Bound, strange, neutral superheavy nuclei, stable against strong decay, may exist. A model effective field theory calculation of the surface energy and density of such systems is carried out assuming vector meson couplings to conserved currents and scalar couplings fit to data where it exists. The nonlinear relativistic mean field equations are solved assuming local density baryon sources. The approach is calibrated through a successful calculation of the known nuclear surface tension.

A semimicroscopical approach is applied to describe photoabsorption and partial photonucleon reactions accompanied by the excitation of the giant dipole resonance (GDR). The approach is based on the continuum random phase approximation (CRPA) with a phenomenological description for the spreading effect. The phenomenological isoscalar part of the nuclear mean field, momentum-independent Landau-Migdal particle-hole interaction, and separable momentum-dependent forces are used as input quantities for the CRPA calculations. The experimental photoabsorption and partial $(n,\gamma )$-reaction cross sections in the vicinity of the GDR are satisfactorily described for ${}^{89}\mathrm{Y},{}^{140}\mathrm{Ce},$ and ${}^{208}\mathrm{Pb}$ target nuclei. The total direct-neutron-decay branching ratio for the GDR in ${}^{48}\mathrm{Ca}$ and ${}^{208}\mathrm{Pb}$ is also evaluated.

Neutral pion photoproduction and electroproduction at threshold is analyzed in the framework of dispersion relations. For this purpose, we evaluate the real threshold amplitudes in terms of Born contributions and dispersion integrals determined by the imaginary parts of the multipoles of the unitary isobar model (MAID) and the phenomenological partial-wave analysis (SAID). The results show considerable cancellations between Born terms and resonance contributions. Good agreement with the data is found for photoproduction. While our dispersion analysis suggests considerable discrepancies for electroproduction, the present state of the experimental multipole analysis at finite $Q^2$ does not permit drawing conclusions at this time.

It is argued that spectral features of quantal systems with random interactions can be given a geometric interpretation. This conjecture is investigated in the context of two simple models: a system of randomly interacting d bosons and one of randomly interacting fermions in a $j=\frac{7}{2}$ shell. In both examples the probability for a given state to become the ground state is shown to be related to a geometric property of a polygon or polyhedron which is entirely determined by particle number, shell size, and symmetry character of the states. The extensions to more general situations are discussed.

Within a theory of breakup reactions formulated in the framework of the post-form distorted wave Born approximation, we calculate contributions of the pure Coulomb and the pure nuclear breakups as well as those of their interference terms, to a variety of cross sections in breakup reactions of the one-neutron halo nucleus ${}^{11}\mathrm{Be}$ on a number of target nuclei. In contrast to the assumption often made, the Coulomb-nuclear interference terms are found to be non-negligible in case of exclusive cross sections of the fragments emitted in this reaction on medium mass and heavy target nuclei. The consideration of the nuclear breakup leads to a better description of such data.

Systematic errors in the database of $\mathrm{np}$ differential cross sections below 350 MeV are studied. By applying angle-dependent normalizations with the help of the energy-dependent Nijmegen partial-wave analysis PWA93, the ${\chi }^2$ values of some seriously flawed data sets can be reduced significantly at the expense of a few degrees of freedom. It turns out that in these special cases the renormalized data sets can be made statistically acceptable such that they do not have to be discarded any longer in partial-wave analyses of the two-nucleon scattering data.

The breakup reactions of ${}^8\mathrm{B}$ on a ${}^{12}\mathrm{C}$ target at intermediate energies are studied with regard to the three-body structure of ${}^8\mathrm{B}.$ One-proton removal cross sections, leading to the production of ${}^7\mathrm{Be}$ fragments in the ground and first excited states, and the longitudinal momentum distributions of the ${}^7\mathrm{Be}$ fragments are calculated in eikonal approximation of the Glauber Model with a three-body wave function of the ${}^8\mathrm{B}$ projectile. The results of the calculations including the contribution of the ${}^7\mathrm{Be}$ excited state to the ground state of ${}^8\mathrm{B}$ are compared with available experimental data obtained recently.

