Whereas the 7.2 min ${}^{240}\mathrm{Np}$, first identified over 60 years ago, has been assigned conflicting configuration by various investigators, the 62 min ${}^{240}\mathrm{Np}$ is assigned a “probable” configuration, deduced in each case by primarily focusing on just a single $\beta$-connected pair of levels in either ${}^{240}\mathrm{Np}$ (${\beta }^{-}$) ${}^{240}$Pu or ${}^{240}$U (${\beta }^{-}$) ${}^{240}\mathrm{Np}$ decay. We evaluate the level energies of physically admissible 2qp configurations in ${}_{93}^{240}$Np${}_{147}$ employing a three-step procedure, with experimental inputs at each step, and using a well tested two-particle rotor model with inclusion of residual $n$-$p$ interaction and other contributions. This exercise clearly establishes that the 62 min ${}^{240}\mathrm{Np}$ and the 7.2 min ${}^{240}\mathrm{Np}$ isomers constitute a Gallagher-Moszkowski (GM) doublet corresponding to the two-quasiparticle (2qp) configuration $5^{+}\{p5/2^{+}\left[642\right]\pm n5/2^{+}\left[622\right]\}{0}^{+}$ with $J^{\pi }\mathit{K}=1^{+}0$ for the higher-lying 7.2 min isomer. This assignment is conclusively confirmed in a level-by-level analysis of data on 23 $\beta$ transitions in these decays. Structures of a few other ${}^{240}\mathrm{Np}$ levels populated in ${}^{240}$U $\beta$ decay are also discussed.

We investigated the information carried by the data on direct photons, $\mathrm{i}.\mathrm{e}.$, the transverse momentum spectrum and the elliptic flow $v_2$ from Pb + Pb collisions at $\sqrt{s_{NN}}=2.76$ TeV measured at the Large Hadron Collider and from Au + Au collisions at $\sqrt{s_{NN}}=200$ GeV measured at the Relativistic Heavy Ion Collider, in the framework of ($3+1$)–dimensional ideal hydrodynamical models constrained with hadronic data. We found that these direct photon data may serve as a useful clock at the early stage of heavy ion collisions. The time scales for reaching thermal and chemical equilibrium, extracted from those data, are about 1/3 and 1.5 fm/$c$, respectively. Thus the large elliptic flow of direct photons is explainable. High-order harmonics, $\mathrm{i}.\mathrm{e}.$, $v_3$, $v_4$, and $v_5$, of direct photons from Pb + Pb collisions at 2.76 TeV are also predicted, as a further test to compete with those who claim new sources of photons to account for the large elliptic flow of direct photons.

The earlier projection method introduced for boost-invariant and cylindrically symmetric systems is used to introduce a new formulation of anisotropic hydrodynamics that allows for three substantially different values of pressure acting locally in three different directions. Our considerations are based on the Boltzmann kinetic equation with the collision term treated in the relaxation-time approximation and the momentum anisotropy is included explicitly in the leading term of the distribution function. A novel feature of our work is the complete analysis of the second moment of the Boltzmann equation, in addition to the zeroth and first moments that have been analyzed in earlier studies. We define the final equations of anisotropic hydrodynamics in the leading order as a subset of the analyzed moment equations (and their linear combinations) which agree with the Israel–Stewart theory in the case of small pressure anisotropies.

Dark matter detectors require calibrations of their energy scale and efficiency to detect nuclear recoils in the 1–50 keV range. Most calibrations use neutron scattering and require mcnp or geant4 simulations of neutron propagation through the detector. For most nuclei heavier than ${}^{16}$O, these simulation libraries ignore the contribution of resolved resonances to the neutron elastic differential cross section. For many isotopes and neutron energies of importance to dark matter detection, this invalid assumption can severely distort simulated nuclear recoil spectra. The correct angular distributions can be calculated from the resonance parameters using $R$-matrix formalism. A set of neutron scattering libraries with high-resolution angular distributions for mcnp and geant4 of ${}^{19}$F, ${}^{40}$Ar, ${}^{50,52}$Cr, ${}^{56}$Fe, ${}^{136}$Xe, and ${}^{206,207,208}$Pb is presented. An mcnpx library for simulating the production of low-energy neutrons in the ${}^9$Be${(\gamma ,n)}^8$Be reaction is also presented. Example dark matter detector calibrations are simulated with the new libraries showing how detector sensitivity could be overestimated by factors of 2 by relying on existing mcnp and geant4 libraries.

Starting from the matrix elements of the nucleon-nucleon interaction in momentum space we present a method to derive an operator representation with a minimal set of operators that is required to provide an optimal description of the partial waves with low angular momentum. As a first application we use this method to obtain an operator representation for the Argonne potential transformed by means of the unitary correlation operator method and discuss the necessity of including momentum-dependent operators. The resulting operator representation leads to the same results as the original momentum space matrix elements when applied to the two-nucleon system and various light nuclei. For applications in fermionic and antisymmetrized molecular dynamics, where an operator representation of a soft but realistic effective interaction is indispensable, a simplified version using a reduced set of operators is given.

