We present a new global optical potential (GOP) for nucleus-nucleus systems, including neutron-rich and proton-rich isotopes, in the energy range of 50–400 MeV/u. The GOP is derived from the microscopic folding model with the complex $G$-matrix interaction CEG07 and the global density presented by the São Paulo group. The folding model accounts for realistic complex optical potentials of nucleus-nucleus systems well and reproduces the existing elastic scattering data for stable heavy-ion projectiles at incident energies above 50 MeV/u. We then calculate the folding-model potentials (FMPs) for projectiles of even-even isotopes, ${}^{8-22}$C, ${}^{12-24}$O, ${}^{16-38}$Ne, ${}^{20-40}$Mg, ${}^{22-48}$Si, ${}^{26-52}$S, ${}^{30-62}$Ar, and ${}^{34-70}$Ca, scattered by stable target nuclei of ${}^{12}$C, ${}^{16}$O, ${}^{28}$Si, ${}^{40}$Ca ${}^{58}$Ni, ${}^{90}$Zr, ${}^{120}$Sn, and ${}^{208}$Pb at incident energies of 50, 60, 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350, and 400 MeV/u. The calculated FMP is represented, with a sufficient accuracy, by a linear combination of 10-range Gaussian functions. The expansion coefficients depend on the incident energy, the projectile and target mass numbers, and the projectile atomic number, while the range parameters depend only on the projectile and target mass numbers. The adequate mass region of the present GOP by the global density is inspected in comparison with FMP by realistic density. The full set of the range parameters and the coefficients for all the projectile-target combinations at each incident energy are provided on a permanent open-access website together with a fortran program for calculating the microscopic-basis GOP (MGOP) for a desired projectile nucleus by the spline interpolation over the incident energy and the target mass number.

Recent $\alpha$-decay data of heavy nuclei are collected and systematic analysis shows that there is a sudden change between the logarithm of decay half-life and the reciprocal of the square root of decay energy across the $N=126$ shell closure. In order to reproduce this sudden change, the new Geiger-Nuttall law is proposed where the effects of the quantum numbers of $\alpha$-core relative motion are naturally embedded in the law. The remedy achieved by a very simple parametrization of these effects is remarkable. By adding terms to the Geiger-Nuttall law, the parameters in the formula of decay half-lives need not be changed, except for some odd nuclei. This is an important development to the original Geiger-Nuttall law, which is valid for the ground-state transitions of even-even nuclei with $N\ge 128$. The law is generalized to the favored and hindered transitions of the $N\le 128$ nuclei and of high-spin isomers. The results of this article point to the simplicity of the underlying mechanism of the decay.

We reexamine the use of ideal hydrodynamics to describe bulk- and multistrange-hadron observables in nuclear collisions at the Relativistic Heavy Ion Collider. Toward this end we augment the 2+1-dimensional code azhydro by employing (a) an equation of state based on recent lattice-QCD computations matched to a hadron-resonance gas with chemical decoupling at $T_{\mathrm{ch}}\simeq 160$ MeV, (b) a compact initial-density profile, (c) an initial-flow field including azimuthal anisotropies, and (d) a sequential kinetic decoupling of bulk ($\pi$, $K$, $p$) and multistrange ($\phi$, $\Xi$, $\Omega$) hadrons at $T\simeq 110$ and 160 MeV, respectively. We find that this scheme allows for a consistent description of the observed chemistry, transverse-momentum spectra, and elliptic flow of light and strange hadrons.

The ultrarelativistic quantum molecular dynamics (UrQMD) model is widely used to simulate heavy-ion collisions in broad energy ranges. It consists of various components to implement the different physical processes underlying the transport approach. A major building block are the shared tables of constants, implementing the baryon masses and widths. Unfortunately, many of these input parameters are not well known experimentally. In view of the upcoming physics program at the facility for antiproton and ion research (FAIR), it is therefore of fundamental interest to explore the stability of the model results when these parameters are varied. We perform a systematic variation of particle masses and widths within the limits proposed by the particle data group (or up to 10$\%$). We find that the model results do only weakly depend on the variation of these input parameters. Thus, we conclude that the present implementation is stable with respect to the modification of not yet well specified particle parameters.

