The nucleon radiative capture reactions are important in pure and applied nuclear physics, especially in nuclear astrophysics. The keV-nucleon radiative capture reactions are studied with ${}^{12}\mathrm{C}$ and ${}^{16}\mathrm{O}$ targets using the bound-to-continuum potential model in which both scattering and bound states are treated simultaneously and based on the Skyrme Hartree-Fock approximation. The obtained results are shown to be in good agreement with the available experimental data. Alongside astrophysical aspects, the nuclear structure features were revisited for enlarging the prospect of adopting the nucleon radiative capture processes as a spectroscopic tool.

Analytic formulas to calculate statistical uncertainties of $v_n\left\{2k\right\}$ harmonics extracted from the Q cumulants are presented. The Q cumulants are multivariate polynomial functions of the weighted means of $2m$-particle azimuthal correlations, $\langle \langle 2m\rangle \rangle$. Variances and covariances of the $\langle \langle 2m\rangle \rangle$ are included in the analytic formulas of the uncertainties that can be calculated simultaneously with the calculations of the $v_n\left\{2k\right\}$ harmonics. The calculations are performed using a simple toy model, which roughly simulates elliptic flow azimuthal anisotropy with magnitudes around 0.05. The results are compared with the results obtained by the many data subsets, and by the bootstrapping method. The first one is a common way of estimation of the statistical uncertainties of the $v_n\left\{2k\right\}$ harmonics in a real experiment. In order to increase precision in the measurement of the $v_n\left\{2k\right\}$ harmonics, a large number of 15 000 subsets and the same number of the resampling in the bootstrap method is used. Unlike the other ways of the analytic calculation of the $v_n\left\{2k\right\}$ statistical uncertainties, our proposal that includes the use of squared weights in the calculation of both the variances and covariances, gives the best agreement with the results obtained from the subsets and bootstrap method. Additionally, a recurrence equation between Q cumulants of any order is also presented.

Mass and total kinetic-energy (TKE) distributions of fission fragments from ${}^{257}\mathrm{Md}$ nucleus populated by complete fusion of ${}^{19}\mathrm{F}$ with ${}^{238}\mathrm{U}$ have been measured in the range of excitation energy $E^{*}\approx 37\text{−}48\mathrm{MeV}$. Due to the skewness of the measured TKE distributions, two Gaussian distributions were required to explain the data. The events with high TKE must originate from the supershort mode of fission, the presence of which has been confirmed by measuring two additional reactions: ${}^{19}\mathrm{F}+{}^{232}\mathrm{Th}$ and ${}^{18}\mathrm{O}+{}^{238}\mathrm{U}$ involving first a different target and then a different projectile leading to compound nuclei ${}^{251}\mathrm{Es}$ and ${}^{256}\mathrm{Fm}$, respectively, at similar excitation energies and comparing their mass-TKE correlation plots. The existence of considerable supershort mode of fission for the ${}^{257}\mathrm{Md}$ nucleus up to $E^{*}\approx 48$ MeV, observed for the first time, reveals that such rare fission modes for neutron-rich exotic nuclei are far off from the liquid drop model predictions, even at high excitation energies.

A method for calculating the symmetry-projected energy of coupled-cluster singles plus doubles (CCSD) wave function through the Monte Carlo method is proposed. We present benchmark calculations in considering the three-level Lipkin model which is a simple and minimal model with two phases: spherical and deformed. It is demonstrated that this method gives good ground-state energy and low-lying spectra.

Neutron destruction reactions of the cosmic $\gamma$-ray emitter ${}^{26}\mathrm{Al}$ are of importance to determine the amount of ${}^{26}\mathrm{Al}$ ejected into our galaxy by supernova explosions and for ${}^{26}\mathrm{Al}$ production in asymptotic giant branch stars. We performed a new measurement of the ${}^{26}\mathrm{Al}(n,\alpha )$ reaction up to 160-keV neutron energy at the neutron time-of-flight facilities n_TOF at CERN and GELINA at EC-JRC. We provide strengths for ten resonances, six of them for the first time. We use our data to calculate astrophysical reactivities for stellar temperatures up to 0.7 GK. Our results resolve a discrepancy between the two previous direct measurements of this reaction, and indicate higher stellar destruction rates than the most recently recommended reactivity.

