isotopes within the ab initio no-core shell model (NCSM) using realistic nucleon-nucleon ($\mathit{NN}$) interactions. In particular, we have applied the inside nonlocal outside Yukawa (INOY) interaction to study energy spectra, electromagnetic properties, and point-proton radii of the boron isotopes. The NCSM results with the charge-dependent Bonn 2000 (CDB2K), the chiral next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$), and optimized next-to-next-to-leading order (${\mathrm{N}}^2{\mathrm{LO}}_{opt}$) interactions are also reported. We have reached basis sizes up to $N_{\max }=10$ for ${}^{10}\mathrm{B}, N_{\max }=8$ for ${}^{11,12,13}\mathrm{B}$, and $N_{\max }=6$ for ${}^{14}\mathrm{B}$ with $m$-scheme dimensions up to $1.7\times {10}^9$. We also compare the NCSM calculations with the phenomenological YSOX interaction using the shell model to test the predictive power of the ab initio nuclear theory. Overall, our NCSM results are consistent with the available experimental data. The experimental ground state spin $3^{+}$ of ${}^{10}\mathrm{B}$ has been reproduced using the INOY $\mathit{NN}$ interaction. Typically, the $3N$ interaction is required to correctly reproduce the aforementioned state.

Background: The formation of superheavy nuclei in fusion reactions is suppressed by a competing quasifission process. The competition between the formation of the compound nucleus and the quasifission depends strongly on the reaction entrance channel.

Purpose: The investigation of fission and quasifission processes in the formation of $Z=120$ superheavy composite systems in the ${}^{52,54}\mathrm{Cr}+{}^{248}\mathrm{Cm}$ and ${}^{68}\mathrm{Zn}+{}^{232}\mathrm{Th}$ reactions, and their comparison with the ${}^{64}\mathrm{Ni}+{}^{238}\mathrm{U}$ reaction at energies in the vicinity of the Coulomb barrier.

Methods: Mass-energy distributions of fissionlike fragments formed in the reactions ${}^{52,54}\mathrm{Cr}+{}^{248}\mathrm{Cm}$ and ${}^{68}\mathrm{Zn}+{}^{232}\mathrm{Th}$ at energies near the Coulomb barrier were measured using the double-arm time-of-flight spectrometer CORSET.

Results: Capture cross sections for the reactions under investigation were measured. The most probable fragment masses and total kinetic energies as well as their variances in dependence on the interaction energy were studied for asymmetric and symmetric fragments. The fusion probabilities were estimated from the analysis of mass-energy distributions.

Conclusions: The estimated fusion probability drops down by a factor of ${10}^3$ in the ${}^{54}\mathrm{Cr}+{}^{248}\mathrm{Cm}$ reaction compared to the reactions of ${}^{48}\mathrm{Ca}$ ions with actinides. Among the studied reactions, the ${}^{54}\mathrm{Cr}+{}^{248}\mathrm{Cm}$ is the most favorable one for the production of the superheavy element with $Z=120$.

The predominant branch in the $\beta$ decay of ${}^{34}\mathrm{Ar}$ is the superallowed $0^{+}\to 0^{+}$ transition to the ground state of ${}^{34}\mathrm{Cl}$. To determine its important branching ratio one must first establish the ratios for the competing Gamow-Teller branches based on the measured intensities of $\gamma$ rays subsequently emitted from the excited states they populate in ${}^{34}\mathrm{Cl}$. The strongest of these branches populates the $1^{+}$ state at 666 keV in ${}^{34}\mathrm{Cl}$, which has three possible $\gamma$-decay paths. We report here a measurement of the decay of this state, which we populated via resonant proton capture in the reaction ${}^{33}\mathrm{S}$($p,\gamma$)${}^{34}\mathrm{Cl}$. We find that the intensity of the 519-keV $\gamma$-ray path is 1.46(19)% relative to that of the 666-keV path. This result is critical to new precise measurements of the superallowed decay of ${}^{34}\mathrm{Ar}$.

Background: An electron localization function was originally introduced to visualize in positional space bond structures in molecules. It became a useful tool to describe electron configurations in atoms, molecules, and solids. In nuclear physics, a nucleon localization function (NLF) has been used to characterize cluster structures in light nuclei, formation of fragments in fission, and pasta phases appearing in the inner crust of neutron stars.

