Analytical formulas are presented which provide quantitative estimates for the suppression of the anticipated back-to-back particle–antiparticle correlations in high-energy nuclear collisions, due to both the finite duration of the transition dynamics and the continuous freeze-out. They show that the effect is unlikely to be observed.

In $\mathit{pp}$ scattering at 900 GeV, large numbers of elementary scatterings will contribute significantly, and the corresponding high-multiplicity events will be of particular interest. Elementary scatterings are parton ladders, identified with color flux tubes. In high-multiplicity events, many of these flux tubes are produced in the same space region, creating high-energy densities. We argue that there are good reasons to employ the successful procedure used for heavy-ion collisions: Matter is assumed to thermalize quickly, such that the energy from the flux tubes can be taken as an initial condition for a hydrodynamic expansion. This scenario gets spectacular support from very recent results on Bose-Einstein correlations in $\mathit{pp}$ scattering at 900 GeV at LHC.

The possibility to draw links between the isospin properties of nuclei and the structure of compact stars is a stimulating perspective. In order to pursue this objective on a sound basis, the correlations from which such links can be deduced have to be carefully checked against model dependence. Using a variety of nuclear effective models and a microscopic approach, we study the relation between the predictions of a given model and those of a Taylor density development of the corresponding equation of state: this establishes to what extent a limited set of phenomenological constraints can determine the core-crust transition properties. From a correlation analysis, we show that (a) the transition density ${\rho }_t$ is mainly correlated with the symmetry energy slope $L$, (b) the proton fraction $Y_{p,t}$ with the symmetry energy and symmetry energy slope $(J,L)$ defined at saturation density, or, even better, with the same quantities defined at $\rho =0.1$ fm${}^{-3}$, and (c) the transition pressure $P_t$ with the symmetry energy slope and curvature $(L,K_{\mathrm{sym}})$ defined at $\rho =0.1$ fm${}^{-3}$.

Cross sections are calculated for single and double photon exchange in ultraperipheral Pb$+$Pb collisions at the CERN Large Hadron Collider. The particle production is simulated with the DPMJET event generator. Large cross sections are found for particle production around midrapidity, making these processes an important background to hadronic nuclear interactions at both the trigger and analysis levels.

Analytical expressions for spectra and wave functions are derived for a Bohr Hamiltonian, describing the collective motion of deformed nuclei, in which the mass is allowed to depend on the nuclear deformation. Solutions are obtained for separable potentials consisting of a Davidson potential in the $\beta$ variable, in the cases of $\gamma$-unstable nuclei, axially symmetric prolate deformed nuclei, and triaxial nuclei, implementing the usual approximations in each case. The solution, called the deformation-dependent mass (DDM) Davidson model, is achieved by using techniques of supersymmetric quantum mechanics (SUSYQM), involving a deformed shape invariance condition. Spectra and $B(E2)$ transition rates are compared to experimental data. The dependence of the mass on the deformation, dictated by SUSYQM for the potential used, reduces the rate of increase of the moment of inertia with deformation, removing a main drawback of the model.

We study extrapolation approaches to evaluate energies of low-lying states for nuclei in the $\mathit{sd}$ and $\mathit{pf}$ shells, by sorting the diagonal matrix elements of the nuclear shell-model Hamiltonian. We introduce an extrapolation method with perturbation and apply our new method to predict both low-lying state energies and $E2$ transition rates between low-lying states. Our predicted results arrive at an accuracy of the root-mean-squared deviations $~40$–60 keV for low-lying states of these nuclei.

An extended version of antisymmetrized molecular dynamics was developed to study the structure of $p$-$\mathit{sd}$ shell hypernuclei. By using an effective $\Lambda$N interaction, we investigated the energy curves of ${}_{\Lambda }^9$Be, ${}_{\Lambda }^{13}$C, and ${}^{20,}{}_{\hspace{0.5em}\Lambda }^{21}$Ne as a function of nuclear quadrupole deformation. The changes to nuclear deformation caused by $\Lambda$ particles are discussed. We found that $\Lambda$ in the $p$ wave enhances nuclear deformation, while that in the $s$ wave reduces it. This effect is most prominent in ${}_{\hspace{0.5em}\Lambda }^{13}$C. The possibility of parity inversion in ${}_{\hspace{0.5em}\Lambda }^{20}$Ne is also examined.

