We study the dominant forbidden transitions in the antineutrino spectra of the fission actinides from 4 MeV onward using the nuclear shell model. Through explicit calculation of the shape factor, we show the expected changes in cumulative electron and antineutrino spectra. Relative to the allowed approximation this results in a minor decrease of electron spectra above 4 MeV, whereas an increase of several percent is observed in antineutrino spectra. We show that forbidden transitions dominate the spectral flux for most of the experimentally accessible range. Based on the shell model calculations we attempt a parametrization of forbidden transitions and propose a spectral correction for all first-forbidden transitions. We enforce correspondence with the Institut Laue-Langevin data set using a summation+conversion approach. When compared against modern reactor neutrino experiments, the resultant spectral change is observed to be of comparable magnitude and shape as the reported spectral shoulder.

The production of charged particles $K^{\pm },p$, and $\overline{p}$ is simulated using the paciae model at scaled midrapidity $\left|y\right|<0.5$ in proton-proton collisions at $\sqrt{s}=7$ TeV. The simulation results are consistent with ALICE experimental data on $K^{\pm },p$, and $\overline{p}$ yield, with the transverse momentum of kaon at 0.2–6 GeV/$c$ and proton at 0.3–6 GeV/$c$. Furthermore, the production of $K^{-}pp$ and $K^{+}\overline{p}\overline{p}$ is predicted in the dynamically constrained phase-space coalescence (dcpc) model, based on the hadronic final states produced in the paciae model. It is found that the yield of $K^{-}pp$ is around $5\times {10}^{-4}$, much larger than the yield of the $K^{+}\overline{p}\overline{p}$ following the hypothesis that $K^{-}pp$ and $K^{+}\overline{p}\overline{p}$ are formed in the way that a $K^{-}\left(K^{+}\right)$ traps two protons (antiprotons) directly, without going through the so-called ${\mathrm{\Lambda }}^{*}p$ doorway state.

We have studied some of the nuclear decay properties of ${}^{58}\mathrm{Co}^m$. The half-life is found to be ($8.853\pm 0.023$) hours, which is significantly different from the evaluations found in the literature. The absolute intensity of the 24.9-keV $\gamma$ ray emitted in the internal transition decay is ($0.0387\pm 0.0016$)%, in agreement with the calculated yield of a transition of $M3$ multipolarity. We observe $\gamma$-ray photons from a previously unreported branch for electron capture decay, with an intensity of ($0.00120\pm 0.00005$)%, consistent with expectations from the calculation of log $ft$.

The nucleus-nucleus reaction cross sections of ${}^{18–34}\text{Ne},{}^{20–36}\text{Mg},{}^{16–24}\text{O}+{}^{12}\mathrm{C}$ at one GeV/u are calculated in the Glauber theory using different models of the nucleon-nucleon ($NN$) cross sections and nuclear densities. For in-medium effects, we consider the phenomenological (Ph), geometrical Pauli (GP), and modified combined (MC) models for the $NN$ reaction cross section. For the density distributions, we used the Sao Paulo (SP), Skyrme-Hartree-Fock (SHF), and the angle-averaged deformed Fermi (DF) densities. The results are compared with experiments as well as other theoretical calculations. It is found that the data can, generally, be described by using the Ph and GP models for in-medium effects with the SP density, which, on the other hand, predicted smaller radii. A satisfactory explanation of the experimental data is obtained by using more realistic densities such as SHF and DF with realistic radii, and the MC model for medium modifications, which involve the combined effect of the phase variation, higher momentum transfer components, and Pauli blocking of the $NN$ amplitude. The in-medium Ph and GP models when used with realistic densities, cannot describe the data at 1 GeV.

