Garrett et al. systematically investigated band-crossing frequencies resulting from the rotational alignment of the first pair of $i_{13/2}$ neutrons (AB) in rare-earth nuclei. In that study, evidence was found for an odd-even neutron number dependence attributed to changes in the strength of neutron pairing correlations. The present paper carries out a similar investigation at higher rotational frequencies for the second pair of aligning $i_{13/2}$ neutrons (BC). Again, a systematic difference in band-crossing frequencies is observed between odd-$N$ and even-$N$ Er, Yb, Hf, and W nuclei, but in the BC case, it is opposite to the AB neutron-number dependence. These results are discussed in terms of a reduction of neutron pairing correlations at high rotational frequencies and of the effects of Pauli blocking on the pairing field by higher-seniority configurations. Also playing a significant role are the changes in deformation with proton and neutron numbers, the changes in location of single-particle orbitals as a function of quadrupole deformation, and the position of the Fermi surface with regard to the various $\mathrm{\Omega }$ components of the neutron $i_{13/2}$ shell.

Isoscalar (IS) monopole and dipole excitations in ${}^{16}\mathrm{O}$ were investigated by the method of shifted basis antisymmetrized molecular dynamics combined with the generator coordinate method. Significant strengths of the IS monopole and dipole transitions were obtained in the low-energy region below the giant resonances. In addition to the compressive mode, which mainly contributes to the high-energy strengths for the IS dipole giant resonance, we obtained a variety of low-energy dipole modes such as the vortical dipole mode in the $1_1^{-}$ state of the vibrating tetrahedral $4\alpha$ and the ${}^{12}\mathrm{C}+\alpha$ cluster structure in the $1_2^{-}$ state. The $1_1^{-}$ state contributes to the significant low-energy strength of the IS dipole transition as 5% of the energy-weighted sum rule, which describes well the experimental data observed by the $\alpha$ inelastic scattering.

Spectra, reduced electromagnetic $B\left(E2\right)$ transition strengths, mean-square charge radii and, for those states above the emission threshold, α-decay widths are calculated by using a local potential cluster model for the ground state $K^{\pi }=0^{+}$ and first-excited $K^{\pi }=0^{-}$ bands of ${}^{20}\mathrm{Ne}, {}^{44}\mathrm{Ti}, {}^{94}\mathrm{Mo}, {}^{104}\mathrm{Te}$, and ${}^{136}\mathrm{Te}$. These nuclei are all modeled as $\alpha$-particles outside double-closed-shell core. The nuclear cluster-core potential is taken as a mixture of Saxon-Woods and cubed Saxon-Woods terms whose depths, radii, and diffuseness parameters are determined by the double folding Michigan-3-Yukawa potential model. Generally good agreement with experimental data is obtained without the introduction of effective charges, and predictions are made for many as yet unmeasured quantities in the two Te isotopes.

Fission fragment angular distributions can provide an important constraint on fission theory, improving predictive fission codes, and are a prerequisite for a precise ratio cross section measurement. Available anisotropy data are sparse, especially at neutron energies above 5 MeV. For the first time, a three-dimensional tracking detector is employed to study fragment emission angles and provide a direct measurement of angular anisotropy. The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) collaboration has deployed the fission time projection chamber to measure nuclear data with unprecedented precision. The fission fragment anisotropy of ${}^{235}\mathrm{U}$ has been measured over a wide range of incident neutron energies from 180 keV to 200 MeV; a careful study of the systematic uncertainties complement the data.

Production of strange hadrons in elementary and heavy-ion reactions is studied with the hadronic transport approach called simulating many accelerated strongly interacting hadrons. The poorly known branching ratios of the relevant hadronic resonances are constrained from the known elementary hadronic cross sections and from invariant mass spectra of dileptons. The constrained model is employed as a baseline to compare to heavy-ion-collision experiments at low energies $[E_{\text{kin}}=(1-2)A\text{GeV}]$ and to predict some of the upcoming pion-beam results at the High-Acceptance Di-Electron Spectrometer, which are expected to be sensitive to the resonance properties. The employed vacuum-resonance approach proves to be viable for small systems at these energies, but for large systems additional in-medium effects might be required.

