$\gamma$ rays were measured at several angles in both singles and coincidence mode in the ${}^{119}\mathrm{Sn}$($\alpha ,n\gamma$)${}^{122}\mathrm{Te}$ reaction at 15 MeV on a thick target. Lifetimes of excited states in ${}^{122}\mathrm{Te}$ were determined from a Monte Carlo Doppler shift attenuation method (DSAM) analysis of the Doppler broadened lines shapes of $\gamma$ rays de-exciting the levels. A comparison of several deduced lifetimes with recent results obtained with the ($n,n^{\prime }$) reaction allowed us to validate the choice of a parameter used to calculate the contribution of the side feeding times. The ingredients of the DSAM line-shape analysis (stopping power, description of instrumental line shapes, and side feeding evaluation) are presented in some detail. It is concluded that with proper treatment of side feeding, a DSAM line-shape analysis of peaks in singles or coincidence spectra obtained following the ($\alpha ,n\gamma$) reaction is able to provide rather accurate values for the lifetimes of levels with low and medium spins.

We discuss the octupole deformation properties of the recently proposed Barcelona-Catania-Paris (BCP) energy density functionals for two sets of isotopes, those of radium and barium, in which it is believed that octupole deformation plays a role in the description of the ground state. The analysis is carried out in the mean field framework (Hartree-Fock-Bogoliubov approximation) by using the axially symmetric octupole moment as a constraint. The main ingredients entering the octupole collective Hamiltonian are evaluated and the lowest-lying octupole eigenstates are obtained. In this way we restore, in an approximate way, the parity symmetry spontaneously broken by the mean field and also incorporate octupole fluctuations around the ground-state solution. For each isotope the energy of the lowest lying $1^{-}$ state and the $B(E1)$ and $B(E3)$ transition probabilities have been computed and compared to both the experimental data and the results obtained in the same framework with the Gogny D1S interaction, which are used here as a well-established benchmark. Finally, the octupolarity of the configurations involved in the way down to fission of ${}^{240}\mathrm{Pu}$, which is strongly connected to the asymmetric fragment mass distribution, is studied. We confirm with this thorough study the suitability of the BCP functionals to describe octupole-related phenomena.

The rapid transition between spherical and $\gamma$-soft shapes in Ba and Xe nuclei in the mass region $A⩾130$ is analyzed using excitation spectra and collective wave functions obtained by diagonalization of a five-dimensional Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. The results reproduce the characteristic evolution of excitation spectra and E2 transition probabilities, and in general, a good agreement with available data is obtained. The calculated spectra display fingerprints of a second-order shape phase transition that can approximately be described by analytic solutions corresponding to the E(5) dynamical symmetry.

The Pauli exclusion principle (PEP) has been tested for nucleons ($n,p$) in ${}^{12}\mathrm{C}$ with the Borexino detector. The approach consists of a search for $\gamma$, $n$, $p$, and ${\beta }^{\pm }$ emitted in a non-Paulian transition of $1P_{3/2}$-shell nucleons to the filled $1S_{1/2}$ shell in nuclei. Due to the extremely low background and the large mass ($278$ tons) of the Borexino detector, the following most stringent up-to-date experimental bounds on PEP violating transitions of nucleons have been established: $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{C}}+\gamma )⩾5.0\times {10}^{31}$ yr, $\tau ({}^{12}\mathrm{C}\to {}^{11}\tilde{\mathrm{B}}+p)⩾8.9\times {10}^{29}$ yr, $\tau ({}^{12}\mathrm{C}\to {}^{11}\tilde{\mathrm{C}}+n)⩾3.4\times {10}^{30}$ yr, $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{N}}+e^{-}+\widetilde{{\nu }_e})⩾3.1\times {10}^{30}$ yr, and $\tau ({}^{12}\mathrm{C}\to {}^{12}\tilde{\mathrm{B}}+e^{+}+{\nu }_e)⩾2.1\times {10}^{30}$ yr, all at $90\%$ C.L. The corresponding upper limits on the relative strengths for the searched non-Paulian electromagnetic, strong and weak transitions have been estimated as ${\delta }_{\gamma }^2⩽2.2\times {10}^{-57}$, ${\delta }_N^2⩽4.1\times {10}^{-60}$, and ${\delta }_{\beta }^2⩽2.1\times {10}^{-35}$.

