The vector analyzing power ${\mathit{iT}}_{11}$ has been measured for the first time for ${\mathrm{\pi }}^{+}$d and ${\mathrm{\pi }}^{\mathrm{-}}$d elastic scattering at ${\mathit{T}}_{\mathrm{\pi }}$=180 MeV in the angular range between 50° and 110°, using a polarized deuteron target and a magnetic spectrometer. The data are compared with theoretical calculations involving different Coulomb prescriptions.

The triple differential cross section ${\mathit{d}}^3$σ/d${\mathrm{\Omega }}_{\mathit{p}1}$d${\mathrm{\Omega }}_{\mathit{p}2}$${\mathit{dp}}_{\mathit{p}1}$ was measured for the ${\mathrm{\pi }}^{+}$d→${\mathrm{\pi }}^0$pp reaction as a function of proton momentum, in a kinematically complete experiment at ${\mathit{T}}_{\mathrm{\pi }}$=228 and 294 MeV. The two outgoing protons were detected in coincidence with plastic scintillator detectors, and their momenta determined by time-of-flight, at several angle pairs in regions of phase space far away from quasifree kinematics. The data are compared with predictions from the relativistic Faddeev calculation of Garcilazo.

An energy-dependent partial-wave analysis of pion photoproduction data through the second-resonance region (0–1 GeV laboratory kinetic energy) is presented. A set of energy-independent analyses has also been obtained starting from the energy-dependent solution. The data set contains 9074 data for the reactions γ+p→p+${\mathrm{\pi }}^0$, γ+p→n+${\mathrm{\pi }}^{+}$, γ+n→n+${\mathrm{\pi }}^0$, γ+n→p+${\mathrm{\pi }}^{\mathrm{-}}$, and the inverse reaction ${\mathrm{\pi }}^{\mathrm{-}}$+p→n+γ (converted to γ+n→p+${\mathrm{\pi }}^{\mathrm{-}}$). The predictions of our solutions are compared with the results of previous analyses. Suggestions are made for future experiments.

Resonance couplings for the resonant states ${\mathit{P}}_{33}$(1232), ${\mathit{P}}_{11}$(1440), ${\mathit{D}}_{13}$(1520), and ${\mathit{S}}_{11}$(1535) are extracted from a recent multipole analysis of pion photoproduction data. We calculate photoproduction residues at the resonance pole in the complex plane for these amplitudes, in addition to the resonance widths at the on-shell resonance energies.

An explanation is given for the nearly linear relationship between the deuteron radius and the triplet scattering length as predicted by potential models of the NN interaction. This is accomplished by showing that the quantity 〈${\mathit{r}}^2$〉/${\mathit{a}}_{\mathit{t}}^2$ can be expanded to high accuracy in terms of the small parameter x=${\mathit{r}}_{\mathit{t}}$/${\mathit{a}}_{\mathit{t}}$. We show that shape dependence only enters at order ${\mathit{x}}^3$ and higher. Possible reasons for the disagreement with the experimental result are discussed.

We study a mechanism for parity violation in the two nucleon meson-exchange interaction by way of the mixing of mesons of opposite parities. This mixing arises from parity violating ${\mathit{W}}^{\pm }$ and Z exchange between the qq¯ pair in the meson. Numerically its effect turns out to be as important as vector meson exchange with a weak meson-nucleon vertex and may partly be used to model this vertex. The calculation is performed using both the standard Born approximation adding the amplitude phases by Watson’s theorem and also using the exact correlated two-nucleon wave functions. The effect of correlations and form factors is found to be crucially important at intermediate energies.

We critically examine two formally equivalent approaches to the many-body problem, one of which is based on an effective energy-dependent interaction and the other on an effective energy-independent interaction (an instantaneous, but nonlocal, potential). The interactions are mediated by the same set of mesons, with common masses, coupling constants, and form factors, and they give similar reproductions of the two-body data. We examine the higher-order contributions in the many-body theory, and we are able to identify specific ingredients that could lead to different rates of convergence for the different interactions. For the three-body system, we find an important contribution to the three-body force that is large in the energy-dependent interaction and nearly cancels out of the instantaneous potential. For the many-body system we find numerous density-dependent terms that contribute to the energy-dependent interaction but not to the instantaneous one. We show numerical results for the binding energy per particle of nuclear matter based on the solution of the two-body Bethe-Goldstone equation. We find substantially less binding for the instantaneous potential, thus observing that in actual calculations the many-body theory converges at a different rate for the two types of interaction. We conclude that nuclear matter properties can be calculated with more reliability and less computational effort for the case of the instantaneous potential.

