Inclusive and exclusive measurements of light-charged particles ${(}^1$,2,3H${,}^4$He) and heavy fragments have been made for the reaction 480 MeV ${}_{}{}^{56}{}_{}{}^{}$Fe${+}^{\mathrm{nat}}$Ag. The backward hemisphere emission of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ in coincidence with a heavy fragment can be well described by evaporative emission from a combination of three sources: the detected fragment, the undetected fragment, and the composite system prior to scission. Multiplicities for each of these sources are determined for two coincident fragment groups: a fusion-fission-like group and a deeply-inelastic-reaction group. These multiplicities have also been studied at two angles for the trigger fragment (${\theta }_{\mathrm{TR}=26\mathrm{}}$° and 50°). For ${\theta }_{\mathrm{TR}=26\mathrm{}}$° the multiplicity of the light-charged particles ${(}^1$H or ${}_{}{}^4{}_{}{}^{}\mathrm{He}$) emitted from the composite nuclear system (i.e., prior to scission) is ≊(2/3 for the fusion-fission-like fragments, compared to ≊(1/3 for the deeply inelastic reactions. This decrease implies that the deeply inelastic reactions occur in ≊(1/2 the time required for fission reactions. For the deeply inelastic reactions, these multiplicities change with trigger angle. This result also suggests that the lifetime of the composite system exerts some control on the extent of evaporative particle emission. Energy and angular distributions of the coincident light particles suggest extensive emission from a strongly deformed composite system, such as that of a system en route to scission. Low-energy ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particles at forward angles, which cannot be attributed to evaporation, exhibit a dependence on the angle with respect to the scission axis. This result is attributed to emission that occurs very near to the instant of scission. High-energy ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ particles at forward angles are emitted prior to thermalization; they do not depend on the angle with respect to the scission axis.

The Boltzmann master equation model was used to study preequilibrium neutrons emitted in coincidence with light fragments from collisions of ${}_{}{}^{14}{}_{}{}^{}$N${+}^{165}$Ho at 35 MeV/nucleon. The input parameters of the model were adopted from earlier analyses of neutron spectra gated by evaporation residues at similar and somewhat lower incident energies. Both the shapes and the absolute magnitudes of the spectra of neutrons in coincidence with light fragments could be reproduced, provided a reduced excitation energy was used in the calculations. The energy removed from the excitation energy was equated with the collective energy of the intermediate state dinuclear complex. For collisions leading to high-energy fragments near the grazing angle, this collective energy corresponds to the kinetic energies above the Coulomb barrier of the projectilelike and targetlike fragments in the center-of-mass system, assuming a binary reaction. For more strongly damped collisions, the spin rotational energies of the fragments was also included. This is qualitatively in agreement with a binary reaction where the energy held in collective modes of the intermediate state is unavailable for preequilibrium emission processes.

We have studied the reaction of 240 MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions with ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ targets using radiochemistry techniques. We measured the formation cross sections of 139 radioactive nuclides. We have used these data to determine the charge and mass distribution of the fission products. The mass distribution is interpreted as a superposition of two main components: (1) products from high-energy fission processes, 3480±700 mb, and (2) products from low-energy fission, 1500±220 mb. We also estimate the production of targetlike nuclides to be 250±100 mb. The high-energy fission products can be resolved into products due to fusion-fission and fast fission, and products due to high-energy sequential fission. We have constructed the excitation functions of some product nuclides with Z-$Z_{\mathrm{pd}>2\mathrm{}}$.

We present a covariant transport theory for heavy-ion collisions based on the σ-ω model. The two-body collision term is introduced in line with relativistic classical kinetic theory assuming the free nucleon-nucleon cross section in the collision integral. Within this approach, we study collisions of ${}_{}{}^{16}{}_{}{}^{}$O${+}^{16}$O at 600 MeV/nucleon for two different parameter sets of the underlying Lagrangian density, i.e., different equations of state. The most striking result is the strong sensitivity of the transverse momentum distribution on the momentum dependence of the mean field which is self-consistently included in the relativistic approach. We find that residual two-particle collisions might even slightly reduce the transverse momentum $p_t$ due to an increase of stopping power obtained from the collisions. An increase of the cross section by a factor of 2 leads to a much smaller enhancement of $p_t$ than observed in nonrelativistic calculations with a momentum independent mean field. We furthermore present a first application to high-energy photon production and study the influence of the equation of state on the differential photon yield.