The $({\mu }^{-}⟶e^{-})$ conversion in ${}^{208}\mathrm{Pb}$ nucleus is studied. For the elementary process we consider the most general effective Lagrangian responsible for the lepton-flavor violation. For the nuclear structure part, the spectrum of ${}^{208}\mathrm{Pb}$ is calculated by performing a diagonalization of the $\delta$-force interaction in the space of particle-hole pairs for neutrons and protons. We calculate the coherent contribution by direct summation of single-particle excitations. The noncoherent muon-to-electron conversion is calculated by summing over the contributions for all possible intermediate states in ${}^{208}\mathrm{Pb}$. We perform the multipole decomposition of the transition amplitude and present the nuclear matrix elements of spin-dependent and spin-independent operators appearing in the total rate of the muon to electron conversion process. The results are presented in a way to facilitate their use in model building of the electroweak process.

The order-by-order renormalization of the self-consistent mean-field potential in many-body perturbation theory for normal Fermi systems is investigated in detail. Building on previous work mainly by Balian and de Dominicis, as a key result we derive a thermodynamic perturbation series that manifests the consistency of the adiabatic zero-temperature formalism with perturbative statistical mechanics—for both isotropic and anisotropic systems—and satisfies at each order and for all temperatures the thermodynamic relations associated with Fermi-liquid theory. These properties are proved to all orders.

Background: Presence of closed proton and/or neutron shells causes deviation from macroscopic properties of nuclei, which are understood in terms of the liquid-drop model. Efforts to synthesize artificial elements are driven by the prediction of the existence of closed shells beyond the heaviest doubly magic nucleus found in nature. It is important to investigate experimentally the stabilizing effects of shell closure, if any, against fission.

Purpose: This Rapid Communication aims to investigate probable effects of proton shell ($Z=82$) closure in the compound nucleus in enhancing survival probability of the evaporation residues formed in heavy ion-induced fusion-fission reactions.

Method: Evaporation residue cross sections have been measured for the reactions ${}^{19}\mathrm{F}+{}^{180}\mathrm{Hf},{}^{19}\mathrm{F}+{}^{181}\mathrm{Ta}$, and ${}^{19}\mathrm{F}+{}^{182}\mathrm{W}$ from $\simeq 9\%$ below to $\simeq 42\%$ above the Coulomb barrier; leading to the formation of compound nuclei with the same number of neutrons ($N=118$) but different numbers of protons across $Z=82$ employing the Heavy Ion Reaction Analyzer. Measured excitation functions have been compared with a statistical model calculation in which the reduced dissipation coefficient is the only adjustable parameter.

Results: Evaporation residue cross section, normalized by the capture cross section, is found to decrease gradually with increasing fissility of the compound nucleus. Measured evaporation residue cross sections require inclusion of nuclear viscosity in the model calculations. Reduced dissipation coefficient in the range of $1–3\times {10}^{21}{\mathrm{s}}^{-1}$ reproduces the data quite well.

Conclusions: Since entrance channel properties of the reactions and structural properties of the heavier reaction partners are very similar, the degree of presence of noncompound nuclear fission, if any, is not expected to be significantly different in the three cases. No abrupt enhancement of evaporation residue cross sections has been observed in the reaction forming a compound nucleus with $Z=82$. Thus, this Rapid Communication does not find enhanced stabilizing effects of the $Z=82$ shell closure against fission in the compound nucleus. One may attempt to measure cross sections of individual exit channels for further confirmation of our observation.

Bethe wrote a pivotal paper providing the formalism for the theory of nuclear level densities. At that time, there were no known deformed nuclei, so Bethe made the assumption that all nuclei are spherical. After deformed nuclei were discovered, theorists predicted that the level density for such nuclei should be substantially enhanced over the level density for neighboring spherical nuclei. Despite these results, two comprehensive level density compilations based on neutron resonances counting at low neutron energy failed to find significant enhancement in level density for deformed nuclei. A recent paper has concluded that the Bethe spin distribution for nuclear levels is not appropriate for deformed nuclei. When a more accurate spin distribution is used in resonance analysis, it is found that an enhancement of approximately the predicted magnitude is observed.