PHENIX has measured the $e^{+}{e}^{-}$ pair continuum in $\sqrt{s_{\mathit{NN}}}=200$ GeV $\mathrm{Au}+\mathrm{Au}$ and $p+p$ collisions over a wide range of mass and transverse momenta. The $e^{+}{e}^{-}$ yield is compared to the expectations from hadronic sources, based on PHENIX measurements. In the intermediate-mass region, between the masses of the $\varphi$ and the $J/\psi$ meson, the yield is consistent with expectations from correlated $c\mathrm{c̄}$ production, although other mechanisms are not ruled out. In the low-mass region, below the $\varphi$, the $p+p$ inclusive mass spectrum is well described by known contributions from light meson decays. In contrast, the $\mathrm{Au}+\mathrm{Au}$ minimum bias inclusive mass spectrum in this region shows an enhancement by a factor of $4.7\pm {0.4}^{\mathrm{stat}}\pm {1.5}^{\mathrm{syst}}\pm {0.9}^{\mathrm{model}}$. At low mass ($m_{\mathit{ee}}<0.3$ GeV/$c^2$) and high $p_T$ ($1<p_T<5$ GeV/$c$) an enhanced $e^{+}{e}^{-}$ pair yield is observed that is consistent with production of virtual direct photons. This excess is used to infer the yield of real direct photons. In central $\mathrm{Au}+\mathrm{Au}$ collisions, the excess of the direct photon yield over the $p+p$ is exponential in $p_T$, with inverse slope $T=221\pm {19}^{\mathrm{stat}}\pm {19}^{\mathrm{syst}}$ MeV. Hydrodynamical models with initial temperatures ranging from $T_{\mathrm{init}}\simeq 300–600$ MeV at times of $0.6–0.15$ fm/$c$ after the collision are in qualitative agreement with the direct photon data in $\mathrm{Au}+\mathrm{Au}$. For low $p_T<1$ GeV/$c$ the low-mass region shows a further significant enhancement that increases with centrality and has an inverse slope of $T\simeq 100$ MeV. Theoretical models underpredict the low-mass, low-$p_T$ enhancement.

We analyze the transverse momentum distribution of $J/\psi$ mesons produced in $\mathrm{Au}+\mathrm{Au}$ collisions at the top RHIC energy within a blast-wave model that accounts for a possible inhomogeneity of the charmonium distribution and/or flow fluctuations. The results imply that the transverse momentum spectra of $J/\psi$, $\varphi$, and $\Omega$ hadrons measured at the RHIC can be described well if kinetic freeze-out takes place just after chemical freeze-out for these particles.

Transverse momentum correlations in the azimuthal angle of hadrons produced owing to minijets are first studied within the HIJING Monte Carlo model in high-energy heavy-ion collisions. Quenching of minijets during thermalization is shown to lead to significant diffusion (broadening) of the correlation. Evolution of the transverse momentum density fluctuation that gives rise to this correlation in azimuthal angle in the later stage of heavy-ion collisions is further investigated within a linearized diffusion-like equation and is shown to be determined by the shear viscosity of the evolving dense matter. This diffusion equation for the transverse momentum fluctuation is solved with initial values given by HIJING and together with the hydrodynamic equation for the bulk medium. The final transverse momentum correlation in azimuthal angle is calculated along the freeze-out hypersurface and is found to be further diffused for higher values of the shear viscosity to entropy density ratio, $\eta /s~0.2–0.4$. Therefore the final transverse momentum correlation in azimuthal angle can be used to study the thermalization of minijets in the early stage of heavy-ion collisions and the viscous effect in the hydrodynamic evolution of strongly coupled quark-gluon plasma.

By adopting a $T$-matrix-based method within the $G_{0}G$ approximation for the pair susceptibility, we studied the effects of pairing fluctuation on the BCS-BEC crossover in symmetric nuclear matter. The pairing fluctuation induces a pseudogap in the excitation spectrum of a nucleon in both superfluid and normal phases. The critical temperature of the superfluid transition was calculated. It differs from the BCS result remarkably when density is low. We also computed the specific heat, which shows a nearly ideal BEC-type temperature dependence at low density, but a BCS-type behavior at high density. This qualitative change of the temperature dependence of specific heat may serve as a thermodynamic signal for the BCS-BEC crossover.

Mass measurements of neutron-rich Cd and Ag isotopes were performed with the Penning trap mass spectrometer ISOLTRAP. The masses of ${}^{112,114-124}$Ag and ${}^{114,120,122-124,126,128}$Cd, determined with relative uncertainties between $2\times {10}^{-8}$ and $2\times {10}^{-7}$, resulted in significant corrections and improvements of the mass surface. In particular, the mass of ${}^{124}\mathrm{Ag}$ was previously unknown. In addition, other masses that had to be inferred from $Q$ values of nuclear decays and reactions have now been measured directly. The analysis includes various mass differences, namely the two-neutron separation energies, the applicability of the Garvey-Kelson relations, double differences of masses $\delta V_{\mathit{pn}}$, which give empirical proton-neutron interaction strengths, as well as a comparison with recent microscopic calculations. The $\delta V_{\mathit{pn}}$ results reveal that for even-even nuclides around ${}^{132}\mathrm{Sn}$ the trends are similar to those in the ${}^{208}\mathrm{Pb}$ region.