A semiclassical model is presented for the calculation of energy spectra of one nucleon transfer reactions to continuum states. Both isolated and overlapping resonances can be discussed. The theory is applied to medium energy heavy-ion reactions and the calculated spectra show general trends in agreement with the experimental data.

Fragment angular momenta are deduced from the radiochemically determined independent isomeric yield ratios of the antimony isotopes ${}_{}{}^{126}{}_{}{}^{}$,128,130Sb in the alpha-particle-induced fission of ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ at various initial excitation energies (18.3–30.2 MeV) and angular momenta (7.86–13.9ħ). It is found that the fragment angular momenta increase with increasing excitation energy and angular momentum of the fissioning nucleus. Calculations of fragment angular momenta are performed based on the Fermi gas approximation for the fissioning nucleus, taking into account the contribution of fissioning nucleus’ angular momentum into that of the fragment. The calculated values agree reasonably well with the experimental values indicating that the fragment angular momenta increase with the increasing initial excitation energy and angular momentum of the fissioning nucleus, with the former playing the dominant role through increased fragment moment of inertia and temperature.

We present a set of coupled integral equations for the reactions γN→πN,ππN and πN→πN,ππN, that satisfy two- and three-body unitarity. These equations are based on a chiral bag Lagrangian in which the coupling to the photon is introduced at the quark level by demanding U(1) local gauge invariance. The final equations include the contribution of both meson exchange and isobar currents.

Within the context of the relativistic Fermi gas model, the concept of ‘‘y scaling’’ for inclusive electron scattering from nuclei is investigated. Specific kinematic shifts of the single-nucleon response in the nuclear medium can be incorporated with this model. Suggested generalizations beyond the strict Fermi gas model, including treatments of separated longitudinal and transverse responses, are also explored.

Formation cross sections of product nuclides in the nuclear reactions of enriched isotope targets, ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$, ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$, ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{60}{}_{}{}^{}\mathrm{Ni}$, ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$, and ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$, by 12-GeV protons were measured with the γ-ray spectroscopy. The measured spallation cross sections were used to obtain the charge-dispersion relation by the least-squares analysis. The present data cover a broader range of the N/Z ratio of the target, (N/Z${)}_T$, from 1.071 to 1.241. The N/Z ratio at the charge-dispersion peak, (N/Z${)}_P$, was found to be consistent with that obtained previously using natural targets in the same mass region. The (N/Z${)}_P$ value for ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ was determined to be 1.110 that is appreciably larger than the (N/Z${)}_T$ value of 1.071. This result seems to contradict a simple statistical interpretation of spallation reactions in terms of the nuclear cascade-evaporation process without including nuclear effects of the target nucleus. Cross sections for (p,capture), (p,p${\pi }^{+}$), and (p,xpyn) reactions were determined unambiguously from the present data. Most of (p,pyn) and (p,2pyn) reactions did not show any noticeable target effect, whereas (p,xpyn) reactions for 3≤x≤9 revealed strong target dependence. The average N/Z ratio of reaction products for x≃7 was found to be consistent with the (N/Z${)}_P$ results of the charge-dispersion analysis. Emission of neutrons depends strongly upon the target nucleus. The A dependence of (N/Z${)}_P$ was estimated.