We provide a microscopic global optical potential (MGOP) for nucleon-nucleus ($NA$) systems in a wide range of nuclear mass numbers ($A=10–276$) and incident energies ($E=50–400\mathrm{MeV}$). The potential is microscopically constructed based on a single-folding (SF) model with the complex $G$-matrix interaction. The nuclear densities used in the SF model are generated, in a nonempirical way, from two kinds of microscopic mean-field models: the relativistic-mean-field (RMF) and Skyrme-Hartree-Fock + BCS (HF+BCS) models. We calculate the $NA$ potentials for more than 1000 even-even nuclei with atomic number $Z=6–92$, involving proton- and neutron-rich unstable nuclei. We confirm that both the MGOP models well reproduce the available experimental data of the total reaction cross sections, the total neutron cross sections, the elastic-scattering cross sections, the analyzing power, and the spin-rotation function $Q$. We also calculate the proton scattering cross sections of ${}^{22}\mathrm{O}$, ${}^{24}\mathrm{O}$, and ${}^{56}\mathrm{Ni}$ targets to compare the experimental data and then the cross sections for unknown ${}^{48}\mathrm{S}$, ${}^{100}\mathrm{Zr}$, and ${}^{110}\mathrm{Zr}$ are presented for future measurements. For the sake of convenience, the real and imaginary parts of the central and spin-orbit components of the $NA$ potentials are respectively represented in a linear combination of 12-range Gaussians. They are provided on the website [http://www2.yukawa.kyoto-u.ac.jp/∼takenori.furumoto/] with a program source file for reconstructing the MGOP.

Background: Small changes in reaction rates due to neutron capture, $\alpha$ capture, and $\beta$ decay by exotic nuclei in the low and medium mass region can direct the $r$-process path in different ways, thereby affecting the abundance pattern. In this context, it is important to find the most abundant carbon isotope closer to the neutron drip line. It was postulated that the $(n,\gamma )$ reaction network will be broken at the ${}^{18}\mathrm{C}$ isotope and follow the ${}^{18}\mathrm{C}(\alpha ,n){}^{21}\mathrm{O}$ reaction path [Terasawa et al., Astrophys. J. 562, 470 (2001)].

Purpose: In this paper, we calculate the radiative capture cross section of ${}^{18}\mathrm{C}(n,\gamma ){}^{19}\mathrm{C}$, taking into consideration the halo character of ${}^{19}\mathrm{C}$. Eventually, we calculate the reaction rate for the same reaction and compare it with Hauser-Feshbach estimates of $(n,\gamma )$ and $(\alpha ,n)$ to determine the abundance pattern of carbon isotopes.

Method: We compute the relative energy spectrum for elastic Coulomb breakup of ${}^{19}\mathrm{C}$ on a Pb target at a beam energy of 67 MeV/u using the finite-range distorted-wave Born approximation (FRDWBA) theory. We use the principle of detailed balance to calculate the radiative capture cross section from the photo disintegration cross section, and subsequently we calculate the reaction rate.

Results: We report the ${}^{18}\mathrm{C}(n,\gamma ){}^{19}\mathrm{C}$ capture cross section as a function of relative energy. Estimation of the energy range contributing to the reaction rates is done by calculating the integrand of the reaction rate expression. A comparison of the ${}^{18}\mathrm{C}(n,\gamma ){}^{19}\mathrm{C}$ with ${}^{18}\mathrm{C}(\alpha ,n){}^{21}\mathrm{O}$ (extracted from the Hauser-Feshbach estimates) shows the domination of the neutron radiative capture reaction in the relevant temperature range $T_9=0.1–4$.

Conclusion: The radiative capture cross section of ${}^{18}\mathrm{C}$ calculated using FRDWBA theory agrees well with the experimental data, whereas the statistical model calculation lies orders of magnitude lower. We conclude that at equilibrium temperature of $T_9=0.62$, the ${}^{18}\mathrm{C}(n,\gamma ){}^{19}\mathrm{C}$ reaction rate is orders of magnitude higher than that of the ${}^{18}\mathrm{C}(\alpha ,n){}^{21}\mathrm{O}$ reaction, thereby pushing the carbon isotope abundance towards the neutron drip line.