Purpose: We use the NLF to study the nuclear response to fast rotation.

Methods: We generalize the NLF to the case of nuclear rotation. The extended expressions involve both time-even and time-odd local particle and spin densities and currents. Since the current density and density gradient contribute to the NLF primarily at the surface, we propose a simpler spatial measure given by the kinetic-energy density. Illustrative calculations for the superdeformed yrast band of ${}^{152}\mathrm{Dy}$ were carried out by using the cranked Skyrme-Hartree-Fock method. We also employed the cranked harmonic-oscillator model to gain insights into spatial patterns revealed by the NLF at high angular momentum.

Results: In the case of a deformed rotating nucleus, several NLFs can be introduced, depending on the definition of the spin-quantization axis, direction of the total angular momentum, and self-consistent symmetries of the system. Contributions to the NLF from the current density, spin-current tensor density, and density gradient terms are negligible in the nuclear interior. The oscillating pattern of the simplified NLF can be explained in terms of a constructive interference between kinetic-energy and particle densities. The characteristic nodal pattern seen in the NLF in the direction of major axis of a rotating nucleus comes from single-particle orbits carrying large aligned angular momentum. The variation of the NLF along the minor axis of the nucleus can be traced back to deformation-aligned orbits.

Conclusions: The NLF allows a simple interpretation of the shell structure evolution in the rotating nucleus in terms of the angular-momentum alignment of individual nucleons. We expect that the NLF will be very useful for the characterization and visualization of other collective modes in nuclei and time-dependent processes.

An extended ${\mathrm{O}}_{\mathcal{S}T}$(8) model with multi-$j$ orbits is constructed based on the angular momentum decomposition with “pseudo”-spin $\mathcal{S}$ for valence nucleons in a $j$ orbit. It is shown that the isovector $\mathcal{S}=0$ and $T=1$ pairs are exactly the $J=0$ and $T=1$ pairs in a given $j$ orbit, while the isoscalar $\mathcal{S}=1$ pairs are linear combinations of $J=\mathrm{odd}$ pairs, with which the pairing Hamiltonian can be used to estimate isovector and isoscalar pairing interactions. As an example of the model application, some low-lying $J=0^{+}$ level energies of even-even and odd-odd $A=18$–28 nuclei up to the half-filling in the $ds$ shell above the ${}^{16}\mathrm{O}$ core are fit by the model and compared with the fitting results of the same Hamiltonian in the ${\mathrm{O}}_{LST}$(8) form. It has been verified from the fitting of both the models that the isoscalar pairing interaction can be neglected in the lower-energy part of the spectra of these $ds$-shell nuclei as far as binding energies and a few $J=0^{+}$ excited levels of these nuclei are concerned. With the mean-field plus isovector pairing interaction only, neutron-neutron, proton-proton, and neutron-proton pairing contributions at the ground or the lowest $J=0^{+}$ state of these nuclei are estimated. It is shown that the isovector $np$ pairing contribution to the binding in the odd-odd $N=Z$ nuclei is systematically larger than that in the even-even nuclei. Furthermore, the isoscalar $np$ pair content at the lowest $J=0^{+}$ state of these nuclei is also estimated. In both the ${\mathrm{O}}_{\mathcal{S}T}$(8) and ${\mathrm{O}}_{LST}$(8) models, it is clearly shown that the isoscalar pair content in the lowest $J=0^{+}$ state of the $N=Z$ and $N=Z\pm 2$ nuclei increases with increasing of the valence nucleons, especially in those even-even nuclei, which indicates the isoscalar pairing correlation to be of importance at low-lying states of $N=Z$ and $N=Z\pm 2$ nuclei, especially in those even-even nuclei with more valence nucleons up to the half-filling, even though the isoscalar pairing interaction is negligible.

