We present a unified study of the role of the $\rho$-exchange interaction in spin-isospin strength distribution effects in a finite nuclear system. We study both the longitudinal ($\overrightarrow{\sigma }·\hat{q}{\tau }_{\lambda }$, where $\overrightarrow{\mathrm{q}}$ is the momentum transfer to the nucleus) and the transverse ($\overrightarrow{\sigma }\times \hat{q}{\tau }_{\lambda }$) spin channels for a large range of momentum transfer ($q\sim 0-600$ MeV/c). We examine a number of effective $\rho$-coupling schemes used in the literature. Using the finite-nucleus formalism of Toki and Weise, we examine in detail the response function in the presence of the $\rho$-meson exchange term. The renormalization of matrix elements of spin-isospin sensitive probes is given for the $J^P=1^{+}$, $T=1\mathrm{}$ level of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. We analyze the results, gaining some insight into the nature of the longitudinal versus transverse channels and into approximations suggested in the past for handling finite-nucleus calculations. A comparison with local density approximation and infinite nuclear matter with a constant density results is presented for a variety of cases.

Total muon-capture rates and inclusive pion-electroproduction cross sections in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ are used to obtain inclusive neutral and charged current neutrino cross sections in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. These results are obtained for $150 \mathrm{MeV} \le E_{\nu }\le 250 \mathrm{MeV}$ for the charged current case and $50 \mathrm{MeV} \le E_{\nu }\le 150 \mathrm{MeV}$ for the neutral current case. Comparison is made with other calculations.

A variety of nuclear structure and proton-nucleus dynamical effects are shown to significantly influence the behavior of the large angle 800 MeV p+${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ elastic angular distribution. While coupled channels effects are found to be important, they are significantly smaller than recently suggested.

The cross sections for the pion single charge exchange reactions ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}({\pi }^{-},{\pi }^0){}_{}{}^{27}{}_{}{}^{}\mathrm{Mg}$, ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}({\pi }^{+},{\pi }^0){}_{}{}^{45}{}_{}{}^{}\mathrm{Ti}$, and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}({\pi }^{-},{\pi }^0){}_{}{}^{65}{}_{}{}^{}\mathrm{Ni}$ were measured at pion kinetic energies from 80 to 400 MeV by activation techniques. The excitation functions measured for these target nuclei do not show any structure near the (3,3) resonance, but rather, all exhibit a monotonic decrease in cross section over this energy range, proportional to $T_{\pi }^{-1\mathrm{}}$. Theoretical predictions based on the impulse approximation with the Fermi gas model show a minimum near the (3,3) resonance, in disagreement with these experimental results.

We formulate a microscopic relativistic treatment of nucleon-nucleus inelastic scattering. Both the continuum and bound state single nucleon wave functions are obtained by solving the Dirac equation with scalar and timelike vector potentials. The interaction which drives the transition is expressed in terms of invariant combinations of Dirac matrices. The structure of the resulting amplitudes is presented, and certain of their features, such as selection rules, are discussed.

Angular distributions for elastic and inelastic scattering of 50 MeV pions from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$, and ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ are reported. The elastic scattering data are fitted with an optical model in configuration space. Distorted wave calculations reproduce the inelastic ${\pi }^{\pm }$ data. The extracted neutron and proton matrix elements are consistent with measurements using other probes.

The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({\pi }^{\pm },{\pi }^{\pm }\mathrm{p})$ reactions were studied at $T_{\pi }=220\mathrm{}$ MeV. The final particles were detected both separately and in coincidence and their momenta were measured. Calculation of the excitation energy of the residual nucleus allowed clear separation of events where an outer proton was removed. The data provide detailed evidence confirming the quasielastic picture of pion knockout reactions. Evidence for this derives from the agreement between the peak energies found in the coincidence spectra and those found in inclusive spectra, from analysis of angular distributions, and from the location of peaks found in missing mass spectra. The coincidence cross section is found to account for about half of the (${\pi }^{+}$,${\pi }^{+\prime }$) reaction, and about half of this in turn corresponds to quasifree knockout of the outer shell protons. Secondary processes in the (${\pi }^{-}$,${\pi }^{-}\mathrm{p}$) reaction are found to play a much more important role than in the (${\pi }^{+}$,${\pi }^{+}\mathrm{p}$) reaction.

The inclusive electroproduction of 30 MeV ${\pi }^{+}$ and ${\pi }^{-}$ mesons has been observed at a laboratory angle of 90° for electron energies from 185 MeV (the kinematic threshold) to 235 MeV. Measurements of the yield were performed and double differential cross sections for photoproduction were obtained using virtual-photon theory. A significant discrepancy between experiment and distorted-wave impulse approximation calculations was found. This is particularly surprising since these calculations agree with the total cross sections for the ${}_{}{}^2{}_{}{}^{}\mathrm{H}(\gamma ,{\pi }^{+})\mathrm{nn}$ reaction from threshold to 20 MeV above threshold.

