The structure of the $N=20$ nucleus ${}^{37}\mathrm{Cl}$ has been investigated in the ${}^{24}\mathrm{Mg}({}^{16}\mathrm{O},3p)$ reaction with a 70 MeV ${}^{16}\mathrm{O}$ beam. A complex level scheme extended up to an excitation energy of 17 MeV and spins ($29/2^{+}$) and ($27/2^{-}$) on positive and negative parity, respectively, has been established. Lifetimes for the new states have been investigated by the Doppler shift attenuation method. Large-scale shell-model calculations have been performed in a valence space involving orbitals in the $\mathit{sd}$ and $\mathit{fp}$ shells using the $\mathit{sdfp}$ and SDPF-M effective interactions. The comparison with the experimental data indicates the need for slight changes of the $\mathit{sd}\text{−}\mathit{fp}$ energy gaps produced by these interactions.

The nonresonant component of radiative neutron capture reactions is parametrized at low energies by a polynomial of second degree. The potential model is first used to reproduce experimental data below 1 MeV with the help of spectroscopic factors. The fits are found sensitive to the scattering length of the initial $s$ or $p$ waves. The coefficients of a Taylor expansion are then calculated by resolution of the Schrödinger equation and its energy derivatives at energy zero. Such theory-guided parametrizations are derived for neutron capture by ${}^7\mathrm{Li}$, ${}^{12}\mathrm{C}$, ${}^{14}\mathrm{C}$, ${}^{16}\mathrm{O}$, and ${}^{18}\mathrm{O}$. When the capture proceeds from the $s$ wave to a weakly bound state, a Padé-like parametrization better approximates the potential-model results.

The transverse momentum $(p_t)$ dependence, the centrality dependence, and the rapidity dependence of the elliptic flow of thermal photons in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{\mathit{NN}}}=200$ GeV are predicted on the basis of a three-dimensional ideal hydrodynamic description of the hot and dense matter. The elliptic flow parameter $v_2$, i.e., the second Fourier coefficient of azimuthal distribution, of thermal photons first increases with $p_t$ and then decreases for $p_t>2$ GeV/$c$, because of the weak transverse flow at the early stage. The $p_t$-integrated $v_2$ first increases with centrality, reaches a maximum at about 50% centrality, and then decreases. The rapidity dependence of the elliptic flow $v_2(y)$ of direct photons (mainly thermal photons) is very sensitive to the initial energy density distribution along the longitudinal direction, which provides a useful tool to extract the realistic initial condition from measurements.

The present study focuses on the superscaling behavior of electron-nucleus cross sections in the region lying above the quasielastic peak, especially the region dominated by electroexcitation of the $\Delta$. Non-quasielastic cross sections are obtained from all available high-quality data for ${}^{12}\mathrm{C}$ by subtracting effective quasielastic cross sections based on the superscaling hypothesis. These residuals are then compared with results obtained within a scaling-based extension of the relativistic Fermi gas model, including an investigation of violations of scaling of the first kind in the region above the quasielastic peak. A way to potentially isolate effects related to meson-exchange currents by subtracting both impulsive quasielastic and impulsive inelastic contributions from the experimental cross sections is also presented.

The level structure of ${}^{25}\mathrm{Al}$ has been studied at the ORNL Holifield Radioactive Ion Beam Facility by measuring the angular and energy distributions of $\alpha$ particles from the ${}^{28}\mathrm{Si}(p,\alpha ){}^{25}\mathrm{Al}$ reaction. Proton beams $(~10\hspace{0.5em}\mathrm{nA})$ at laboratory energies of 40 and 42 MeV were generated by the 25 MV tandem accelerator and bombarded a natural silicon target $(50\hspace{0.5em}\mu \mathrm{g}/{\mathrm{cm}}^2)$. Seventeen levels were observed and spins for several were constrained through a distorted-wave Born approximation analysis of the angular distributions.

Nucleon transfer in symmetric heavy-ion reactions at energies below the Coulomb barrier is investigated in the framework of a microscopic stochastic mean-field theory. Although mean field alone is known to significantly underpredict the dispersion of the fragment mass distribution, a considerable enhancement of the dispersion is obtained in the stochastic mean-field theory. The variance of the fragment mass distribution deduced from the stochastic theory scales with the number of exchanged nucleons. Therefore, the new approach provides the first fully microscopic theory consistent with the phenomenological analysis of the experimental data.

