The astrophysical origin of a rare isotope ${}^{115}\mathrm{Sn}$ remains an open question. An isomer ($T_{1/2}=14.1\mathrm{y}$) in ${}^{113}\mathrm{Cd}$ is an $s$-process branching point from which a nucleosynthesis flow reaches ${}^{115}\mathrm{Sn}$. The $s$-process abundance of ${}^{115}\mathrm{Sn}$ depends on the isomer production ratio in the ${}^{112}\mathrm{Cd}(n,\gamma ){}^{113}\mathrm{Cd}$ reaction. However, the ratio has not been measured in an energy region higher than the thermal energy. We have measured $\gamma$ rays following neutron capture reactions on ${}^{112}\mathrm{Cd}$ using two cluster high-purity germanium (HPGe) detectors in conjunction with a time-of-flight method at J-PARC. We have obtained the result that the relative $\gamma$-ray intensity ratio of the isomer is almost constant in an energy region of up to 5 keV. This result suggests that the $s$-process contribution to the solar abundance of ${}^{115}\mathrm{Sn}$ is minor. We have found that the ratio of a resonance at 737 eV is about 1.5 times higher than other ratios. This enhancement can be explained by a $p$-wave neutron capture. This result suggests measurements of decay $\gamma$ rays to isomers are effective to assign the spin and parity for neutron capture resonances.

The recoil-$\beta$ tagging technique has been used in conjunction with the ${}^{40}\mathrm{Ca}({}^{32}\mathrm{S},2n)$ reaction at a beam energy of 88 MeV to identify transitions associated with the decay of the $2^{+}$ and, tentatively, $4^{+}$ states in the nucleus ${}^{70}\mathrm{Kr}$. These data are used, along with previously published data, to examine the triplet energy differences (TED) for the mass 70 isobars. The experimental TED values are compared with shell model calculations, performed with the JUN45 interaction in the $fpg$ model space, that include a $J=0$ isospin nonconserving (INC) interaction with an isotensor strength of 100 keV. The agreement is found to be very good up to spin 4 and supports the expectation for analog states that all three nuclei have the same oblate shape at low-spin. The $A=70$ results are compared with the experimental and shell model predicted TED and mirror energy differences (MED) for the mass 66 and 74 systems. The comparisons clearly demonstrate the importance of the isotensor INC interaction in replicating the TED data in this region. Issues related to the observed MED values and their interpretation within the shell model are discussed.

High spin states in ${}^{41}\mathrm{Ca}$ have been investigated by using $\gamma$-ray spectroscopic techniques following the ${}^{27}\mathrm{Al}({}^{16}\mathrm{O},pn){}^{41}\mathrm{Ca}$ fusion-evaporation reaction. Around twelve new transitions belonging to ${}^{41}\mathrm{Ca}$ have been observed and placed in the level scheme, which now has been extended up to $E_x\sim 9$ MeV. The spin-parity assignments for the observed levels were arrived at following the analysis of both the coincidence intensity anisotropies and linear polarization measurements. The established 5p-4h band was extended up to $J^{\pi }=19/2^{-}$. The observations of Doppler shape and shifts facilitated the estimation of the level lifetimes by using the Doppler shift attenuation method. The lifetimes were validated with respect to previous measurements and lifetime of a few levels has been arrived at for the first time. Shell-model calculations were carried out to explain the observed level structure of the nucleus and are indicative of both single-particle and collective degrees of freedom in this $N\sim Z\sim 20$ nucleus.

The root mean square radii of ${}^{16}\mathrm{O}$ in the short-lived $0^{+}$ excited states were experimentally deduced for the first time from the analyses of $\alpha +{}^{16}\mathrm{O}$ diffraction scattering. Differential cross sections of the elastic and inelastic $\alpha +{}^{16}\mathrm{O}$ and ${}^{16}\mathrm{O}+{}^{16}\mathrm{O}$ scattering in the incident energy range from a few MeV/nucleon up to 100 MeV/nucleon were analyzed by the modified diffraction model. No significant radius enhancement in any state in comparison with the ground state was observed. This concerns, in particular, the 15.1-MeV $0_6^{+}$ state of ${}^{16}\mathrm{O}$, located in the vicinity of the four-$\alpha$-particle complete dissociation threshold, for which we did not confirm the “gigantic” size predicted by the $\alpha$-particle condensation model. This result does not support the idea that ${}^{16}\mathrm{O}$ in the $0_6^{+}$ state has a dilute structure and can be considered as an analog of the famous 7.65-MeV $0_2^{+}$ Hoyle state of ${}^{12}\mathrm{C}$.