Production of deuterons and antideuterons was studied by the NA49 experiment in the 23.5$\%$ most central Pb+Pb collisions at the top CERN Super Proton Synchroton (SPS) energy of $\sqrt{s_{{}_{NN}}}=17.3$ GeV. Invariant yields for $\overline{d}$ and $d$ were measured as a function of centrality in the center-of-mass rapidity range $-1.2<y<-0.6$. Results for $\overline{d}\left(d\right)$ together with previously published $\overline{p}\left(p\right)$ measurements are discussed in the context of the coalescence model. The coalescence parameters $B_2$ were deduced as a function of transverse momentum $p_t$ and collision centrality.

Within the framework of a multiphase transport (AMPT) model that includes both initial partonic and final hadronic interactions, we show that including mean-field potentials in the hadronic phase leads to a splitting of the elliptic flows of particles and their antiparticles, thus providing a plausible explanation of the different elliptic flows between $p$ and $\overline{p}$, $K^{+}$ and $K^{-}$, and ${\pi }^{+}$ and ${\pi }^{-}$ observed in the recent Beam Energy Scan (BES) program at the Relativistic Heavy-Ion Collider (RHIC).

In-beam $\gamma$ spectroscopy of the stable nucleus ${}^{127}$I has been studied experimentally using the ${}^{124}$Sn(${}^7$Li, 4$n\gamma$)${}^{127}$I reaction at a beam energy of 32 MeV. The high-spin level scheme of ${}^{127}$I is extended significantly. Negative-parity levels built on the $11/2^{-}$, $\pi h_{11/2}$ particle state are observed up to $(35/2^{-})$ and described as a decoupled band, extending our knowledge of decoupled structures to the most neutron-rich stable iodine isotope. Two $\Delta I=2$ yrast positive-parity sequences are proposed to be associated with the $\pi g_{7/2}$ configuration due to observations of several strong interband transitions, and two weakly populated $\Delta I=2$ positive-parity bands are newly identified and interpreted as arising mainly from the $\pi d_{5/2}$ configuration. Three-quasiparticle configurations are assigned to the $I^{\pi }=15/2^{+}$ and $23/2^{+}$ states according to the existing knowledge in neighboring nuclei; irregular noncollective and regular collective excitations built on these two ($15/2^{+}$ and $23/2^{+}$) states are observed to coexist at similar energies. The observed three-quasiparticle band structures are further interpreted with the aid of configuration-constrained potential energy surface calculations.

The proton pygmy dipole resonances (PDRs) in the proton-rich nuclei ${}^{17,18}$Ne are investigated in the framework of the interacting shell model. The shell model with the self-consistent Skyrme-Hartree-Fock wave functions well reproduces the experimental data of the ground-state properties. The proton PDRs in the neighboring ${}^{17,18}$Ne are predicted. However, the detailed study involving the transition densities and collectivity shows that the PDR in ${}^{17}$Ne is highly collective and due to the oscillation of the valence protons against the interior core, while in ${}^{18}$Ne the dipole resonance in the PDR region is noncollective and more likely to be the configuration splitting of the giant dipole resonances.

We investigate the fusion barriers for reactions involving Ca isotopes ${}^{40}\mathrm{Ca}{+}^{40}\mathrm{Ca}$, ${}^{40}\mathrm{Ca}{+}^{48}\mathrm{Ca}$, and ${}^{48}\mathrm{Ca}{+}^{48}\mathrm{Ca}$ using the microscopic time-dependent Hartree-Fock (TDHF) theory coupled with a density constraint. In this formalism the fusion barriers are directly obtained from TDHF dynamics. We also study the excitation of the preequilibrium GDR for the ${}^{40}\mathrm{Ca}{+}^{48}\mathrm{Ca}$ system and the associated $\gamma$-ray emission spectrum. Fusion cross sections are calculated using the incoming-wave boundary condition approach. We examine the dependence of fusion barriers on collision energy as well as on the different parametrizations of the Skyrme interaction.

The matter created in relativistic heavy ion collisions is fairly well described by ideal hydrodynamics and somewhat better described by viscous hydrodynamics. To this point, most viscous calculations have been two dimensional, based on an assumption of Bjorken boost invariance along the beam axis. Here, first results are presented for a fully three-dimensional viscous model. The model is described, and tests of the numerical accuracy of the code are presented. Two- and three-dimensional runs are compared, and modest changes are observed for midrapidity observables at the highest Relativistic Heavy Ion Collider energies.

