A measurement of the $\beta$-delayed $\alpha$ decay of ${}^{16}\mathrm{N}$ using a set of twin ionization chambers is described. Sources were made by implantation, using a ${}^{16}\mathrm{N}$ beam produced via the In-Flight Technique. The energies and emission angles of the ${}^{12}\mathrm{C}$ and $\alpha$ particles were measured in coincidence and very clean $\alpha$ spectra, down to energies of $450$ keV, were obtained. The structure of the spectra from this experiment is in good agreement with results from previous measurements. An analysis of our data with the same input parameters as used in earlier studies gives $S_{E1}(300)=86\pm 22$ keVb for the $E1$ component of the $S$-factor. This value is in excellent agreement with results obtained from various direct and indirect measurements. In addition, the influence of new measurements including the phase shift data from Tischhauser et al. on the value of $S_{E1}(300)$ is discussed.

The $\beta$-delayed proton decays of ${}^{145,147}\mathrm{Er}$ have been studied experimentally using the ${}^{58}\mathrm{Ni}+{}^{92}\mathrm{Mo}$ reaction at beam energy of $383$ MeV. On the basis of a He-jet apparatus coupled with a tape transport system, the $\beta$-delayed proton radioactivities both from the $\nu s_{1/2}$ ground state and the $\nu h_{11/2}$ isomer in ${}^{145,147}\mathrm{Er}$ were observed by proton-$\gamma$ coincidence measurements. By analyzing the time distributions of the $4$${}^{+}\to 2^{+}\gamma$ transitions in the granddaughter nuclei ${}^{144,146}\mathrm{Dy}$, the half-lives of $1.0\pm 0.3$ s and $1.6\pm 0.2$ s have been deduced for the $\nu h_{11/2}$ isomers in ${}^{145,147}\mathrm{Er}$, respectively.

The structure of the neutron-rich sodium isotopes ${}^{31,32,33}\mathrm{Na}$ was investigated by means of in-beam $\gamma$-ray spectroscopy following one-neutron knockout and inelastic scattering of radioactive beams provided by the RIKEN Radioactive Ion Beam Factory. The secondary beams were selected and separated by the fragment separator BigRIPS and incident at $\approx$240 MeV/nucleon on a natural carbon (secondary) target, which was surrounded by the DALI2 array to detect coincident de-excitation $\gamma$ rays. Scattered particles were identified by the spectrometer ZeroDegree. In ${}^{31}\mathrm{Na}$, a new decay $\gamma$ ray was observed in coincidence with the known $(5/2_1^{+})\to 3/2_{\mathrm{g}.\mathrm{s}.}^{(+)}$ transition, while for ${}^{32,33}\mathrm{Na}$ excited states are reported for the first time. From a comparison to state-of-the-art shell-model calculations it is concluded that the newly observed excited state in ${}^{31}\mathrm{Na}$ belongs to a rotational band formed by a $2p$$2h$ intruder configuration within the “Island of Inversion.”

The level scheme of ${}^{238}\mathrm{U}$ has been extended using the so-called unsafe Coulomb excitation technique. One positive-parity band was uncovered for the first time, and its most important features can be related to a double-octupole phonon excitation. This band decays to the known $K=0$ octupole band via $E1$ transitions, with strengths much larger than those to the ground-state band. It also decays to the $K=1$ and 2 octupole bands. Comparisons among the proposed zero-, one-, and two-phonon bands in ${}^{238}\mathrm{U}$ and those in ${}^{240}\mathrm{Pu}$ shed more light on the recently proposed concept of rotationally aligned octupole phonon condensation.

Using modern nucleon-nucleon interactions in the description of $A=3,4$ nuclei, it is not possible to reproduce both the three- and the four-nucleon binding energies simultaneously. This is one manifestation of the necessity of including a three-nucleon force in the nuclear Hamiltonian. In this paper we perform a comparative study of some widely used three-nucleon force models. We analyze their capability to describe the aforementioned binding energies as well as the $n$-$d$ doublet scattering length. The correct description of these quantities can be considered a stringent requirement for a nuclear Hamiltonian containing two- and three-nucleon interaction terms. As we show, this requirement is not fulfilled by several of the models available in the literature. To satisfy it, we propose modifications in the parametrization of the three-nucleon forces and we study their effects on a few selected $N$-$d$ low-energy scattering observables.

The cross sections and analyzing powers for the ${}^{40}\mathrm{Ca}$($\mathrm{p⃗},2p$) reaction were measured. The strength distributions for the deep-hole states were obtained by a multipole decomposition analysis. The centroid energies and widths of the hole-state strengths of the $1p$ and $1s_{1/2}$ orbitals in ${}^{40}\mathrm{Ca}$ were determined. The spectroscopic factors for the deeply bound $1p$ and $1s_{1/2}$ orbitals were extracted as $49\pm 10\%$ and $78\pm 14\%$ of the sum-rule limits of the independent-particle shell model, respectively. A strong influence of the nucleon-nucleon correlations on the spectroscopic factors is suggested.

