Collective vibrations and rotations of atomic nuclei are investigated from the classical viewpoint within the geometric collective model. It is shown that the model, even in its truncated form, exhibits a very sophisticated interplay of regular and chaotic modes of motions. We quantify the proportion of regular and chaotic orbits in the phase space and analyze its sensitive dependence on the model control parameters, energy, and angular momentum. A quasi-regular region is observed at low excitation energies in a bounded domain of the control parameter on the deformed side of the shape phase diagram, and another one at higher energies around the transition between spherical and deformed shapes. We also demonstrate a tendency for overall suppression or enhancement of chaos with angular momentum, depending on the values of control parameters.

Energy and angular correlation distributions of the three fragments in ${}^6\mathrm{He}$ breakup on ${}^{208}\mathrm{Pb}$ at a collision energy of 240 MeV/nucleon are discussed within the microscopic four-body distorted wave model and compared with experimental data. The nuclear structure of the ground state and low-energy three-body continuum of ${}^6\mathrm{He}$ is calculated by the method of hyperspherical harmonics within the three-body cluster model. Reflections of the fundamental permutation symmetry of the halo neutrons in angular and energy correlations are pointed out. The calculations describe the experimental data for fragment correlations near breakup threshold rather well, and the physics is contained in a few elementary modes; but with increasing excitation energy of ${}^6\mathrm{He}$, some striking deviations from experimental distributions are encountered. Possible reasons for this are discussed.

The role of 5-quark components in the pion and electromagnetic decays and transition form factors of the $N(1440)$ resonance is explored. The $\mathit{qqqq}\overline{q}$ components, where the 4-quark subsystem has the flavor-spin symmetries $[4]{}_{\mathrm{FS}}[22]{}_F[22]{}_S$ and $[4]{}_{\mathrm{FS}}[31]{}_F[31]{}_S$, which are expected to have the lowest energy of all $\mathit{qqqq}\overline{q}$ configurations, are considered in detail with a nonrelativistic quark model. The matrix elements between the 5-quark components of the $N(1440)$ and the nucleon, $\mathit{qqqq}\overline{q}\to \mathit{qqqq}\overline{q}$, play a minor role in these decays, whereas the transition matrix elements $\mathit{qqqq}\overline{q}\to \mathit{qqq}$ and $\mathit{qqq}\to \mathit{qqqq}\overline{q}$ that involve quark antiquark annihilation are very significant. Both for electromagnetic and strong decays the change from the valence quark model value is dominated by the confinement triggered $q\overline{q}$ annihilation transitions. In the case of pion decay the calculated decay width is enhanced substantially both by the direct $q\overline{q}\to \pi$ and also by the confinement triggered $q\overline{q}\to \pi$ transitions. Agreement with the empirical value for the pion decay width may be reached with a $~30\%\hspace{1em}\mathit{qqqq}\overline{q}$ component in the $N(1440)$.

A novel concept for the nuclear symmetry energy (NSE) is corroborated by large scale calculations. The paper firmly demonstrates that within the local density approximation, the value of the NSE coefficient, $a_{\mathrm{sym}}(A)$, depends on two basic ingredients: the mean-level spacing, $\varepsilon (A)$, and the effective strength of the isovector mean-potential, $\kappa (A)$. Surprisingly, our results reveal that these two basic ingredients of $a_{\mathrm{sym}}$ are almost equal after rescaling them linearly by the isoscalar and the isovector effective masses, respectively. This result points towards a hidden and hitherto unresolved fundamental property of the effective nuclear interaction. In addition, our analysis yields naturally the ratio of the surface-to-volume contributions to $a_{\mathrm{sym}}$ with a value of ∼1.6, consistent with hydrodynamical estimates for the static dipole polarizability as well as the neutron-skin. Although the present study is restricted to energy density functionals obtained from Skyrme forces the method is general and can easily be applied to more general local energy density functionals and nonnuclear bifermionic systems.

The interference effects among $J^{\pi }=3/2^{+}$ resonances in the ${}^{18}\mathrm{F}+p$ system have not been previously measured. $R$-matrix calculations show that the cross sections above the $E_{c.m.}=665$ keV resonance are sensitive to the interference between the $E_{c.m.}=8$, 38, and 665 keV resonances. An excitation function for the ${}^1\mathrm{H}$(${}^{18}\mathrm{F}$,α)${}^{15}\mathrm{O}$ reaction has been measured in the energy range of $E_{c.m.}=663\text{−}877$ keV using radioactive ${}^{18}\mathrm{F}$ beams at the Holifield Radioactive Ion Beam Facility (HRIBF). By comparing the observed cross sections with the $R$-matrix calculations, we provide the first experimental constraints on the interference. Upper limits on proton widths (${\Gamma }_p$) of the $E_{c.m.}=827$ and 842 keV resonances have been set as well.

