We develop and solve a network of rate equations for the production of baryons and antibaryons in high energy nuclear collisions. We include all members of the baryon octet and decuplet and allow for transformations among them. This network is solved during a relativistic $2+1$ hydrodynamical expansion of the of the hot matter created in the collision. As an application we compare to the number of protons, $\Lambda$’s, negative cascades, and $\Omega$ baryons measured at midrapidity in central collisions of gold nuclei at $65\text{GeV}$ per nucleon at the Relativistic Heavy Ion Collider (RHIC).

We consider two methods to find the effective parameters of the pion traversing a nuclear medium. One is the first order chiral perturbation theoretic evaluation of the pion pole contribution to the two-point function of the axial-vector current. The other is the exact, first order virial expansion of the pion self-energy. We find that, although the results of chiral perturbation theory are not valid at normal nuclear density, those from the virial expansion may be reliable at such density. The latter predicts both the mass shift and the in-medium decay width of the pion to be small, of about a few MeV.

The neutrino flux from the sun is predicted to have a CNO-cycle contribution as well as the known $pp$-chain component. Previously, only the fluxes from ${\beta }^{+}$ decays of ${}^{13}\mathrm{N}$, ${}^{15}\mathrm{O}$, and ${}^{17}\mathrm{F}$ have been calculated in detail. Another neutrino component that has not been widely considered is electron capture on these nuclei. We calculate the number of interactions in several solar neutrino detectors due to neutrinos from electron capture on ${}^{13}\mathrm{N}$, ${}^{15}\mathrm{O}$, and ${}^{17}\mathrm{F}$, within the context of the standard solar model. We also discuss possible nonstandard models where the CNO flux is increased.

The fusion cross section of ${}^3\mathrm{He}({}^3\mathrm{He},2p){}^4\mathrm{He}$ at a center of mass energy of $30–50\text{keV}$ has been measured by using a helium-3 doubly ionized beam at a low-energy high current accelerator facility OCEAN. Free from molecular interference in the beam, the measurement determines the astrophysical $S$ factor with better statistical and systematic errors than previous data. By using singly and doubly charged helium-3 ions, the facility envisages to provide the data from high-energy to Gamow energy regions.

The electromagnetic potential consisting in the Coulomb plus the magnetic moment interactions between two nucleons is studied in nucleon-deuteron scattering. For states in which the relative $N\text{−}d$ angular momentum $L$ has low values the three-nucleon problem has been solved using the correlated hyperspherical harmonic expansion basis. For states in which the angular momentum $L$ has large values, explicit formulas for the nucleon-deuteron magnetic moment interaction are derived and used to calculate the corresponding $T$ matrices in Born approximation. Then, the transition matrices describing $N\text{−}d$ elastic scattering have been derived including an infinite number of partial waves as required by the $1∕r^3$ behavior of the magnetic moment interaction. Appreciable effects are observed in the vector analyzing powers at low energies. The evolution of these effects by increasing the collision energy is examined.

Recent $(n,xp)$ continuum spectra at incident energies of 28 to $63\text{MeV}$ have been used to expand an earlier study at lower neutron energies of the amount of surface localization of the initital target-projectile interaction. The $(n,xp)$ data show a reduction in surface localization for heavy targets—a trend that grows with increasing bombarding energy. This target mass dependence is not evident in $(n,xn)$ reactions up to $26\text{MeV}$ and should be verified with additional heavy target $(n,xp)$ data as well as $(n,xn)$ data at higher bombarding energies. It can be described and included in model calculations in terms of a difference in surface localization between initial $nn$ and $np$ interactions.