We study the low-energy dipole (LED) strength distribution along the Sn isotopic chain in both the isoscalar (IS) and the isovector (IV, or E1) electric channels, to provide testable predictions and guidance for new experiments with stable targets and radioactive beams. We use the self-consistent quasi-particle random-phase approximation (QRPA) with finite-range interactions and mainly the Gogny D1S force. We analyze also the performance of a realistic two-body interaction supplemented by a phenomenological three-body contact term. We find that from $N=50$ and up to the $N=82$ shell closure (${}^{132}$Sn) the lowest-energy part of the IS-LED spectrum is dominated by a collective transition whose properties vary smoothly with neutron number and which cannot be interpreted as a neutron-skin oscillation. For the neutron-rich species this state contributes to the E1 strength below particle threshold, but much more E1 strength is carried by other, weak but numerous transitions around or above threshold. We find that strong structural changes in the spectrum take effect beyond $N=82$, namely increased LED strength and lower excitation energies. Our results with the Gogny interaction are compatible with existing data. On this basis we predict that (a) the summed IS strength below particle threshold shall be of the same order of magnitude for $N=50$–82, (b) the summed E1 strength up to approximately 12 MeV shall be similar for $N=50$–82 MeV, while (c) the summed E1 strength below threshold shall be of the same order of magnitude for $N\approx 64$–82 and much weaker for the lighter, more-symmetric isotopes. We point out a general agreement of our results with other nonrelativistic studies, the absence of a collective IS mode in some of those studies, and a possibly radical disagreement with relativistic models.

By combining the complex scaling method with relativistic mean-field theory, single-proton resonances are probed for spherical nuclei. The energy and width are shown to decrease with the increasing neutron number for the Sn isotopes and increase with the increasing proton number for the $N=82$ isotones. Furthermore, the influence of the Coulomb exchange term is investigated for the doubly magic nuclei ${}^{40}\mathrm{Ca}$, ${}^{56,78}\mathrm{Ni}$, ${}^{100,132}\mathrm{Sn}$, and ${}^{208}\mathrm{Pb}$. It is found that the Coulomb exchange term reduces the proton resonance energy within the range of 0.4–0.6 MeV, which depends on the particular nucleus as well as the quantum numbers of the resonant state.

We present an analysis of multifragmentation events observed in central $\text{Xe}+\text{Sn}$ reactions at Fermi energies. Performing a comparison between the predictions of the stochastic mean-field (SMF) transport model and experimental data, we investigate the impact of the compression-expansion dynamics on the properties of the final reaction products. We show that the amount of radial collective expansion, which characterizes the dynamical stage of the reaction, influences directly the onset of multifragmentation and the kinematic properties of multifragmentation events. For the same set of events, we also undertake a shape analysis in momentum space, looking at the degree of stopping reached in the collision, as proposed in recent experimental studies. We show that full stopping is achieved for the most central collisions at Fermi energies. However, considering the same central event selection as in the experimental data, we observe a similar behavior of the stopping power with the beam energy, which can be associated with a change of the fragmentation mechanism, from statistical to prompt fragment emission.

Background: The effects of nonlocal potentials have historically been approximately included by applying a correction factor to the solution of the corresponding equation for the local equivalent interaction. This is usually referred to as the Perey correction factor.

Purpose: In this work we investigate the validity of the Perey correction factor for single-channel bound and scattering states, as well as in transfer $(p,d)$ cross sections.

Method: We solve the scattering and bound state equations for nonlocal interactions of the Perey-Buck type, through an iterative method. Using the distorted wave Born approximation, we construct the $T$ matrix for $(p,d)$ on ${}^{17}$O, ${}^{41}$Ca, ${}^{49}$Ca, ${}^{127}$Sn, ${}^{133}$Sn, and ${}^{209}$Pb at 20 and 50 MeV.

Results: We found that for bound states, the Perey corrected wave function resulting from the local equation agreed well with that from the nonlocal equation in the interior region, but discrepancies were found in the surface and peripheral regions. Overall, the Perey correction factor was adequate for scattering states, with the exception of a few partial waves corresponding to the grazing impact parameters. These differences proved to be important for transfer reactions.

Conclusions: If only local optical potentials are used in the analysis of experimental $(p,d)$ cross sections, without any correction factors, as compared to the analysis with nonlocal potentials, the spectroscopic factors could be affected by approximately 20%. The Perey correction factor does offer an improvement over taking a direct local equivalent solution. However, if the desired accuracy is to be better than 10%, the exact solution of the nonlocal equation should be pursued.