The charge-symmetry-breaking corrections due to the isospin breaking part of the quantum chromodynamic Hamiltonian, determined by the up-down current quark mass difference, $H_{\mathrm{QCD}=\mathrm{half}\left(m_u\mathrm{-}{m}_d\right)(\mathrm{ū}\mathrm{u}\mathrm{-}\mathrm{d}\mathrm{¯}\mathrm{d}}$), on πNN and ηNN coupling constants and their effect on (δa${)}_{\mathrm{CSB}=a_{\mathrm{pp}}\mathrm{-}{a}_{\mathrm{nn}}}$ are estimated. The effects of $H_{\mathrm{QCD}}$ on the pseudoscalar meson-nucleon coupling constants are calculated via ${\pi }^0$-η,η’ mixing, giving rise to charge-symmetry-breaking one-boson-exchange [one-pion-exchange and one-η-exchange] and two-boson-exchange [two-pion-exchange, πη-exchange etc.] potentials. The importance of charge-symmetry-breaking two-boson exchange is emphasized.

Based on a meson exchange NN interaction, which contains NΔ and ΔΔ box diagrams, the contributions of one-pion loop self-energy corrections to the nucleon and delta-isobar propagators are studied. In the framework of time-ordered perturbation theory, their independent iteration on both baryon lines leads to dressing factors which give well-defined off-shell corrections to the meson exchange contributions and provide the isobar width. Results are presented for the NN phase shifts and a number of observables up to 1 GeV. Satisfactory agreement with empirical data is found, indicating no need for introduction of genuine quark effects.

${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$(EC${)}^{44}$Sc was studied both experimentally and theoretically. The experimental study–motivated by current interest in first-forbidden beta decay–leads to more precise branching ratios for the electron capture decay to the $0^{\mathrm{-}}$ and $1^{\mathrm{-}}$ levels of ${}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$ as well as to other ancillary results including precision γ-ray energy determinations, γ-ray branching ratios from the 146-keV level of ${}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$, and lifetimes of the 68- and 146-keV excited states of ${}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$. Beta and gamma decays were considered in a spherical shell model calculation utilizing 0h-4p and 1h-5p model spaces (relative to ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$). The formulae relating non-unique first-forbidden electron capture decay rates to nuclear matrix elements have apparently never before been applied; therefore, the application is discussed in detail. The model predictions are not in very good agreement with experiment. Possible reasons for the poor agreement are discussed. Nevertheless, the $0^{+}$→$0^{\mathrm{-}}$ decay provides some further evidence for the existence of a large meson enhancement of the ΔJ=0 timelike component of the axial current.

A new technique has been recently described for the absolute calibration of intense sources of pulsed radiation in the 0.2–1.5 MeV range of photon energies. An activation technique, it depended upon the storage of samples of the irradiating spectrum in the form of populations of nuclei excited to isomeric states with lifetimes of seconds to hours. Described here is the use of such a calibrated source to resolve severe conflicts in previous studies of the reaction ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$(γ,γ’${)}^{115}$${\mathrm{In}}^{\mathit{m}}$ through the 1078 keV ${\mathit{J}}^{\mathrm{\pi }}$=(5/$2^{+}$ level; this mode has traditionally served as the archetype for (γ,γ’) reactions. We report an integrated cross section of (18.7±2.7)×${10}^{\mathrm{-}2}$ ${\mathrm{cm}}^2$ keV with no evidence of any importance of nonresonant channels of excitation.

The half-life of ${}_{}{}^{163}{}_{}{}^{}\mathrm{Ho}$ was investigated by a mass spectrometric determination of the quantity of ${}_{}{}^{163}{}_{}{}^{}\mathrm{Dy}$ formed by the electron-capture decay of ${}_{}{}^{163}{}_{}{}^{}\mathrm{Ho}$. The half-life of ${}_{}{}^{163}{}_{}{}^{}\mathrm{Ho}$ was measured to be 4569±30 yr (68% confidence level). The result of this work is in excellent agreement with the value previously obtained by Baisden et al.

The particle-hole spectra of light nuclei are examined in the self-consistent random phase approximation based on fully relativistic Hartree and Hartree-Fock models for the nuclear ground state. The particle-hole interaction is completely prescribed by the ground-state calculation. It includes σ, ω, ρ, and π meson exchanges, with σ and ω parameters adjusted to fit the bulk properties of nuclear matter. Differences between Hartree (no exchange) and Hartree-Fock (with exchange) predictions for the spectra are discussed.

