Inclusive inelastic electron scattering cross sections for ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ were measured for excitation energies below 18 MeV. Longitudinal and transverse response functions were determined from these cross sections for six values of the three-momentum transfer q in the range 0.88 <q<2.87 ${\mathrm{fm}}^{\mathrm{-}1}$. A previously observed C0 multipole enhancement near threshold in the two-body channel for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is confirmed but is not observed for ${}_{}{}^3{}_{}{}^{}\mathrm{H}$. The experimental data are found to be in good agreement with two recent calculations of the longitudinal and transverse response functions. The first uses variational ground-state wave functions and the orthogonal correlated states method to describe the two- and three-body breakup channels. The second uses bound and continuum Faddeev wave functions obtained for a simple central potential. Agreement with the data is good for the first model and better for the second. The inclusion of final-state interactions (FSI) in the Faddeev continuum is found to be very important in these threshold breakup kinematics; in many cases inclusion of FSI changes the response functions by factors of two or three giving excellent agreement with the data. The transverse response functions are well reproduced, even though neither model includes meson exchange currents. Ratios of the response functions for the two nuclei are also well described.

Recent evidence of the importance of the pion in the dynamics of few-nucleon systems is reviewed. Calculations of the triton binding energy and the nucleon-nucleon phase shifts, and the application of chiral perturbation theory to few-nucleon systems, have highlighted the role of the pion. Qualitative aspects of chiral constraints in few-nucleon forces are reviewed, and the connection between the static Brueckner-Watson and Taketani-Machida-Ohnuma two-pion-exchange two-nucleon forces is shown to be the same as that between the Weinberg and Coon-Friar two-pion-exchange three-nucleon forces. Compact expressions for these forces are given in the Appendix.

The equivalent two-body method [H. Feshbach and S. I. Rubinow, Phys. Rev. 98, 188 (1955)] has been applied to investigate the weakly bound states of a three-body system. An analytical expression for the long-range effective potential is derived if two-body interactions are short-range potentials with Yukawa forms. The weakly bound excited state for the system with two heavy particles and a light particle is first obtained if there is no bound state for two-body subsystems.

Recent data on the reaction pp→pp${\mathrm{\pi }}^0$ close to threshold indicate unexpectedly large s-wave pion production, with a possible explanation from a heavy meson exchange contribution to the axial charge. An amplitude with the same quantum numbers appears also in negative-pion absorption on proton pairs in light nuclei. In this paper the effect of this enhancement is estimated and found to be significant in the observables of absorption on ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. Also some predictions are given for the qualitative effect in pn→(pp${)}_{\mathit{s}\mathrm{wave}}$ ${\mathrm{\pi }}^{\mathrm{-}}$

The interacting boson model with s and d bosons has been used to describe the nuclear structure effects in sub-barrier fusion. We generalize the previous formalism to include arbitrary kinds of bosons in the target nucleus and investigate whether g bosons have any discernible effect on fusion reactions. In particular, we compare the fusion cross sections, barrier distributions, and the average angular momentum of the compound nucleus in the sd and sdg boson models.

The Schwinger-Dyson equations for the nucleon and meson propagators are solved self-consistently in an approximation that goes beyond the Hartree-Fock approximation. The traditional approach consists in solving the nucleon Schwinger-Dyson equation with bare meson propagators and bare meson-nucleon vertices; the corrections to the meson propagators are calculated using the bare nucleon propagator and bare nucleon-meson vertices. It is known that such an approximation scheme produces the appearance of ghost poles in the propagators. In this paper the coupled system of Schwinger-Dyson equations for the nucleon and the meson propagators are solved self-consistently including vertex corrections. The interplay of self-consistency and vertex corrections on the ghosts problem is investigated. It is found that the self-consistency does not affect significantly the spectral properties of the propagators. In particular, it does not affect the appearance of the ghost poles in the propagators.