Singlet $\left({}^{1}S_0\right)$ and triplet $\left({}^{3}S_1\right)$ nucleon-nucleon potentials are obtained in the framework of the SU(2) nonrelativistic quark model using the resonating-group method in the Born-Oppenheimer approximation. The full Hamiltonian used in the investigation includes the kinetic energy, two-body confinement potential, one-gluon-exchange potential (OGEP), one-pion exchange potential (OPEP), and instanton induced interaction (III), which includes the effect of quark exchange between the nucleons. The contribution of the OGEP, III, and OPEP to the nucleon-nucleon adiabatic potential is discussed.

The density profiles of spherical nuclei are calculated with two methods based on the energy density functional approach. Isotopic trends are discussed in nuclear surface diffuseness. The simple parametrizations of the dependencies of nuclear diffuseness and radius on neutron number are suggested. The nucleus-nucleus potentials are calculated with the nucleon densities obtained and are compared with those resulting from the phenomenological treatment. The height of the Coulomb barrier is suggested to be used in the fit of the density-dependent nucleon-nucleon interaction.

To describe the dynamics of ternary fission of ${}^{252}\mathrm{Cf}$ an equation of motion of the tri-nuclear system was obtained and it was solved numerically. The fission of the ${}^{70}\mathrm{Ni}+{}^{50}\mathrm{Ca}+{}^{132}\mathrm{Sn}$ channel was chosen as one of the more probable channels of true ternary fission of ${}^{252}\mathrm{Cf}$. The collinearity of ternary fission was checked by analyzing the results of the equation of motion. The results show that if initially all nuclei are placed collinearly (potential energy of this position is the smallest) and the component of the middle fragment's initial velocity which is perpendicular to this line is zero, then ternary fission is collinear, otherwise noncollinear ternary fission takes place.

I investigate the volume corrections on cumulants of total charge distributions and net proton distributions. The required volume information is generated by an optical Glauber model. I find that the corrected statistical expectations of multiplicity distributions mimic the negative binomial distributions at noncentral collisions, and they tend to approach the Poisson ones at most-central collisions due to the “boundary effects,” which suppress the volume corrections. However, net proton distributions and reference multiplicity distributions are sensitive to the external volume fluctuations at most-central collisions, which imply that one has to consider the details of volume distributions in event-by-event multiplicity fluctuation studies.

We perform a Markov chain Monte Carlo (MCMC) statistical analysis of a number of measured ground-state-to-ground-state single ${\beta }^{+}$/electron-capture and ${\beta }^{-}$ decays in the nuclear mass range of $A=62–142$. The corresponding experimental comparative half-lives ($logft$ values) are compared with the theoretical ones obtained by the use of the proton-neutron quasiparticle random-phase approximation $\left(pn\mathrm{QRPA}\right)$ with $G$-matrix-based effective interactions. The MCMC analysis is performed separately for 47 isobaric triplets and 28 more extended isobaric chains of nuclei to extract values and uncertainties for the effective axial-vector coupling constant $g_A$ in nuclear-structure calculations performed in the $pn\mathrm{QRPA}$ framework. As far as available, measured half-lives for two-neutrino $\beta {\beta }^{-}$ decays occurring in the studied isobaric chains are analyzed as well.

The recently reported wobbling bands in ${}^{135}\mathrm{Pr}$ are investigated by the collective Hamiltonian, in which the collective parameters, including the collective potential and the mass parameter, are respectively determined from the tilted axis cranking (TAC) model and the harmonic frozen alignment (HFA) formula. It is shown that the experimental energy spectra of both yrast and wobbling bands are well reproduced by the collective Hamiltonian. It is confirmed that the wobbling mode in ${}^{135}\mathrm{Pr}$ changes from transverse to longitudinal with the rotational frequency. The mechanism of this transition is revealed by analyzing the effective moments of inertia of the three principal axes, and the corresponding variation trend of the wobbling frequency is determined by the softness and shapes of the collective potential.