A recently developed formulation for treating two- and three-nucleon bound states in a three-dimensional formulation based on spin-momentum operators is extended to nucleon-nucleon scattering. Here the nucleon-nucleon $T$-matrix is represented by six spin-momentum operators accompanied by six scalar functions of momentum vectors. We present the formulation and provide numerical examples for the deuteron and nucleon-nucleon scattering observables. A comparison to results from a standard partial-wave decomposition establishes the reliability of this formulation.

We report on an implementation of a new method to calculate random phase approximation (RPA) strength functions with iterative non-Hermitian Arnoldi diagonalization method, which does not explicitly calculate and store the RPA matrix. We discuss the treatment of spurious modes, numerical stability, and how the method scales as the used model space is enlarged. We perform the particle-hole RPA benchmark calculations for double magic nucleus ${}^{132}\mathrm{Sn}$ and compare the resulting electromagnetic strength functions against those obtained within the standard RPA.

The angular distributions of fission fragments for the ${}^{32}\mathrm{S}+{}^{184}\mathrm{W}$ reaction at center-of-mass energies of 118.8, 123.1, 127.3, 131.5, 135.8, 141.1, and 144.4 MeV are measured. The experimental fission excitation function is obtained. The anisotropy (${\mathcal{A}}_{\exp }$) is found by extrapolating each fission fragment angular distribution. The measured fission cross sections of the ${}^{32}\mathrm{S}+{}^{182,184}\mathrm{W}$ reaction are decomposed into fusion-fission, quasifission, and fast-fission contributions by the dinuclear system model (DNS). The angular momentum distributions of the dinuclear system and compound nucleus calculated by the DNS model are used to reproduce the experimental capture and fusion excitation functions for both reactions and quantities $K_0^2$, $\langle {\ell }^2\rangle$, and ${\mathcal{A}}_{\exp }$, which characterize angular distributions of the fission products at the considered range of beam energy. The total evaporation residue excitation function for the ${}^{32}\mathrm{S}+{}^{184}\mathrm{W}$ reaction calculated in the framework of the advanced statistical model is close to the available experimental data only up to about $E_{\mathrm{c}.\mathrm{m}.}\approx 160$ MeV. The underestimation of the experimental data at high excitation energies $E_{\mathrm{c}.\mathrm{m}.}>160$ MeV is explained by the fact that the statistical model cannot reproduce the cross section of evaporation residues formed by the nonequilibrium mechanism, that is, without formation of the compound nucleus in the statistical equilibrium state.

We study the effects of shear and bulk viscosities in the hadronic phase on the expansion of the fireball and on particle production in relativistic heavy-ion collisions. Comparing simulation with versus without viscosity in hadronic matter, we find that elliptic flow observables are strongly dependent on dissipative effects in the late stage. On the contrary, interferometry radii are sensitive, through early transverse flow, to the viscosity value at high temperatures. We present first calculations including the effects of bulk viscosity on the hadronic phase and on hadron emission. We find them to be important in obtaining a low freeze-out temperature consistent with the measured transverse momentum spectra and elliptic flow of identified particles.

In this article we will discuss the energy dependence of particle ratio fluctuations in heavy-ion collisions. We study how the inherent multiplicity dependence of ratio fluctuations is reflected in the excitation function of the dynamical fluctuations. Specifically, we will show that the observed excitation function of dynamical $K/\pi$ fluctuations is consistent with the expected dependence on the number of accepted pions and kaons in both the STAR and the NA49 experiments.

The theory of quantum electrodynamics predicts that the $\beta$ decay of the neutron into a proton, electron, and antineutrino is accompanied by a continuous spectrum of emitted photons described as inner bremsstrahlung. While this phenomenon has been observed in nuclear $\beta$ decay and electron-capture decay for many years, it has only been recently observed in free-neutron decay. We present a detailed discussion of an experiment in which the radiative decay mode of the free neutron was observed. In this experiment, the branching ratio for this rare decay was determined by recording photons that were correlated with both the electron and proton emitted in neutron decay. We determined the branching ratio for photons with energy between 15 and 340 keV to be $(3.09\pm 0.32)\times {10}^{-3}$ (68% level of confidence), where the uncertainty is dominated by systematic effects. This value for the branching ratio is consistent with theoretical predictions. The characteristic energy spectrum of the radiated photons, which differs from the uncorrelated background spectrum, is also consistent with the theoretical spectrum.