We show that for S-wave scattering at an energy ${\mathit{k}}^2$ by a local potential which supports no more than one bound state, the shape parameter P and coefficients of higher powers of ${\mathit{k}}^2$ in the effective range expansion function cotδ=-1/a+1/2${\mathit{r}}_0$${\mathit{k}}^2$-${\mathit{Pr}}_0^3$${\mathit{k}}^3$+${\mathit{Qr}}_0^5$${\mathit{k}}^6$+..., where δ is the phase shift, may be obtained from the zero-energy wave function, ${\mathit{u}}_0$(r). Thus δ itself may be determined from ${\mathit{u}}_0$. We show that ${\mathit{Pr}}_0^3$=${\mathcal{F}}_0^{\mathit{R}}$[β(r)${\mathit{u}}_0^2$(r)-β¯(r)u¯ ${}_0{}^2{}_{}{}^{}$(r)]dr, where ${\mathit{r}}_0$ is the effective range, β(r) is determined from an integral involving the wave function, and β¯(r) is a simple function of r which involves the scattering length and effective range.

Bremsstrahlung double cross sections for p+α collisions are computed by using the wave functions obtained from a single-configuration resonating-group calculation. The photon-emission operator employed is translationally invariant and the center-of-mass motion is strictly eliminated from the transition amplitude. Analytical expressions for the reduced matrix elements are derived without invoking the long-wavelength approximation. With no adjustable parameters, it is found that there is a very good agreement between calculated and experimental values. Effects of the p+α, 3/$2^{\mathrm{-}}$ resonance show up distinctly in the cross-section curve when this resonance occurs in the final channel. On the other hand, the presence of the very broad 1/$2^{\mathrm{-}}$ level becomes detectable from the bremsstrahlung cross-section result only when there is a proper choice of the geometrical arrangement of the particle detectors.

The results of a nonrelativistic calculation of the exclusive ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(p,2p)n cross section and inclusive ${}_{}{}^1{}_{}{}^{}\mathrm{H}$(d→,p)X cross section and tensor analyzing power ${\mathit{T}}_{20}$, based on an expansion of the scattering τ matrix up to double scattering, are presented. Five different wave functions, including Reid with soft core, Paris, Bonn, Amsterdam, and Moscow, as well as two NN phase-shift amplitude sets, VPI and Saclay-Geneva, are used. Detailed comparison with the data available indicates that double scattering is indeed important for both reaction channels. For (p,2p) the complete calculation removes a discrepancy of a factor of 2 to 8 present if comparison is made with the impulse approximation only; the Paris wave function gives the best results. For (d→,p) the complete calculation results agree fairly well with both cross section and ${\mathit{T}}_{20}$ data up to q=200 MeV/c. However, neither an enhancement in ${\mathit{d}}^2$σ, nor an abrupt turn toward less negative ${\mathit{T}}_{20}$ values, both occurring for q>250 MeV/c, can be explained by the present calculation. Neither the wave functions nor the NN amplitudes used are Lorentz invariant, but the kinematics is treated relativistically. Possible causes for the discrepancy are briefly discussed.

Laser spectroscopic measurement of the optical isotope shifts of all the naturally occurring Gd isotopes have been made using a collimated atomic beam system. The isotope shift and hyperfine splitting of all the stable isotopes have been measured for five optical transitions of Gd I at 570.135, 574.466, 574.636, 575.188, and 579.138 nm. The data were combined with the available muonic and electronic x-ray isotope shift data to extract the specific mass shift and the field shift constant. The change in charge radii, λ≊δ〈${\mathit{r}}^2$〉, have been extracted and compared with droplet model predictions. The accuracy of the isotope shift measurements is 0.1% and the extracted charge radius changes have an uncertainty of about 3%.

The atomic mass excess of ${}_{}{}^{187}{}_{}{}^{}\mathrm{Ir}$ is determined to be -39.725±0.007 MeV from the measured Q value of -1.521±0.006 MeV for the ${}_{}{}^{187}{}_{}{}^{}\mathrm{Os}$${(}^3$He,t${)}^{187}$Ir reaction. The result is compared with some predicted values.

The ground state proton decays of ${}_{}{}^{65}{}_{}{}^{}\mathrm{As}$ and ${}_{}{}^{69}{}_{}{}^{}\mathrm{Br}$ have been searched for in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ bombardments of a natural calcium target. These studies employed a newly developed rapidly rotating recoil-catcher wheel and a low-energy particle-identification telescope. No proton groups that could be assigned to either of these nuclides were observed. The minimum detectable limits indicate that ${}_{}{}^{65}{}_{}{}^{}\mathrm{As}$ and ${}_{}{}^{69}{}_{}{}^{}\mathrm{Br}$ either decay predominantly by beta emission or have half-lives less than 100 μs. The overall evidence strongly indicates that ${}_{}{}^{65}{}_{}{}^{}\mathrm{As}$ predominantly beta decays.

We present cross sections for the reactions ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$${,}^{56}$Fe(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$) leading to the residual ground states and double-isobaric-analog states (DIAS) for incident pion energies from 100 to 300 MeV. Data include both angular distributions and 5° excitation functions. Ground-state cross sections were also obtained from the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ contaminants in the ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ca}$ target. The DIAS data are compared to known systematics and to theoretical predictions. Some features of the data are reproduced by the theoretical predictions, but major discrepancies exist.