The application of the hyperspherical harmonic approach to the case of the $N\text{−}d$ scattering problem below deuteron breakup threshold is described. The nuclear Hamiltonian includes two- and three-nucleon interactions, in particular the Argonne $v_{18}$, the N3LO-Idaho, and the $V_{\mathrm{low}\text{−}k}$ two-nucleon, and the Urbana IX and N2LO three-nucleon interactions. Some of these models are local, whereas some are nonlocal. Also electromagnetic effects are included. Accurate calculations for many scattering observables at various center-of-mass energies are performed and the results are compared with the available experimental data. Furthermore, a ${\chi }^2$ analysis of some of the Hamiltonian models has been performed to compare their capability to describe the scattering process.

Production cross sections for neutron-rich nuclei from the fragmentation of a ${}^{76}\mathrm{Ge}$ beam at 132 MeV/u were measured. The longitudinal momentum distributions of 34 neutron-rich isotopes of elements $13⩽Z⩽27$ were scanned using a novel experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei, including 15 isotopes first observed in this work. These are the most neutron-rich nuclides of the elements $17⩽Z⩽25$ (${}^{50}\mathrm{Cl}$, ${}^{53}\mathrm{Ar}$, ${}^{55,56}\mathrm{K}$, ${}^{57,58}\mathrm{Ca}$, ${}^{59,60,61}\mathrm{Sc}$, ${}^{62,63}\mathrm{Ti}$, ${}^{65,66}\mathrm{V}$, ${}^{68}\mathrm{Cr}$, and ${}^{70}\mathrm{Mn}$). A one-body $Q_g$ systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. Some of the fragments near ${}^{58}\mathrm{Ca}$ show anomalously large production cross sections.

The Jensen theorem is used to derive inequalities for semiclassical tunneling probabilities for systems involving several degrees of freedom. These Jensen inequalities are used to discuss several aspects of sub-barrier heavy-ion fusion reactions. The inequality hinges on general convexity properties of the tunneling coefficient calculated with the classical action in the classically forbidden region.

The excited states of the neutron-rich nuclei ${}^{155,156}\mathrm{Pm}$ and ${}^{91,92,93}\mathrm{Rb}$ were studied from the spontaneous fission of ${}^{252}\mathrm{Cf}$. The $\gamma \text{−}\gamma \text{−}\gamma$ and $\mathrm{x}(\mathrm{Pm})\text{−}\gamma \text{−}\gamma$ triple coincidence relations were applied to identify the $\gamma$ transitions. Fourteen, six, three, twelve, and twelve new $\gamma$ transitions from high-spin states were observed in ${}^{155,156}\mathrm{Pm}$, ${}^{91,92}\mathrm{Rb}$, and ${}^{93}\mathrm{Rb}$ (first levels), respectively. The $\pi 5/2[532]$ rotational band in ${}^{155}\mathrm{Pm}$ was extended up to $23/2^{-}$. The $\pi g_{9/2}$ particle states and $\pi f_{5/2}$ particle states in ${}^{91,93}\mathrm{Rb}$ weakly coupled to ${}^{90,92}\mathrm{Kr}$, respectively, are reported.

It is revealed that in the normal phase of dense relativistic matter in a magnetic field, there exists a contribution to the axial current associated with a relative shift of the longitudinal momenta in the dispersion relations of opposite chirality fermions. Unlike the topological contribution in the axial current at the lowest Landau level, recently discussed in the literature, the dynamical one appears only in interacting matter and affects the fermions in all Landau levels, including those around the Fermi surface. The induced axial current and the shift of the Fermi surfaces of the left-handed and right-handed fermions are expected to play an important role in transport and emission properties of matter in various types of compact stars as well as in heavy ion collisions.

A global nucleon-nucleus optical potential for elastic scattering has been produced which replicates experimental data to high accuracy and compares well with other recently formulated potentials. The calculation that has been developed describes proton and neutron scattering from target nuclei ranging from carbon to nickel and is applicable for projectile energies from 30 to 160 MeV. With these ranges it is suitable for calculations associated with experiments performed by exotic beam accelerators. The potential has both real and imaginary isovector asymmetry terms to better describe the dynamics of chains of isotopes and mirror nuclei. An analysis of the validity and strength of the asymmetry term is included with connections established to other optical potentials and charge-exchange reaction data.

A new method for solving relativistic ideal hydrodynamics in ($1+3$)D is developed. Longitudinal and transverse radial flows are explicitly embedded into the ansatz for the velocity field and the hydrodynamic equations are reduced to a single equation for the transverse velocity field only, which is analytically more tractable as compared to the full hydrodynamic equations. As an application we use the method to find analytically all possible solutions whose transverse velocity fields have power dependence on the proper time and transverse radius. The possible applications to relativistic heavy ion collisions and possible generalizations of the method are discussed.