An efficient method, the preconditioned conjugate gradient method with a filtering function (PCG-F), is proposed for solving iteratively the Dirac equation in three-dimensional (3D) lattice space for nuclear systems by defining a variational subspace, in which the positive-energy solutions are minima rather than saddle points as in the full variational space. This allows one to obtain the single nucleon energies and wave functions of the Dirac equation in 3D lattice space efficiently. The PCG-F method is demonstrated to solve the Dirac equation with given spherical and deformed Woods-Saxon potentials. The solutions given by the inverse Hamiltonian method in 3D lattice space and the shooting method in radial coordinate space are reproduced with high accuracy. In comparison with the existing inverse Hamiltonian method, the present PCG-F method is much faster in the convergence of the iteration, in particular for deformed potentials. It may also provide a promising way to solve the relativistic Hartree-Bogoliubov equation iteratively in the future.

Within the generalized liquid drop model (GLDM), the effects of the Strutinsky shell correction on ${\alpha }_{}$ decay processes have been systematically studied. Before the scission point, the shell correction energy $E_{\mathrm{sh}}$, which brings noticeable change to potential barriers for most nuclei, varies with nuclear deformation described by quasimolecular shapes (QMSs). To investigate the subsequent influence on ${\alpha }_{}$ decay, we performed systematic calculations involving more than 400 favored ground-to-ground ${\alpha }_{}$ emissions with atomic number $Z$ = 52 to 118. We found that the shell correction remarkably reduces the notorious deviation between theoretical and experimental half-lives around the neutron shell closure $N=126$. It will also shed new light on predicting $\alpha$-decay half-life of superheavy nuclei.

Time-dependent covariant density functional theory with the density functional PC-PK1 is developed in a three-dimensional coordinate space without any symmetry restrictions, and benchmark calculations for the ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ reaction are performed systematically. The relativistic kinematics, the conservation laws of the momentum, total energy, and particle number, as well as the time-reversal invariance are examined and confirmed to be satisfied numerically. Two primary applications including the dissipation dynamics and above-barrier fusion cross sections are illustrated. The obtained results are in good agreement with the ones given by the nonrelativistic time-dependent density functional theory and the data available. This demonstrates that the newly developed time-dependent covariant density functional theory could serve as an effective approach for the future studies of nuclear dynamical processes.

The dynamics of exotic hypernuclei in heavy-ion collisions has been investigated thoroughly with the Lanzhou quantum molecular dynamics model. All possible channels on hyperon ($\mathrm{\Lambda }$, $\mathrm{\Sigma }$, and $\mathrm{\Xi }$) production near threshold energies are implemented in the transport model. The light complex fragments ($Z\le 2$) are constructed with the Wigner-function method. The classical phase-space coalescence is used for recognizing heavy nuclear and hyperfragments and the statistical model is taken for describing the decay process. The nuclear fragmentation reactions of the available experimental data from the ALADIN Collaboration are well reproduced by the combined approach. It is found that the in-medium potentials of strange particles influence the strangeness production and fragment formation. The hyperfragments are mainly created in the projectile or target-like rapidity region and the yields are reduced about three orders of magnitude in comparison to the nuclear fragments. The hypernuclear dynamics of HypHI data is well described with the model. The possible experiments for producing the neutron-rich hyperfragments at the high-intensity heavy-ion accelerator facility (HIAF) are discussed.

We study the diffusion of charm and beauty in the early stage of high-energy nuclear collisions at RHIC and LHC energies, considering the interaction of these heavy quarks with the evolving Glasma by means of the Wong equations, in the color-$SU\left(2\right)$ case. In comparison with previous works, we add the longitudinal expansion of the gluon medium as well as we estimate the diffusion coefficient in momentum space, and the effect of energy loss due to gluon radiation. We find that heavy quarks diffuse in the strong transverse color fields in the very early stage (0.2–0.3 fm/c) and this leads to a suppression at low $p_T$ and enhancement at intermediate low $p_T$. The shape of the observed nuclear suppression factor obtained within our calculations is in qualitative agreement with the experimental results of the same quantity for $D$ mesons in proton-nucleus collisions. We compute the nuclear suppression factor in nucleus-nucleus collisions as well, for both charm and beauty, finding a substantial impact of the evolving Glasma phase on these, suggesting that initialization of heavy quarks spectra in the quark-gluon plasma phase should not neglect the early evolution in the strong gluon fields.