α-cluster states in ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ have been investigated in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${(}^6$Li,d${)}^{44}$Ti reaction at E=50 MeV. The angular distributions of 34 levels at excitation energies for ${\mathit{E}}_{\mathit{x}}$=0–13 MeV allow us to analyze the data. The angular distributions of positive-parity members of the ground-state band (the ${\mathit{K}}^{\mathrm{\pi }}$=$0^{+}$ band) in ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ were well reproduced by the finite-range distorted-wave Born approximation calculations up to the transferred angular momentum of L=8. For the members of the negative-parity band (the ${\mathit{K}}^{\mathrm{\pi }}$=$0^{\mathrm{-}}$ band) with the primary quantum number N=13, three levels at 6.22, 7.34, and 9.43 MeV were identified as the $1^{\mathrm{-}}$, $3^{\mathrm{-}}$, and $5^{\mathrm{-}}$ states, respectively. The existence of a negative-parity band in ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ has been investigated for a long time and persistently gives considerable support to α-cluster models for nuclei heavier than A=40.

In nuclear resonance fluorescence (NRF) measurements of well deformed rare-earth nuclei we observe for most of the excited J=1 levels of both parities the ground-state transition and the corresponding transition to the $2_1^{+}$ state. The experimental branching ratios ${\mathit{R}}_{\exp }$=B(1→2)/B(1→0) are compared with the predictions of the Alaga rules. The examination of 171 levels found in NRF experiments yields that most values of ${\mathit{R}}_{\exp }$ are in good agreement with the Alaga rules. Nevertheless, some branching ratios suggest a possible mixing of K values.

Electron-scattering cross sections, measured between 0.4 and 3.1 ${\mathrm{fm}}^{\mathrm{-}1}$, have been unfolded to obtain charge transition densities for the low-lying $2^{+}$, $4^{+}$, $6^{+}$, and $8^{+}$ states in ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$. A comparison is made to analogous levels in ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$. Angular momentum recoupling in the 1${\mathit{g}}_{9/2}$ shell of two protons in ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}$ and two neutron holes in ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$ are the dominant configurations for these levels. Proton core polarization in ${}_{}{}^{86}{}_{}{}^{}\mathrm{Sr}$ neutron valence transitions diminishes with increasing multipolarity, indicating the residual interaction weakens with increasing momentum transfer.

The decay scheme of the ground-state configuration of ${}_{}{}^{159}{}_{}{}^{}\mathrm{Tb}_{94}^{}{}_{}{}^{}$ has been extended to ${\mathit{I}}^{\mathrm{\pi }}$=37/$2^{+}$ (tentatively to 39/$2^{+}$) by Coulomb exciting ${}_{}{}^{159}{}_{}{}^{}\mathrm{Tb}$ using a 981.7-MeV ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ beam. A band crossing, associated with the excitation of a pair of ${\mathit{i}}_{13/2}$ quasineutrons, was observed for the first time in a rotational sequence based on a 3/$2^{+}$[411] quasiproton. The basis of the observed small signature dependence of the energies corresponding to this configuration is discussed as is the effect of an odd 3/$2^{+}$[411] quasiproton on the moment of inertia.

Decay of on-line mass-separated ${}_{}{}^{133}{}_{}{}^{}\mathrm{Pr}$ sources were carried out. γ, x-ray, conversion-electron singles and time-multiscale, and γ-γ-t and ${\mathit{e}}^{\mathrm{-}}$-γ-t measurements were used to deduce the ${}_{}{}^{133}{}_{}{}^{}\mathrm{Pr}$ decay scheme with 20 levels up to 1881 keV. The low-energy excitation structure of ${}_{}{}^{133}{}_{}{}^{}\mathrm{Ce}$ is compared with predications of interacting boson-fermion model calculations.

The formalism for the Dirac-Brueckner approach to the nuclear many-body problem is described including its basis in relativistic two-nucleon scattering. A family of relativistic meson-exchange potentials is constructed which (apart from the usual coupling terms for heavy mesons) apply the pseudovector (gradient) coupling for the interaction of pseudoscalar mesons (π,η) with nucleons. These potentials describe low-energy two-nucleon scattering and the deuteron data accurately. Using these potentials, the properties of nuclear matter are calculated in the Dirac-Brueckner-Hartree-Fock approximation, in which the empirical nuclear matter saturation is explained quantitatively. The effective two-body interaction in the nuclear matter medium (G matrix) is calculated directly in the nuclear matter rest frame. Thus, cumbersome transformations between the two-nucleon center-of-mass frame and the nuclear matter rest frame are avoided. Size and nature of relativistic effects included in the present approach are examined in detail. The formalism, the potentials, and the results of this paper may also serve as a basis and a realistic starting point for systematic relativistic nuclear structure studies as well as for the investigation of further relativistic many-body corrections and of contributions of higher order.