Carbon-carbon burning plays an important role in many stellar environments. Recently, Tumino et al. [Nature (London) 557, 687 (2018)] reported a sharp rise of the astrophysical $S$ factor for carbon-carbon fusion determined using the indirect Trojan horse method. We demonstrate that the rise at low energies seen in the aforementioned work is an artifact of using an invalid plane-wave approximation that neglects the Coulomb interactions between charged particles. Our analysis shows that such a rise disappears if the Coulomb (or Coulomb-nuclear) interactions in the initial and final states are included.

Resonance energies are frequently derived from precisely measured excitation energies and reaction $Q$ values. The latter quantities are usually calculated from atomic instead of nuclear mass differences. This procedure disregards the energy shift caused by the difference in the total electron binding energies before and after the interaction. Assuming that the interacting nuclei in a stellar plasma are fully ionized, this energy shift can have a significant effect, considering that the resonance energy enters exponentially into the expression for the narrow-resonance thermonuclear reaction rates. As an example, the rate of the ${}^{36}\mathrm{Ar}(p,\gamma ){}^{37}\mathrm{K}$ reaction is discussed, which, at temperatures below $1\mathrm{GK}$, depends only on the contributions of a single resonance and direct capture. In this case, disregarding the energy shift caused by the total electron binding energy difference erroneously enhances the rate by $\approx 40\%$ near temperatures of $70\mathrm{MK}$.

Background: About 50% of the heavy elements are produced in stars during the slow neutron capture process. The analysis of branching points allows us to set constraints on the temperature and the neutron density in the interior of stars.

Purpose: The temperature dependence of the branch point ${}^{171}\mathrm{Tm}$ is weak. Hence, the ${}^{171}\mathrm{Tm}$ neutron capture cross section can be used to constrain the neutron density during the main component of the $s$ process in thermally pulsing asymptotic giant branch (TP-AGB) stars.

Methods: A ${}^{171}\mathrm{Tm}$ sample produced at the ILL was activated with thermal and epithermal neutrons at the TRIGA research reactor at the Johannes Gutenberg-Universität Mainz.

Results: The thermal neutron capture cross section and the resonance integral have been measured for the first time to be ${\sigma }_{\text{th}}=9.9\pm 0.9\text{b}$ and ${\sigma }_{\text{RI}}=193\pm 14\text{b}$.

Conclusions: Based on our results, new estimations of the direct capture components' impact on the Maxwellian-nAveraged cross sections (MACS) are possible.

We consider the breaking of Galilean invariance due to different lattice cutoff effects in moving frames and a nonlocal smearing parameter, which is used in the construction of the nuclear lattice interaction. The dispersion relation and neutron-proton scattering phase shifts are used to investigate the Galilean invariance breaking effects and ways to restore it. For $S$-wave channels, ${}^{1}S_0$ and ${}^{3}S_1$, we present the neutron-proton scattering phase shifts in moving frames calculated using both Lüscher's formula and the spherical wall method, as well as the dispersion relation. For the $P$ and $D$ waves, we present the neutron-proton scattering phase shifts in moving frames calculated using the spherical wall method. We find that the Galilean invariance breaking effects stemming from the lattice artifacts partially cancel those caused by the nonlocal smearing parameter. Due to this cancellation, the Galilean invariance breaking effect is small, and the Galilean invariance can be restored by introducing Galilean invariance restoration operators.

We investigate the performance of the Skyrme energy-density functional with respect to magnetic modes, checking in particular the impact of the spin-orbit and spin-spin interaction. Test cases are the low-energy $M1$ excitations in ${}^{208}\mathrm{Pb}$ treated within the self-consistent random-phase approximation based on the Skyrme energy-density functional. We scan a large variety of Skyrme parametrizations to find out which parameters of the functional have strongest correlations with $M1$ properties. We explore a simple method of the modification of the spin-related parameters, which delivers a better description of $M1$ excitations while basically maintaining the good description of ground-state properties.

We report on the observation of excited states in the neutron-deficient phosphorus isotopes ${}^{26,27,28}\mathrm{P}$ via in-beam $\gamma$-ray spectroscopy with both high-efficiency and high-resolution detector arrays. In ${}^{26}\mathrm{P}$, a previously unobserved level has been identified at 244(3) keV, two new measurements of the astrophysically important $3/2^{+}$ resonance in ${}^{27}\mathrm{P}$ have been performed, $\gamma$ decays have been assigned to the proton-unbound levels at 2216 and 2483 keV in ${}^{28}\mathrm{P}$, and the $\gamma$-ray line-shape method has been used to make the first determination of the lifetimes of the two lowest-lying excited states in ${}^{28}\mathrm{P}$. The expected Thomas-Ehrman shifts were calculated and applied to levels in the mirror nuclei. The resulting level energies from this procedure were then compared with the energies of known states in ${}^{26,27,28}\mathrm{P}$.