In a recent experiment, carried out at the Radioactive Isotope Beam Factory/RIKEN, the ${}^{25}\mathrm{F}(p,2p){}^{24}\mathrm{O}$ reaction was studied at 270 MeV/A in inverse kinematics. Derived spectroscopic factors suggest that the effective core of ${}^{25}\mathrm{F}$ significantly differs from a free ${}^{24}\mathrm{O}$ nucleus. We interpret these results within the particle-rotor model and show that the experimental level scheme of ${}^{25}\mathrm{F}$ can be understood in the rotation-aligned coupling scheme with its $5/2_1^{+}$ ground state as the bandhead of a decoupled band. The excitation energies of the observed $1/2_1^{+}$ and $9/2_1^{+}$ states correlate strongly with the rotational energy of the effective core, seen by the odd proton, and allow us to estimate its $2^{+}$ energy at $\approx 3.2\mathrm{MeV}$ and a moderate quadrupole deformation ${\epsilon }_2\approx 0.15$. The measured fragmentation of the $\pi d_{5/2}$ single-particle strength is discussed, and some further experiments suggested.

Background: ${}^{19}\mathrm{Ne}$ is an important isotope in nuclear astrophysics due to its role in both the ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ and ${}^{15}\mathrm{O}(\alpha ,\gamma ){}^{19}\mathrm{Ne}$ reactions in novae and Type I x-ray bursts, respectively. The energy levels of ${}^{19}\mathrm{Ne}$ near the $\alpha$ and proton thresholds ($S_{\alpha }=3529$ keV, $S_p=6410$ keV) correspond to resonances in both of these reactions. Previous measurements to study the structure of ${}^{19}\mathrm{Ne}$ have focused on both regions in an effort to constrain these reaction rates.

Purpose: Discrepancies in the energies, spins, and parities for levels in ${}^{19}\mathrm{Ne}$ from previous measurements contribute to the reaction-rate uncertainties. Gamma rays from the depopulation of excited states in ${}^{19}\mathrm{Ne}$ were measured to reduce the level-energy uncertainties and inconsistencies in previous spin-parity assignments.

Methods: The ${}^{19}\mathrm{F}({}^3\mathrm{He},t){}^{19}\mathrm{Ne}$ reaction was used to elucidate the structure of ${}^{19}\mathrm{Ne}$ levels up to $E_x=6.9$ MeV. The reaction products were measured using Gammasphere ORRUBA: Dual Detectors for Experimental Structure Studies—a coupling of the Oak Ridge Rutgers University Barrel Array and Gammasphere at Argonne National Laboratory. Tritons produced in the reaction were measured in coincidence with $\gamma$ rays from the deexcitation of ${}^{19}\mathrm{Ne}$ energy levels.

Results: Previously unobserved transitions allowed for discrepancies in the resonance properties relevant to these two reactions to be resolved. In total, 41 transitions from 21 energy levels were measured in ${}^{19}\mathrm{Ne}$, with 21 of those transitions being previously unobserved. Of particular importance, transitions from two $3/2^{+}$ states with energies of 6423(3) and 6441(3) keV, crucial for accurate estimations of the ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction rate, were found.

Conclusions: Energies and spin-parities of important energy levels near the proton and $\alpha$ thresholds were measured and some of the discrepancies in previous measurements were resolved. Measurement of the two near-threshold $3/2^{+}$ states reduced the calculated upper limit of the ${}^{18}\mathrm{F}(p,\alpha ){}^{15}\mathrm{O}$ reaction rate by factors of 1.5–17 in the nova temperature range.

Uncertainty quantification has emerged as a rapidly growing field in nuclear science. Theoretical predictions of physical observables often involve extrapolations to regions that are poorly constrained by laboratory experiments and astrophysical observations. Without properly quantified theoretical errors, such model predictions are of limited value. Also, one often deals with theoretical constructs that involve fundamental quantities that are not accessible to experiment or observation. Particularly relevant in this context is the pressure of pure neutron matter. In this Rapid Communication, we develop an analytic framework to answer the question of “How can new data reduce uncertainties of current theoretical models?” [Reinhard and Nazarewicz, Phys. Rev. C 81, 051303(R) (2010)]. Simple and insightful expressions are obtained to quantify the impact of one or two new observables on theoretical uncertainties in two critical quantities: The slope of the symmetry energy at saturation density and the pressure of pure neutron matter at twice nuclear matter saturation density.

