The neutron induced fission cross sections of ${}^{240,242}\mathrm{Pu}$ have been measured as a function of incident neutron energy from 1 eV to 200 MeV. This is part of an effort to reduce experimental uncertainties of nuclear data in support of next generation nuclear reactors and transmutation technology. These two plutonium isotopes are nonfissile, and the available data are limited below reaction threshold. The present data demonstrate the presence of a 2.67 eV resonance in the ${}^{242}\mathrm{Pu}$ fission cross section, which is missing in the ENDF/B-VII evaluation, and resolve discrepancies in the keV region. The measured cross sections are also compared with statistical model calculations made with the nuclear reaction code GNASH.

The JAERI quantum molecular dynamics (JQMD) model has been successfully used for a long time now to describe many different aspects of nuclear reactions in a unified way. In some cases, however, the JQMD model cannot produce consistent results: First, it lacks a fully relativistically covariant approach to the problem of molecular dynamics; second, the quantum-mechanical ground state of nuclei cannot be faithfully reproduced in a semiclassical framework. Therefore, we introduce R-JQMD, an improved version of JQMD that also features a new ground-state initialization algorithm for nuclei. We compare the structure of the two codes and discuss whether R-JQMD can be adjusted to improve JQMD's agreement with measured heavy-ion fragmentation cross sections.

Measurements of the $\mathit{pd}\to p_{\text{sp}}{\mathit{dK}}^{+}{K}^{-}$ reaction, where $p_{\text{sp}}$ is a spectator proton, have been undertaken at the Cooler Synchrotron COSY-Jülich by detecting a fast deuteron in coincidence with a $K^{+}{K}^{-}$ pair in the ANKE facility. Although the proton beam energy was fixed, the moving target neutron allowed values of the nonresonant quasifree $\mathit{pn}\to {\mathit{dK}}^{+}{K}^{-}$ total cross section to be deduced up to an excess energy $\epsilon \approx 100$ MeV. Evidence is found for the effects of $K^{-}d$ and $K\overline{K}$ final state interactions. The comparison of these data with those of $\mathit{pp}\to {\mathit{ppK}}^{+}{K}^{-}$ and $\mathit{pp}\to {\mathit{dK}}^{+}{\overline{K}}^0$ shows that all the total cross sections are very similar in magnitude.

A new isotope of Hs was produced in the reaction ${}^{208}\mathrm{Pb}({}^{56}\mathrm{Fe},n){}^{263}\mathrm{Hs}$ at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope ${}^{263}\mathrm{Hs}$. The measured cross section was ${21}_{-8.4}^{+13}$ pb at 276.4 MeV lab frame center-of-target beam energy. ${}^{263}\mathrm{Hs}$ decays with a half-life of $0.{74}_{-0.21}^{+0.48}$ ms by $\alpha$-decay and the measured $\alpha$-particle energies are 10.57 ± 0.06, 10.72 ± 0.06, and 10.89 ± 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Świątecki et al., Phys. Rev. C 71, 014602 (2005)].

We present a Poincaré covariant Faddeev equation, which enables the simultaneous prediction of meson and baryon observables using the leading order in a truncation of the Dyson-Schwinger equations that can systematically be improved. The solution describes a nucleon's dressed-quark core. The evolution of the nucleon mass with current-quark mass is discussed. A nucleon-photon current, which can produce nucleon form factors with realistic $Q^2$ evolution, is described. Axial-vector diquark correlations lead to a neutron Dirac form factor that is negative, with $r_1^{\mathit{nu}}>r_1^{\mathit{nd}}$. The proton electric-magnetic form factor ratio falls with increasing $Q^2$.

A method to implement a realistic nucleon-nucleon residual interaction based on the Brueckner $G$ matrix (for the Bonn-CD force) into the quasiparticle random phase approximation (QRPA) for deformed nuclei is formulated. The two-neutrino double $\beta$ decay for ground state to ground state transitions ${}^{76}\mathrm{Ge}\to {}^{76}\mathrm{Se}$ and ${}^{150}\mathrm{Nd}\to {}^{150}\mathrm{Sm}$ is calculated along with the Gamow-Teller strength distributions. The effect of deformation on the observables is studied.

The $J$-matrix inverse scattering approach can be used as an alternative to a conventional $R$-matrix in analyzing scattering phase shifts and extracting resonance energies and widths from experimental data. A great advantage of the $J$-matrix is that it provides eigenstates directly related to the ones obtained in the shell model in a given model space and with a given value of the oscillator spacing $\hslash \Omega$. This relationship is of particular interest in the cases when a many-body system does not have a resonant state or the resonance is broad and its energy can differ significantly from the shell-model eigenstate. We discuss the $J$-matrix inverse scattering technique, extend it for the case of charged colliding particles, and apply it to the analysis of $n\alpha$ and $p\alpha$ scattering. The results are compared with the no-core shell-model calculations of ${}^5\mathrm{He}$ and ${}^5\mathrm{Li}$.