We have checked the adequacy of various available parametrization schemes proposed for the determination of the safe lower limit of the impact parameter needed to ensure the pure Coulomb excitation process, i.e., negligible absorption effects in the Coulomb excitation experiments. The absorption effects are found to be nonzero for all of these parametrization schemes at experimental midtarget beam energies. Thus in the present work we have proposed a new parametrization scheme which is found to be more appropriate and useful for planning absorption-free Coulomb excitation experiments.

The atomic masses of ${}^{74}\mathrm{Ge}$, ${}^{74}\mathrm{Se}$, ${}^{76}\mathrm{Ge}$, and ${}^{76}\mathrm{Se}$ have been determined from cyclotron frequency ratios of pairs of ions simultaneously trapped in a cryogenic Penning trap. Allowing for cancellation of systematic errors in the mass differences between isobars, we determine the $Q$ value for double-electron capture of ${}^{74}\mathrm{Se}$ to be 1209.240(7) keV, and the $Q$ value for double-electron emission of ${}^{76}\mathrm{Ge}$ to be 2039.061(7) keV. The new $Q_{2\mathrm{EC}}$ value for ${}^{74}\mathrm{Se}$ precludes a large resonant enhancement for neutrinoless double-electron capture.

Single-particle bound and resonant states are obtained by solving the Dirac equation with quadrupole-deformed Woods-Saxon potential in coordinate space with the coupled-channel approach. Taking the $m^{\pi }=1/2^{+}$ resonant states at deformation $\beta =0.1$ as examples, the roles of their spherical components have been investigated based on the behaviors of the eigenphases and the corresponding probabilities weighted by the scalar spherical potential. It is shown that the realization of the $m^{\pi }=1/2^{+}$ resonances is supported mainly by the $l\ne 0$ components, and the mixture of the $s_{1/2}$ component can lead to the disappearance of some resonances at finite energy. The dominance of the $l\ne 0$ component ($d_{3/2}$) in the small-energy region guarantees the continuation of a certain resonance to the corresponding bound state.

A simple straightforward method has been presented to predict the dependence of barrier distributions at arbitrary orientations on different deformations. The proposed interpretation is developed independently of the complicated numerical calculations. It is related to the change of half-density radius of the deformed nucleus, in the direction of the separation vector. The microscopic calculations of Coulomb barrier are carried out by using a realistic density dependent nucleon-nucleon ($\mathit{NN}$) interaction, BDM3Y, for the interaction between spherical, ${}^{48}\mathrm{Ca}$, and deformed, ${}^{244}\mathrm{Pu}$, nuclei, as an example. To do so, the double-folding model for the interaction of spherical-deformed nuclei is put in a suitable computational form for the calculation of the potential at several separation distances and orientation angles using the density dependent $\mathit{NN}$ force without consuming computational time. We found that the orientation distributions of the Coulomb barrier parameters show similar patterns to those of the interacting deformed nucleus radius. It is found that the orientation distribution of the Coulomb barrier radius follows the same variation of the deformed nucleus radius while the barrier height distribution follows it inversely. This correlation (anticorrelation) allows a simple evaluation of the orientation barrier distribution which would be very helpful to estimate when the barrier parameters will increase or decrease and at which orientations they will be independent of the deformation. This also allows us to estimate the compact and elongated configurations of the interacting nuclei which lead to hot and cold fusion, respectively.

The surrogate nuclear reaction method can be used to determine neutron-induced reaction cross sections from measured decay properties of a compound nucleus created using a different reaction and calculated formation cross sections. The reliability of $(n,\gamma )$ cross sections determined using the Weisskopf-Ewing and ratio approximations are explored for the ${}^{155,157}\mathrm{Gd}$$(n,\gamma )$ reactions. Enriched gadolinium targets were bombarded with 22-MeV protons and $\gamma$ rays were detected in coincidence with scattered protons using the Silicon Telescope Array for Reaction Studies/Livermore-Berkeley Array for Collaborative Experiments (STARS/LiBerACE) silicon and germanium detector arrays. The $\gamma$-emission probabilities for the ${}^{154,156,158}\mathrm{Gd}$ compound nuclei were measured at excitation energies up to 12 MeV. It is found that the approximations yield results that deviate from directly measured ${}^{155,157}\mathrm{Gd}$$(n,\gamma )$ cross sections at low energies. To extract reliable cross sections, a more sophisticated analysis should be developed that takes into account angular-momentum differences between the neutron-induced and surrogate reactions.