Angular distributions are reported for ${}^{37}\mathrm{Ar}$ and ${}^{127}\mathrm{Xe}$ from 381-GeV ${}^{28}\mathrm{Si}+\text{Au}$ interactions and for products between ${}^{24}\mathrm{Na}$ and ${}^{149}\mathrm{Gd}$ from 28-GeV ${}^1\mathrm{H}+\text{Au}$. Sideward peaking and forward deficits for multifragmentation products are significantly enhanced for heavy ions compared with protons. Projectile kinetic energy does not appear to be a satisfactory scaling variable. The data are discussed in terms of a kinetic-focusing model in which sideward peaking is due to transverse motion of the excited product from the initial projectile-target interaction.

The α-decay half-lives of deformed nuclei are investigated in a new version of the density-dependent cluster model. By the multipole expansion method, the deformation- and orientation-dependent double-folding potential is derived to calculate the α-decay width through a deformed Coulomb barrier. We perform systematic calculations for the ground-state α transitions of even-even nuclei with $Z=52\mathrm{-}104$. The theoretical results are in good agreement with the experimental data. This is, to our knowledge, the first deformed calculation of α-decay half-lives within the framework of microscopic double-folding potentials. A unified description of α-decay half-lives of both spherical and deformed nuclei is obtained by the microscopic potentials.

The $g_{9/2}$ shell of identical particles is the first one for which one can have seniority-mixing effects. We consider three interactions: A delta interaction that conserves seniority, a quadrupole-quadrupole ($Q·Q$) interaction that does not, and a third one consisting of two-body matrix elements taken from experiment (${}^{98}\mathrm{Cd}$) that also leads to some seniority mixing. We deal with proton holes relative to a $Z=50,N=50$ core. One surprising result is that, for a four-particle system with total angular momentum $I=4$, there is one state with seniority $v=4$ that is an eigenstate of any two-body interaction—seniority conserving or not. The other two states are mixtures of $v=2$ and $v=4$ for the seniority-mixing interactions. The same thing holds true for $I=6$. Another point of interest is that, in the single-j-shell approximation, the splittings $\Delta E=E(I_{max})-E(I_{min})$ are the same for three and five particles with a seniority conserving interaction (a well-known result), but are equal and opposite for a $Q·Q$ interaction. We also fit the spectra with a combination of the delta and $Q·Q$ interactions. The $Z=40,N=40$ core plus $g_{9/2}$ neutrons (Zr isotopes) is also considered, although it is recognized that the core is deformed.

Fragmentation reactions with intermediate-energy heavy-ion beams exhibit a wide range of reaction mechanisms, ranging from direct reactions to statistical processes. We examine this transition by measuring the relative population of excited states in several sd-shell nuclei produced by fragmentation with the number of removed nucleons ranging from two to sixteen. The two-nucleon removal is consistent with a non-dissipative process, whereas the removal of more than five nucleons appears to be mainly statistical.

Hydrodynamic simulations of neutron star cores that are based on a two-fluid description in terms of a neutron-proton superfluid mixture require the knowledge of the Andreev-Bashkin entrainment matrix which relates the momentum of one constituent to the currents of both constituents. This matrix is derived for arbitrary nuclear asymmetry at zero temperature and in the limits of small relative currents in the framework of the energy density functional theory. The Skyrme energy density functional is considered as a particular case. General analytic formulas for the entrainment parameters and various corresponding effective masses are obtained. These formulas are applied to the liquid core of a neutron star composed of homogeneous plasma of nucleons, electrons, and possibly muons in β equilibrium.

If deconfined quark matter exists inside compact stars, the primary cooling mechanism is neutrino radiation via the direct Urca processes $d\to u+e+{\overline{\nu }}_e$ and $u+e\to d+{\nu }_e$. Below a critical temperature, $T_c$, quark matter forms a color superconductor, one possible manifestation of which is a condensate of $\langle ud\rangle$ quark Cooper pairs in an electric-charge neutralizing background of electrons. We compute the neutrino emission rate from such a phase, including charged pair-breaking and recombination effects, and find that on a material temperature domain below $T_c$ the pairing-induced suppression of the neutrino emission rate is not uniformly exponential. If gapless modes are present in the condensed phase, the emissivity at low temperatures is moderately enhanced above that of completely unpaired matter. The importance of charged current pair-breaking processes for neutrino emission both in the fully gapped and partially gapped regimes is emphasized.

The spectroscopy of the unstable ${}^8\mathrm{He}$ and unbound ${}^7\mathrm{He}$ nuclei is investigated via the $p({}^8\mathrm{He}$, d) transfer reaction with a 15.7A MeV ${}^8\mathrm{He}$ beam from the SPIRAL facility. The emitted deuterons were detected by the telescope array MUST. The results are analyzed within the coupled-channels Born approximation framework, and a spectroscopic factor $C^{2}S=4.4\pm 1.3$ for neutron pickup to the ${}^7{\mathrm{He}}_{g.s.}$ is deduced. This value is consistent with a full p3/2 subshell for ${}^8\mathrm{He}$. Tentative evidence for the first excited state of ${}^7\mathrm{He}$ is found at E${}^{*}=0.9\pm 0.5$ MeV (width $\Gamma =1.0\pm 0.9$ MeV). The second one is observed at a position compatible with previous measurements, E${}^{*}=2.9\pm 0.1$ MeV. Both are in agreement with previous separate measurements. The reproduction of the first excited state below 1 MeV would be a challenge for the most sophisticated nuclear theories.