The neutron-neutron ($\mathit{nn}$) final-state interaction has been investigated in the $n+d\to p+2n$ reaction in kinematically incomplete geometry at $E_n=17.4$ MeV, detecting the protons emitted around zero degrees. Absolute cross-section data for the neutron-deuteron breakup reaction were obtained via ($n,d)$ elastic scattering, which was measured simultaneously. The data were analyzed by means of detailed Monte Carlo simulations based on rigorous three-body calculations using CD-Bonn and two other high-quality potentials for the nucleon-nucleon interaction. The breakup spectrum is described very well on an absolute scale over the entire energy range investigated. The value of the $\mathit{nn}$ scattering length deduced from the cross section in the FSI peak is $a_{\mathit{nn}}=-16.5\pm 0.9$ fm, where the error indicates the combined statistical and systematic uncertainty.

The bound single-particle states for neutrons are calculated from our previous global spherical optical model potential containing dispersive terms and a local energy approximation. Reasonably good results are obtained for the single-particle states as well as for the neutron binding energies. This constitutes a further test of our potential.

The elliptic flow for $Z\le 2$ particles in heavy ion collisions at energies from several tens to several hundreds MeV per nucleon is investigated by means of a transport model, i.e., a new version of the improved quantum molecular dynamics model (ImQMD05). This model employs a complete Skyrme potential energy density functional. The influence of different effective interactions and medium corrections of nucleon-nucleon cross sections on the elliptic flow are studied. Our results show that a soft nuclear equation of state and incident energy dependent in-medium nucleon-nucleon cross sections are required to describe the excitation function of the elliptic flow at intermediate energies. The size dependence of transition energies for the elliptic flow at intermediate energies is also studied. The system size dependence of transition energies fits a power of system size with an exponent of 0.223.

A variety of physical phenomena can lead to viscous effects. Several sources of shear and bulk viscosity are reviewed with an emphasis on the bulk viscosity associated with chiral restoration and with chemical nonequilibrium. We show that in linear response approximation and in a mean field treatment of the limiting case of a second-order phase transition, the bulk viscosity peaks in a singularity at the critical point.

We carried out the three-dimensional cranking calculations for osmium ${}^{182}\mathrm{Os}$ within the Hartree-Fock-Bogoliubov framework. It turned out that the state in the $g$-band is stable (unstable) with respect to the tilt angle of the cranking axis when the angular momentum is below (above) a critical value. However, the states in the $s$-band with the angular momentum below $30\hslash$ are unstable everywhere along the band. In our model calculations, the wobbling motion does not exist on top of the $s$-band state characterized by the component of two aligned particles.

The candidate chiral doublet bands recently observed in ${}^{126}\mathrm{Cs}$ have been extended to higher spins, several new linking transitions between the two partner members of the chiral doublet bands are observed, and γ-intensities related to the chiral doublet bands are presented by analyzing the $\gamma$-$\gamma$ coincidence data collected earlier at the NORDBALL through the ${}^{116}\mathrm{Cd}$(${}^{14}\mathrm{N}$, $4n$)${}^{126}\mathrm{Cs}$ reaction at a beam energy of 65 MeV. The intraband $B(M1)/B(E2)$ and interband $B(M1){}_{\mathrm{in}}/B(M1){}_{\mathrm{out}}$ ratios and the energy staggering parameter, S(I), have been deduced for these doublet bands. The results are found to be consistent with the chiral interpretation for the two structures. Furthermore, the observation of chiral doublet bands in ${}^{126}\mathrm{Cs}$ together with those in ${}^{124}\mathrm{Cs}$, ${}^{128}\mathrm{Cs}$, ${}^{130}\mathrm{Cs}$, and ${}^{132}\mathrm{Cs}$ also indicates that the chiral conditions do not change rapidly with decreasing neutron number in these odd-odd Cesium isotopes.

The yrast states in the light platinum isotopes ${}^{169-173}\mathrm{Pt}$ have been investigated in a recoil-decay tagging experiment using the JUROGAM γ-ray spectrometer in conjunction with the RITU gas-filled recoil separator and the GREAT tagging spectrometer. Gamma-ray transitions have been established for the first time in the odd-$N$ isotopes, ${}^{169}\mathrm{Pt}$ and ${}^{173}\mathrm{Pt}$, and the yrast sequences in ${}^{170}\mathrm{Pt}$ and ${}^{172}\mathrm{Pt}$ have been extended. We discuss the possibility that the weakly deformed yrast structures of ${}^{170}\mathrm{Pt}$, ${}^{172}\mathrm{Pt}$, and ${}^{173}\mathrm{Pt}$ are crossed by a deformed intruder configuration at spin $~8\hslash$.

The two-body currents for $s$-wave pion photoproduction on the $\mathit{NN}$ system are derived to $\mathcal{O}(Q^4)$ in chiral perturbation theory. For the interesting case of ${}^3{S}_1\leftrightarrow {}^1{S}_0$ transitions, we show that an axial isovector two-nucleon contact term connects the short-distance physics of pion photoproduction to pion production and several important electroweak reactions. We also find that the standard chiral Lagrangian gives a $\gamma \pi \pi \mathit{NN}$ vertex that has not been explicitly mentioned in previous literature. The corresponding Feynman rule is presented here and some processes where it should be important are briefly discussed.