An effective two nucleon interaction is defined by an optimal fit to select on- and half-off-of-the-energy shell t and g matrices determined by solutions of the Lippmann-Schwinger and Brueckner-Bethe-Goldstone equations with the Paris two nucleon interaction as input. As such, it reproduces the interaction on which it is based better than other commonly used, density dependent effective interactions. This new (medium modified) effective interaction, when folded with appropriate density matrices, has been used to define proton${\mathrm{-}}^{12}$C and proton${\mathrm{-}}^{16}$O optical potentials. With them elastic scattering data are well fit and the medium effects identifiable.

Relativistic density-dependent effective interactions for nucleon-nucleus scattering based upon a complete set of Lorentz-invariant NN amplitudes are used in calculations of elastic and inelastic scattering to normal-parity states of self-conjugate targets. Owing to distortion of Dirac spinors by the relativistic mean fields, the effective interaction appropriate for use in a Schrödinger formalism incorporates relativistic density dependence, which is stronger for inelastic than elastic scattering. The dominant effect for normal-parity transitions is equivalent to a short-ranged repulsive contribution to the real central interaction that is proportional to density and nearly independent of energy. Pauli blocking of occupied intermediate states is included and gives results similar to the familiar Clementel-Villi damping of the absorptive potential. The relativistic effective interaction is compared with nonrelativistic G-matrix calculations and with empirical effective interactions fitted to data for proton elastic and inelastic scattering. Calculations for elastic and inelastic scattering are compared with data for 200, 318, and 500 MeV and we find that the agreement with data improves as the energy increases. The density dependence of the relativistic model is much stronger at low energies than either the G matrix or the empirical interaction; its repulsive contribution to the central interaction is too strong to give a good description of the data for 200 MeV. Near 500 MeV the relativistic interaction is closer to the empirical interaction and better agreement with the data is obtained, whereas the density dependence of nonrelativistic effective interactions is too small.

Recent calculations of s-wave pion production have severely underestimated the accurately known pp→pp${\mathrm{\pi }}^0$ total cross section near threshold. In these calculations, only the single-nucleon axial-charge operator is considered. We have calculated, in addition to the one-body term, the two-body contributions to this reaction that arise from the exchange of mesons. We find that the inclusion of the scalar σ-meson exchange current (and lesser ocntributions from other mesons) increases the cross section by about a factor of 5 and leads to excellent agreement with the data. The results are sensitive neither to changes in the distorting potential that generates the NN wave functions nor to different choices for the meson-nucleon form factors.

High-spin states in the nuclei ${}_{}{}^{47}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{47}{}_{}{}^{}\mathrm{V}$, ${}_{}{}^{47}{}_{}{}^{}\mathrm{Cr}$, ${}_{}{}^{48}{}_{}{}^{}\mathrm{V}$, and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Cr}$ have been observed using the reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${+}^{10}$B at E${(}^{40}$Ca)=150 MeV. The prompt γ rays were detected in an array of nineteen escape-suppressed Ge detectors in coincidence with the recoiling nuclei which were identified in A and Z with a recoil separator. Rotational structures were observed in all these nuclei, apart from ${}_{}{}^{47}{}_{}{}^{}\mathrm{Ti}$, up to spins near the maximum for the (${\mathit{f}}_{7/2}$${)}^{\mathit{z}+\mathit{n}}$ configuration. A rapid increase in the Coulomb displacement energy for mirror states in ${}_{}{}^{47}{}_{}{}^{}\mathrm{V}$ and ${}_{}{}^{47}{}_{}{}^{}\mathrm{Cr}$ occurs at ${\mathit{J}}^{\mathrm{\pi }}$=25/$2^{\mathrm{-}}$. A backbend occurs in ${}_{}{}^{48}{}_{}{}^{}\mathrm{Cr}$ at ${\mathit{J}}^{\mathrm{\pi }}$=${10}^{+}$.