A model Hamiltonian is advanced which provides a computationally efficient means of investigating nuclear dynamics. The Hamiltonian includes both Coulomb and isospin-dependent terms, and incorporates antisymmetrization effects through a momentum-dependent potential. Unlike many other classical or semiclassical models, the nuclei of this simulation have a well-defined ground state with a nonvanishing 〈$p^2$〉. It is shown that the binding energies per nucleon and rms radii of these ground states are close to the measured values over a wide mass range.

The structure of the alpha particle is examined through microscopic studies with a variety of interaction models. Variational calculations are presented for the Argonne, Bonn r space, Reid V8, and Nijmegen nucleon-nucleon interaction models, as well as results obtained with the Urbana model 7 three-nucleon interaction. Green’s function Monte Carlo results are reported for the Reid V8 interaction and compared with variational results to illustrate the strengths and shortcomings of the variational method. In addition to ground-state energies, one- and two-body distribution functions are shown for the various models, as well as D-state probabilities. Information about the distribution can, in principle, be determined from electron scattering, while the D-state probability may be accessible through d+d→α+γ experiments.

We describe a new approach to the computation of ground-state energies of nuclear matter (and by extension finite nuclei) and of excited states of predominantly particle-hole character. We assume that a phenomenological Hamiltonian can be defined containing two- and more-body smooth effective potentials which sum the results of short-range correlations. A formula for the ground-state energy is then developed wherein the effects of long-range correlations are treated explicitly in terms of ground-state correlation amplitudes; determining equations for the latter can be obtained either by a variational method or by an equation of motion approach. In leading order these are the equations of the random-phase approximation. The variational method is described only to leading order, but the equation of motion method is carried sufficiently far to provide a closed phenomenological framework. The aim of an accompanying paper is to provide a microscopic foundation for this phenomenology.

In an accompanying paper, we have described a new approach to the computation of ground-state energies and of correlated particle-hole excitations in terms of a phenomenological pseudo-Hamiltonian containing two- and more-body smooth effective potentials which sum the results of short-range correlations and of density fluctuation amplitudes which describe long-range correlations. In this paper we study the problem of relating the pseudopotentials to a (possibly singular) microscopic interaction with the aid of tools developed within the framework of the coupled cluster theory of Kümmel and his collaborators, the results containing both familiar and unfamiliar elements. For example, the formulas derived, which depend on Bethe-Goldstone and Bethe-Faddeev amplitudes, include new definitions of particle-hole scattering matrix elements. An important consistency check is satisfied, in that the problem of defining the phenomenological potentials in terms of the microscopic ones must yield two separate but equivalent solutions, once within the framework of the theory of the ground-state energy and a second time within the framework of the theory of excitations. The entire package is studied with the aid of a modified version of coupled cluster theory, and shown to form a self-consistent entity. Among the desirable features of the formalism is that the large gap in the single-particle energy spectrum often utilized in existing formalisms is naturally absent from the current one.

The variational Hartree method is applied to a system of N bosons interacting via Skyrme-type attractive and repulsive forces. When the system condenses into its ground state, the wave function for a single boson, φ, may be described by means of the nonlinear, time-independent Schrödinger equation, ${\mathrm{\nabla }}^2$φ=${\mathrm{\epsilon }}_1$φ-A‖φ${\mathrm{\Vert }}^2$φ+B‖φ${\mathrm{\Vert }}^4$φ. In one dimension, this equation has a single, analytic, bound state solution and exhibits the property of saturation. In the physically more interesting case of three dimensions with spherical symmetry, no analytic solutions are known, so that a numerical solution must be resorted to, and this shows that saturation is again obtained. However, an analytic approximation to the three-dimensional wave function, which is very accurate for values of ${\epsilon }_1$B/$A^2$>0.1, is deduced and studied. Approximate analytic expressions for the Hartree potential energy, kinetic energy, and mean square radius of the system are thereby derived, and applications to finite nuclei and infinite nuclear matter are considered.