Isotopic distributions were measured for the light fragment group in the transition region from asymmetric to symmetric fission for thermal neutron induced fission of ${}^{239}\mathrm{Pu}$ and ${}^{241}\mathrm{Pu}$ using the novel technology of calorimetric low temperature detectors in combination with the passive absorber method. Nuclear charge distributions were determined for 24 masses in the range $A=89$ to $A=112$ for ${}^{241}\mathrm{Pu}(n_{\mathrm{th}},f)$ for the first time with the LOHENGRIN mass spectrometer. Moving from asymmetric to symmetric fission, known data were supplemented for masses from $A=110$ to $A=112$ for ${}^{241}\mathrm{Pu}(n_{\mathrm{th}},f)$ and from $A=109$ to $A=113$ for ${}^{239}\mathrm{Pu}(n_{\mathrm{th}},f)$. The isotopic yields were used to evaluate the charge polarization $\mathrm{\Delta }Z$ and the proton odd-even effect $\delta p$ with emphasis on the borderline between asymmetric and symmetric fission. This highlighted a virtual shell effect near $Z=44$ which mirrors the effect of the $Z=50$ shell in the complementary heavy fragment group of the two Pu isotopes $(Z=94)$ studied.

We report the value of the electric quadrupole moment of ${}^{209}\mathrm{Bi}$ extracted from the atomic data. For this, we performed electronic structure calculations for the ground ${}^{4}S_{3/2}^o$ and excited ${}^{2}P_{3/2}^o$ states of atomic Bi using the Dirac-Coulomb-Breit Hamiltonian and the Fock space coupled-cluster method with single, double, and full triple amplitudes for the three-particle Fock space sector. The value of the quadrupole moment of ${}^{209}\mathrm{Bi}, Q{(}^{209}\mathrm{Bi})=-418\left(6\right)$ mb, derived from the resulting electric field gradient values and available atomic hyperfine splittings is in excellent agreement with molecular data. Due to the availability of the hyperfine constants for unstable isotopes of Bi, current atomic calculation allows also to correct their quadrupole moments.

Background: A Bayesian neural network (BNN) approach has been applied to evaluate and predict the nuclear data. The BNN is a numerical algorithm. When one incorporates this algorithm in nuclear physics analyses, how to maintain the scientific rigor is a key problem and presents new challenges.

Purpose: In this paper, a case study on giant dipole resonance (GDR) energy is presented to illustrate the effectiveness and maneuverability of the method to provide physics guidance in the BNN from the input layer.

Methods: Pearson's correlation coefficients are applied to assess the statistical dependence between nuclear properties in the ground state and the GDR energies. Then the optimal ground-state properties are employed as variables of the input layer in the BNN to evaluate and predict the GDR energies.

Results: Those selected ground-state properties actively contribute to reduce the predicted errors and avoid the overfitting.

Conclusions: This paper gives a demonstration to find effects of the GDR energy by using the BNN without the physics motivated model, which may be helpful to discover physics effects from the complex nuclear data.

The excitation function for quasielastic scattering of the weakly bound projectile ${}^6\mathrm{Li}$ on a ${}^{159}\mathrm{Tb}$ target, at large backward angle, has been measured at energies around the Coulomb barrier. The corresponding quasielastic barrier distribution has been extracted from the experimental cross sections, both including and excluding the $\alpha$ particles produced in the reaction. The quasielastic scattering cross sections, excluding the $\alpha$ particles, have been analyzed in the framework of coupled channels calculations. The centroid of the quasielastic barrier distribution, including the $\alpha$ particles, is found to shift towards higher energy relative to the centroid of the fusion barrier distribution for the system. This has been attributed to the low $\alpha$-breakup threshold of the nucleus ${}^6\mathrm{Li}$.

We study the behavior of the ${\chi }_{c1}\left(3872\right)$, also known as $X\left(3872\right)$, in dense nuclear matter. We begin from a picture in vacuum of the $X\left(3872\right)$ as a purely molecular $\left(D{\overline{D}}^{*}\text{-c.c.}\right)$ state, generated as a bound state from a heavy-quark symmetry leading-order interaction between the charmed mesons, and analyze the $D{\overline{D}}^{*}$ scattering $T$ matrix ($T_{D{\overline{D}}^{*}}$) inside of the medium. Next, we consider also mixed-molecular scenarios and, in all cases, we determine the corresponding $X\left(3872\right)$ spectral function and the $D{\overline{D}}^{*}$ amplitude, with the mesons embedded in the dense environment. We find important nuclear corrections for $T_{D{\overline{D}}^{*}}$ and the pole position of the resonance, and discuss the dependence of these results on the $D{\overline{D}}^{*}$ molecular component in the $X\left(3872\right)$ wave function. These predictions could be tested in the finite-density regime that can be accessed in the future CBM and PANDA experiments at the Facility for Antiproton and Ion Research (FAIR).