A certain two-channel $s$-wave scattering model containing a resonance at low energy is studied, and it is shown that both the multichannel effective range approximation and the $K$ matrix pole test for compositeness of the resonance fail for this model. When the model is applied to the low-energy $I=0\mathrm{}$ $\overline{\mathrm{K}}$N interaction, it leads to a $K$ matrix which is very different from those used in the phenomenological $K$ matrix parametrizations hitherto carried out. Implications of this are discussed.

The excitation function for ${\pi }^{+}$ inelastic scattering to the $0^{+}$, $T=1\mathrm{}$, 3.563-MeV level of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ has been measured at a constant momentum transfer $q\simeq 109$ MeV/c for incident pion energies from 100 to 260 MeV. Although the differential cross sections extracted for the natural-parity transitions to the $3^{+}$, $T=0\mathrm{}$, 2.185-MeV and $2^{+}$, $T=0\mathrm{}$, 4.25-MeV levels are well reproduced within the framework of the distorted-wave impulse approximation, distorted-wave impulse approximation calculations fail to reproduce the anomalous excitation function observed for the transition to the 3.563-MeV level. The shape of the 3.563-MeV excitation function is similar to that previously observed for ${\pi }^{\pm }$ inelastic scattering to the $1^{+}$, $T=1\mathrm{}$, 15.11-MeV state of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ [C. L. Morris et al., Phys. Lett. 108B, 172 (1982)]. The same mechanism may be responsible for the observed excitation functions of both $\Delta S=\Delta T=1\mathrm{}$ transitions. A possible mechanism is the previously proposed direct excitation of $\Delta$-particle-nucleon-hole ($\Delta -h$) components in the wave functions.

The model dependence of high $L$ partial waves in nucleon-nucleon scattering for $T_{\mathrm{lab}}=400-1000\mathrm{}$ MeV is studied. Unlike at low energy, model predictions are not unique. This is due to the delta isobar, which plays a major role in determining high $L$ inelasticities as well as real phase shifts. The differences between various model predictions are mainly due to the use of different delta propagators and delta vertex functions.

Results from ${\pi }^{\pm }$ elastic and inelastic scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ are reported. The data were all taken at an incident momentum of 800 MeV/c over an angular range from 4° to 38°. The elastic data are compared to first-order optical model calculations in momentum space; qualitative agreement is obtained. The inelastic data (from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ only) are compared to distorted-wave Born approximation calculations, and reasonable agreement is found if realistic inelastic transition densities are used.

The intensities of mass-separated radon beams have been improved by means of a new high temperature thorium spallation target. The production yields of the selectively produced radon ions were determined. The new nuclide ${}_{}{}^{198}{}_{}{}^{}\mathrm{Rn}$ was found to have an $\alpha$-decay energy of 7196±10 keV and a half-life of 50±9 ms. Decay energies and half-lives for ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}_{}^m{}_{}{}^{}$, ${}_{}{}^{199}{}_{}{}^{}\mathrm{Rn}$, and ${}_{}{}^{200}{}_{}{}^{}\mathrm{Rn}$ were remeasured.

The effective hyperfine splitting frequencies $\overline{\nu }$ of ${}_{}{}^{196}{}_{}{}^{}\mathrm{Au}$ ($I^{\pi }=2^{-}$, $T_{\frac{1}{2}}=6.2\mathrm{}$ d), ${}_{}{}^{198}{}_{}{}^{}\mathrm{Au}$ ($I^{\pi }=2^{-}$, $T_{\frac{1}{2}}=2.7\mathrm{}$ d), and ${}_{}{}^{200}{}_{}{}^{}\mathrm{Au}_{}^m{}_{}{}^{}$ ($I^{\pi }={12}^{-}$, $T_{\frac{1}{2}}=18.7\mathrm{}$ h) in nickel at a temperature of ∼10 mK were measured with nuclear magnetic resonance on oriented nuclei to be 59.65(6) MHz, 60.06(5) MHz, and 99.1(3) MHz, respectively. All frequencies are considerably larger than those known from previous nuclear magnetic resonance on oriented nuclei measurements. Our results show that the noncontact contribution to the hyperfine field of $\mathrm{Au}\mathrm{Ni}$ is smaller than deduced before. The magnetic moment of ${}_{}{}^{200}{}_{}{}^{}\mathrm{Au}_{}^m{}_{}{}^{}$ [configuration ${\left|\right(\pi {\frac{11}{2}}^{-}\left)\right(\nu {\frac{13}{2}}^{+})〉}_{{12}^{-}}$], $\left|\mu \mathrm{}\right|=5.90\left(9\mathrm{}\right)\mathrm{}{\mu }_N$, fits well into the systematics of magnetic moments of ${12}^{-}$ isomers in this mass region.