Some aspects of asymptotic freedom are discussed in the context of a simple two-particle nonrelativistic confining potential model. In this model, asymptotic freedom follows from the similarity of the free-particle and bound state radial wave functions at small distances and for the same angular momentum and the same large energy. This similarity, which can be understood using simple quantum mechanical arguments, can be used to show that the exact response function approaches that obtained when final state interactions are ignored. A method of calculating corrections to this limit is given, and explicit examples are given for the case of a harmonic oscillator.

The in-medium properties of the vector mesons are known to be modified significantly in hot and dense hadronic matter due to vacuum polarization effects from the baryon sector in the Walecka model. The vector meson mass drops significantly in the medium due to the effects of the Dirac sea. In the variational approach adopted in the present paper, these effects are taken into account through a realignment of the ground state with baryon condensates. Such a realignment of the ground state becomes equivalent to summing of the baryonic tadpole diagrams in the relativistic Hartree approximation (RHA). The approximation scheme adopted here goes beyond RHA to include quantum effects from the scalar meson and is nonperturbative and self-consistent. It includes multiloop effects, thus corresponding to a different approximation as compared to the one loop approximation of including scalar field quantum corrections. In the present work, we study the properties of the vector mesons in the hot and dense matter as modified due to such quantum correction effects from the baryon as well as scalar meson sectors. These medium modifications of the properties of the vector mesons are reflected, through the shifting and broadening of the respective peaks, in the low mass dilepton spectra. There is broadening of the peaks due to corrections from scalar meson quantum effects as compared to the relativistic Hartree approximation. It is seen to be rather prominent for the $\omega$ meson in the invariant mass plot.

We analyze the effect of noncentral forces on the magnetic susceptibility of degenerate Fermi systems. These include the presence of contributions from transitions to states containing more than one quasiparticle-quasihole pair, which cannot be calculated within the framework of Landau Fermi-liquid theory, and the renormalization of the quasiparticle magnetic moment, as well as explicit noncentral contributions to the quasiparticle interaction. Consequently, the relationship between the Landau parameters and the magnetic susceptibility for Fermi systems with noncentral forces is considerably more complicated than for systems with central forces. We use sum-rule arguments to place a lower bound on the contribution to the static susceptibility coming from transitions to multipair states.

Self-consistent quasiparticle random phase approximation (SCQRPA) is for the first time applied to a more level pairing case. Various filling situations and values for the coupling constant are considered. Very encouraging results in comparison with the exact solution of the model are obtained. The nature of the low-lying mode in SCQRPA is identified. The strong reduction of the number fluctuation in SCQRPA vs BCS is pointed out. The transition from superfluidity to the normal fluid case is carefully investigated.

We have observed the breakup of the isobaric analog state at 11.193 MeV in ${}^{17}\mathrm{F}$ into three particles via three channels: proton decay to the $\alpha$-unbound 9.585 MeV state in ${}^{16}\mathrm{O};$ and $\alpha$ decay to the proton-unbound 2.365 and 3.502/3.547 MeV states in ${}^{13}\mathrm{N}.$ Laboratory $\alpha$-particle spectra corresponding to these three modes have been generated in Monte Carlo simulations using single-channel, single- and multilevel R-matrix formulas. A fit of these spectra to the $\alpha$ spectrum resulting from a triple-coincidence measurement results in excellent agreement with the experimental spectrum and allows branching ratios to be deduced for these rare decay modes.

Invariant transverse-velocity spectra of intermediate-mass fragments were measured with the $4\pi$ multidetector system INDRA for collisions of ${}^{197}\mathrm{Au}$ on ${}^{197}\mathrm{Au}$ at incident energies between 40 and 150 MeV per nucleon. Their scaling properties as a function of incident energy and atomic number Z are used to distinguish and characterize the emissions in (i) peripheral collisions at the projectile and target rapidities, and in (ii) central and (iii) peripheral collisions near midrapidity. The importance of dynamical effects is evident in all three cases and their origin is discussed.

