Differential cross sections for inelastic pion scattering from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at incident energies of 100 to 291 MeV and momentum transfers ≤300 MeV/c have been measured and are compared to results obtained from other probes, particularly electrons and protons. Angular distributions and excitation functions are presented for many of the bound states, including the 4.44-MeV ($2^{+}$,0), 7.66-MeV ($0^{+}$,0), 9.64-MeV ($3^{\mathrm{-}}$,0), 12.71-MeV/15.11-Mev ($1^{+}$;0,1) doublet, 16.11-MeV ($2^{+}$,1), 19-MeV ($4^{\mathrm{-}}$;0,1) doublet, and $2^{\mathrm{-}}$ states at 18.25 and 19.4 MeV. Distorted-wave impulse-approximation calculations using both macroscopic and microscopic descriptions of the nuclear wave functions are compared to the data. The observation of an anomalous excitation function for the 15.11-MeV level and the observation of dramatic ${\pi }^{+}$/${\pi }^{\mathrm{-}}$ asymmetries near 18 and 19 MeV excitation due to isospin mixing between $2^{\mathrm{-}}$ states and between members of the $4^{\mathrm{-}}$ doublet are of particular interest.

We present a multichannel unitary theory of single pion photoproduction from a baryon B. Here, B is the nucleon or Δ(1232), with possible extension to include the Roper resonance and strange baryons. We treat the baryon as a three-quark state within the framework of the gauge and chiral Lagrangian, derived from the Lagrangian for the chiral bag model. By first exposing two-body, and then three-body unitarity, taking into consideration the ππB and γπB intermediate states, we derive a set of equations for the amplitudes both on and off the energy shell. The Born term in the expansion of the amplitude has the new feature that the vertices in the pole diagram are undressed, while those in the crossed, contact, and pion pole diagrams are dressed.

Based on some arguments from relativistic field theory, the individual nucleons in a nucleus at rest are assumed to act as static sources for potentials which then enter the Dirac equation describing a projectile proton additively. The two-component version of the eikonal approximation is then used to estimate the scattering amplitude both for the full model and using the relativistic impulse approximation. In both cases the lowest order corrections to simple Glauber theory are quadratic in the nuclear densities, but dependence on the nucleon-nucleon interaction differs: In the complete model the corrections depend on the range of the nucleon-nucleon interaction even in the short range approximation, while in the relativistic impulse approximation they do not. Some numerical results are presented for the elastic scattering of 800 MeV protons on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$.

Microscopic calculations of low energy alpha neutron scattering are reported for the resonant $J^{\pi }$${=(1/2\mathrm{}}^{\mathrm{-}}$ and ${(3/2\mathrm{}}^{\mathrm{-}}$ states. A good qualitative fit to the experimental L⋅S splitting is obtained, although discrepancies of the order of 1–2 MeV remain. Results with two different nucleon-nucleon interaction models are presented, and the effects of three-nucleon interactions are discussed.

The possibility of π-N bound states in nuclear matter is examined. It turns out that a very special many-body effect allows states which have no counterpart in the two-body system. In fact, around a logarithmic singularity, generated by the Pauli blocking, an attractive interaction—however small—creates bound states whose origin greatly resembles that of the Cooper bound state of two electrons in a superconductor or the Suhl-Abrikosov resonance in the Kondo effect. Coupling with other reaction channels gives the bound states a finite lifetime.

Contributions of the two-gluon exchange diagrams to the nucleon-nucleon spin-orbit interaction are investigated via the Glauber approximation, and comparisons are made with the gluon-quark exchange diagrams calculated in the resonating group method. Numerical results at $E_{\mathrm{lab}=800\mathrm{}}$ MeV show that contributions from these diagrams are relatively small as compared to those from the resonating group calculations when the oscillator parameter λ of the three-quark cluster and the interaction range a are fitted from the nucleon radius $r_{\mathrm{N}}$ at 0.83 and 0.59 fm. A non-negligible contribution for λ and a at $r_{\mathrm{N}=0.42\mathrm{}}$ fm. Possible reasons are briefly discussed.

A unified treatment is presented of allowed and forbidden nuclear β decay in the presence of an intense, low-frequency, coherent classical electromagnetic wave. After discussing the various scales in the problem, a straightforward evaluation of the transition probabilities is presented which avoids techniques that have been previously criticized. A brute force integration of the electron spectrum for the nonrelativistic (electron) case demonstrates that there is no field-dependent enhancement of the total rate in the long-wavelength limit, which agrees with some previous conclusions. A classical argument is presented which demonstrates in all of our cases that there is no enhancement of the total rate in that limit. Finally, a discussion in perturbation theory of many of the appropriate quantum mechanical excitation mechanisms is presented, together with a discussion of gauge invariance.