Motivated by the unknown nature of the $2.50\text{–}2.67M_{\odot }$ compact object in the binary merger event GW190814, we study the maximum neutron star mass based on constraints from low-energy nuclear physics, neutron star tidal deformabilities from GW170817, and simultaneous mass-radius measurements of PSR J0030+045 from NICER. Our prior distribution is based on a combination of nuclear modeling valid in the vicinity of normal nuclear densities together with the assumption of a maximally stiff equation of state at high densities, a choice that enables us to probe the connection between observed heavy neutron stars and the transition density at which conventional nuclear physics models must break down. We demonstrate that a modification of the highly uncertain suprasaturation density equation of state beyond 2.64 times normal nuclear density is required in order for chiral effective field theory models to be consistent with current neutron star observations and the existence of $2.6M_{\odot }$ neutron stars. We also show that the existence of very massive neutron stars strongly impacts the radii of $\approx 2.0M_{\odot }$ neutron stars (but not necessarily the radii of $1.4M_{\odot }$ neutron stars), which further motivates future NICER radius measurements of PSR $\mathrm{J1614}-2230$ and PSR J0740+6620.

Differential cross sections for elastic $p\text{−}{}^6\mathrm{He}$ and $p\text{−}{}^8\mathrm{He}$ scattering, measured in inverse kinematics at high momentum transfer up to the first diffraction minimum and at projectile energies around 700 MeV/u at GSI Darmstadt, are analyzed applying the sum-of-Gaussians (SOG) method based on the Glauber multiple-scattering theory. The rms point matter radii of ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$ are deduced to be 2.29(6) fm and 2.53(7) fm, respectively, in close agreement with those from former analyses using phenomenological parametrizations for describing the matter distributions. With the aid of the measurement at high momentum transfer, the overall radial density distributions of ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$ are precisely deduced using the SOG method, in particular at small radii. A pronounced core rearrangement by adding the valence neutrons to an $\alpha$-like core to form ${}^6\mathrm{He}$ and ${}^8\mathrm{He}$ is elucidated, and briefly discussed.

The meson-baryon molecular components for the $N^{*}$ and ${\mathrm{\Delta }}^{*}$ resonances are investigated in terms of the compositeness, which is defined as the norm of the two-body wave function from the meson-baryon scattering amplitudes. The scattering amplitudes are constructed in a $\pi N\text{−}\eta N\text{−}\sigma N\text{−}\rho N\text{−}\pi \mathrm{\Delta }$ coupled-channels problem in a meson exchange model together with several bare $N^{*}$ and ${\mathrm{\Delta }}^{*}$ states, and parameters are fitted so as to reproduce the on-shell $\pi N$ partial wave amplitudes up to the center-of-mass energy $1.9\mathrm{GeV}$ with the orbital angular momentum $L\le 2$. As a result, the Roper resonance $N\left(1440\right)$ is found to be dominated by the $\pi N$ and $\sigma N$ molecular components while the bare-state contribution is small. The squared wave functions in coordinate space imply that both in the $\pi N$ and $\sigma N$ channels the separation between the meson and baryon is about more than $1\mathrm{fm}$ for the $N\left(1440\right)$ resonance. On the other hand, dominant meson-baryon molecular components are not observed in any other $N^{*}$ and ${\mathrm{\Delta }}^{*}$ resonances in the present model, although they have some fractions of the meson-baryon clouds.