We use the recently developed MCMC/MCEF (multicollisional Monte Carlo plus Monte Carlo for evaporation-fission calculations) model to calculate the photofissility and the photofission cross section at intermediate energies for the ${}^{243}\mathrm{Am}$ and for ${}^{209}\mathrm{Bi},$ and compare them to results obtained for other actinides and to available experimental data. As expected, the results for ${}^{243}\mathrm{Am}$ are close to those for ${}^{237}\mathrm{Np}.$ The fissility for preactinide nuclei is nearly one order of magnitude lower than that for the actinides. Both fissility and photofission cross section results for ${}^{209}\mathrm{Bi}$ are in good agreement with the experimental data.

Volume integrals of the real potentials derived from proton elastic scattering studies have been calculated for data available from the lowest to the highest energy. Because of the spread of the volume integrals at low energies, an average of volume integrals in each 1 MeV bin was calculated. These average volume integrals show a logarithmic dependence on the beam energy. A similar analysis of neutron potentials shows that the proton energy dependence can be applied to neutron data. The data for proton scattering from Ca isotopes at 1044 MeV were analyzed in terms of the optical model, and an isospin component of the potential was determined. The derived isospin potential is compared with those obtained for proton and neutron scattering in previous investigations.

We investigate the deformation properties of atomic nuclei in a hadronic chiral ${\mathrm{SU}}_{\mathrm{flavor}}\mathrm{}\left(3\right)\mathrm{}$ model approach. The parameters are fitted to hadron mass properties and adjustments for spherical finite nuclei have been performed. Using these parameters the deformation of a series of light and heavy nuclei are obtained in a two-dimensional self-consistent calculation. In addition a case of superdeformation in a heavy nucleus is studied.

We have performed shell-model calculations for nuclei with proton particles and neutron holes around ${}^{132}\mathrm{Sn}$ using a realistic effective interaction derived from the CD-Bonn nucleon-nucleon potential. For the proton-neutron channel this is explicitly done in the particle-hole formalism. The calculated results are compared with the available experimental data, particular attention being focused on the proton particle-neutron hole multiplets. A very good agreement is obtained for all four nuclei considered, ${}^{132}\mathrm{Sb},$ ${}^{130}\mathrm{Sb},$ ${}^{133}\mathrm{Te},$ and ${}^{131}\mathrm{Sb}.$ We predict many low-energy states which have no experimental counterpart. This may stimulate, and be helpful to, future experiments.

Pseudospin symmetry imposes conditions on the Dirac eigenfunctions independent of the potentials, from triaxial to spherical potentials. The general conditions on the relativistic mean field eigenfunctions in the pseudospin symmetry limit are derived. For the upper components, these conditions include differential realtions. These differential realtions are tested for realistic eigenfunctions in the spherical symmetry limit.

Proton single-particle strengths in ${}^{19}\mathrm{F}$ were investigated up to an excitation energy of 14 MeV through the $\mathrm{}(d,n)\mathrm{}$ reaction on ${}^{18}\mathrm{O}$ at $E_d=25\mathrm{}$ MeV. Spectroscopic strengths were deduced from adiabatic-deuteron-breakup-approximation analysis. Most of the strengths for the $2s1d$-shell orbitals were observed in the present measurement. Strength distributions were compared with the shell-model predictions in the framework of the complete $2s1d$-shell basis. Results for the ${1d}_{5/2}$ and ${2s}_{1/2}$ strengths were in good agreement with the shell-model calculation, but the theoretical estimate for the ${1d}_{3/2}$ strength did not reproduce the observation. The occupation probabilities and single-particle energies of proton orbitals near the Fermi surface for ${}^{18}\mathrm{O}$ were evaluated from a combined analysis of the present stripping data and previous proton pickup data.

Lifetimes have been measured for states in four magnetic-rotational bands in ${}^{196}\mathrm{Pd}$ using the Doppler-shift attenuation method. Line shapes of several transitions in each band have been analyzed in γ-ray coincidence spectra measured with the EUROBALL spectrometer array. The $B\left(M1\mathrm{}\right)\mathrm{}$ values deduced from the lifetimes show a decrease with increasing spin within the bands as expected for the shears mechanism. The $B\left(M1\mathrm{}\right)\mathrm{}$ values are compared to calculations within the framework of the tilted-axis cranking model.