Novel measurements of $(\alpha ,\gamma )$ and $(\alpha$,$n$) reaction cross sections on the target nucleus ${}^{151}\mathrm{Eu}$, close to the reaction thresholds, support the choice of recently proposed parameters of the $\alpha$-particle optical model potential below the Coulomb barrier. A better understanding of the $\alpha$-particle optical potential at these energies leads to a statistical model analysis of additional partial cross sections that were measured but not considered within a former model analysis. On this basis we have tentatively assigned a modified $J^{\pi }=9^{-}$ spin and parity to the 22.7-h isomer in ${}^{154}\mathrm{Tb}$.

We study the effects of electron screening on nuclear reaction rates occurring during the big-bang nucleosynthesis epoch. The sensitivity of the predicted elemental abundances on electron screening is studied in detail. It is shown that electron screening does not produce noticeable results in the abundances unless the traditional Debye-Hückel model for the treatment of electron screening in stellar environments is enhanced by several orders of magnitude. This work rules out electron screening as a relevant ingredient to big-bang nucleosynthesis, confirming a previous study [see Itoh et al., Astrophys. J. 488, 507 (1997)] and ruling out exotic possibilities for the treatment of screening beyond the mean-field theoretical approach.

We study the effect of isospin degree of freedom on the balance energy ($E_{\mathrm{bal}}$) as well as its mass dependence throughout the mass range 48–270 for two sets of isobaric systems with $N/Z=1$ and 1.4 at different colliding geometries ranging from central to peripheral ones. Our findings reveal the dominance of Coulomb repulsion in isospin effects on $E_{\mathrm{bal}}$ as well as its mass dependence throughout the range of the colliding geometry. Our results also indicate that the effect of symmetry energy and nucleon-nucleon cross section on $E_{\mathrm{bal}}$ is uniform throughout the mass range and throughout the colliding geometry. We also present the counterbalancing of nucleon-nucleon collisions and mean field by reducing the Coulomb and the counterbalancing of Coulomb and mean field by removing the nucleon-nucleon collisions.

At the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC), for example, virtual photons produce many particles. At small impact parameters where the colliding nuclei make peripheral collisions, photon fluxes are very large and these are responsible for the multiple photonuclear interactions. Free pair productions, bound free pair productions, and nuclear Coulomb excitations are important examples of such interactions, and these processes play important roles in the beam luminosity at RHIC and LHC. Here we obtained the impact parameter dependence of bound free pair production cross sections and by using this probability we obtained bound free electron-positron pair production with nuclear breakup for heavy ion collisions at RHIC and LHC. We also compared our results to the other calculations.

The inclusive double Pomeron exchange cross section for heavy-quark pair production is calculated for nucleus-nucleus collisions at the Large Hadron Collider. The present estimate is based on hard diffractive factorization, corrected by absorptive corrections and nuclear effects. The theoretical uncertainties for nuclear collisions are investigated and a comparison to other approaches is presented. The production channels giving a similar final state configuration are discussed as well.

Ongoing experiments at JLAB investigate the nuclear transparency in exclusive $\rho {}^0(770)$ electroproduction off nuclei. In this work we present transport model predictions for the attenuation of $\rho {}^0$s in nuclei and for color transparency (CT) effects as observable at CLAS with a 5 $\mathrm{GeV}$ electron beam energy. A full event simulation developed here permits to study the impact of actual experimental acceptance conditions and kinematical cuts. The exclusive $(e,e^{\prime }\rho {}^0)$ cross section off nucleons is described by diffractive and color string breaking mechanisms extended toward the onset of the deep inelastic regime. Different hadronization and CT scenarios are compared. We show that a detailed analysis of the elementary cross section, nuclear effects, and experimental cuts is needed to reveal the early onset of $\rho$-CT at present JLAB energies.

The level structure of ${}^{114}\mathrm{Ru}$ has been investigated via the $\beta$ decay of very neutron-rich ${}^{114}\mathrm{Tc}$ by means of Penning-trap-assisted $\gamma$ spectroscopy. The deduced $\beta$-decay scheme suggests the existence of two $\beta$-decaying states in ${}^{114}\mathrm{Tc}$ with $I^{\pi }=1^{+}$ and $I⩾$ 4, with half-lives of $t_{1/2}(1^{+})=90(20)$ ms and $t_{1/2}(I⩾4)=100(20)$ ms, respectively. The $Q_{\beta }$ value, which covers a possible mixture of two states, has been determined to be $Q_{\beta }=11\hspace{0.5em}785(12)$ keV. The level energies in ${}^{114}\mathrm{Ru}$ are compared with theory by using a microscopic Bohr Hamiltonian approach with the Sly4 version of the Skyrme interaction.