We study the effects of bulk viscosity on $p_T$ spectra and elliptic flow in heavy-ion collisions. For this purpose, we compute the dissipative correction $\delta f$ to the single-particle distribution functions in leading-log QCD, and in several simplified models. We consider, in particular, the relaxation time approximation and a kinetic model for the hadron resonance gas. We implement these distribution functions in a hydrodynamic simulation of Au + Au collisions at the Relativistic Heavy Ion Collider (RHIC). We find significant corrections due to bulk viscosity in hadron $p_T$ spectra and the differential elliptic flow parameter $v_2\left(p_T\right)$. We observe that bulk viscosity scales as the second power of conformality breaking $\zeta \sim \eta {(c_s^2-1/3)}^2$, whereas $\delta f$ scales as the first power. Corrections to the spectra are therefore dominated by viscous corrections to the distribution function, and reliable bounds on the bulk viscosity require accurate calculations of $\delta f$ in the hadronic resonance phase. Based on viscous hydrodynamic simulations and a simple kinetic model of the resonance phase, which correctly extrapolates to the kinetic description of a dilute pion gas, we conclude that it is difficult to describe the $v_2$ spectra at RHIC unless $\zeta /s\lesssim 0.05$ near freeze-out. We also find that effects of the bulk viscosity on the $p_T$ integrated $v_2$ are small.

We analyze event-by-event fluctuations of the transverse momentum in relativistic heavy-ion collisions at $\sqrt{s_{NN}}=200$ GeV in the framework based on the fluctuating Glauber-model initial conditions, event-by-event ($3+1$)-dimensional viscous hydrodynamics, and statistical hadronization. We use the scaled fluctuation measure $\langle \Delta p_{Ti}\Delta p_{Tj}\rangle /\langle \langle p_T\rangle \rangle$. The identified “geometric” mechanism of generating the transverse-momentum fluctuations from the initial size fluctuations, transmitted to the final statistical-hadronization phase with hydrodynamics, is capable of easily reproducing the magnitude of the effect and explains the basic features of the data. On the other hand, it is somewhat too strong, hinting on modification of the popular Glauber approach to the earliest phase of the collision. We have checked that the considered measure is insensitive of the values of the shear and bulk viscosity coefficients, the freeze-out temperature, and the smoothing parameter for the initial distribution. It remains unaltered in the core-corona picture and is insensitive to the transverse-momentum conservation, approximately imposed in the statistical hadronization.

The masses of 40 neutron-rich nuclides from $Z=51$ to 64 were measured at an average precision of $\delta m/m={10}^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a ${}^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.

Based on reflection symmetry in the reaction plane, it is shown that measuring the transverse spin-transfer coefficient $K_{yy}$ in the $\overline{K}N\to K\Xi$ reaction directly determines the parity of the produced cascade hyperon in a model-independent way as ${\pi }_{\Xi }^{}=K_{yy}$, where ${\pi }_{\Xi }^{}=\pm 1$ is the parity. This result based on Bohr's theorem provides a completely general, universal relationship that applies to the entire hyperon spectrum. A similar expression is obtained for the photoreaction $\gamma N\to KK\Xi$ by measuring both the double-polarization observable $K_{yy}$ and the photon-beam asymmetry $\Sigma$. Regarding the feasibility of such experiments, it is pointed out that the self-analyzing property of the $\Xi$s can be invoked, thus requiring only a polarized nucleon target.

We investigate the structure of proto-neutron stars (PNSs) with trapped neutrinos by using a quark-meson coupling model. We adopt a phenomenological lepton density which is diffuse near the surface. We calculate the populations of baryons and leptons, the equations of state, and the mass-radius relation for isentropic PNS models. In addition, the moment of inertia is calculated for both PNS and cold-neutron-star (CNS) models as a means to study the change of the spin period due to the neutrino emission from a PNS. Neutrino emission from a hyperonic neutron star is shown to increase the spin by about 10$\%$ of the initial spin, while the spin of a nucleonic neutron star with a central density above ${\rho }_C\approx 5{\rho }_0$ is decreased by a few $\%$ by the emission of neutrinos. Therefore, the spin change owing to the leakage of neutrinos from a PNS is a small ($<$10$\%$) correction compared to other processes related to the spin change.