Low-energy dipole (LED) excitations in ${}^{20}\mathrm{O}$ were investigated by variation after $K$ projection of $\mathrm{deformation}(\beta$)-constraint antisymmetrized molecular dynamics combined with the generator coordinate method. A low-energy $E1$ mode, which is caused by surface neutron oscillation along the prolate deformation was obtained as the $1_2^{-}$ state. Moreover, a toroidal dipole (TD) mode with vortical nuclear current was obtained as the $1_1^{-}$ state with one-proton excitation on the relatively weak deformation. The low-energy $E1$ mode is a LED excitation peculiar to neutron-rich systems that does not appear in stable oxygen isotopes, whereas the TD (vortical) mode is a LED excitation that was obtained also in ${}^{16}\mathrm{O}$ and ${}^{18}\mathrm{O}$. The TD and $E1$ modes separately appear as the $K^{\pi }=1^{-}$ and $K^{\pi }=0^{-}$ components of the deformed states, respectively, but couple with each other because of $K$ mixing, and shape fluctuation. As a result of the mixing, TD and $E1$ transition strengths are fragmented into the $1_1^{-}$ and $1_2^{-}$ states. The excited bands of $K^{\pi }=0^{+}, K^{\pi }=0^{-}$, and $K^{\pi }=1^{-}$ with cluster structures were also obtained in the energy region higher than the LED states.

Background: The island of inversion near the $N=20$ shell gap is home to nuclei with reordered single-particle energy levels compared with the spherical shell model. Studies of ${}^{31}\mathrm{Ne}$ have revealed that its ground state has a halo component characterized by a valence neutron orbiting a deformed ${}^{30}\mathrm{Ne}$ core. This lightly bound nucleus with a separation energy of only $S_n=170$ keV is expected to have excited states that are neutron unbound.

Purpose: The purpose of this experiment was to investigate the low-lying excited states in ${}^{31}\mathrm{Ne}$ that decay by the emission of a single neutron.

Methods: An 89 MeV/nucleon ${}^{33}\mathrm{Mg}$ beam impinged on a segmented Be reaction target. Neutron-unbound states in ${}^{31}\mathrm{Ne}$ were populated via a two-proton knockout reaction. The ${}^{30}\mathrm{Ne}$ fragment and associated neutron from the decay of ${}^{31}\mathrm{Ne}$ were detected by the MoNA-LISA-Sweeper experimental setup at the National Superconducting Cyclotron Laboratory. Invariant-mass spectroscopy was used to reconstruct the two-body decay energy (${}^{30}\mathrm{Ne}+n$).

Results: The two-body decay energy spectrum exhibits two features: a low-lying peak at $0.30\pm 0.17$ MeV and a broad enhancement at $1.50\pm 0.33$ MeV, each fit with an energy-dependent asymmetric Breit-Wigner lineshape representing a resonance in the continuum. Accompanying shell-model calculations using the FSU interaction within NuShellX, combined with cross-section calculations using the eikonal reaction theory, indicate that these peaks in the decay energy spectrum are caused by multiple resonant states in ${}^{31}\mathrm{Ne}$.

Conclusions: Excited states in ${}^{31}\mathrm{Ne}$ were observed for the first time. Transitions from calculated shell-model final states in ${}^{31}\mathrm{Ne}$ to bound states in ${}^{30}\mathrm{Ne}$ are in good agreement with the measured decay energy spectrum. Cross-section calculations for the two-proton knockout populating ${}^{31}\mathrm{Ne}$ states as well as spectroscopic factors pertaining to the decay of ${}^{31}\mathrm{Ne}$ into ${}^{30}\mathrm{Ne}$ are used to examine the results within the context of the shell-model expectations.

Single-nucleon transfer reactions are processes that selectively probe single-particle components of the populated many-body nuclear states. In this context, recent efforts have been made to build a unified description of the rich nuclear spectroscopy accessible in heavy-ion collisions. An example of this multichannel approach is the study of the competition between successive nucleon transfer and charge exchange reactions, the latter being of particular interest in the context of single and double beta decay studies. To this extent, the one-proton pickup reaction ${}^{48}\mathrm{Ti}({}^{18}\mathrm{O},{}^{19}\mathrm{F}){}^{47}\mathrm{Sc}$ at 275 MeV was measured for the first time, under the NUMEN experimental campaign. Differential cross-section angular distribution measurements for the ${}^{19}\mathrm{F}$ ejectiles were performed at INFN-LNS in Catania by using the MAGNEX large acceptance magnetic spectrometer. The data were analyzed within the distorted-wave and coupled-channels Born approximation frameworks. The initial and final-state interactions were described adopting the São Paulo potential, whereas the spectroscopic amplitudes for the projectile and target overlaps were derived from shell-model calculations. The theoretical cross sections are found to be in very good agreement with the experimental data, suggesting the validity of the optical potentials and the shell-model description of the involved nuclear states within the adopted model space.