A common flaw in the theoretical structure of the generalized-Hartree-Fock approximation of Kerman and Klein and of the equivalent generalized density matrix method of Belyaev and Zelevinsky is analyzed. This deficiency appears as soon as one attempts to go beyond the semiclassical approximation equivalent to time dependent Hartree-Fock theory. A new version based on a revised factorization of the generalized two-body density matrix in terms of generalized one-body matrices is proposed. This factorization fulfills the requirements of antisymmetry and Hermiticity imposed by the properties of the exact two-body density matrix. It leads to a set of equations of motion which satisfy the conservation laws associated with the exact equations and guarantees that an energy-weighted and an energy-squared-weighted sum rule are fulfilled. Several associated approximate variational principles are described. The generalized-Hartree-Fock dynamics is salvaged in a reinterpretation as a generalized core-particle coupling model. Both the old and new theories coincide in the semiclassical limit where, in equivalent versions, they yield the time dependent Hartree-Fock and a self-consistent cranking theory. Standard applications to the random phase approximation phonons are reviewed. Theories of damping of single-particle excitations and of random phase approximation phonons are proposed. The latter, in particular, carries the analysis to the point of including quantum corrections which differ in the new and old generalized density matrix theories, and thus pinpoint the need for the revised formulation.

The quadrupole coupling constant of the $\pi {\left(h_{\frac{11}{2}}^{-1\mathrm{}} s_{\frac{1}{2}}^{-1\mathrm{}}\right)}_{5^{-}}$ isomer in polycrystalline ${}_{}{}^{206}{}_{}{}^{}\mathrm{Hg}$ at 225 K has been measured by means of the perturbed angular distribution method. The result is $\frac{e^2\mathrm{Qq}}{h}=136.5\mathrm{}\pm 3$ MHz, from which we deduce $eQ=65\mathrm{}\pm 13 e$ ${\mathrm{fm}}^2$ and an effective charge $e_{\mathrm{eff}}\left(\pi h_{\frac{11}{2}}^{-1\mathrm{}}\right)=(2.2\mathrm{}\pm 0.5)e$.

Highly excited states observed in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{16}{}_{}{}^{}\mathrm{O},\alpha ){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ reaction are analyzed within the statistical model. Evidence that the $E^{*}=28.21, 33.34, \mathrm{and} 38.22$ MeV states correspond to high spin states is found. The ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ yrast line can be identified up to the ${12}^{+}$ state located at 28.21 MeV excitation energy.

A model of quantal Brownian motion in fermionic reservoirs is applied to study the time evolution of a giant isovector dipole mode in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The coupled equations of irreversible motion for the excited collective mode and for the nucleon intrinsic degrees of freedom are simultaneously solved and their energies, entropies, and relative populations are observed over a lengthy time interval. The resonant decay can be seen together with the excitation of the Fermi sea towards a non-Fermi asymptotic distribution. It is found that the effective decay rate is smaller than the downwards transition rate, in contrast to the widespread assumption in microscopic models of resonance damping. Diffusion, as well as dissipation, appears as a feature of mutual equilibration.

Deformed Hartree-Fock calculations with the Skyrme interactions are carried out for various nuclei in the $s-d$ and $f-p$ shell regions to obtain $E2\mathrm{}$, $E4\mathrm{}$, and $E6\mathrm{}$ intrinsic multiple moments. It is found that the higher moments have an increasing sensitivity to the size of the basis used in the calculation and that the basis must span at least nine major shells to produce reliable results for $E6\mathrm{}$ moments in this mass region. The results are sometimes not monotonic in the number of shells that are included. The results differ greatly for the Skyrme SI and SII interactions used here. More insight into these moments and a better understanding of the Hartree-Fock results is gained by using deformed harmonic oscillator wave functions. The results are compared with shell model calculations. It is found that the collective model approach, when used sensibly, can be very useful in understanding the experimental results. Much of the data can be explained, although some discrepancies still remain. It is found that in open shell nuclei, the simple use of an effective charge calculated for a closed shell plus one nucleon is inadequate. A necessary (but not sufficient) condition for obtaining sensible results for higher moments is that the lower moments come out correctly.

A quark model of N-N interactions with relativistic effects is developed. The relativistic total Hamiltonian for the many-body system is constructed, from which an equation of relative motion between two clusters is derived. Then the equation is applied to the deuteron. The binding energy of the deuteron, the effective potential between neutron and proton, and the wave function of relative motion between two nucleons are calculated. The results are quite promising.