Measurements of inelastic electron scattering from ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ and ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$ have been performed at low energy and backward angle to determine the distribution of M1 and M2 strength in these nuclei. The total observed M1 strength in ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ is approximately 93% of that predicted in the measured energy region by shell-model calculations using effective M1 operators. In ${}_{}{}^{38}{}_{}{}^{}\mathrm{Ar}$, the single strong M1 transition predicted by shell-model calculations was not observed. Instead, a number of weak transitions were observed, with total M1 strength equal to about 134% of the predicted strength.

We have investigated correlations between evaporated protons and discrete γ rays in the heavy-ion fusion-evaporation reactions ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${(}^{27}$Al,3p${)}^{82}$Sr and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${(}^{28}$Si,4p${)}^{82}$Sr. 3p-γ and 4p-γ coincidences were measured using a 4π charged-particle detector array. The events studied were completely reconstructed kinematically in order to determine the excitation energy of formation of ${}_{}{}^{82}{}_{}{}^{}\mathrm{Sr}$. Correlations arising from well-understood kinematic effects were measured and found to be well reproduced by predictions made by the statistical-model evaporation code pace2. Dynamical correlations due to nuclear structure effects were searched for by measuring proton spectra in coincidence with discrete γ rays from four rotational bands in ${}_{}{}^{82}{}_{}{}^{}\mathrm{Sr}$. Contrary to published results, no significant shifts of the first moment of the spectra were observed.

Strong evidence for the existence of previously postulated deformed excited states in ${}_{}{}^{98}{}_{}{}^{}\mathrm{Zr}_{58}^{}{}_{}{}^{}$ has been obtained by an accurate measurement of the ${\mathrm{\rho }}^2$($0_3^{+}$→$0_2^{+}$) value for the decay of the second excited $0^{+}$ state at 1436 keV. In the neighboring isotope ${}_{}{}^{99}{}_{}{}^{}\mathrm{Zr}_{59}^{}{}_{}{}^{}$, at the edge of the region of strong ground-state deformation, evidence is found for a rotational band built on the state at 614 keV. Systematics of the excitation energies of the deformed states in Zr nuclei and their Sr neighbors show that the apparent sudden onset of deformation is explained by the steady lowering of a strongly deformed potential minimum. Therefore, an extra strong interaction between proton-neutron spin-orbit partners, acting in the $0_2^{+}$ states, need not be invoked to explain the origin of the sudden onset of deformation.

The low-energy neutron resonance data of the even-even nuclei ${}_{}{}^{152}{}_{}{}^{}\mathrm{Sm}$, ${}_{}{}^{158}{}_{}{}^{}\mathrm{Gd}$, ${}_{}{}^{162}{}_{}{}^{}\mathrm{Dy}$, ${}_{}{}^{166,168}{}_{}{}^{}\mathrm{Er}$, ${}_{}{}^{182}{}_{}{}^{}\mathrm{W}$, ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$, and ${}_{}{}^{236,238}{}_{}{}^{}\mathrm{U}$ have been examined in order to test the validity of the Porter-Thomas distribution of the reduced neutron widths—a chi-squared distribution with one degree of freedom (v=1). In an attempt to circumvent the ever-present problems of missed or spurious s wave levels as well as extra p wave levels, a maximum likelihood statistic was employed which used only measured widths greater than some minimum value. A Bayes-theory test applied to the data helped to ensure that p wave contamination of the s wave level population was not significant. The error-weighted value of the number of degrees of freedom for the nine nuclei studied, 〈v〉=0.98±0.10, is consistent with the theoretical expectation of v=1.

It is shown that in a soluble triaxial quasispin model the good quasispin states ‖JK〉 and ‖J〉 can be established on basis SU(2)×SU(2) by means of the diagonalization method. The energy eigenstate ‖J〉 has an approximate good quantum number K which can be determined through the procedure proposed here. The triaxiality of the exact solutions of the model Hamiltonian and the characteristics of the energy spectra are discussed. Two new constrained Hartree-Fock (CHF) methods are proposed and solved. The comparisons of calculated CHF spectra with exact solutions show that the new CHF prescriptions proposed in this paper are the effective methods for producing states having good quasispin quantum numbers and the spectra with multiband structure.