Background: Reactions that probe the compound nucleus structure of ${}^{16}$O near the $\alpha$ and proton separation energies have important implications for nuclear astrophysics. New, more sensitive measurements of the reaction ${}^{15}$N${(p,\gamma )}^{16}$O have motivated the need for improved compound-nucleus reaction data in other channels. A previous work [P. Tischhauser et al., Phys. Rev. C 79, 055803 (2009)] reported extensive $\alpha$-scattering data over the energy region from $E_{\alpha }=2.6$ to $E_{\alpha }=6.6$ MeV. During this experiment data for higher energies, from $E_{\alpha }=6.6$ to $E_{\alpha }=8.2$ MeV, were also recorded but were not analyzed. The unpublished data cover the excitation energy range from the proton separation energy at $E_x$ $=$ 12.13 MeV up to 13.31 MeV, the same energy range important for the reaction ${}^{15}$N${(p,\gamma )}^{16}$O.

Purpose: These previously unpublished data for ${}^{12}$C${(\alpha ,\alpha )}^{12}$C as well as the reactions ${}^{12}$C${(\alpha ,{\alpha }_1)}^{12}$C and ${}^{12}$C${(\alpha ,p)}^{15}$N are analyzed in order to provide additional data for a comprehensive $R$-matrix analysis of compound-nucleus reactions populating ${}^{16}$O.

Methods: Expanding on the previous publication's analysis, the ratio of the reaction yields was analyzed using a multiple-channel $R$-matrix calculation.

Results: The excitation curves resolved resonances at $E_{\alpha }$ ($J^{\pi })=7.05(1^{-}$), 7.75 (2${}^{+}$), 7.91 (1${}^{-}$), 7.97 (3${}^{-}$), and 8.13 (3${}^{-}$) MeV. The $R$-matrix analysis revealed excellent agreement between the measured yield ratios and cross-section data from the literature. The two 1${}^{-}$ levels at $E_{\alpha }=7.05$ and 7.91 MeV are those that dominate the ${}^{15}$N${(p,\gamma )}^{16}$O cross section.

Conclusions: In a future publication, the additional constraints provided by these data will be used in a comprehensive multiple-channel $R$-matrix analysis to investigate the low-energy cross section of the reaction ${}^{15}$N${(p,\gamma )}^{16}$O.

The available experimental information on ${}^{34}$P has been greatly increased through the analysis of $\gamma$ decays in coincidence with protons from the interaction of an ${}^{18}$O beam at 24 MeV with an ${}^{18}$O target. Light charged particles from the reaction were detected with Microball, and multiple $\gamma$-ray coincidences with Gammasphere. Many observed $\gamma$ transitions have been identified and placed in the level scheme. Additionally, for most states, spins have been assigned based on measured $\gamma$-ray angular distributions while parities were inferred from lifetimes determined through Doppler-broadened line-shape analysis. Most of the states observed have been interpreted in terms of shell-model calculations using the WBP-a and SDPF-NR interactions having one particle in the $0f_{7/2}$ or $1p_{3/2}$ orbital. The two calculations agree almost equally well with the data resulting in root-mean-square differences of about 200 keV. However, a few high-lying states observed with long lifetimes challenge current calculations. Two of these may be associated with stretched $\pi f_{7/2}\otimes \nu f_{7/2}$ states, but the calculations overpredict their energies by 2–3 MeV. Furthermore, a long-lived 7919-keV state is established for which no explanation is available at present.

We compute the electromagnetic fields generated in heavy-ion collisions by using the HIJING model. Although after averaging over many events only the magnetic field perpendicular to the reaction plane is sizable, we find very strong electric and magnetic fields both parallel and perpendicular to the reaction plane on the event-by-event basis. We study the time evolution and the spatial distribution of these fields. In particular, the electromagnetic response of the quark-gluon plasma can give nontrivial evolution of the electromagnetic fields. The implications of the strong electromagnetic fields on the hadronic observables are also discussed.

We perform a coupled-channel calculation of the H dibaryon within a chiral constituent quark model. The problem is solved within a quark model constrained by the experimental data of strangeness $-1$ and $-2$ two-baryon systems. We examine in detail the role played by the different contributions of the interacting potential as well as the number of coupled channels considered. Special attention has been paid to the parameter dependence, flavor symmetry breaking, and spatial configurations. The value extracted for the binding energy of the H dibaryon, being compatible with the restrictions imposed by the Nagara event, falls within a plausible extrapolation of recent lattice QCD results.