The problem of production and study of heavy neutron-rich nuclei has been intensively discussed during recent years. Many reasons arouse a great interest in this problem. The present limits of the upper part of the nuclear map are very close to the $\beta$ stability line while the unexplored area of heavy neutron-rich nuclides (also those located along the neutron closed shell $N=126$ to the right-hand side of the stability line) is extremely important for nuclear astrophysic investigations and, in particular, for the understanding of the $r$ process of astrophysical nucleogenesis. For elements with $Z>100$ only neutron deficient isotopes (located to the left of the stability line) have been synthesized so far. The “northeast” area of the nuclear map can be reached neither in fusion–fission reactions nor in fragmentation processes widely used nowadays for the production of new nuclei. Multinucleon transfer processes in near barrier collisions of heavy (and very heavy, U-like) ions seem to be the only reaction mechanism allowing us to produce and explore neutron-rich heavy nuclei including those located at the superheavy island of stability. In this paper several transfer reactions for different projectile–target combinations are studied in detail. Besides the predictions for the cross sections of such processes, we also analyze the angular and energy distributions of primary and survived reaction products in the laboratory frame. These results, as well as predicted excitation functions for the yields of neutron-rich superheavy isotopes, might be useful for the design of appropriate experimental equipment and for carrying out experiments of such kind.

Electron capture rates in Ni isotopes are studied in stellar environments, that is, at high densities and high temperatures during the core-collapse and postbounce explosive nucleosynthesis in supernovae. Reaction rates in ${}^{58}\mathrm{Ni}$ and ${}^{60}\mathrm{Ni}$, as well as in ${}^{56}\mathrm{Ni}$, ${}^{62}\mathrm{Ni}$, and ${}^{64}\mathrm{Ni}$, are evaluated by shell-model calculations with the use of a new shell-model Hamiltonian in the $\mathit{fp}$ shell, GXPF1J. While the previous shell-model calculations failed to reproduce the measured peaks of Gamow-Teller strength in ${}^{58}\mathrm{Ni}$ and ${}^{60}\mathrm{Ni}$, the present new Hamiltonian is found to reproduce them very well, as well as the capture rates obtained from the observed strengths. Strengths and energies of the Gamow-Teller transitions in ${}^{56}\mathrm{Ni}$, ${}^{62}\mathrm{Ni}$, and ${}^{64}\mathrm{Ni}$ are also found to be consistent with the observations.

Calculation of the thermonuclear ${}^{30}\mathrm{P}$($p$,γ)${}^{31}\mathrm{S}$ rate in oxygen-neon nova explosions depends critically upon nuclear structure information for states within ∼600 keV of the ${}^{30}\mathrm{P}+p$ threshold in ${}^{31}\mathrm{S}$. We have studied the ${}^{31}\mathrm{P}$(${}^3\mathrm{He},t$)${}^{31}\mathrm{S}$ reaction at 25 MeV using a high-resolution quadrupole-dipole-dipole-dipole magnetic spectrograph. Tritons corresponding to the states $E_x$(${}^{31}\mathrm{S}$) ∼ 6.1–7.1 MeV were observed at ten angles between ${\theta }_{\mathrm{lab}}$ $=$ 10° and 55°. States that were only tentatively identified in past studies have been observed unambiguously. For the first time, we have measured and analyzed angular distributions of the ${}^{31}\mathrm{P}$(${}^3\mathrm{He},t$)${}^{31}\mathrm{S}$ reaction. We present, also for the first time, a consistent set of experimental spin constraints for all except one of the critical proton-threshold states in ${}^{31}\mathrm{S}$. Hydrodynamic nova simulations have been calculated in order to assess the impact on nova nucleosynthesis of remaining uncertainties in $J^{\pi }$ values of ${}^{31}\mathrm{S}$ states and the unknown relevant proton spectroscopic factors. We find that these uncertainties may lead to a factor of up to 20 variation in the ${}^{30}\mathrm{P}$($p$,γ)${}^{31}\mathrm{S}$ rate over typical nova peak temperatures, which may then lead to a factor of up to 4 variation in the nova yields of Si-Ar isotopes.

We introduce a self-consistent microscopic theoretical framework for modeling the process of electron capture on nuclei in stellar environment, based on relativistic energy density functionals. The finite-temperature relativistic mean-field model is used to calculate the single-nucleon basis and the occupation factors in a target nucleus, and $J^{\pi }=0^{\pm }$, $1^{\pm }$, and $2^{\pm }$ charge-exchange transitions are described by the self-consistent finite-temperature relativistic random-phase approximation. Cross sections and rates are calculated for electron capture on ${}^{54,56}\mathrm{Fe}$ and ${}^{76,78}\mathrm{Ge}$ in stellar environment, and results compared with predictions of similar and complementary model calculations.