We examine the predictions for nuclear charge radii made by an extended Thomas-Fermi mass formula, the first to be built entirely on microscopic forces, and the finite-range droplet model mass formula, the most refined of the droplet-model approaches. The former is highly successful, the parameters emerging from the mass fit giving an optimal fit to charge radii also, without any further adjustment. The latter model in its published form seems to suffer from an inappropriate choice for the values of some of the parameters, and we discuss how improvement might be possible.

The Λ binding energies obtained from the (${\mathrm{\pi }}^{+}$, ${\mathit{K}}^{+}$) data are analyzed with the aid of suitable Λ-nucleus potentials. Exact and approximate analytic expressions, as functions of the mass number, for the binding energy and other energy quantities of a Λ hyperon in hypernuclei in ground and excited states are proposed and the region of their validity is discussed. The density dependence of the Λ-nucleus potential is taken into account in an approxiamte way and it turns out that its role is essential for a reliable description of the recent hypernuclear data. The formulas for the ground state Λ energy are used to derive approximate expressions for the Λ binding energy in double Λ hypernuclei.

We apply the auxiliary-field Monte Carlo approach to the nuclear shell model in the 1s-0d configuration space. The Hamiltonian was chosen to have isovector pairing and isoscalar multipole-multipole interactions, and the calculations were performed within the fixed-particle, canonical ensemble. The results demonstrate the feasibility of the method for N≠Z even-even and odd-odd N=Z nuclei. In particular, static observables for even-even Ne isotopes and ${}_{}{}^{22}{}_{}{}^{}\mathrm{Na}$ compare well with results obtained from exact diagonalization of the Hamiltonian. Response functions are presented for ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ and compared with exact results, and the viability of cranked calculations for N≠Z even-even nuclei is addressed. We present methods for computing observables in the canonical ensemble using Fourier extraction, and for determining the nucelar shape.

Starting from the shell model, we develop the foundations for a quantum theory of large amplitude collective motion that generalizes and extends some of our earlier work and is otherwise distinct from other methods espoused in the literature. The technical basis of our approach is the amalgamation of the Born-Oppenheimer approximation into the framework of the Kerman-Klein method. The version of the latter that is utilized is one that is applicable to an arbitrary two-body interaction and in which the Pauli principle is satisfied at each level of approximation. In the approximation considered, the one-band or adiabatic approximation, the fit is smooth and seamless, so much so that it is suggested that a multiband approach will be necessary to uncover the Berry potentials. The physics is worked out to the first two orders in the reciprocal of the number of particles participating in the collective motion, comprising the mean-field approximation and the first quantum fluctuations thereto, respectively. It is emphasized that the quantization procedure is integral to the method: there is no ad hoc requantization of a classical limit.

In an accompanying paper we have described a method that provides a foundation for a quantum theory of large amplitude collective motion. In this method, only the collective degrees of freedom are initially bosonized, i.e., represented by canonical variables. By contrast, in this paper, we describe an alternative method in which all elementary (fermion) density operators defined in the shell model are bosonized. Once again it involves an amalgamation of the Born-Oppenheimer approximation with a version of the Kerman-Klein method. Compared to the alternative it has the advantages of bearing a closer resemblance to the corresponding molecular problem and bringing the role of the Berry potentials clearly into focus. On the other hand, the physical justification for bosonizing the noncollective degrees of freedom is not obvious, and the Pauli principle is only satisfied approximately at every stage of approximation. The method in this paper may also be considered to be an extension to the large amplitude domain of the quantum theory of anharmonic vibrations developed by Marshalek and Weneser. The boson formalism is applied to the problem of the coupling of the giant dipole mode to a quadrupole mode, studied recenty for the effect of Berry potentials by LeTourneux and Vinet.