First results on charm quarkonia production in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) are presented. The yield of $J∕\psi$’s measured in the PHENIX experiment via electron-positron decay pairs at midrapidity for $\text{Au-Au}$ reactions at $\sqrt{s_{NN}}=200\text{GeV}$ is analyzed as a function of collision centrality. For this analysis we have studied $49.3\times {10}^6$ minimum bias $\text{Au-Au}$ reactions. We present the $J∕\psi$ invariant yield $dN∕dy$ for peripheral and midcentral reactions. For the most central collisions where we observe no signal above background, we quote $90\%$ confidence level upper limits. We compare these results with our $J∕\psi$ measurement from proton-proton reactions at the same energy. We find that our measurements are not consistent with models that predict strong enhancement relative to binary collision scaling.

In this paper we analyze nuclear medium effects on deeply virtual Compton scattering (DVCS) amplitudes in the $x_{bj}$ range of ${10}^{-1}–{10}^{-4}$ for a large range of $Q^2$ and four different nuclei. We use our nucleon generalized parton distribution model capable of describing all currently available DVCS data on the proton and extend it to the nuclear case using two competing parametrizations of nuclear effects. The two parametrizations, though giving different absolute numbers, yield the same type and magnitude of effects for the imaginary and real parts of the nuclear DVCS amplitude. The imaginary part shows stronger nuclear shadowing effects compared to the inclusive case, i.e., $F_2^N$, whereas in the real part nuclear shadowing at small $x_{bj}$ and antishadowing at large $x_{bj}$ combine through evolution to yield an even greater suppression than in the imaginary part up to large values of $x_{bj}$. This is the first time that such a combination of nuclear effects has been observed in a hadronic amplitude. The experimental implications will be discussed in a subsequent publication.

The production of $\eta$ mesons in $NN$ collisions in the near threshold region is analyzed with special emphasis on the role of final state interaction which is calculated using three-body scattering theory. The three-body aspects are shown to be very important in interpreting experimental results for the total cross section of $pp\to \eta pp$. Furthermore, energy spectra and angular distributions of the emitted particles are calculated and compared to experimental data.

We investigate the systematics of fission barriers in superheavy elements in the range $Z=108–120$ and $N=166–182$. Results from two self-consistent models for nuclear structure, the relativistic mean-field (RMF) model as well as the nonrelativistic Skyrme-Hartree-Fock approach are compared and discussed. We restrict ourselves to axially symmetric shapes, which provides an upper bound on static fission barriers. We benchmark the predictive power of the models examining the barriers and fission isomers of selected heavy actinide nuclei for which data are available. For both actinides and superheavy nuclei, the RMF model systematically predicts lower barriers than most Skyrme interactions. In particular, the fission isomers are predicted too low by the RMF, which casts some doubt on recent predictions about superdeformed ground states of some superheavy nuclei. For the superheavy nuclei under investigation, fission barriers drop to small values around $Z=110$, $N=180$, and increase again for heavier systems. For most of the forces, there is no fission isomer for superheavy nuclei, as superdeformed states are in most cases found to be unstable with respect to octupole distortions.

Neutron-deficient americium isotopes ${}^{233,234,235,236}\mathrm{Am}$ were produced in the bombardment of multiple thin targets of ${}^{233}\mathrm{U}$ and ${}^{235}\mathrm{U}$ with $7.6–10.5\text{MeV}∕\mathrm{nucleon}$ ${}^6\mathrm{Li}$ ions. The reaction products were effectively mass-separated using the on-line isotope separator (JAERI-ISOL) coupled to a helium gas-jet transport system. For the first time, the $\alpha$ transition of ${}^{235}\mathrm{Am}$ was observed, and some improved $\alpha$-decay data for ${}^{233,234,236}\mathrm{Am}$ and ${}^{229}\mathrm{Np}$ ($\alpha$-decay daughter of ${}^{233}\mathrm{Am}$) were accumulated. The $\alpha$-particle energies of ${}^{233}\mathrm{Am}$ and ${}^{235}\mathrm{Am}$ were determined to be $6780\pm 17\text{keV}$ and $6457\pm 14\text{keV}$ and their half-lives were $3.2\pm 0.8\min$ and $10.3\pm 0.6\min$, respectively. Measured $\alpha$-decay branching ratios of ${}^{235}\mathrm{Am}$ and ${}^{229}\mathrm{Np}$ were $\left(4.0\pm 0.5\right)\times {10}^{-3}$ and $0.68\pm 0.11$, respectively, while the lower limit for $\alpha$-decay of ${}^{233}\mathrm{Am}$ was deduced to be $3\times {10}^{-2}$. Hindrance factors and probable assignments of the levels involved in those $\alpha$ transitions are discussed.

