The continuum of the ${}^{10}\mathrm{He}$ nucleus is studied theoretically in a three-body ${}^8\mathrm{He}$$+n+n$ model based on recent information concerning the ${}^9\mathrm{He}$ spectrum [M. S. Golovkov et al., Phys. Rev. C 76, 021605(R) (2007)]. The ${}^{10}\mathrm{He}$ ground state (g.s.) candidate with structure $[p_{1/2}]{}^2$ for new g.s. energy of ${}^9\mathrm{He}$ is predicted to be at about 2.0–2.3 MeV. The peak in the cross section associated with this state may be shifted to a lower energy (e.g., $~1.2$ MeV) when ${}^{10}\mathrm{He}$ is populated in reactions with ${}^{11}\mathrm{Li}$ due to a peculiar reaction mechanism. Formation of the low-energy ($E<250$ keV) “alternative” ground state with structure $[s_{1/2}]{}^2$ is highly probable in ${}^{10}\mathrm{He}$ when there is considerable attraction (e.g., $a<-5$ fm) in the $s$-wave ${}^9\mathrm{He}$ channel, whose properties are still quite uncertain. This result either questions the existing experimental low-energy spectrum of ${}^{10}\mathrm{He}$ or places a limit on the scattering length in the ${}^9\mathrm{He}$ channel, which contradicts existing data.

In this work we simulate a viscous hydrodynamical model of noncentral Au-Au collisions in 2+1 dimensions, assuming longitudinal boost invariance. The model fluid equations were proposed by Öttinger and Grmela [Grmela, M., and Öttinger, H. C., Phys. Rev. E, 56, 6620 (1997)]. Freeze-out is signaled when the viscous corrections become large relative to the ideal terms. Then viscous corrections to the transverse momentum and differential elliptic flow spectra are calculated. When viscous corrections to the thermal distribution function are not included, the effects of viscosity on elliptic flow are modest. However, when these corrections are included, the elliptic flow is strongly modified at large $p_T$. We also investigate the stability of the viscous results by comparing the nonideal components of the stress tensor (${\pi }^{\mathit{ij}}$) and their influence on the $v_2$ spectrum to the expectation of the Navier-Stokes equations (${\pi }^{\mathit{ij}}=-\eta \langle \partial {}_i{u}_j\rangle$). We argue that when the stress tensor deviates from the Navier-Stokes form the dissipative corrections to spectra are too large for a hydrodynamic description to be reliable. For typical Relativistic Heavy Ion Colloder initial conditions this happens for $\eta /s\gtrsim 0.3$.

The effective $\overline{K}N$ interaction based on chiral SU(3) coupled-channel dynamics is derived and its extrapolation below the $\overline{K}N$ threshold is studied in detail. Starting from the coupled-channel scattering equations, we eliminate the channels other than $\overline{K}N$ and obtain an effective interaction in the single $\overline{K}N$ channel. An equivalent local potential in coordinate space is constructed such as to reproduce the full scattering amplitude of the chiral SU(3) coupled-channel framework. We discuss several realistic chiral SU(3)-based models in comparison to reach conclusions about the uncertainties involved. It turns out that, in the region relevant to the discussion of deeply bound $\overline{K}$-nuclear few-body systems, the resulting energy-dependent, equivalent local potential is substantially less attractive than the one suggested in previous purely phenomenological treatments.

We calculate the equation of state of nuclear matter based on the general analysis of the grand canonical partition function in the $S$-matrix framework. In addition to the low mass stable particles and their two-body scattering channels considered earlier, the calculation includes systematically all the higher mass particles and their exited states as well as the scattering channels formed by any number of these species. We estimate the latter contribution by resonances in all the channels. The resulting model-independent virial series for pressure gets substantial contribution from the heavy particles and the channels containing them. The series converges for larger values of baryon density than found earlier.