For even isotopes of nuclei U, Pu, Cm, Cf, Fm, No, Rf, Sg, and Hs, spontaneous fission and $\alpha$-decay half-lives are calculated within the dinuclear system model and compared with existing experimental data. Cluster radioactivity half-lives are also described for even U, Pu, and Cm isotopes. All these processes are considered for the evolution of a nucleus in the charge (mass) asymmetry coordinate and in the relative distance between the centers of clusters formed. The important roles of the driving potential and mass parameter in the charge asymmetry coordinate are shown for spontaneous fission. The global isotopic trends of spontaneous fission and $\alpha$-decay half-lives are studied. Drastic changes in the functional dependence of spontaneous fission half-life on the neutron number and in the absolute values of half-lives in the U–No and Rf–Hs nuclear groups are explained.

High energy collisions are the laboratories within our reach to study strongly interacting matter under extreme temperatures. In the present study, we use a quarkonia suppression scheme to explain the bottomonium production at the two energies available at the CERN Large Hadron Collider. We employ echo-qgp to model the $(3+1)$-dimensional relativistic viscous hydrodynamic evolution of the medium. Bottomonia produced in the early stage dissociates due to color screening, gluonic dissociation, and collisional damping in addition to shadowing as an initial state effect. In the color screening mechanism, the temperature from hydrodynamics is used to find the screening radii at each centrality and rapidity. The shadowing effect utilizes the parton distribution functions obtained from the CT14 global analysis and shadowing factors from EPPS16. A lattice QCD based equation of state from the Wuppertal-Budapest Collaboration has been used. The experimental values of pion $\left({\pi }^{+}\right)$ spectra were used to constrain the initial conditions of the dynamics. The bottomonium suppression is determined as a function of centrality, transverse momentum, and rapidity for $\mathrm{{\rm Y}}\left(1S\right)$ and $\mathrm{{\rm Y}}\left(2S\right)$ states at the LHC energies of 2.76 and $5.02\mathrm{TeV}$. We find a fairly good agreement between our theoretically calculated survival probability and the measured nuclear modification factor $\left(R_{AA}\right)$ at the two energies.

In this paper we study the low-lying states of neutron-rich ${}^{122,124,126,128}\mathrm{Cd}$ and ${}^{130,132,134,136,138}\mathrm{Cd}$ within the nucleon-pair approximation of the shell model. We adopt the phenomenological Hamiltonian for ${}^{122,124,126,128}\mathrm{Cd}$, and the shell-model effective interaction $jj46$ for ${}^{130,132,134,136,138}\mathrm{Cd}$. The available experimental excitation energies and quadrupole transition probabilities are well reproduced by our calculation, and we also make predictions for very neutron-rich Cd nuclei. Based on our calculation, the $B(E2;0_{\mathrm{g}.\mathrm{s}.}^{+}\to 2_1^{+})$ values exhibit an asymmetric feature with respect to the $N=82$ shell closure, which mainly comes from the contributions of the proton transition matrix elements. We also investigate for the eight open-shell Cd nuclei, whether two low-lying yrast states with spins differing by 2 can be connected by a quadrupole-phonon excitation, and here we take the proton and neutron quadrupole operators multiplied by $1/r_0^2$ as our quadrupole phonon operators. We calculate explicit overlaps between the low-lying yrast states and the constructed quadrupole-phonon states based on the low-lying yrast states with lower spins, and the results indicate that, for all eight open-shell Cd nuclei, $|2_1^{+}\rangle$ and $|4_1^{+}\rangle$ can be well described to be the states constructed by coupling the proton or neutron phonon to $|0_{\mathrm{g}.\mathrm{s}.}^{+}\rangle$ and $|2_1^{+}\rangle$, respectively. Very interestingly, for ${}^{126,124,122}\mathrm{Cd}$ and ${}^{136,138}\mathrm{Cd}$, the $2_1^{+}$ state can be well described to be both the proton phonon state and the neutron phonon state, which indicates a nonorthogonal feature of these two phonon states. We further present an analytic relation for the overlap between these two phonon states, which implies that the proton and neutron phonon states constructed using the quadrupole operators and the $0_{\mathrm{g}.\mathrm{s}.}^{+}$ state in an open-shell nucleus are almost impossibly orthogonal.