We investigate properties of the generator coordinate method (GCM) on a collective basis of antisymmetrized quasicluster states to describe the cluster-shell competition in ${}^{20}\mathrm{Ne}$ and ${}^{24}\mathrm{Mg}$ owing to the spin-orbit interaction. By introducing a single additional parameter in the antisymmetrized-cluster basis function, a continuous transformation of the $\alpha$ cluster(s) into independent nucleons can be described. We apply this GCM trial wave function to study in detail the transition from cluster states $[{}^{16}\mathrm{O}+\mathrm{\alpha }]$ and $[{}^{16}\mathrm{O}+\mathrm{\alpha }+\mathrm{\alpha }]$ to shell-model states $[{}^{16}\mathrm{O}+4N]$ and $[{}^{16}\mathrm{O}+8N]$, respectively. An optimal value of the strength of the spin-orbit interaction is deduced by reproducing level spacing in ${}^{20}\mathrm{Ne}$. A possible connection to the group theoretical understanding of the cluster-shell configuration transition is also discussed.

We report on microscopic model calculations of the first step of direct pre-equilibrium ($n$,$x$$n$) emission in neutron interaction with ${}^{90}\mathrm{Zr}$ and ${}^{208}\mathrm{Pb}$ below 20 MeV. Our model is based on both an accurate description of the target excited states, provided by the self-consistent random-phase approximation (RPA) method implemented with the Gogny D1S force, and well-established in-medium two-body forces to represent the residual nucleon-nucleon interaction for the inelastic processes. Two goals have been achieved: The present microscopic approach provides a unified description of collective state excitations and the pre-equilibrium one-step process, and our reaction model reproduces the available data fairly well, without any parameter adjustment.

We study the shape of $\Lambda$ hypernuclei in the full ($\beta ,\gamma$) deformation plane, including both axially symmetric and triaxial quadrupole deformations. To this end, we use the constrained Skyrme Hartree-Fock $+$ BCS method on a three-dimensional Cartesian mesh. The potential energy surface is analyzed for carbon hypernuclei as well as for sd-shell hypernuclei such as ${}_{\Lambda }^{27,29}$Si and ${}_{\Lambda }^{25,27}$Mg. We show that the potential energy surfaces in the ($\beta ,\gamma$) plane of the hypernuclei and the corresponding core nuclei are similar to each other, although the addition of the $\Lambda$ hyperon makes the energy surface somewhat softer along the $\gamma$ direction.

One single line of universal (UNIV) curve for $\alpha$ decay and cluster radioactivities is obtained by plotting the sum of the decimal logarithm of the half-life and cluster preformation probability versus the decimal logarithm of the penetrability of external barrier. This fission-like theory is compared to the universal decay law (UDL) derived using $\alpha$-like $R$-matrix theory. The experimental data on heavy cluster decay in three groups of even-even, even-odd, and odd-even parent nuclei are reproduced with comparable accuracy by both types of universal curves, UNIV and UDL.

The yields of (anti)protons were measured by the NA49 Collaboration in centrality-selected Pb $+$ Pb collisions at $40A$ and $158A$ GeV. Particle identification was obtained in the laboratory momentum range from 5 to 63 GeV$/c$ by measuring the energy loss $dE/dx$ in the time projection chamber detector gas. The corresponding rapidity coverage extends 1.6 units from midrapidity into the forward hemisphere. Transverse-mass spectra, the rapidity dependences of the average transverse mass, and rapidity density distributions were studied as a function of collision centrality. The values of the average transverse mass as well as the midrapidity yields of protons normalized to the number of wounded nucleons show only modest centrality dependences. In contrast, the shape of the rapidity distribution changes significantly with collision centrality, especially at $40A$ GeV. The experimental results are compared to calculations of the hadron-string dynamics and the ultrarelativistic quantum-molecular-dynamics transport models.