We found the same staggering pattern in the evolution of the spin-orbit (SO) and pseudospin-orbit (PSO) splittings in neutron drops obtained by the energy-density functional (EDF) theory using SAMi-T and SLy5 parametrizations, with and without the tensor terms respectively. This staggering evolution is similar to the results recently obtained by the relativistic Brueckner-Hartree-Fock (RBHF) theory with the Bonn A potential, which was claimed to be a tensor effect. In this work, we present an intuitive but essential explanation on the origin of this staggering evolution in the Skyrme EDF theory. We found that, for both the SO and PSO partners, the energy splittings mainly originate from the SO potential. The staggering evolution of both the SO and PSO splittings is mainly due to the drastic change of density while neutrons fill different single-particle orbits. The key to determine the specific staggering pattern is the strength of the neutron density gradient term and the SO density term in the SO potential, not necessarily the tensor force.

Transitions in ${}^{163}\mathrm{Tb}$ following $\beta$ decay of ${}^{163}\mathrm{Gd}$ were obtained as part of investigations of $\gamma$ rays emitted following ${}^{163}\mathrm{Eu}\beta$ decay to ${}^{163}\mathrm{Gd}$. Detailed analysis of the low-energy structure of ${}^{163}\mathrm{Tb}$ has been carried out with these data to expand previous $\beta$-decay studies and reactions studies of levels in ${}^{163}\mathrm{Tb}$. Data were collected at the LeRIBSS station of the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory with an array of four Clover HPGe detectors for $\gamma$ rays and two plastic scintillators for $\beta$ detection. The $\gamma$ rays were identified as belonging to ${}^{163}\mathrm{Gd}$ and ${}^{163}\mathrm{Tb}$ via mass selection and $\gamma -\gamma -\beta , \gamma -\gamma$, or $\gamma$-x-ray coincidence. In total, 38 new $\gamma$-ray transitions were observed in ${}^{163}\mathrm{Tb}$ from 15 newly identified levels and 12 previously identified levels. Potential energy surface calculations were performed which support a rigid prolate deformation. Previously identified unplaced transitions in ${}^{163}\mathrm{Tb}$ have been placed within the level scheme of ${}^{163}\mathrm{Tb}$ and additional states and transitions have been identified.

A new method has been proposed to determine the strength of the isoscalar proton-neutron pairing interaction applicable to many nuclei. The principle is the equivalence between the double-charge change and the double transfer of like-particle pairs, and a constraint is derived for the effective interactions used in approximations. This method was applied to the quasiparticle random-phase approximation for determining that interaction strength. In this paper, details of this method are explained thoroughly, and applications to nuclei of several instances of the double-$\beta$ decays are shown. The systematics of the strengths determined for those nuclei is understood in terms of a midshell effect. The effect of the new interaction strength is examined in two examples of the Gamow-Teller strength function with comparisons with the experimental data. The nuclear matrix elements of the neutrinoless double-$\beta$ decay are also calculated.

We report on the measurement of the thermal neutron capture cross section by ${}^9\mathrm{Be}$, using ${}^{14}\mathrm{N}$ as a benchmark for the development of our protocol, which implies the combination of two precise techniques: neutron activation in a nuclear research reactor and accelerator mass spectrometry (AMS). Beryllium oxide (BeO), graphite, and uracil (${\mathrm{C}}_4{\mathrm{H}}_4{\mathrm{N}}_2{\mathrm{O}}_2$) samples were irradiated at the TRIGA MARK III nuclear research reactor facility at Instituto Nacional de Investigaciones Nucleares (ININ), México. Later on, isotopic concentrations were quantified by AMS at Laboratorio de Espectrometría de Masas con Aceleradores (LEMA) of the Instituto de Física, Universidad Nacional Autónoma de México (IF-UNAM), Mexico. Cross sections for the ${}^9\mathrm{Be}(n,\gamma ){}^{10}\mathrm{Be}$ and ${}^{14}\mathrm{N}(n,p){}^{14}\mathrm{C}$ nuclear reactions were extracted for thermal neutrons.