The Pu($n,\gamma$) cross section has been measured over the energy range 10 eV to 1 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center as part of a campaign to produce precision ($n,\gamma$) measurements on Pu. Fission coincidences were measured with a parallel-plate avalanche counter and used to measure the prompt fission $\gamma$-ray spectrum in this region to accurately characterize background. The resulting ($n,\gamma$) cross section is generally in agreement with current evaluations. The experimental method utilizes much more detailed information than past measurements on Pu and can be used to extend the measurement to higher incident neutron energies.

Background: Couplings between relative motion and internal structures are known to affect fusion barriers by dynamically modifying the densities of the colliding nuclei. The effect is expected to be stronger at energies near the barrier top, where changes in density have longer time to develop than at higher energies. This gives rise to an energy dependence of the barriers as predicted by modern time-dependent Hartree-Fock (TDHF) calculations [K. Washiyama and D. Lacroix, Phys. Rev. C 78, 024610 (2008)]. Quantitatively, modern TDHF calculations are able to predict realistic fusion thresholds. However, the evolution of the potential barrier with bombarding energy remains to be confronted with the experimental data.

Purpose: The aim is to find signatures of the energy dependence of the barrier by comparing fusion cross-sections calculated from potentials obtained at different bombarding energies with the experimental data.

Method: This comparison is made for the ${}^{40}$Ca+${}^{40}$Ca and ${}^{16}$O${+}^{208}$Pb systems. Fusion cross-sections are computed from potentials calculated with the density-constrained TDHF method.

Results: The couplings decrease the barrier at low-energy in both cases. A deviation from the Woods-Saxon nuclear potential is also observed at the lowest energies. In general, fusion cross-sections around a given energy are better reproduced by the potential calculated at this energy. The coordinate-dependent mass plays a crucial role for the reproduction of sub-barrier fusion cross-sections. Effects of the energy dependence of the potential can be found in experimental barrier distributions only if the variation of the barrier is significant in the energy-range spanned by the distribution. It appears to be the case for ${}^{16}$O${+}^{208}$Pb but not for ${}^{40}$Ca+${}^{40}$Ca.

Conclusions: These results show that the energy dependence of the barrier predicted in TDHF calculations is realistic. This confirms that the TDHF approach can be used to study the couplings between relative motion and internal degrees of freedom in heavy-ion collisions.

Single-particle levels of seven magic nuclei are calculated within the energy density functional (EDF) method by Fayans et al. [Nucl. Phys. A 676, 49 (2000)]. Three versions of the EDF are used, the initial Fayans functional, DF3, and its two variations, DF3-a and DF3-b, with different values of spin-orbit parameters. Comparison is made with predictions of the Skyrme-Hartree-Fock method with the HFB-17 functional. For the DF3-a functional, phonon coupling (PC) corrections to single-particle energies are found self-consistently with an approximate account for the tadpole diagram. Accounting for the PC corrections improves the agreement with the data for heavy nuclei, e.g., for ${}^{208}$Pb. On the other hand, for lighter nuclei, e.g., ${}^{40,48}$Ca, PC corrections make the agreement a little worse. As estimations show, the main reason is that the approximation we use for the tadpole term is less accurate for light nuclei.

Based on the recent experimental observations of the dominance of tensor interaction in the $\sim$250–600 MeV/c momentum range of nucleons in nuclei, the existence of two new properties for high-momentum distribution of nucleons in asymmetric nuclei is suggested. The first property is the approximate scaling relation between proton and neutron high-momentum distributions weighted by their relative fractions in the nucleus. The second property is the inverse proportionality of the strength of the high-momentum distribution of protons and neutrons to the same relative fractions. Based on these two properties the high-momentum distribution function for asymmetric nuclei has been modeled and demonstrated so that it describes reasonably well the high-momentum characteristics of light nuclei. However, the most surprising result is obtained for neutron rich nuclei with large $A$, for which a substantial relative abundance of high-momentum protons as compared to neutrons is predicted. For example, the model predicts that in Au the relative fraction of protons with momenta above $k_F\sim 260$ MeV/c is $50\%$ more than that of neutrons. Such a situation may have many implications for different observations in nuclear physics related to the properties of a proton in neutron-rich nuclei.

The Skyrme potential energy density functional is introduced into the ultrarelativistic quantum molecular dynamics model and the updated version is applied to studying the directed and elliptic flows of light particles (protons, neutrons, deuterons, tritons, ${}^3$He, and ${}^4$He) in ${}^{197}$Au + ${}^{197}$Au collisions at beam energies 150, 250, and 400 MeV$/$nucleon. The results are compared with the recent FOPI experimental data. It is found that the yields and collective flows of light particles can be described quite well. The influence of the equation of state, medium-modified nucleon-nucleon elastic cross sections (NNECS) and cluster recognition criteria on the directed and elliptic flows is studied in detail. It is found that the flows of light particles are sensitive to the medium-modified NNECS, but not sensitive to the isospin dependent cluster recognition criteria. It seems difficult, however, even with the new data and calculations, to obtain a more accurate constraint on the nuclear incompressibility $K_0$ than the interval 200–260 MeV.