The process $\mathit{ep}\to \mathit{ep}{\pi }^0$ has been measured at $Q^2=6.4$ and 7.7 (GeV/$c^2$)${}^2$ in Jefferson Lab's Hall C. Unpolarized differential cross sections are reported in the virtual photon-proton center-of-mass frame considering the process ${\gamma }^{*}p\to p{\pi }^0$. Various details relating to the background subtractions, radiative corrections, and systematic errors are discussed. The usefulness of the data with regard to the measurement of the electromagnetic properties of the well-known $\Delta (1232)$ resonance is covered in detail. Specifically considered are the electromagnetic and scalar-magnetic ratios $R_{\mathrm{EM}}$ and $R_{\mathrm{SM}}$ along with the magnetic transition form factor $G_M^{*}$. It is found that the rapid falloff of the $\Delta (1232)$ contribution continues into this region of momentum transfer and that other resonances may be making important contributions in this region.

The total cross sections for the ${}^{120}\mathrm{Te}(p,\gamma ){}^{121}\mathrm{I}$ and ${}^{120}\mathrm{Te}(p,n){}^{120}\mathrm{I}$ reactions have been measured by the activation method in the effective center-of-mass energies 2.47 MeV$\hspace{0.5em}⩽\hspace{0.5em}{E}_{\mathrm{c}.\mathrm{m}.}^{\mathrm{eff}}\hspace{0.5em}⩽\hspace{0.5em}7.93$ MeV and $6.44\hspace{0.5em}\mathrm{MeV}\hspace{0.5em}⩽\hspace{0.5em}{E}_{\mathrm{c}.\mathrm{m}.}^{\mathrm{eff}}\hspace{0.5em}⩽\hspace{0.5em}7.93\hspace{0.5em}\mathrm{MeV},$ respectively. The targets were prepared by evaporation of $99.4\%$ isotopically enriched ${}^{120}\mathrm{Te}$ on aluminum and carbon backing foils, and bombarded with proton beams provided by the FN tandem accelerator at the University of Notre Dame. The cross sections and $S$ factors were deduced from the observed $\gamma$ ray activity, which was detected off-line by two Clover HPGe detectors mounted in close geometry. The results are presented and compared with the predictions of statistical model calculations using the codes NON-SMOKER and TALYS.

We study the energy and angular distributions of two emitted neutrons from the dipole excitation of two typical, weakly bound Borromean nuclei, ${}^{11}\mathrm{Li}$ and ${}^6\mathrm{He}$, by using a three-body model. Our calculation indicates that those distributions are considerably different between the two nuclei, even though both the nuclei exhibit similar strong dineutron correlations in the ground state to each other. We point out that this different behavior primarily reflects the interaction between the neutron and the core nucleus, especially the $s$-wave virtual state in ${}^{10}\mathrm{Li}$, rather than the interaction between the valence neutrons.

The energies of subsets of excited $0^{+}$ states in geometric collective models are investigated and found to exhibit intriguing regularities. In models with an infinite square well potential, it is found that a single formula, dependent on only the number of dimensions, describes a subset of $0^{+}$ states. The same behavior of a subset of $0^{+}$ states is seen in the large boson number limit of the interacting boson approximation (IBA) model near the critical point of a first-order phase transition, in contrast to the fact that these $0^{+}$ state energies exhibit a harmonic behavior in all three limiting symmetries of the IBA. Finally, the observed regularities in $0^{+}$ energies are analyzed in terms of the underlying group theoretical framework of the different models.

The effect of ${}^7\mathrm{Li}$ breakup on the fusion of the ${}^7\mathrm{Li}+{}^{165}\mathrm{Ho}$ system has been investigated using the continuum-discretized coupled channels (CDCC) calculations. Coupling of the breakup channel leads to a large enhancement in the total fusion cross sections at energies below the Coulomb barrier, while it leads to a small reduction of the fusion cross sections at above barrier energies. A large contribution to this enhancement is found because of dipole couplings arising from the $L=0$ continuum excitation of ${}^7\mathrm{Li}$ to its ground state. The dynamic polarization potential generated by the ${}^7\mathrm{Li}$ breakup couplings is found to have an attractive real part at below barrier energies, due to the dominance of dipole $(E1)$ couplings. Inelastic couplings due to the target deformation are found to have negligible effects on the fusion cross section.

The symmetry energy coefficients, incompressibility, and single-particle and isovector potentials of clusterized dilute nuclear matter are calculated at different temperatures employing the $S$-matrix approach to the evaluation of the equation of state. Calculations have been extended to understand the aforesaid properties of homogeneous and clusterized supernova matter in the subnuclear density region. A comparison of the results in the $S$-matrix and mean-field approach reveals some subtle differences in the density and temperature region we explore.