The dynamic polarization potential contribution to the effective interaction between ${}^6\mathrm{He}$ and ${}^{208}\mathrm{Pb}$ at 27 MeV, due to breakup channels, is recalculated exploiting a recently developed improved model for ${}^6\mathrm{He}$. The most general features of the long-range attractive and absorptive components remain the same as were found in an earlier study, but the asymptotic magnitudes are reduced by factors of about 2.5 and 4.5, respectively. We draw conclusions from these results, as well as from further calculations at 22 MeV, closer to the Coulomb barrier, and at 32 MeV.

${}^{11}\mathrm{Li}+p$ elastic scattering data at three energies, 62, 68.4, and 75 MeV/nucleon, are analyzed with density-dependent M3Y and KH effective nucleon-nucleon $(\mathit{NN})$ interactions in the framework of the single folding model. The parameters of the density-dependent term are adjusted to fulfill saturation of nuclear matter. The optical potentials (OP's) and cross sections are calculated using four model densities of ${}^{11}\mathrm{Li}$, G (one-parameter Gaussian), GG (Gaussian-Gaussian), GO (Gaussian- oscillator), and the COSMA (cluster orbital shell model approximation). Comparative studies are performed for real, imaginary, and spin-orbit potentials with the phenomenological and microscopic forms. The microscopic volume and surface imaginary potentials are constructed from both the renormalized folded potentials and their derivatives. The sensitivity of the differential cross section to the four densities is tested. It is found that the ${}^{11}\mathrm{Li}+p$ elastic scattering cross sections depend strongly upon the behavior of the corresponding potentials. The GG and GO densities obtained from analyzing the data, using Glauber multiple scattering theory at high energies, give good results at energies below 100 MeV/nucleon in the framework of the folding model. The OP's calculated in the microscopic form using few parameters give good agreement with the data. Thus, it is not necessary to introduce a large number of arbitrary fitting parameters as done in the phenomenological and semimicroscopic OP's. The KH effective interaction successfully describes ${}^{11}\mathrm{Li}+p$ elastic scattering as the popular M3Y interaction. The obtained results of the reaction cross section are in good agreement with previous calculations.

We investigate the yield of $\Lambda (1520)$ resonance in heavy ion collisions within the framework of a kinetic master equation without the assumption of chemical equilibrium. We show that reactions such as $\Lambda (1520)+\pi \leftrightarrow {\Sigma }^{*}$ can favor ${\Sigma }^{*}$ production, thereby decreasing the $\Lambda (1520)$ yield. Within the same approach we thus find a yield enhancement for $\Sigma (1385)$ and a yield suppression for $\Lambda (1520)$.

Employing a perturbative QCD based parton cascade we calculate the elliptic flow $v_2$ and its transverse momentum dependence $v_2(p_T)$ for the gluon matter created in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV. To make comparisons with the experimental data at the BNL Relativistic Heavy Ion Collider (RHIC), parton-hadron duality is assumed. We find that whereas the integrated $v_2$ matches the experimental data, the gluon (or pion) $v_2(p_T)$ is about 20–50% smaller than the experimental data. Hadronization via gluon fragmentation and quark recombination seems to be the key to explaining the necessary jump of $v_2(p_T)$ from the partonic to the hadronic phase. We also show that the elliptic flow values moderately depend on the chosen freezeout condition, which will thus constrain the shear viscosity to the entropy density ratio of the quark gluon plasma created at RHIC.

We calculate the centrality dependence of transverse momentum $(p_t)$ spectra for direct photons in $\mathrm{Au}+\mathrm{Au}$ collisions at the BNL Relativistic Heavy Ion Collider (RHIC) energy $\sqrt{s_{\mathit{NN}}}=200\hspace{0.5em}\mathrm{GeV}$, based on a realistic data-constrained $(3+1)$-dimensional hydrodynamic description of the expanding hot and dense matter, a reasonable treatment of the propagation of partons and their energy loss in the fluid, and a systematic study of the main sources of direct photons. The resultant $p_t$ spectra agree with recent PHENIX data in a broad $p_t$ range. The competition among the different direct photon sources is investigated at various centralities. Parton energy loss in the plasma is considered for photons from fragmentation and jet-photon conversion, which causes about 40% decrease in the total contribution. In the high $p_t$ region, the observed $R_{\mathit{AA}}$ of photons is centrality independent at the accuracy of 5% based on a realistic treatment of energy loss. We also link the different behavior of $R_{\mathit{AA}}$ for central and peripheral collisions, in the low $p_t$ region, to the fact that the plasma in central collisions is hotter than that in peripheral ones.