$\alpha$ clustering in nuclei is considered with the quartet model (QM) where four valence nucleons (the quartet) move on the top of the core (daughter) nucleus. In the QM approach, it is assumed that the intrinsic wave function of the quartet is changed from the pure cluster configuration to the shell-model configuration when it crosses some critical radius and enters into the core nucleus. The QM approach could give not only the level scheme, the electromagnetic transition, and the nuclear radius but also the $\alpha$-cluster formation probability. Numerical results are calculated for ${}^{20}\mathrm{Ne}$, ${}^{44}\mathrm{Ti}$, and ${}^{212}\mathrm{Po}$, where a quartet moves on top of a double magic nucleus. Good agreement with experimental data and previous theoretical studies is obtained. The QM approach is a useful complement to the present phenomenological and microscopic models and could help deepen our understanding of $\alpha$ clustering across the nuclide chart.

The reduced transition probability $\mathrm{B}(E2;0_1^{+}\to 2_1^{+})$ to the first excited $2^{+}$ state of the neutron-rich nucleus ${}^{136}\mathrm{Te}$, with two protons and two neutrons outside the doubly magic ${}^{132}\mathrm{Sn}$ core, was measured via Coulomb excitation at relativistic energies at the RIKEN Radioactive Isotope Beam Factory. A value of $\mathrm{B}\left(E2\right)=0.191\left(26\right)$ ${\mathrm{e}}^2{\mathrm{b}}^2$ was extracted from the measured inelastic scattering cross section on an Au target taking into account the contributions from both Coulomb and nuclear excitations. In addition, an upper limit for the transition strength to a $2^{+}$ state of mixed-symmetry character in the excitation energy range of 1.5–2.2 MeV was determined and compared to the predictions of various theoretical calculations. Because of the high statistics gathered in the present experiment the error of the deduced $\mathrm{B}\left(E2\right)$ value is dominated by the systematic uncertainties involved in the analysis of Coulomb excitation experiments at beam energies around 150 MeV/u. Therefore, the latter are for the first time assessed in detail in the present work.

Pion photoproduction amplitudes are calculated from a set of equations that have been derived by coupling an external photon to all places in a dressed pion-nucleon vertex. The calculation is consistent with gauge invariance, charge conservation, unitarity, and covariance. To provide input to the photoproduction amplitude, a photon-nucleon vertex is calculated from a set of equations derived by complete attachment of photons to a dressed nucleon propagator. We check the accuracy of this vertex by extracting its nucleon electromagnetic form factors.

Background: Compared to the axially deformed nuclei, triaxially deformed ones are relatively scarce. This is mainly due to the difficulties in the identification of experimental signatures pertaining to the triaxial degree of freedom. In the nucleus ${}^{138}\mathrm{Nd}$, a number of rotational bands have been observed to have medium or high spin values. They have been interpreted in the macroscopic-microscopic method, to be based on triaxial minima. In particular, for a few configurations, the calculations suggested that a reorientation of the rotational axis may have occurred along the rotational bands.

Purpose: The present work aims at a quantitative description of the experimentally observed bands in ${}^{138}\mathrm{Nd}$, using the cranked self-consistent Skyrme-Hartree-Fock (SHF) method or cranked nuclear density functional theory (DFT). Such a study, which is still missing, will provide alternative interpretations of the structure of the bands and hence, shed new light on the triaxiality issue in connection with experimental data.

Methods: The rotational bands are described using cranked self-consistent mean-field method with SLy4 and SkM* Skyrme energy density functionals (EDFs). For SLy4 EDF, the time-odd pieces are included using Landau parameters (denoted with ${\mathrm{SLy}4}_{\mathrm{L}}$). For SkM* EDF, the local gauge invariance argument has been used to determine the time-odd components of the mean field.