The heaviest particle-bound carbon isotope, ${}^{22}\mathrm{C}$, is thought to have a Borromean three-body structure. We discuss and compare four-body, i.e. three-body projectile plus target, reaction model calculations of reaction cross sections for such systems that use the fast adiabatic approximation. These methods are efficient and well-suited for quantitative analyses of reactions of neutron-rich nuclei with light target nuclei at secondary beam energies of $\approx 300$ MeV/nucleon, as are now becoming available. We compare the predictions of the adiabatic model of the reaction both without and when including the additional eikonal approximation that has been used extensively. We show that the reaction cross section calculations have only limited sensitivity to the size and structure of ${}^{22}\mathrm{C}$ and that the differences arising from use of the eikonal approximation of the reaction mechanism are of a similar magnitude.

The shear viscosity of the quark-gluon plasma is predicted to be lower than the collisional viscosity for weak coupling. The estimated ratio of the shear viscosity to entropy density is rather close to the ratio calculated by $\mathcal{N}=4$ super Yang–Mills theory for strong coupling, which indicates that the quark-gluon plasma might be strongly coupled. However, in the presence of momentum anisotropy, the Weibel instability can arise and drive the turbulent transport. Shear viscosity can be lowered by enhanced collisionality due to turbulence, but the decorrelation time and its relation to underlying dynamics and color-magnetic fields have not been calculated self-consistently. In this paper, we use resonance broadening theory for strong turbulence to calculate the anomalous viscosity of the quark-gluon plasma for nonequilibrium. For saturated Weibel instability, we estimate the scalings of the decorrelation rate and viscosity and compare these with collisional transport. This calculation yields an explicit connection between the underlying momentum-space anisotropy and the viscosity anomaly.

We present a fit of the spin-independent electromagnetic polarizabilities of the proton to low-energy Compton scattering data in the framework of covariant baryon chiral effective field theory. Using the Baldin sum rule to constrain their sum, we obtain ${\alpha }_{E1}=[10.6\pm 0.25\left(\text{stat}\right)\pm 0.2\left(\text{Baldin}\right)\pm 0.4\left(\text{theory}\right)]\times {10}^{-4}{\mathrm{fm}}^3$ and ${\beta }_{M1}=[3.2\mp 0.25\left(\text{stat}\right)\pm 0.2\left(\text{Baldin}\right)\mp 0.4\left(\text{theory}\right)]\times {10}^{-4}{\mathrm{fm}}^3$, in excellent agreement with other chiral extractions of the same quantities.

Background: Accurate knowledge of the ${}^{238}\mathrm{U}$($n$,$\gamma$) cross section is important for developing theoretical nuclear reaction models and for applications. However, capture cross sections are difficult to calculate accurately and often must be measured.

Purpose: We seek to confirm previous measurements and test cross-section calculations with an emphasis on the unresolved resonance region from 1 to 500 keV.

Method: Cross sections were measured from 10 eV to 500 keV using the DANCE detector array at the LANSCE spallation neutron source. The measurements used a thin target, 48 mg/cm${}^2$ of depleted uranium. Gamma cascade spectra were also measured to provide an additional constraint on calculations. The data are compared to cross-section calculations using the code CoH${}_3$ and cascade spectra calculations made using the code dicebox.

Results: This new cross-section measurement confirms the previous data. The measured gamma-ray spectra suggest the need for additional low-lying dipole strength in the radiative strength function. New Hauser-Feshbach calculations including this strength accurately predict the capture cross section without renormalization.

Conclusions: The present cross-section data confirm previous measurements. Including additional low-lying dipole strength in the radiative strength function may lead to more accurate cross-section calculations in nuclei where $\langle {\Gamma }_{\gamma }\rangle$ has not been measured.

We present theoretical predictions for electron scattering on the $N=14,20$, and 28 isotonic chains from proton-deficient to proton-rich nuclei. The calculations are performed within the framework of the distorted-wave Born approximation and the proton and neutron density distributions are evaluated adopting a relativistic Hartree-Bogoliubov (RHB) approach with a density dependent meson-exchange interaction. We present results for the elastic and quasi-elastic cross sections and for the parity-violating asymmetry parameter. Owing to the correlations between the evolution of the electric charge form factors along each chain with the underlying proton shell structure of the isotones, elastic electron scattering experiments on isotones can provide useful information about the occupation and filling of the single-particle levels of protons.