The isomeric ratios for the neutron capture reaction ${}^{176}\mathrm{Lu}(n,\gamma )$ to the $J^{\pi }=5/2^{-}$, 761.7 keV, $T_{1/2}=32.8$ ns and the $J^{\pi }=15/2^{+}$, 1356.9 keV, $T_{1/2}=11.1$ ns levels of ${}^{177}\mathrm{Lu}$ have been measured for the first time. The experiment was carried out with the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos National Laboratory. Measured isomeric ratios are compared with talys calculations using different models for photon strength functions, level densities, and optical potentials. In order to reproduce the experimental $\gamma$-ray spectra, a low-energy resonance must be added in the photon strength function used in our Hauser-Feshbach calculations.

Background: Suppression of compound nucleus formation in the reactions with heavy ions by a quasifission process in dependence on the reaction entrance channel.

Purpose: Investigation of fission and quasifission processes in the reactions ${}^{36}\mathrm{S},{}^{48}\mathrm{Ca},{}^{48}\mathrm{Ti}$, and ${}^{64}\mathrm{Ni}+{}^{238}\mathrm{U}$ at energies around the Coulomb barrier.

Methods: Mass-energy distributions of fissionlike fragments formed in the reaction ${}^{48}\mathrm{Ti}+{}^{238}\mathrm{U}$ at energies of 247, 258, and 271 MeV have been measured using the double-arm time-of-flight spectrometer CORSET at the U400 cyclotron of the Flerov Laboratory of Nuclear Reactions and compared with mass-energy distributions for the reactions ${}^{36}\mathrm{S},{}^{48}\mathrm{Ca},{}^{64}\mathrm{Ni}+{}^{238}\mathrm{U}$.

Results: The most probable fragment masses as well as total kinetic energies and their dispersions in dependence on the interaction energies have been investigated for asymmetric and symmetric fragments for the studied reactions. The fusion probabilities have been deduced from the analysis of mass-energy distributions.

Conclusion: The estimated fusion probability for the reactions S, Ca, Ti, and Ni ions with actinide nuclei shows that it depends exponentially on the mean fissility parameter of the system. For the reactions with actinide nuclei leading to the formation of superheavy elements the fusion probabilities are of several orders of magnitude higher than in the case of cold fusion reactions.

Theoretical predictions for the $\alpha$-decay chain of the nucleus ${}^{296}118$ are performed. The synthesis of this nucleus is being attempted in experiments running in Dubna. The $\alpha$-decay energies $Q_{\alpha }$, and the $\alpha$-decay and spontaneous-fission half-lives, $T_{\alpha }$ and $T_{\mathrm{sf}}$, are studied. The analysis of the $\alpha$ decay is based on a phenomenological model using only three parameters. The calculations are performed in nine variants using masses obtained within nine nuclear-mass models describing masses of the heaviest nuclei. The experimental $Q_{\alpha }$ energies, known from earlier experiments for the potential daughter, ${}^{292}\mathrm{Lv}$, and grand-daughter, ${}^{288}\mathrm{Fl}$, nuclei are reproduced with an average of the absolute values of the discrepancies: from 0.13 to 1.52 MeV within the considered variants. Measured half-lives $T_{\alpha }$ are reconstructed within average ratios: from 1.7 to 1054. Within all variants considered, the half-life $T_{\alpha }$ of the nucleus ${}^{296}118$ is obtained larger than needed (around $1 \mu \mathrm{s}$) for its observation.