Results: The survey of different configurations near Fermi surface of ${}^{138}\mathrm{Nd}$ results in 12 lowest configurations, at both positive- and negative-$\gamma$ deformations. These are calculated to be the energetically lowest configurations. The results show that, for both EDFs, the rotational states based on positive-$\gamma$ minimum, which is at $\gamma \approx {35}^{\circ }$, are lower than the respective configurations with negative-$\gamma$ deformation. The general trends of the spin-versus-$\omega$ curve, and the energy-versus-spin curve reproduce well those of the experimental data. Further, for the observed bands T1–T8, the calculated results using ${\mathrm{SLy}4}_{\mathrm{L}}$ allows the configurations of the observed bands to be assigned. The calculations predict transitional quadrupole moments, which can be used to compare with future experimental data.

Conclusions: The current cranked self-consistent mean-field calculations of the near-yrast high-spin rotational bands in ${}^{138}\mathrm{Nd}$ reproduce well the experimental data. The results suggest that the experimentally observed bands can be assigned to the calculated bands with various configurations at the positive-$\gamma$ deformation. The predictions of the current calculations are complementary to that of the well-known macroscopic-microscopic calculations, both of which await future experiment to verify.

The understanding of nucleon ($N$) and triton emissions from nucleon-${}^7\mathrm{Li}$ collision is important for the development of some fusion-related facilities. Both nucleon and triton emissions from nucleon-induced reactions on ${}^7\mathrm{Li}$ leading to three final particles at incident energies below 20 MeV are analyzed by using a three-body continuum discretized coupled-channels method (CDCC), final-state interaction (FSI) model, and sequential decay (SD) model. The CDCC is applied to predict nucleon and triton emissions via breakup continuum channels, ${}^7\mathrm{Li}(N,N^{\prime }){}^7\mathrm{Li}^{*}\to t+\alpha$. Triton emission from the $p\left(n\right)$ + ${}^7\mathrm{Li}\to t+{}^5\mathrm{Li}\left({}^5\mathrm{He}\right)$ channel and nucleon emission from sequential decay of the ground-state ${}^5\mathrm{Li}\left({}^5\mathrm{He}\right)$ are described by the FSI model and the SD model, respectively. The double differential cross sections (DDXs) of nucleon and triton emissions are calculated and compared with experimental data. In most cases, the calculated DDXs are in good agreement with the measured ones except at relatively low nucleon emission energies. It is clarified that triton production takes place mainly via the breakup continuum channels.

The strong deformation present immediately after scission has consequences for the angular momentum population of the fragments as well as the angular distribution of their decay radiation. We find that the usual spin-cutoff parametrization describes very well the angular momentum distribution associated with the deformation of the fragments at the scission point. Depending on the deformation, its contribution can be comparable to the thermal contribution to the angular momentum of the newly formed fragments. The $M$ distribution of the angular momentum is highly polarized and gives rise to large anisotropies in the subsequent $\gamma$ cascade. We treat in detail a typical $\gamma$ cascade in a daughter nucleus, following usual model assumptions except for the anisotropy of the initial state. In principle, the observed anisotropy can provide information on the relative amounts of deformation and thermal energy present at the scission point.

The spectroscopy of ${}^{19}\mathrm{F}$ is of interest for nuclear astrophysics and nuclear structure. In astrophysics, fluorine and the reactions producing and destroying it play a key role in constraining models of stars in different evolutionary stages, such as the asymptotic giant branch (AGB) stars, responsible of the production of about half of the elements heavier than Fe. In nuclear structure, ${}^{19}\mathrm{F}$ has been subject to many investigations aiming at the identification of $\alpha$ and more exotic cluster structures. Also, its spectroscopy is very useful to constrain the nuclear properties of the ${}^{19}\mathrm{Ne}$ mirror nucleus. In this work, we report on the measurement of the ${}^{15}\mathrm{N}\text{−}\alpha$ elastic scattering using the thick target inverse kinematics approach, allowing us to span a very large fluorine excitation energy range ($\sim 6$–10 MeV). The use of ${}^{15}\mathrm{N}\text{−}\alpha$ scattering proves very useful to study $\alpha$ clustering in ${}^{19}\mathrm{F}$ thanks to the likelihood for populating states with such a structure. Indeed, the $R$-matrix analysis of the measured differential cross sections shows the occurrence of many candidate $\alpha$-cluster states of ${}^{19}\mathrm{F}$. It also calls for the redefinition of the spin-parity and widths of a number of ${}^{19}\mathrm{F}$ states with respect to what reported in the literature.