We discuss the derivation of an equivalent polarization potential independent of angular momentum $l$ for use in the optical Schrödinger equation that describes the elastic scattering of heavy ions. Three different methods are used for this purpose. Application of our theory to the low energy scattering of light heavy-ion systems at near-barrier energies is made. It is found that the notion of an $l$-independent polarization potential has some validity but cannot be a good substitute for the $l$-dependent local equivalent Feshbach polarization potential.

Mass-angle correlations of binary fragments produced in ${}^{16}\mathrm{O}+{}^{204}\mathrm{Pb}$, ${}^{34}\mathrm{S}+{}^{186}\mathrm{W}$, and ${}^{48,50}\mathrm{Ti}+{}^{166,170}\mathrm{Er}$ reactions have been measured for a range of bombarding energies around their Coulomb barriers. At above-barrier energies, the width of the mass distributions for the fission-like fragments in the ${}^{50}\mathrm{Ti}+{}^{170}\mathrm{Er}$ reaction are found to be higher than those from the same compound system at similar excitation energies populated via the more mass asymmetric entrance channel reaction ${}^{34}\mathrm{S}+{}^{186}\mathrm{W}$, which in turn is higher than those for the ${}^{16}\mathrm{O}+{}^{204}\mathrm{Pb}$ system. The width of the mass distributions of the $\mathrm{Ti}+\mathrm{Er}$ systems is found to increase with decreasing bombarding energies, in contrast with those of the ${}^{16}\mathrm{O}+{}^{204}\mathrm{Pb}$ and ${}^{34}\mathrm{S}+{}^{186}\mathrm{W}$ systems, which show a monotonic reduction in mass widths. This may be associated with the elongated contact configuration at sub-barrier energies.

Addressing the recent criticisms of Kvinikhidze and Miller, we prove that the spectator wave functions and currents based on “fixed-axis” polarization states (previously introduced by us) are Lorentz covariant, and find an explicit connection between them and conventional direction-dependent polarization states. The discussion shows explicitly how it is possible to construct pure $S$-wave models of the nucleon.

The $\beta \text{−}\nu$ correlation coefficient, $a_{\beta \nu }$, is measured in ${}^{21}\mathrm{Na}$ by detecting the time of flight of the recoil nucleus detected in coincidence with the atomic electrons shaken off in β decay. The sample of ${}^{21}\mathrm{Na}$ is confined in a magneto-optic trap. High detection efficiency allows low trap density, which suppresses the photoassociation of molecular sodium, which can cause a large systematic error. Suppressing the fraction of trapped atoms in the excited state by using a dark trap also reduces the photoassociation process, and data taken with this technique are consistent. The main remaining systematic uncertainties come from the measurement of the position and size of the atom trap and the subtraction of background. We find $a_{\beta \nu }=0.5502(60)$, in agreement with the Standard Model prediction of $a_{\beta \nu }=0.553(2)$, and disagreeing with a previous measurement, which was susceptible to an error introduced by the presence of molecular sodium.

The renormalization of the $\mathit{NN}$ interaction with the chiral two-pion exchange potential computed using Lorentz-invariant baryon chiral perturbation theory is considered. The short distance singularity reduces the number of counterterms to about half those in the heavy baryon expansion. Phase shifts and deuteron properties are evaluated with clear improvements in some cases.

Isomers in near-spherical $Z=51$, antimony isotopes are reported here for the first time using fusion-fission reactions between ${}^{27}\mathrm{Al}$ and a pulsed ${}^{178}\mathrm{Hf}$ beam of energy, 1150 MeV. γ rays were observed from the decay of isomeric states with half-lives, $T_{1/2}=200(30)$ and $52(3)\mu$s, and angular momenta $I=(\frac{25}{2})$ and $I^{\pi }={\frac{23}{2}}^{+}$, in ${}^{121,123}\mathrm{Sb}$, respectively. These states are proposed to correspond to $\nu (h_{\frac{11}{2}}){}^2$ configurations, coupled to an odd $d_{\frac{5}{2}}$ or $g_{\frac{7}{2}}$ proton. Nanosecond isomers were also identified at $I^{\pi }={\frac{19}{2}}^{-}$ [$T_{1/2}=8.5(5)$ ns] in ${}^{121}\mathrm{Sb}$ and $I^{\pi }=({\frac{15}{2}}^{-})$ [$T_{1/2}=37(4)$ ns] in ${}^{123}\mathrm{Sb}$. Information on spins and parities of states in these nuclei was obtained using a combination of angular correlation and intensity-balance measurements. The configurations of states in these nuclei are discussed using a combination of spin/energy systematics and shell-model calculations for neighboring tin isotones and antimony isotopes.