Self-affine multiplicity scaling is investigated in the framework of two-dimensional factorial moment methodology using the concept of Hurst exponent (H). Our investigation on experimental data of the compound multiplicity produced in ${}^{24}\mathrm{Mg}\text{−}\text{AgBr}$ interactions at $4.5A\text{GeV}$ shows that a better power-law behavior is exhibited when anisotropic scaling behavior is probed. This work reveals a clear evidence of self-affine compound multiplicity fluctuation pattern.

We expand on an interesting proposal (by Flambaum and Sushkov) to constrain parity-odd time-reversal noninvariant interactions with measurements of the energy dependence of parity-violating polarized neutron capture on unpolarized targets. We show that the perturbation in energy dependence due a $P$-odd $T$-odd interaction is obscured by terms due to electroweak effects. We evaluate for a practicable experiment the influence of these terms on the locations of zeros in a parity-violating asymmetry. Measurements which succeed in putting limits on these shifts of slightly more than the $1\text{meV}$ or so that we estimate them to be, would constrain the ratio of the rms value of compound nucleus matrix elements of any $P$-odd $T$-odd nucleon-nucleon interaction to the rms value of compound nucleus matrix elements of the $P$-odd nucleon-nucleon interaction to be less than of order of ${10}^{-2}$.

In response to recent papers which suggest that a level around $9.5\text{MeV}$ in excitation in ${}^{10}\mathrm{Be}$ nucleus is its first $J^{\pi }T=3^{+}1$ state, the experimental results are presented which undoubtedly prove that it is the fourth $2^{+}1$ state. Recent observations that the state at $7.00\text{MeV}$ in ${}^{10}\mathrm{B}$ decays also into $\alpha +{}^6\mathrm{Li}*\left(2.19\text{MeV}\right)$ are interpreted as a strong evidence that it is the third $3^{+}0$ state of this nucleus. The structure of these states is discussed.

The non-energy-weighted Gamow-Teller (GT) sum rule is satisfied in relativistic models, when all nuclear density-dependent terms, including Pauli blocking terms from nucleon-antinucleon excitations, are taken into account in the random phase approximation (RPA) correlation function. The no-sea approximation is equivalent to this approximation for the giant GT resonance state and satisfies the sum rule, but each of the total ${\beta }_{-}$ and ${\beta }_{+}$ strengths is different in the two approximations. It is also shown that the energy-weighted sum of the GT strengths for the ${\beta }_{-}$ and ${\beta }_{+}$ transitions in RPA is equal to the expectation value of the double commutator of the nuclear Hamiltonian with the GT operator, when the expectation value is calculated with the ground state in the mean field approximation. Since the present RPA neglects renormalization of the divergence, however, the energy-weighted strengths outside of the giant GT resonance region become negative. These facts are shown by calculating in an analytic way the GT strengths of nuclear matter.