Elastic scattering and transfer cross sections for the ${}^7\mathrm{Be}+{}^9\mathrm{Be}$ system have been measured at $E_{\mathrm{lab}}=23.1\mathrm{MeV}$ using the ${}^7\mathrm{Be}$ radioactive secondary beam produced at Radioactive Ion Beams in Brazil facility at the University of São Paulo. The elastic scattering has been measured by detecting the ${}^7\mathrm{Be}$ scattered at forward angles in the laboratory system. The transfer reaction ${}^9\mathrm{Be}({}^7\mathrm{Be},{}^9\mathrm{Be}){}^7\mathrm{Be}$ was identified by detecting the ${}^9\mathrm{Be}$ scattered at the same laboratory angles. The elastic angular distribution has been analyzed by optical model calculations using a Woods-Saxon form factor whose parameters have been varied to best reproduce the experimental data at forward angles. Coupled reaction channels calculations (CRC) have been performed to describe the transfer, considering the coupling to the transfer channel and including contributions to the ground state and to the first excited state of ${}^7\mathrm{Be}(1/2-;429\mathrm{keV}$) in the final state. The spectroscopic amplitudes used in the CRC calculation have been derived from shell-model calculations. Similar CRC calculations were applied to existing ${}^9\mathrm{Be}(p,t){}^7\mathrm{Be}$ data to check the consistency of our results results for the (${}^7\mathrm{Be},{}^9\mathrm{Be}$) transfer reaction.

Recently we investigated an effective method of multicranked configuration mixing for angular-momentum-projection calculations, where several cranked mean-field states are coupled after projection: The basic idea was originally proposed by Peierls and Thouless more than fifty years ago. With this method a good description of the rotational band has been achieved in a fully microscopic manner. In the present work, we apply the method to the high-spin superdeformed band, for which a long rotational sequence is observed, and study how a good description is obtained for the rotational spectrum as well as the ${\mathcal{J}}^{\left(1\right)}$ and ${\mathcal{J}}^{\left(2\right)}$ moments of inertia as functions of angular momentum. The Gogny D1S force is employed as an effective interaction, and the yrast superdeformed bands in ${}^{152}\mathrm{Dy}$ and ${}^{194}\mathrm{Hg}$ are taken as typical examples in the $A\approx 150$ and $A\approx 190$ regions, respectively. The effect of pairing correlations is examined by the method of variation after particle-number projection to understand the different behaviors of ${\mathcal{J}}^{\left(2\right)}$ moments of inertia observed in these two nuclei. The particle-number projection on top of the angular-momentum projection has been performed for the first time with the multicranked configuration mixing.

We compute the cross section of inclusive dijet photoproduction in ultraperipheral Pb-Pb collisions at the CERN Large Hadron Collider using next-to-leading order perturbative QCD. We demonstrate that our theoretical calculations provide a good description of various kinematic distributions measured by the ATLAS Collaboration. We find that the calculated dijet photoproduction cross section is sensitive to nuclear modifications of parton distribution functions (PDFs) at the level of 10% to 20%. Hence, this process can be used to reduce uncertainties in the determination of these nuclear PDFs, whose current magnitude is comparable to the size of the calculated nuclear modifications of the dijet photoproduction cross section.

The potential model for nuclear astrophysical reactions requires a considerably shallow nuclear potential when a square-well potential is employed to fit experimental data. We discuss the origin of this apparently different behavior from that obtained with a smooth Woods-Saxon potential, for which a deep potential is often employed. We argue that due to the sharp change of the potential at the boundary the radius parameter tends to be large in the square-well model, which results in a large absorption radius. The wave function then needs to be suppressed in the absorption region, which can eventually be achieved by using a shallow potential. We thus clarify the reason why the square-well potential has been able to reproduce a large amount of fusion data.