Because of thermal expansion and residual interactions, hot nuclear fragments produced in multifragmentation reactions may have nucleon density lower than the equilibrium density of cold nuclei. In terms of a liquid-drop model this effect can be taken into account by reducing the bulk energy of fragments. We study the influence of this change on fragment yields and isotope distributions within the framework of the statistical multifragmentation model. Similarities and differences with previously discussed modifications of symmetry and surface energies of nuclei are analyzed.

We examine the model dependence of the phase diagram of inhomogeneous nulcear matter in supernova cores using the quantum molecular dynamics (QMD). Inhomogeneous matter includes crystallized matter with nonspherical nuclei—“pasta” phases—and the liquid-gas phase-separating nuclear matter. Major differences between the phase diagrams of the QMD models can be explained by the energy of pure neutron matter at low densities and the saturation density of asymmetric nuclear matter. We show the density dependence of the symmetry energy is also useful to understand uncertainties of the phase diagram. We point out that, for typical nuclear models, the mass fraction of the pasta phases in the later stage of the collapsing cores is higher than $10\text{−}20\%$.

The low energy level structure of $N=20$ ${}^{32}\mathrm{Mg}$ obtained via β-delayed γ spectroscopy is reported. The level structure of ${}^{32}\mathrm{Mg}$ is found to be completely dominated by intruders. An inversion between the 1p-1h and 3p-3h states is observed for the negative parity states, similar to the 0p-0h and 2p-2h inversion for the positive parity states in these $N~20$ nuclei. The intruder excited states, both positive and negative parity, are reasonably explained by Monte Carlo shell model calculations, which suggest a shrinking $N=20$ shell gap with decreasing $Z$.

The applicability of anisotropic flow measurement techniques and their extension for detectors with nonuniform azimuthal acceptance are discussed. Considering anisotropic flow measurements with two and three (mixed harmonic) azimuthal correlations we introduce a set of observables based on the $x$ and $y$ components of the event flow vector. These observables provide independent measures of anisotropic flow and can be used to test the self-consistency of the analysis. Based on these observables we propose a technique that explicitly takes into account the effects of nonuniform detector acceptance. Within this approach the acceptance corrections, as well as parameters that define the method applicability, can be determined directly from experimental data. For practical purposes a brief summary of the method is provided at the end.

By choosing appropriate generators for the Similarity Renormalization Group (SRG) flow equations, different patterns of decoupling in a Hamiltonian can be achieved. Sharp and smooth block-diagonal forms of phase-shift equivalent nucleon-nucleon potentials in momentum space are generated as examples and compared to analogous low-momentum interactions (“$V_{\mathrm{low}k}$”).