We examine the correlations of neutron star radii with the nuclear matter incompressibility, symmetry energy, and their slopes, which are the key parameters of the equation of state (EoS) of asymmetric nuclear matter. The neutron star radii and the EoS parameters are evaluated using a representative set of 24 Skyrme-type effective forces and 18 relativistic mean field models, and two microscopic calculations, all describing $2M_{\odot }$ neutron stars. Unified EoSs for the inner-crust–core region have been built for all the phenomenological models, both relativistic and nonrelativistic. Our investigation shows the existence of a strong correlation of the neutron star radii with the linear combination of the slopes of the nuclear matter incompressibility and the symmetry energy coefficients at the saturation density. Such correlations are found to be almost independent of the neutron star mass in the range $0.6\text{–}1.8M_{\odot }$. This correlation can be linked to the empirical relation existing between the star radius and the pressure at a nucleonic density between one and two times saturation density, and the dependence of the pressure on the nuclear matter incompressibility, its slope, and the symmetry energy slope. The slopes of the nuclear matter incompressibility and the symmetry energy coefficients as estimated from the finite nuclei data yield the radius of a $1.4M_{\odot }$ neutron star in the range $11.09\text{–}12.86$ km.

The $1s$ level shift in kaonic deuterium was calculated using Coulomb Sturmian expansion of Faddeev equations. The convergence of the method yields an $\sim 1\mathrm{eV}$ accuracy for the level shifts. We used three different, realistic, multichannel $\overline{K}N$ interactions reproducing all known experimental two-body $K^{-}N$ data. The different results suggest that the level shift should be in the range $\mathrm{\Delta }E\sim (800\pm 30)-(480\pm 20)i\mathrm{eV}$. The exact level shifts were compared with values, given by the commonly used approximations.

Radiative thermal neutron capture cross sections over the range of thermal energies from 1 keV to 1 MeV are studied in the statistical Hauser-Feshbach formalism. The optical model potential is constructed by folding the density-dependent M3Y nucleon-nucleon interaction with radial matter densities of target nuclei obtained from relativistic-mean-field (RMF) theory. The standard nuclear reaction code talys1.8 is used for calculation of cross sections. The nuclei studied in the present work reside near the $Z=28$ proton shell closure and are of astrophysical interest, taking part in $p,s$, and $r$ processes of nucleosynthesis. The Maxwellian-averaged cross-section (MACS) values for energies important for astrophysical applications are presented.

Spectral properties of nuclei near the critical point of the quantum phase transition between spherical and axially symmetric shapes are studied in a hybrid collective model which combines the $\gamma$-stable and $\gamma$-rigid collective conditions through a rigidity parameter. The model in the lower and upper limits of the rigidity parameter recovers the $\text{X}\left(5\right)$ and $\text{X}\left(3\right)$ solutions respectively, while in the equally mixed case it corresponds to the $\text{X}\left(4\right)$ critical point symmetry. Numerical applications of the model on nuclei from regions known for critical behavior reveal a sizable shape phase mixing and its evolution with neutron or proton numbers. The model also enables a better description of energy spectra and electromagnetic transitions for these nuclei.

Neutron matter is an ideal laboratory for nuclear interactions derived from chiral effective field theory since all contributions are predicted up to next-to-next-to-next-to-leading order (${\mathrm{N}}^3\mathrm{LO}$) in the chiral expansion. By making use of recent advances in the partial-wave decomposition of three-nucleon ($3N$) forces, we include for the first time ${\mathrm{N}}^3\mathrm{LO} 3N$ interactions in many-body perturbation theory (MBPT) up to third order and in self-consistent Green's function theory (SCGF). Using these two complementary many-body frameworks we provide improved predictions for the equation of state of neutron matter at zero temperature and also analyze systematically the many-body convergence for different chiral EFT interactions. Furthermore, we present an extension of the normal-ordering framework to finite temperatures. These developments open the way to improved calculations of neutron-rich matter including estimates of theoretical uncertainties for astrophysical applications.

We use a relativistic model of meson-exchange currents to compute the proton-neutron and proton-proton yields in $(e,e^{\prime })$ scattering from ${}^{12}\mathrm{C}$ in the 2p-2h channel. We compute the response functions and cross section with the relativistic Fermi gas model for a range of kinematics from intermediate- to high-momentum transfers. We find a large contribution of neutron-proton configurations in the initial state, as compared to proton-proton pairs. The different emission probabilities of distinct species of nucleon pairs are produced in our model only by meson-exchange currents, mainly by the $\mathrm{\Delta }$ isobar current. We also analyze the effect of the exchange contribution and show that the direct-exchange interference strongly affects the determination of the $np/pp$ ratio.