We analyze the cross section for vector meson photoproduction off a deuteron for the intermediate range of photon energies starting at a few giga-electron-volts above the threshold and higher. We reproduce the steps in the derivation of the conventional nonrelativistic Glauber expression based on an effective diagrammatic method while making corrections for Fermi motion and intermediate-energy kinematic effects. We show that, for intermediate-energy vector meson production, the usual Glauber factorization breaks down, and we derive corrections to the usual Glauber method to linear order in longitudinal nucleon momentum. The purpose of our analysis is to establish methods for probing interesting physics in the production mechanism for ϕ mesons and heavier vector mesons. We demonstrate how neglecting the breakdown of Glauber factorization can lead to errors in measurements of basic cross sections extracted from nuclear data.

Recent Wilkinson Microwave Anisotropy Probe (WMAP) measurements have determined the baryon density of the Universe ${\Omega }_b$ with a precision of about 4%. With ${\Omega }_b$ tightly constrained, comparisons of Big Bang nucleosynthesis (BBN) abundance predictions to primordial abundance observations can be made and used to test BBN models and/or to further constrain abundances of isotopes with weak observational limits. To push the limits and improve constraints on BBN models, uncertainties in key nuclear reaction rates must be minimized. To this end, we made new precise measurements of the ${}^2\mathrm{H}$$(d,p)$${}^3\mathrm{H}$ and ${}^2\mathrm{H}$$(d,n)$${}^3\mathrm{He}$ total cross sections at lab energies from 110 to 650 keV. A complete fit was performed in energy and angle to both angular distribution and normalization data for both reactions simultaneously. By including parameters for experimental variables in the fit, error correlations between detectors, reactions, and reaction energies were accurately tabulated by computational methods. With uncertainties around $2\%\pm 1\%$ scale error, these new measurements significantly improve on the existing data set. At relevant temperatures, by using the data of the present work, both reaction rates are found to be about 7% higher than those in the widely used NACRE (nuclear astrophysics compilation of reaction rates) database. These data will thus lead not only to reduced uncertainties, but also to modifications in the BBN abundance predictions.

We present a simultaneous analysis of the elastic scattering and fusion cross-section data of the ${}^{12}\mathrm{C}+{}^{24}\mathrm{Mg}$ system around the Coulomb barrier and over energies by using the microscopic $\alpha \text{−}\alpha$ double folding cluster potential within the framework of the optical model and the coupled-channels formalism. The $\alpha \text{−}\alpha$ double folding cluster potential is obtained by using the α-cluster distribution densities of the nuclei in the usual double folding procedure. The microscopic potential results are compared with the findings of the phenomenological deep and shallow potentials. It is subsequently shown that only phenomenological deep, real, microscopic nucleon-nucleon and $\alpha \text{−}\alpha$ double folding cluster potentials provide a consistent description of the angular distributions and fusion cross-section data simultaneously. The effect of the inclusion of the excited states of the target nucleus ${}^{24}\mathrm{Mg}$ on the fusion cross-section predictions is also determined by the coupled-channels calculations, which are shown to improve the agreement.

Angular distributions and angular correlations have been measured for the emission of one and two α-particles in the ${}^{18}\mathrm{O}+{}^{207,208}\mathrm{Pb}$,${}^{209}\mathrm{Bi}$ reactions at several beam energies above the Coulomb barrier. The results rule out fusion evaporation as the main reaction mechanism for the channels involving α-particle emission and support the interpretation of the breakup of the ${}^{18}\mathrm{O}$ projectiles into at least ${}^{14}\mathrm{C}$+α and ${}^{10}\mathrm{Be}+{}^8\mathrm{Be}$ before fusion.

Calculations of nuclear structure functions (SFs) $F_{k=1,2}^A(x,Q^2)$ routinely exploit a generalized convolution, involving the SFs for nucleons $F_k^N$ and the linking SF $f^{\mathit{PN},A}$ of a fictitious nucleus, composed of point particles, with the latter usually expressed in terms of hadronic degrees of freedom. For finite $Q^2$ the approach seemed to be lacking a solid justification and the same is the case for recently proposed, effective nuclear parton distribution functions, which exactly reproduce the above-mentioned hadronically computed $F_k^A$. Many years ago Jaffe and West proved the above convolution in the plane-wave impulse approximation for the nuclear components in the convolution. We extend the above proof to include classes of nuclear final-state interactions. One and the same function appears to relate parton distribution functions in nuclei and nucleons and SFs for nuclear targets and for nucleons. That relation is the previously conjectured one, with an entirely different interpretation of $f^{\mathit{PN},A}$. We conclude with an extensive analysis of moments of nuclear SFs based on the generalized convolution. Characteristics of those moments are shown to be quite similar to those for a nucleon. We conclude that the above is evidence of asymptotic freedom of a nucleon in a medium and not the same for a composite nucleus.