Excited states above the ${16}^{+}$ isomer in ${}^{210}\mathrm{Po}$ have been identified using time-correlated γ-ray spectroscopy techniques and the ${}^{204}\mathrm{Hg}$(${}^{13}\mathrm{C}$,3$n$α)${}^{210}\mathrm{Po}$ reaction. States up to $~27\hslash$ have been identified, including an isomer at 8074 keV with a mean life of 13(2) ns. Among the new states, a candidate for the ${17}^{+}$ state obtained from maximal coupling of the $\pi [h_{9/2}{i}_{13/2}]{}_{{11}^{-}}$ valence proton configuration and the $\nu [p_{1/2}^{-1}{i}_{11/2}]{}_{6^{-}}$ neutron core excitation has been identified. This and other results are compared with semiempirical shell-model calculations that predict that single core excitations from the $i_{13/2}$ neutron orbital and double core excitations out of the $p_{1/2}$ and $f_{5/2}$ orbitals, populating the $g_{9/2},i_{11/2}$, and $j_{15/2}$ orbitals above the $N=126$ shell, will compete in energy. Good agreement is obtained for the lower states but there are systematic discrepancies at high spins including the absence of states that are calculated to lie low in the spectrum, implying uncertainties for configurations associated either with the $i_{13/2}$ neutron hole or double core excitations.

The ${}^{237}\mathrm{Np}$($n,\gamma$)${}^{238}\mathrm{Np}$ cross section has been measured in the neutron energy range from 20 meV to 500 keV using the DANCE array at the Los Alamos National Laboratory. This new facility allows experiments with submilligram samples and is therefore well suited to investigate isotopes with half-lives as low as a few hundred days. In this benchmark measurement, only 0.42 mg of ${}^{237}\mathrm{Np}$ was sufficient to determine differential cross sections relative to the well-known resonance at 0.5 eV. The thermal cross section was measured to ${\sigma }_{2200\mathrm{m}/\mathrm{s}}=177\pm 5$ barn, ${\sigma }_{\mathit{kT}=25.3\mathrm{meV}}=167\pm 4$ barn and the resonance integral to $\mathit{RI}=693\pm 6$ barn.

We introduce a new scenario for heavy ion collisions that could solve the lingering problems associated with the so-called Hanbury Brown-Twiss (HBT) puzzle. We postulate that the system starts expansion as the perfect quark-gluon fluid but close to freeze-out it splits into clusters, due to a sharp rise of bulk viscosity in the vicinity of the hadronization transition. We then argue that the characteristic cluster size is determined by the viscosity coefficient and the expansion rate. Typically it is much smaller and at most weakly dependent of the total system volume (hence reaction energy and multiplicity). These clusters maintain the pre-existing outward-going flow, as a spray of droplets, but develop no flow of their own, and hadronize by evaporation. We provide an ansatz for converting the hydrodynamic output into clusters.

A fully self-consistent model of the neutron star inner crust based upon models of the nucleonic equation of state at zero temperature is constructed. The results nearly match those of previous calculations of the inner crust given the same input equation of state. The extent to which the uncertainties in the symmetry energy, the compressibility, and the equation of state of low-density neutron matter affect the composition of the crust are examined. The composition and pressure of the crust is sensitive to the description of low-density neutron matter and the nuclear symmetry energy, and the latter dependence is nonmonotonic, giving larger nuclei for moderate symmetry energies and smaller nuclei for more extreme symmetry energies. Future nuclear experiments may help constrain the crust and future astrophysical observations may constrain the nuclear physics input.

Using nonlocal $\mathit{NN}$ interactions which reproduce the three-nucleon binding energies, this work investigates the dependence of the theoretical $p\text{−}d$ and $n\text{−}d$ elastic scattering results on the triplet $P$-wave $\mathit{NN}$ interactions. The low-energy tensor analyzing powers $T_{20}$ and $T_{21}$ are found to be also sensitive to the triplet $P$-wave interactions. A link seems to exists between the $N\text{−}N$ and $N\text{−}d$ analyzing powers which makes it possible to define sets of low-energy (between 1 and 100 MeV) modified nonlocal triplet $P$-wave interactions capable of reproducing most of the known experimental $N\text{−}d$ elastic scattering data up to 30 MeV. The same results could be achieved with analogously modified local triplet $P$-wave interactions. Based on these results, a nonlocal interaction is constructed, which reproduces simultaneously the $N\text{−}N$ data and most of the known $N\text{−}d$ elastic scattering experiments up to 30 MeV.