A static microscopic study of potential-energy surfaces within the Skyrme-Hartree-Fock-plus-BCS model is carried out for the ${}^{256}\mathrm{Fm}$ and ${}^{258}\mathrm{Fm}$ isotopes with the goal of deducing some properties of spontaneous fission. The calculated fission modes are found to be in agreement with the experimentally observed asymmetric-to-symmetric transition in the fragment-mass distributions and with the high- and low-total-kinetic-energy modes experimentally observed in ${}^{258}\mathrm{Fm}$. Most of the results are similar to those obtained in macroscopic-microscopic models as well as in recent Hartree-Fock-Bogolyubov calculations with the Gogny interaction, with a few differences in their interpretations. In particular an alternative explanation is proposed for the low-energy fission mode of ${}^{258}\mathrm{Fm}$.

In this work we derive a formalism to incorporate asymmetry and temperature effects in the Brown-Rho (BR) scaled Lagrangian model in a mean field theory. The Lagrangian density discussed in this work requires less parameters than the usual models with density dependent couplings. We also present the formalism with the inclusion of the eight lightest baryons, two lightest leptons, β equilibrium and charge neutrality in order to apply the BR scaled model to the study of neutron stars. The results are again compared with the ones obtained from another density dependent parametrization model. The role played by the rearrangement term at $T=0$ for nuclear or neutron star matter and at finite temperature is investigated. The BR scaled model is shown to be a good tool in studies involving density dependent effective masses and in astrophysics applications.

We present a full $\mathit{pf}$-shell spectroscopy of the low-lying states of ${}^{56}\mathrm{Ni}$ using the GXPF1A interaction. Both the ground-state band and the first deformed band, as well as the transition probabilities, compare favorably with the experimental data. We analyze the significance of the contributions of $N$-particle $N$-hole configurations to the full model calculations, similarly to the analysis obtained for ${}^{28}\mathrm{Si}$ in the $\mathit{sd}$ shell some 20 years ago.

For negative-parity mirror states in ${}^{17}\mathrm{N}$ and ${}^{17}\mathrm{Ne}$, we computed Coulomb energies in three different models. Results, along with spectroscopic factors for ${}^{18}\mathrm{Na}$ (ground state) to various states in ${}^{17}\mathrm{Ne}$, are used to calculate the ${}^{18}\mathrm{Na}$ mass excess.

Prescission neutron, proton, and α-particle multiplicities for the reaction ${}^{28}\mathrm{Si}$+${}^{175}\mathrm{Lu}$ at 159 MeV were measured simultaneously. The multiplicity data were analyzed using deformation dependent particle transmission coefficients, binding energies, and level densities to extract fission time scales and the mean deformation of the saddle-to-scission emitter. The neutron and charged particle data could be explained consistently, a better fit being obtained by considering the emission of neutrons to be favored toward larger deformation as compared to charged particles. The total fission time scale is deduced as $36\text{−}41\times {10}^{-21}$s.

The pion source as seen through Hanbuary-Brown–Twiss (HBT) correlations at BNL Relativistic Heavy Ion Collider (RHIC) energies is investigated within the UrQMD approach. We find that the calculated transverse momentum, centrality, and system size dependence of the Pratt-HBT radii $R_L$ and $R_S$ are reasonably well in line with experimental data. The predicted $R_O$ values in central heavy ion collisions are larger as compared to experimental data. The corresponding quantity $\sqrt{R_O^2-R_S^2}$ of the pion emission source is somewhat larger than experimental estimates.

The ${}^{30}\mathrm{P}$($p,\gamma$)${}^{31}\mathrm{S}$ reaction rate is expected to be the principal determinant for the endpoint of nucleosynthesis in classical novae. To date, the reaction rate has only been estimated through Hauser-Feschbach calculations and is unmeasured experimentally. This paper aims to remedy this situation. Excited states in ${}^{31}\mathrm{S}$ and ${}^{31}\mathrm{P}$ were populated in the ${}^{12}\mathrm{C}$(${}^{20}\mathrm{Ne}$,$n$) and ${}^{12}\mathrm{C}$(${}^{20}\mathrm{Ne}$,$p$) reactions, respectively, at a beam energy of 32 MeV, and their resulting $\gamma$decay was detected with the Gammasphere array. Around half the relevant proton unbound states in ${}^{31}\mathrm{S}$ corresponding to the Gamow window for the ${}^{30}\mathrm{P}$($p,\gamma$)${}^{31}\mathrm{S}$ reaction were identified. The properties of the unobserved states were inferred from mirror symmetry using our extended data on ${}^{31}\mathrm{P}$. The implications of this new spectroscopic information for the ${}^{30}\mathrm{P}$($p,\gamma$)${}^{31}\mathrm{S}$ reaction rate are considered and recommendations for future work with radioactive beams are discussed.