We study the emergence of neutron gas effects in the description of nuclei with large neutron excess within the Bardeen-Cooper-Schrieffer approach. We consider Ni and Sn isotopes where, in the literature, these effects have been found. We investigate the role of the single-particle states with positive energy generating the neutron gas, and we find that the contribution of these states is numerically irrelevant for the various observables that we evaluate.

The gross theory, a global method for the calculation of nuclear $\beta$ decay, is improved using single-particle treatment. We analyzed the $\beta$-decay channel for the entire region of nuclides and found that the allowed transition is suppressed systematically in the neighborhood of heavier doubly magic nuclei. This is mainly due to the shift of neutron and proton single-particle levels in one major shell, which leads to a change in the spin and parity between parent and daughter nuclei. Under this consideration, the nuclear matrix elements for the allowed transition in the gross theory are suppressed in the above condition. In the vicinity of the doubly magic numbers of neutron-rich nuclides, such as nuclei with $Z=50$ and 82, the calculated half-lives are longer than those reported in previous work, where only parity mismatch was considered. In superheavy neutron-rich nuclei with $N=184$, the half-lives are predicted to be longer due to the same mechanism.

Background: The recent observation of a neutron-star merger finally confirmed one astrophysical location of the rapid neutron-capture process (r-process). Evidence of the production of $A<140$ nuclei was seen, but there is still little detailed information about how those lighter elements are produced in such an environment. Many of the questions surrounding the $A\approx 80$ nuclei are likely to be answered only when the nuclear physics involved in the production of r-process nuclei is well understood. Neutron-capture reactions are an important component of the r-process, and neutron-capture cross sections of r-process nuclei, which are very neutron rich, have large uncertainties.

Purpose: Indirectly determine the neutron-capture cross section and reaction rate of ${}^{73}\mathrm{Zn}(n,\gamma ){}^{74}\mathrm{Zn}$.

Methods: The nuclear level density (NLD) and $\gamma$-ray strength function ($\gamma \mathrm{SF}$) of ${}^{74}\mathrm{Zn}$ were determined following a total absorption spectroscopy (TAS) experiment focused on the $\beta$ decay of ${}^{74}\mathrm{Cu}$ into ${}^{74}\mathrm{Zn}$ performed at the National Superconducting Cyclotron Laboratory. The NLD and $\gamma \mathrm{SF}$ were used as inputs in a Hauser-Feshbach statistical model to calculate the neutron-capture cross section and reaction rate.

Results: The NLD and $\gamma \mathrm{SF}$ of ${}^{74}\mathrm{Zn}$ were experimentally constrained for the first time using $\beta$-delayed $\gamma$ rays measured with TAS and the $\beta$-Oslo method. The NLD and $\gamma \mathrm{SF}$ were then used to constrain the neutron-capture cross section and reaction rate for the ${}^{73}\mathrm{Zn}(n,\gamma ){}^{74}\mathrm{Zn}$ reaction.

Conclusions: The uncertainty in the neutron-capture cross section and reaction rate of ${}^{73}\mathrm{Zn}(n,\gamma ){}^{74}\mathrm{Zn}$ calculated in TALYS was reduced to under a factor of 2 from a factor of 5 in the cross section and a factor of 11 in the reaction rate using the experimentally obtained NLD and $\gamma \mathrm{SF}$.