We have measured the upper range of the positron momentum spectrum from the decay of ${}_{}{}^8{}_{}{}^{}\mathrm{B}$. This spectrum is compared to that predicted on the basis of various available measured alpha spectra from the breakup of the daughter ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$ nucleus. Recoil order corrections are included in the comparison. After choosing the most consistent alpha spectrum we infer the ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ neutrino spectrum which we integrate over the ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$(${\nu }_{\mathrm{e}}$,${\mathrm{e}}^{\mathrm{-}}$)${\mathrm{}}^{37}$Ar cross section. We obtain (1.07±0.02)×${10}^{\mathrm{-}42}$ ${\mathrm{cm}}^2$ for this average cross section where the error is an estimate of the rms (i.e., 1σ) statistical uncertainty from our positron spectrum measurement. This value is appropriate for predicting the solar neutrino capture rate in ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$ detectors. Systematic errors in the determination of the integrated cross section are discussed.

Decay studies of on-line mass-separated low-spin ${}_{}{}^{83}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{83}{}_{}{}^{}\mathrm{Y}$ sources were carried out. γ, x-ray, conversion-electron singles and time-multiscale, and γ-γ-t measurements were used to deduce the ${}_{}{}^{83}{}_{}{}^{}\mathrm{Zr}$ decay scheme with 18 levels up to 1250 keV. The investigations establish the decay properties of ${}_{}{}^{83}{}_{}{}^{}\mathrm{Y}_{}^{\mathrm{m}}{}_{}{}^{}$${\mathrm{}\left(\right(3/2\mathrm{})\mathrm{}}^{\mathrm{-}}$) and do not confirm the previously proposed high-spin ${}_{}{}^{83}{}_{}{}^{}\mathrm{Zr}_{}^{\mathrm{m}}{}_{}{}^{}$(${\mathrm{T}}_{1/2}$=6 s). The low lying structure of ${}_{}{}^{83}{}_{}{}^{}\mathrm{Y}$ is compared with published theoretical calculations in terms of collective models.

The conditions necessary to exhibit rotational bands are investigated for near-vibrational systems (vibrational systems with anharmonicities which can be treated perturbatively) in any spatial dimension. Rotational bands obtained by Buck and collaborators in their study of potentials describing alpha-clustering nuclei, and the O(5) bands arising in the vibrational limit of the collective model are shown to have a similar origin.

Realistic calculations of the pair transfer strength functions were performed for the nuclei ${}_{}{}^{162}{}_{}{}^{}\mathrm{Dy}$ and ${}_{}{}^{164}{}_{}{}^{}\mathrm{Dy}$ as a function of the angular momentum and excitation energy in the frame of the self-consistent, cranked Hartree-Fock-Bogoliubov and random-phase-approximation theories. At low angular momenta most of the strength is concentrated in the ground-to-ground transition, whereas at high angular momenta, after the pairing correlation has dropped, the strength is spread among several states located a few (≤4) MeV above the yrast line.

Mean lifetimes of levels in ${}_{}{}^{30}{}_{}{}^{}\mathrm{P}$ have been measured by application of the Doppler-shift attenuation method and the ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$(p,γ${)}^{30}$P reaction. Values or limits were determined for the lifetimes of 27 bound levels below the excitation energy of 6.1 MeV; the lifetimes of eight of these levels are reported for the first time. The targets were prepared by implanting ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$ into Ta backings in order to provide effective stopping of recoils. The Monte Carlo method and experimental stopping powers were used in the Doppler-shift attenuation analysis. The experimental transition strengths are compared with the predictions of recent shell-model calculations.

Electromagnetic properties of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ are studied using a microscopic (α+d) cluster model. In addition to the ground state of the clusters, their breathing excited states are included in the wave function in order to take into account the distortion of the clusters. The generator coordinate calculations are free from the spurious center-of-mass motion and arbitrary parameters. The cluster stability condition is satisfied. The elastic charge form factor $F_{C0}$ is in good agreement with experiment up to momentum transfer 8 ${\mathrm{fm}}^{\mathrm{-}2}$. The discrepancy appearing at momentum transfer $q^2$>8 ${\mathrm{fm}}^{\mathrm{-}2}$ must be attributed to the omission of the short range nucleon correlation. The ground state magnetic form factor $F_{M1}$ and the inelastic charge form factor $F_{C2}^{\mathrm{*}}$ are also well described. The breathing excited states of d influence the behavior of $F_{C0}$ at high momentum transfer only, but they have an effect on $F_{M1}$ and $F_{C2}^{\mathrm{*}}$ even at low momentum transfer. The effect of the breathing states of α on the form factors proves to be negligible except at high momentum transfer. The ground-state charge density, rms charge radius, the magnetic dipole moment and a reduced transition strength are also obtained in fair agreement with experiment.