We propose some new, efficient, and practical extrapolation methods to obtain a few low-lying eigenenergies of a large-dimensional Hamiltonian matrix in the nuclear shell model. We obtain those energies at the desired accuracy by extrapolation after diagonalizing small-dimensional submatrices of the sorted Hamiltonian matrix.

We show that the sharp maximum corresponding to ${}^{107}\mathrm{Mo}$ in the fragment distribution of the ${}^{252}\mathrm{Cf}$ cold fission is actually a Sn-like radioactivity, similar to other decay processes in which magic nuclei are involved, namely $\alpha$ decay and heavy cluster emission, also called Pb-like radioactivity. It turns out that the mass asymmetry degree of freedom has a key role in connecting initial Sn with the final Mo isotopes along the fission path. We investigate the cold rearrangement of nucleons within the framework of the two-center shell model in order to compute the cold valleys in the charge equilibrated fragmentation potential. The fission yields are estimated by using the semiclassical penetration approach. We consider 5 degrees of freedom, namely the interfragment distance, the shapes of fragments, the neck parameter, and mass asymmetry. We found an isomeric minimum between the internal and external barriers. It turns out that the inner cold valley of the total potential energy is connected to the doubly magic isotope ${}^{132}\mathrm{Sn}$.

A deuteron microscopic optical model potential is obtained by the Green function method through nuclear-matter approximation and local-density approximation based on the effective Skyrme interaction. The microscopic optical model potential is used to calculate the deuteron reaction cross sections and the elastic scattering angular distributions for some target nuclei in the mass range $6⩽A⩽208$ with incident deuteron energies up to $200$ MeV. The calculated results are compared with the experimental data.

We discuss experimental evidence for a nuclear phase transition driven by the different concentrations of neutrons to protons. Different ratios of the neutron to proton concentrations lead to different critical points for the phase transition. This is analogous to the phase transitions occurring in ${}^4\mathrm{He}$-${}^3\mathrm{He}$ liquid mixtures. We present experimental results that reveal the $N/A$ (or $Z/A$) dependence of the phase transition and discuss possible implications of these observations in terms of the Landau free energy description of critical phenomena.

We compute the finite temperature density response function of nonrelativistic cold fermions with an isotropic condensate. The pair-breaking contribution to the response function is evaluated in the limit of small three-momentum transfers $q$ within an effective theory which exploits series expansion in powers of small $q/p_F$, where $p_F$ is the Fermi momentum. The leading order $O(q^2)$ contribution is universal and depends only on two fundamental scales, the Fermi energy and the pairing gap. The particle-hole Landau Fermi-liquid interaction contributes first at the next-to-leading-order $O(q^4)$. The scattering contribution to the polarization tensor is nonperturbative (in the above sense) and is evaluated numerically. The spectral functions of density fluctuations are constructed and the relevance of the $q^2$ scaling for the pair-breaking neutrino emission from neutron stars is discussed.

By using 14 different versions and parametrizations of a proximity potential and two new versions of the potential proposed in this paper, we perform a comparative study of fusion barriers by studying 26 symmetric reactions. The mass asymmetry ${\eta }_A=(\frac{A_2-A_1}{A_2+A_1})$, however, is very large. Our detailed investigation reveals that most of the proximity potentials reproduce experimental data within $\pm 8\%$ on average. A comparison of fusion cross sections indicates that Bass 80, AW 95, and Denisov DP potentials have a better edge than other potentials. We also propose new versions of the proximity potential as well as Denisov parametrized potential. These new versions improve agreement with the data.

The ($n,\gamma$) cross section of ${}^{197}\mathrm{Au}$ has been measured at n_TOF in the resolved resonance region, up to 5 keV, with the aim of improving the accuracy in an energy range where it is not yet considered standard. The measurements were performed with two different experimental setup and detection techniques, the total energy method based on ${\mathrm{C}}_6$${\mathrm{D}}_6$ detectors, and the total absorption calorimetry based on a 4$\pi$ BaF${}_2$ array. By comparing the data collected with the two techniques, two accurate sets of neutron-capture yields have been obtained, which could be the basis for a new evaluation leading to an extended cross-section standard. Overall good agreement is found between the n_TOF results and evaluated cross sections, with some significant exceptions for small resonances. A few resonances not included in the existing databases have also been observed.

We investigate the equation of state of hadronic matter at finite values of baryon density and temperature reachable in high-energy heavy-ion collisions. The analysis is performed by requiring the Gibbs conditions on the global conservation of baryon number, electric charge fraction, and zero net strangeness. We consider an effective relativistic mean-field model with the inclusion of $\Delta$ isobars, hyperons, and the lightest pseudoscalar and vector meson degrees of freedom. In this context, we study the influence of the $\Delta$-isobar degrees of freedom in the hadronic equation of state and, in connection, the behavior of different particle-antiparticle ratios and strangeness production.