The $\beta$-delayed $\gamma$ and proton decay of ${}^{23}\mathrm{Al}$ has been studied with an alternative detector setup at the focal plane of the momentum achromat recoil separator MARS at Texas A&M University. We could detect protons down to an energy of 200 keV and determine the corresponding branching ratios. Contrary to results of previous $\beta$-decay studies, no strong proton intensity from the decay of the isobaric analog state (IAS) of the ${}^{23}\mathrm{Al}$ ground state at $E_x=7803$ keV in ${}^{23}\mathrm{Mg}$ was observed. Instead we assign the observed low-energy group $E_{p,\mathrm{c}.\mathrm{m}.}=206$ keV to the decay from a state that is 16 keV below the IAS. We measured both proton and gamma branches from the decay of this state at $E_x=7787$ keV in ${}^{23}\mathrm{Mg}$, which is a very rare case in the literature. Combining our data with its measured lifetime, we determine its resonance strength to be $\omega \gamma ={1.4}_{-0.4}^{+0.5}$ meV. The value is in agreement with older direct measurements, but disagrees with a recent direct measurement. This state is the most important resonance for the radiative proton capture ${}^{22}\mathrm{Na}$($p,\gamma$)${}^{23}\mathrm{Mg}$ in some astrophysical environments, such as novae.

We use results from long-time core-collapse supernovae simulations to investigate the impact of the late time evolution of the ejecta and of the nuclear physics input on the calculated $r$-process abundances. Based on the latest hydrodynamical simulations, heavy $r$-process elements cannot be synthesized in the neutrino-driven winds that follow the supernova explosion. However, by artificially increasing the wind entropy, elements up to $A=195$ can be made. In this way one can reproduce the typical behavior of high-entropy ejecta where the $r$ process is expected to occur. We identify which nuclear physics input is more important depending on the dynamical evolution of the ejecta. When the evolution proceeds at high temperatures (hot $r$ process), an $(n,\gamma )\rightleftarrows (\gamma ,n)$ equilibrium is reached, while at low temperatures (cold $r$ process) there is a competition between neutron captures and beta decays. In the first phase of the $r$ process, while enough neutrons are available, the most relevant nuclear physics inputs are the nuclear masses for the hot $r$ process and the neutron capture and beta-decay rates for the cold $r$ process. At the end of this phase, the abundances follow a steady beta flow for the hot $r$ process and a steady flow of neutron captures and beta decays for the cold $r$ process. After neutrons are almost exhausted, matter decays to stability and our results show that in both cases neutron captures are key for determining the final abundances, the position of the $r$-process peaks, and the formation of the rare-earth peak. In all the cases studied, we find that the freeze-out occurs in a time scale of several seconds.

The recently observed large cross sections for the Coulomb dissociation of ${}^{31}\mathrm{Ne}$ nucleus indicate that this nucleus takes a halo structure in the ground state. We analyze these experimental data using the particle-rotor model that takes into account the rotational excitation of the core nucleus ${}^{30}\mathrm{Ne}$. We show that the experimental data can be well reproduced when the quadrupole deformation parameter of ${}^{30}\mathrm{Ne}$ is around ${\beta }_2=0.2~0.3$, at which the ground state takes the spin and parity of $I^{\pi }=3/2^{-}$. This state corresponds to the Nilsson level [330 1/2] in the adiabatic limit of the particle-rotor model. On the other hand, the state corresponding to the Nilsson level [321 3/2] with ${\beta }_2~0.55$ can be excluded when the finite excitation energy of the core is taken into account, even though this configuration is a candidate for the ground state of ${}^{31}\mathrm{Ne}$ in the Nilsson model analysis. We discuss briefly also a possibility of the $I^{\pi }=1/2^{+}$ configuration with ${\beta }_2~1$ and ${\beta }_2~-0.4$.

The updated ultrarelativistic quantum molecular dynamics (UrQMD) model, a microscopic transport model, is used to study the directed and elliptic collective flows and the nuclear stopping in Au$+$Au collisions at incident energies covered by INDRA and lower-energy FOPI experiments. It is seen clearly that these observables are sensitive to both the potential terms (including isoscalar and isovector parts as well as the momentum dependent term) in the equation of state (EoS) and the collision term [including the Pauli blocking and the medium-modified nucleon-nucleon elastic cross section (NNECS)]. The momentum modifications of both, the mean-field potentials and the density dependent NNECS, are found to affect the collectivity of heavy-ion collisions. At INDRA energies ($⩽$$150$ MeV/nucleon) the dynamic transport with a soft EoS with momentum dependence and with the momentum-modified density-dependent NNECS describes the directed flow exhibited by hydrogen isotopes ($Z=1$) emitted at midrapidity fairly well.

Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au$+$Au collisions compared to expectations from binary-scaled $p$$+$$p$ collisions. These measurements indicate that charm and bottom quarks interact with the hot dense matter produced in heavy-ion collisions much more than expected. Here we extend these studies to two-particle correlations where one particle is an electron from the decay of a heavy-flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interactions between heavy quarks and the matter, such as whether the modification of the away-side-jet shape seen in hadron-hadron correlations is present when the trigger particle is from heavy-meson decay and whether the overall level of away-side-jet suppression is consistent. We statistically subtract correlations of electrons arising from background sources from the inclusive electron-hadron correlations and obtain two-particle azimuthal correlations at $\sqrt{s_{\mathit{NN}}}=200$ GeV between electrons from heavy-flavor decay with charged hadrons in $p$$+$$p$ and also first results in Au$+$Au collisions. We find the away-side-jet shape and yield to be modified in Au$+$Au collisions compared to $p$$+$$p$ collisions.

Anisotropic flow measurements in heavy-ion collisions provide important information on the properties of hot and dense matter. These measurements are based on analysis of azimuthal correlations and might be biased by contributions from correlations that are not related to the initial geometry, so-called nonflow. To improve anisotropic flow measurements, advanced methods based on multiparticle correlations (cumulants) have been developed to suppress nonflow contribution. These multiparticle correlations can be calculated by looping over all possible multiplets, however, this quickly becomes prohibitively CPU intensive. Therefore, the most used technique for cumulant calculations is based on generating functions. This method involves approximations, and has its own biases, which complicates the interpretation of the results. In this paper we present a new exact method for direct calculations of multiparticle cumulants using moments of the flow vectors.

We propose a novel formulation of the interacting boson model (IBM) for rotational nuclei with axially symmetric, strong deformation. The intrinsic structure represented by the potential-energy surface (PES) of a given multinucleon system has a certain similarity to that of the corresponding multiboson system. Based on this feature, one can derive an appropriate boson Hamiltonian, as already reported. This prescription, however, has a major difficulty in the rotational spectra of strongly deformed nuclei: the bosonic moment of inertia is significantly smaller than the corresponding nucleonic one. We present that this difficulty originates in the difference between the rotational response of a nucleon system and that of the corresponding boson system, and could arise even if the PESs of the two systems were identical. We further suggest that the problem can be solved by implementing the $\mathrm{L̂}·\mathrm{L̂}$ term into the IBM Hamiltonian, with the coupling constant derived from the cranking approach of Skyrme mean-field models. The validity of the method is confirmed for rare-earth and actinoid nuclei, as their experimental rotational yrast bands are reproduced nicely.

The transient-field-perturbed angular correlation technique was used with Coulomb excitation in inverse kinematics to perform a systematic measurement of the $g$ factors of the first excited $2_1^{+}$ states in the stable even-$A$ isotopes ${}^{96-104}\mathrm{Ru}$. The measurements have been made relative to one another under matched kinematic conditions and include a measurement of $g(2_1^{+})=+0.47(3)$ in ${}^{96}\mathrm{Ru}$.

High-spin states in ${}^{71}\mathrm{As}$ were studied using the ${}^{54}\mathrm{Fe}$$({}^{23}$Na,$\alpha 2p)$ reaction at 80 MeV. Prompt $\gamma$-$\gamma$ coincidences were measured using the Florida State University Compton-suppressed Ge array consisting of three clover detectors and seven single-crystal detectors. The existing high-spin level scheme has been verified, and 21 new transitions have been added based on an investigation of weak $\gamma$-ray coincidence relations and relative $\gamma$-ray intensities. Lifetimes of 16 excited states were measured using the Doppler-shift attenuation method applied to the experimental line shapes of decays in all of the known rotational bands. The $B(E2)$ strengths inferred from the lifetimes indicate that moderate to high collective behavior persists to the highest observed spins in the lowest positive- and negative-parity bands, in qualitative agreement with projected shell-model calculations. The band suggested to be based on the $\pi f_{7/2}$ orbital shows a similar degree of collectivity within the same spin range, with $B(E2)$ values in good agreement with those predicted by the projected shell model assuming a constant prolate deformation of ${\epsilon }_2=+0.27$. The experimental $Q_t$ values in this band are somewhat smaller than predicted by cranked Woods-Saxon calculations.