In chiral perturbation theory, the dominant next-to-leading-order correction to the $\pi \gamma$-exchange NN-potential proportional to the large isovector magnetic moment ${\kappa }_v=4.7$ of the nucleon is calculated. The corresponding spin-spin and tensor potentials ${\tilde{V}}_{S,T}(r)$ in coordinate space have a very simple analytical form. At long distances, $r\simeq 2$ fm, these potentials are of similar size (but opposite in sign) as the leading-order $\pi \gamma$-exchange potentials. Effects from virtual Δ-isobar excitation are also considered, as well as other isospin-breaking contributions to the $2\pi$-exchange NN potential induced by additional one-photon exchange.

The origin and dynamical evolution of isoscaling was studied using classical molecular dynamics simulations of ${}^{40}\mathrm{Ca}+{}^{40}\mathrm{Ca}$, ${}^{48}\mathrm{Ca}+{}^{48}\mathrm{Ca}$, and ${}^{52}\mathrm{Ca}+{}^{52}\mathrm{Ca}$ at beam energies ranging from 20 to 85 MeV/nucleon. The analysis included a study of the time evolution of this effect. Isoscaling was observed to exist at all energies in these reactions from the early primary isotope distributions (produced by systems not yet in thermal equilibrium) all the way to 5000 fm/c.

From velocity-gated small-angle correlation functions, the emission chronology can be deduced for nonidentical particles, if the emission is independent. This is not the case for nonidentical particles that originate from two-body decay of fragments. Experimental results may contain contributions from both independent emission and two-body decay, so care is needed in interpreting the velocity-gated correlation functions. It is shown that in some special cases, it is still possible to deduce the emission chronology, even if there is a contribution from two-body decay.

We have analyzed and evaluated ${}^{35}\mathrm{Cl}$, ${}^{37}\mathrm{Cl}$, and ${}^{\mathrm{nat}}$Cl neutron cross section data in the resolved resonance region with the multilevel Reich-Moore R-matrix formalism. Energies and widths were determined for 388 resonances in the range 0.2 to 1200 keV. New J assignments were made for 33 resonances, and parities were assigned for 15 of these resonances. Neutron strength functions were calculated for both s and p waves; our results include the first reported p-wave values for Cl. Resonance analyses were carried out with the computer code SAMMY, which utilizes Bayes’ method, a generalized least-squares technique. Because SAMMY now has the ability to calculate charged-particle penetrabilities, it was possible to include a proton exit channel in the analysis and to deduce proton widths for several resonances. Our resonance parameter representation describes the data much better than pre-vious evaluations, and it should lead to improved criticality safety calculations for systems where Cl is present.

The present study brings forward important information, within the framework of spectral distribution theory, about the types of forces that dominate three realistic interactions, CD-Bonn, CD-Bonn+3terms, and GXPF1, in nuclei and their ability to account for many-particle effects such as the formation of correlated nucleon pairs and enhanced quadrupole collective modes. Like-particle and proton-neutron isovector pairing correlations are described microscopically by a model interaction with $\mathfrak{s}\mathfrak{p}$(4) dynamical symmetry, which is extended to include an additional quadrupole-quadrupole interaction. The analysis of the results for the $1f_{7/2}$ level shows that both CD-Bonn+3terms and GXPF1 exhibit a well-developed pairing character compared to CD-Bonn, while the latter appears to build up more (less) rotational isovector $T=1$ (isoscalar $T=0$) collective features. Furthermore, the three realistic interactions are in general found to correlate strongly with the pairing+quadrupole model interaction, especially for the highest possible isospin group of states where the model interaction can be used to provide a reasonable description of the corresponding energy spectra.

Differential cross sections and photon-beam asymmetries for the $\overrightarrow{\gamma }p\to K^{+}\Lambda$ and $\overrightarrow{\gamma }p\to K^{+}{\Sigma }^0$ reactions have been measured in the photon energy range from 1.5 to 2.4 GeV and in the angular range from ${\Theta }_{c.m.}=0^{°}$ to 60${}^{°}$ of the $K^{+}$ scattering angle in the center-of-mass system at the SPring-8/LEPS facility. The photon-beam asymmetries for both the reactions have been found to be positive and to increase with the photon energy. The measured differential cross sections agree with the data measured by the CLAS Collaboration at $\cos {\Theta }_{c.m.}<0.9$ within the experimental uncertainties, but the discrepancy with the SAPHIR data for the $K^{+}\Lambda$ reaction is large at $\cos {\Theta }_{c.m.}>0.9$. In the $K^{+}\Lambda$ reaction, the resonance-like structure found in the CLAS and SAPHIR data at $W=1.96$ GeV is confirmed. The differential cross sections at forward angles suggest a strong K-exchange contribution in the t-channel for the $K^{+}\Lambda$ reaction, but not for the $K^{+}{\Sigma }^0$ reaction.