We examine the role of many-body effects provided by the chiral sigma model in the equation of state of symmetric nuclear matter and neutron-rich matter. Using the parameters determined by fitting the known equilibrium properties of symmetric and slightly neutron-rich matter, the equation of state with arbitrary neutron excess is calculated. The role of the nuclear symmetry energy on the structure of beta stable neutron stars is discussed.

Relativistic Hartree orbitals for nonspherical (even-even) nuclei have been calculated self-consistently from a Lagrangian field theory using the mean field approximation. All parameters in this model are determined from the properties of infinite nuclear matter, so there are no parameters which can be adjusted in the calculation of the orbitals. The energy levels, rms radii, and quadrupole moments are in qualitative agreement with earlier nonrelativistic calculations and with experiment; however, the overall deformations (which are fixed by the self-consistency) are somewhat smaller than those obtained experimentally and from nonrelativistic calculations. The difference may be due to the large compressibility characteristic of relativistic mean field calculations. These orbitals and the self-consistently determined mean fields provide a framework for a detailed investigation of the compressibility as well as other relativistic effects.

It is shown that the standard self-consistency argument, reconciling the nuclear independent-particle model with the large low-energy nucleon-nucleon cross sections, loses its validity for nucleon bags with a radius larger than about 1 fm.

The recently formulated fermion dynamical symmetry model treats low-lying collective levels as states classified in a pseudo-orbit pseudo-spin (k-i) basis having either k=1 and zero i seniority, or i=(3/2) and zero k seniority. The validity of this suggestion, which has not previously been subjected to a microscopic examination, is determined for even-even nuclei in the sd shell, for which the model is phenomenologically successful, by comparing these states with the eigenfunctions of a realistic Hamiltonian. Most low-lying levels are almost orthogonal to the fermion dynamical symmetry model zero seniority subspaces.

The structure of infinite nuclear matter and finite nuclei is studied in the framework of the relativistic Hartree-Fock approximation. Particular attention is paid to the contribution of isovector mesons (π,ρ). A satisfactory description of binding energies and densities can be obtained for light as well as heavy nuclei. The spin-orbit splittings are well reproduced. Connections with nonrelativistic formulations are also discussed.

We report an efficient method for the calculation of geometrical structure coefficients for coupling between all symmetry components of the wave function for the trinucleon system through central and tensor interactions, which makes the calculation of geometrical structure coefficients simple, economical, and accurate. We also derive sum rules for all kinds of geometrical structure coefficients which can be utilized as an independent check for the calculated geometrical structure coefficients. We compare the present and other existing methods for calculating geometrical structure coefficients for S-S coupling and also report the accuracy of calculated geometrical structure coefficients for coupling between other symmetry components of the wave function.

Cesium isotopes have been oriented in iron, following on-line implantation at temperatures down to 8 mK. Analysis of results on transitions in the decay of ${}_{}{}^{119}{}_{}{}^{}\mathrm{Cs}_{}^{\mathrm{m}}{}_{}{}^{}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Cs}_{}^{\mathrm{g}}{}_{}{}^{}$, and ${}_{}{}^{121}{}_{}{}^{}\mathrm{Cs}_{}^{\mathrm{m}}{}_{}{}^{}$ yields the hyperfine field $B_{\mathrm{hf}}$(CsFe)=(+)40.8(7) T. A repeated sequence of short pulse implantation followed by relaxation has been used to measure the Korringa constant, $C_K$=0.059(15) K s for ${}_{}{}^{121}{}_{}{}^{}\mathrm{Cs}_{}^{\mathrm{m}}{}_{}{}^{}$ in iron. The magnetic moment of ${}_{}{}^{118}{}_{}{}^{}\mathrm{Cs}_{}^{\mathrm{m}}{}_{}{}^{}$ ($T_{1/2}$=17 s), previously unknown, is deduced to be ‖μ‖=5.4(11) ${\mu }_{\mathrm{N}}$, which identifies the presence of the $g_{9/2}$ intruder Nilsson orbital.