A second $\gamma$-decaying high-spin isomeric state, with a half-life of 197(22)ns, has been identified in the $N=Z+2$ nuclide ${}^{94}\mathrm{Pd}$ as part of a stopped-beam Rare Isotope Spectroscopic INvestigation at GSI (RISING) experiment. Weisskopf estimates were used to establish a tentative spin/parity of ${19}^{-}$, corresponding to the maximum possible spin of a negative parity state in the restricted ($p$${}_{1/2}$, $g$${}_{9/2}$) model space of empirical shell model calculations. The reproduction of the $E3$ decay properties of the isomer required an extension of the model space to include the $f$${}_{5/2}$ and $p$${}_{3/2}$ orbitals using the CD-Bonn potential. This is the first time that such an extension has been required for a high-spin isomer in the vicinity of ${}^{100}\mathrm{Sn}$ and reveals the importance of such orbits for understanding the decay properties of high-spin isomers in this region. However, despite the need for the extended model space for the $E3$ decay, the dominant configuration for the ${19}^{-}$ state remains ($\pi$$p$${}_{1/2}^{-1}$$g$${}_{9/2}^{-3}$)${}_{11}$$\otimes$($\nu$$g$${}_{9/2}^{-2}$)${}_8$. The half-life of the known, ${14}^{+}$, isomer was remeasured and yielded a value of 499(13) ns.

We set up a framework in which in-medium charmonium properties are constrained by thermal lattice quantum chromodynamics and subsequently implemented into a thermal rate equation enabling the comparison with experimental data in heavy-ion collisions. Specifically, we evaluate phenomenological consequences for charmonium production originating from two different scenarios in which either the free or the internal energy are identified with the in-medium two-body potential between charm and anticharm quarks. These two scenarios represent $J/\psi$ “melting temperatures” of approximately $1.25T_c$ (“weak binding”) and $2T_c$ (“strong binding”), respectively. Within current uncertainties in dissociation rates and charm-quark momentum spectra, both scenarios can reproduce the centrality dependence of inclusive $J/\psi$ yields in nuclear collisions at the Super Proton Synchrotron (SPS) and the Relativistic Heavy-Ion Collider (RHIC) reasonably well. However, the “strong-binding” scenario associated with the internal energy as the potential tends to better reproduce current data on transverse momentum spectra at both SPS and RHIC.

We develop a theoretical finite nucleus framework for the evaluation of the coincidence number of pairs $N_{\mathit{nN}}$ and the asymmetry parameter $a_{\Lambda }$ in nonmesonic hypernuclear decay $\Lambda N\to \mathit{nN}$, and introduce the effect of final-state interactions. The primary nonmesonic weak hyperon-nucleon decay process is described through the independent-particle shell model. We work within the $2p1h$ subspace of final states, assuming a simple approach for finite nuclei based on the eikonal approximation. An optical potential including the nucleon-nucleus isoscalar and isovector interactions is introduced to take into account the minimum nuclear-medium effects. The calculated values for ${}_{\Lambda }^5\mathrm{He}$ and ${}_{\Lambda }^{12}\mathrm{C}$ show that our treatment of final-state interactions, even those considered as restricted to a subspace of states, brings the independent-particle model results closer to the experimental data.

A detailed $\gamma$-ray spectroscopy of the lowest two negative-parity bands in ${}^{156}\mathrm{Gd}$ has been performed in the framework of the TetraNuc collaboration. Relative $\gamma$-ray intensities of all transitions connecting these bands as well as the ones to the ground-state band are presented. Angular distribution analysis has been performed to determine the nature and the mixing ratio of one of the newly established transitions linking the two excited bands.

A study of the properties of the symmetry energy of nuclei is presented based on density-functional theory. Calculations for finite nuclei are given so that the study includes isospin-dependent surface symmetry considerations as well as isospin-independent surface effects. Calculations are done at both zero and nonzero temperature. It is shown that the surface symmetry energy term is the most sensitive to the temperature while the bulk energy term is the least sensitive. It is also shown that the temperature-dependence terms are insensitive to the force used and even more insensitive to the existence of neutron skin. Results for a symmetry energy with both volume and surface terms are compared with a symmetry energy with only volume terms along the line of $\beta$ stability. Differences of several MeV are shown over a good fraction of the total mass range in $A$. Also given are calculations for the bulk, surface and Coulomb terms.