The paper describes a multilevel, multichannel $R$-matrix code, AZURE, for applications in nuclear astrophysics. The code allows simultaneous analysis and extrapolation of low-energy particle scattering, capture, and reaction cross sections of relevance to stellar hydrogen, helium, and carbon burning. The paper presents a summary of $R$-matrix theory, code description, and a number of applications to demonstrate the applicability and versatility of AZURE.

Calculations for infinite nuclear matter with realistic nucleon-nucleon interactions suggest that the isoscalar effective mass of a nucleon at the saturation density $m^{*}/m$ equals $0.8\pm 0.1$. This result is at variance with empirical data on the level density in finite nuclei, which are consistent with $m^{*}/m\approx 1$. Ma and Wambach suggested that these two contradicting results may be reconciled within a single theoretical framework by assuming a radial-dependent effective mass, peaked at the nuclear surface. The aim of this exploratory work is to investigate this idea within the density functional theory by using a Skyrme-type local functional enriched with new terms, $\tau (\nabla \rho ){}^2$ and $\tau (d\rho /\mathit{dr})$, where $\tau$ and $\rho$ denote the kinetic and particle densities, respectively. We show that each of these terms can give rise to a surface peak in the effective mass, but of a limited height. We investigate the influence of the radial profile of the effective mass on the spin-orbit splittings and centroids. In particular, we demonstrate that the $\tau (d\rho /\mathit{dr})$ term quenches the $1f_{5/2}$-$1f_{7/2}$ splitting in ${}^{40}\mathrm{Ca}$, which is strongly overestimated within conventional Skyrme parametrizations.

Based on time-dependent Hartree-Fock theory, a new inverse quasifission mechanism is proposed to produce neutron-rich transfermium nuclei in the collision of prolate deformed actinides. Calculations show that the collision of the tip of one nucleus with the side of the other results in a nucleon flux toward the latter. The roles of nucleon evaporation and impact parameter, as well as collision time, are discussed.

The nucleon-nucleus optical potential has been obtained from calculations of the mass operator of the one-particle Green function with the effective nucleon-nucleon density-dependent Skyrme interaction by perturbation theory up to the second order. By means of fitting angular distributions of nucleon-nucleus scattering with simultaneous control of calculated characteristics of the nuclear matter, binding energy and rms radius of the target nucleus new variants of Skyrme-force parameters have been found. Analyses of differential cross sections and analyzing powers of elastic neutron scattering by nuclei in a wide range of mass numbers have been carried out. It has been shown that using the found Skyrme-force parameters enables us to describe satisfactorily both the main nuclear structure characteristics and the experimental data on elastic neutron-nucleus scattering simultaneously.

The space-time scales of the hadronization process in the framework of the string model are investigated. It is shown that the average formation lengths of pseudoscalar mesons, produced in semi-inclusive deep inelastic scattering of leptons on different targets, depend on their electrical charges. In particular, the average formation lengths of positively charged hadrons are larger than those of negatively charged ones. This statement is fulfilled for all scaling functions used, for $z$ (the fraction of the virtual photon energy transferred to the detected hadron) larger than $0.15$, for all nuclear targets, and for any value of the Björken scaling variable $x_{\mathrm{Bj}}$. In all cases, the main mechanism is direct production of pseudoscalar mesons. Including in consideration an additional mechanism of production resulting in decay of resonances leads to a decrease in average formation lengths. It is shown that the average formation lengths of positively (negatively) charged mesons are slowly increasing (decreasing) functions of $x_{\mathrm{Bj}}$. The results obtained can be important, in particular, for understanding of the hadronization process in the nuclear environment.

Production of the ${\Sigma }^{+}$ hyperon through the $\mathit{pp}\to K^{+}n{\Sigma }^{+}$ reaction has been investigated at four energies close to threshold, $1.826,1.920,1.958$, and $2.020$ GeV. At low energies, correlated $K^{+}{\pi }^{+}$ pairs can only originate from ${\Sigma }^{+}$ production so their measurement allows the total cross section for the reaction to be determined. The results obtained are completely consistent with the values extracted from the study of the $K^{+}$-proton correlation spectra obtained in the same experiment. These spectra, as well as the inclusive $K^{+}$ momentum distributions, also provide conservative upper limits on ${\Sigma }^{+}$ production rates. The measurements show a ${\Sigma }^{+}$ production cross section that varies roughly like phase space, and, in particular, none of the three experimental approaches used supports the anomalously high, near-threshold $\mathit{pp}\to K^{+}n{\Sigma }^{+}$ total cross section previously reported [T. Rożek et al., Phys. Lett. B 643, 251 (2006)].