Nonstatistical fluctuation in pseudorapidity ($\eta$), azimuthal ($\varphi$), and pseudorapidity-azimuthal ($\eta \text{–}\varphi$) distribution spectra of primary particles of PYTHIA Monash (default) generated $pp$ events at $\sqrt{s}=2.76$, 7, and 13 TeV have been studied using the scaled factorial moment technique. A weak intermittent type of emission could be realized for minimum-bias (MB) $pp$ events in $\chi \left(\eta \text{–}\varphi \right)$ space and a much stronger intermittency could be observed in high-multiplicity (HM) $pp$ events in all $\chi \left(\eta \right)$, $\chi \left(\varphi \right)$, and $\chi \left(\eta \text{–}\varphi \right)$ spaces at all the studied energies. For HM $pp$ events, at a particular energy, the intermittency index ${\alpha }_q$ is found to be largest in two-dimensional $\chi \left(\eta \text{–}\varphi \right)$ space and least in $\chi \left(\eta \right)$ space, and no center of mass energy dependence of ${\alpha }_q$ could be observed. The anomalous dimensions $d_q$ are observed to be increased with the order of the moment $q$, suggesting a multifractal nature of the emission spectra of various studied events. While, the coefficient ${\lambda }_q$ is found to decrease monotonically with the order of the moment $q$ for two-dimensional analysis of MB $pp$ events as well as for one-dimensional analysis of HM $pp$ events, a clear minimum in ${\lambda }_q$ values could be observed from the two-dimensional HM $pp$ data analysis. For PYTHIA Monash generated sets of data, the strength of the intermittency is found to vary significantly with the variation of the strength of the color reconnection (CR) parameter, i.e., reconnection range RR, for $\mathrm{RR}=0.0$, 1.8 and 3.0, thereby, establishing a strong connection between the CR mechanism and the observed intermittent type of emission of primary charged particles of the studied high-multiplicity $pp$ events.

We perform a combined analysis of inclusive electron scattering data from $A=3$ nuclei in the deep-inelastic and quasielastic scattering regions, using Monte Carlo analysis methods and the nuclear weak binding approximation to establish the range over which the data can be described within the same theoretical framework. Comparison with quasielastic ${}^3\mathrm{He}$ cross sections from SLAC and Jefferson Lab suggests that most features of the $x\gtrsim 1$ data can be reasonably well described in the impulse approximation with finite-$Q^2$ nuclear smearing functions for momentum transfers $Q^2\gtrsim 1{\mathrm{GeV}}^2$. For the DIS region, we analyze the recent ${}^3\mathrm{He}$ to deuterium cross-section ratio from the Jefferson Lab E03-103 experiment to explore the possible isospin dependence of the nuclear effects. We discuss the implications of this for the MARATHON experiment at Jefferson Lab and outline how a Bayesian analysis of ${}^3\mathrm{He}$, ${}^3\mathrm{H}$, and deuterium data can robustly determine the free neutron structure function.

The superfluid tunneling model is applied to the calculation of half-lives of the observed $\alpha$ decays in $N=84$ isotones. Results of our calculations are compared to experimental data on the ground-state $\alpha$ decays along the isotonic chain from ${}^{144}\mathrm{Nd}$ to ${}^{159}\mathrm{Re}$. Good agreement is found. The $\alpha$ decays of the known high-spin isomers in ${}^{155}\mathrm{Lu}, {}^{156}\mathrm{Hf}, {}^{157}\mathrm{Ta}$, and ${}^{158}\mathrm{W}$ are also well reproduced, once a reduction in the pairing strength is taken into account. This includes reproduction of the main features of the recently observed fine structure from ${}^{155}\mathrm{Lu}(25/2^{-})$ and ${}^{156}\mathrm{Hf}\left(8^{+}\right)$. Predictions for the $\alpha$-decay fine structure of ${}^{157}\mathrm{Ta}(25/2^{-})$ and ${}^{158}\mathrm{W}\left(8^{+}\right)$ high-spin isomers are presented.