Starting from the original collective Hamiltonian of Bohr and separating the $\beta$ and $\gamma$ variables as in the X(5) model of Iachello, an exactly soluble model corresponding to a harmonic oscillator potential in the $\beta$ variable [to be called $\mathrm{X}\left(5\right)\text{−}{\beta }^2$] is constructed. Furthermore, it is proved that the potentials of the form ${\beta }^{2n}$ (with $n$ being an integer) provide a “bridge” between this new $\mathrm{X}\left(5\right)\text{−}{\beta }^2$ model (occurring for $n=1$) and the X(5) model (corresponding to an infinite well potential in the $\beta$ variable, materialized for $n\to \infty$). Parameter-free (up to overall scale factors) predictions for spectra and $B\left(E2\right)$ transition rates are given for the potentials ${\beta }^2$, ${\beta }^4$, ${\beta }^6$, ${\beta }^8$, corresponding to $R_4=E\left(4\right)∕E\left(2\right)$ ratios of 2.646, 2.769, 2.824, and 2.852, respectively, compared to the $R_4$ ratios of 2.000 for U(5) and 2.904 for X(5). Hints about nuclei showing this behavior, as well as about potentials “bridging” the X(5) symmetry with SU(3) are briefly discussed.

Properties of hypernuclei ${}_{\Lambda \Lambda }{}^5\mathrm{H}$ and ${}_{\Lambda \Lambda }{}^5\mathrm{He}$ are studied in a two-channel approach with explicit treatment of coupling of channels ${}^3\mathit{Z}+\Lambda +\Lambda$ and $\alpha +\Xi$. Diagonal $\Lambda \Lambda$ and coupling $\Lambda \Lambda -\Xi N$ interactions are derived within $G$-matrix procedure from Nijmegen meson-exchange models. Bond energy $\Delta B_{\Lambda \Lambda }$ in ${}_{\Lambda \Lambda }{}^5\mathrm{He}$ exceeds significantly that in ${}_{\Lambda \Lambda }{}^5\mathrm{H}$ due to the channel coupling. Diagonal $\Xi \alpha$ attraction amplifies the effect, which is sensitive also to $\Lambda$-core interaction. The difference of the $\Delta B_{\Lambda \Lambda }$ values can be an unambiguous signature of the $\Lambda \Lambda -\Xi N$ coupling in $\Lambda \Lambda$ hypernuclei. However, improved knowledge of the hyperon-nucleus potentials is needed for quantitative extraction of the coupling strength from future data on the $\Lambda \Lambda$ hypernuclear binding energies.

The sextic oscillator is proposed as a two-parameter solvable $\gamma$-independent potential in the Bohr Hamiltonian. It is shown that closed analytical expressions can be derived for the energies and wave functions of the first few levels and for the strength of electric quadrupole transitions between them. Depending on the parameters this potential has a minimum at $\beta =0$ or at $\beta >0$, and might also have a local maximum before reaching its minimum. A comparison with the spectral properties of the infinite square well and the ${\beta }^4$ potential is presented, together with a brief analysis of the experimental spectrum and $E2$ transitions of the ${}^{134}\mathrm{Ba}$ nucleus.

In the framework of the symplectic extension of the interacting vector boson model a good description of the first excited positive and negative parity bands of the nuclei in the rare earth and the actinide region is achieved. The bands investigated in the model are extended to very high angular momenta as a result of their consideration as “yrast” bands with respect to the symplectic classification of the basis states. The analysis of the eigenvalues of the model Hamiltonian reveals the presence of an interaction between these bands. Due to this interaction the $\Delta L=1$ staggering effect between the energies of the states of two bands is also reproduced including the “beat” patterns.

A coupled-channels analysis has been carried out for fusion reactions in the system ${}^{60}\mathrm{Ni}+{}^{89}\mathrm{Y}$. It demonstrates that conventional coupled-channels calculations are unable to reproduce the unexpected steep falloff of the recently measured cross sections at extreme sub-barrier energies. Heavy-ion fusion excitation functions are also analyzed in terms of the $S$ factor, as this offers a pragmatic way to study fusion behavior in the energy regime of interest. It is shown that the steep falloff in cross section observed in several heavy-ion systems translates into a maximum of the $S$ factor. The energies where the maximum occurs can be parametrized with a simple empirical formula. The parametrization, which is derived here for rather stiff heavy-ion systems, provides an upper limit for reactions involving softer nuclei.