We utilize nonequilibrium covariant transport theory to determine the region of validity of causal Israel-Stewart (IS) dissipative hydrodynamics and Navier-Stokes (NS) theory for relativistic heavy ion physics applications. A massless ideal gas with $2\to 2$ interactions is considered in a Bjorken scenario in 0 + 1 dimension (D) appropriate for the early longitudinal expansion stage of the collision. In the scale-invariant case of a constant shear viscosity to entropy density ratio $\eta /s\approx \mathrm{const}$, we find that IS theory is accurate within 10% in calculating dissipative effects if initially the expansion time scale exceeds half the transport mean free path ${\tau }_0/{\lambda }_{\mathrm{tr},0}\gtrsim 2$. The same accuracy with NS requires three times larger ${\tau }_0/{\lambda }_{\mathrm{tr},0}\gtrsim 6$. For dynamics driven by a constant cross section, on the other hand, about 50% larger ${\tau }_0/{\lambda }_{\mathrm{tr},0}\gtrsim 3$ (IS) and 9 (NS) are needed. For typical applications at energies currently available at the BNL Relativistic Heavy Ion Collider (RHIC), i.e., $\sqrt{s_{\mathit{NN}}}~100\text{−}200$ GeV, these limits imply that even the IS approach becomes marginal when $\eta /s\gtrsim 0.15$. In addition, we find that the “naive” approximation to IS theory, which neglects products of gradients and dissipative quantities, has an even smaller range of applicability than Navier-Stokes. We also obtain analytic IS and NS solutions in 0 + 1D, and present further tests for numerical dissipative hydrodynamics codes in 1 + 1, 2 + 1, and 3 + 1D based on generalized conservation laws.

We study the effect of strong magnetic fields, of the order of ${10}^{18}\text{−}{10}^{19}$ G, on the instability region of nuclear matter at subsaturation densities. Relativistic nuclear models both with constant couplings and with density-dependent parameters are considered. It is shown that a strong magnetic field can have large effects on the instability regions giving rise to bands of instability and wider unstable regions. As a consequence, we predict larger transition densities at the inner edge of the crust of compact stars with strong magnetic fields. The direction of instability gives rise to a very strong distillation effect if the last Landau level is only partially filled. However, for almost completed Landau levels, an antidistillation effect may occur.

A potential-model calculation has given reasonably precise values for the energies of the $1/2^{+}$ first excited state of ${}^9\mathrm{B}$ and the excited $0^{+}$ state of ${}^{10}\mathrm{C}$. We here extend this calculation to allow for nonzero widths of the $1/2^{+}$ and $5/2^{+}$ levels of ${}^9\mathrm{Be}$ and ${}^9\mathrm{B}$ that are involved in the calculation. The ${}^9\mathrm{B}\hspace{0.5em}1/2^{+}$ peak energy (but not the resonance energy) appears to be well determined. The ${}^{10}\mathrm{C}\hspace{0.5em}{0}^{+}$ energy is determined sufficiently well to make it unlikely that a state recently observed in ${}^{10}\mathrm{C}$ at 4.20 MeV could be the $0^{+}$ state, as has been suggested.

A measurement performed at the Argonne National Laboratory (ANL) Intense Pulsed Neutron Source (IPNS) facility studied the incident neutron energy-dependent charged particle and fission fragment yields from a ${}^{239}\mathrm{Pu}$ target. The analysis of the data showed a set of previously unknown resonances identified as arising from a $(n,\alpha )$ reaction channel. These resonances differ from the known fission and radiative capture resonances in ${}^{239}\mathrm{Pu}$ and do not correspond to any known capture resonances from structural material around the ${}^{239}\mathrm{Pu}$ target assembly. The new resonances decay uniquely via $\alpha$-emission, and represent new states not explained by current models. The yield of the observed $(n,\alpha )$ reaction channel is 60 ± 5 times as strong as the fission channel, as determined from the high-energy $\alpha$-particle and fission fragment peak area observed in the Si detectors.

Excited states of neutron-rich odd-$A$ and odd-odd Sc isotopes, populated in deep inelastic multinucleon transfer reactions, induced by a ${}^{238}\mathrm{U}$ beam on a thin ${}^{48}\mathrm{Ca}$ target, have been identified. A strong feeding of both yrast and nonyrast states in such a reaction is illustrated using a combination of a large efficiency spectrometer and a $\gamma$ detector array. The structure of the populated states is interpreted in terms of the role of the valence proton and neutrons and compared to shell model calculations in the full $\mathit{pf}$ shell.

A search was made for sub-threshold $J/\psi$ production from a carbon target by using a mixed real and quasireal Bremsstrahlung photon beam with an endpoint energy of 5.76 GeV. No events were observed, which is consistent with predictions under the assumption of quasifree production. The results place limits on exotic mechanisms that strongly enhance quasifree production.