The breathing-mode giant monopole resonance (GMR) is studied within the framework of the relativistic mean-field theory (RMF) using the generator coordinate method (GCM). The constrained incompressibility and the excitation energy of isoscalar giant monopole states are obtained for finite nuclei with various sets of Lagrangian parameters. A comparison is made with the results of nonrelativistic constrained Skyrme Hartree-Fock (HF) calculations and with those from Skyrme random phase approximation (RPA) calculations. In the RMF theory the GCM calculations give a transition density for the breathing mode, which greatly resembles that obtained from the Skyrme HF+RPA approach and also that from the scaling mode of the GMA. From the systematic study of the breathing-mode as a function of the incompressibility in GCM, it is shown that the GCM succeeds in describing the GMR energies in nuclei and that the empirical breathing-mode energies of heavy nuclei can be reproduced by forces with an incompressibility close to K=300 MeV in the RMF theory.

In this work we formulate the reaction theory of parity violation in compound nuclear states using Feshbach’s projection operator formalism. We derive in this framework a complete set of terms that contribute to the longitudinal asymmetry measured in experiments with polarized epithermal neutrons. We also discuss the parity violating spreading width resulting from this formalism. We then use the above formalism to derive expressions which hold in the case when the doorway state approximation is introduced. In applying the theory we limit ourselves in this work to the case when the parity violating (PV) potential and the strong interaction are one body. In this approximation, using as the doorway the giant spin-dipole resonance and employing well-known optical potentials and a time-reversal even, parity odd one-body interaction we calculate or estimate the terms we derived. Among others, we evaluate numerically a new ‘‘direct’’ term and the channel coupling term first derived by Lewenkopf and Weidenmüller, this in addition to the evaluation of the main ‘‘compound’’ term. In our calculations we explicitly orthogonalize the continuum and bound wave functions. We find the effects of orthogonalization to be very important. Our conclusion is that the present one-body theory cannot explain the average longitudinal asymmetry found in the recent polarized neutron experiments. We also confirm the discrepancy, first pointed out by Auerbach and Bowman, that emerges, between the calculated average asymmetry and the parity violating spreading width, when distant doorways are used in the theory.

The basis states generated in the sp(6)⊃u(3) algebra of the fermion dynamical symmetry model (FDSM) are studied. The assumption made in the FDSM that the lowest-lying states of even nuclei are states with u=0 and the largest SU(3) quantum numbers is analyzed. A pairing plus quadrupole-quadrupole interaction is diagonalized for valence nucleons of the actinide region in (i) a complete basis for two protons and two neutrons, (ii) a truncated FDSM basis for 10 protons and 14 neutrons, and (iii) a strongly-coupled FDSM basis for 24 nucleons. The existence of a multiplicity of FDSM bases is taken into account. In all cases, the overlap between the truncated FDSM subspace and the full shell model space is very small for the n-identical-particle calculations. This implies that a complicated renormalization of shell model effective interactions is required before they can be used in the individual proton and and neutron spaces. However, with the proper forced choice of proton and neutron bases, a strong proton-neutron quadrupole-quadrupole interaction drives the states with the largest possible FDSM-SU(3) quantum numbers to lie lowest in energy. This leads to a rotational band structure in actinide nuclei with excited rotational bands ordered by the FDSM-SU(3) quantum numbers in the strong coupling limit.

Longitudinal and transverse form factors are calculated for the transition into the low-lying excited T=0 and T=1 states of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ in the framework of the resonating group model. All form factors are reproduced simultaneously using three cluster wavefunctions. Meson exchange currents yield only minor corrections and do not lead to any specific structures at large momentum transfers.

The properties of charge-exchange excitations of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ with ΔL=0, i.e., the isobaric analog and Gamow-Teller resonances, are studied within a self-consistent model making use of an effective force of the Skyrme type. The well-known isobaric analog case is used to assess the reliability of the model. The calculated properties of the Gamow-Teller resonance are compared with recent experimental measurements with the aim of better understanding the microscopic structure of this mode.

The role of final state interactions in y scaling in quasielastic electronuclear reactions is investigated in a physically realistic model, which incorporates the final state interactions via the optical model Green’s function. Relativistic and nonrelativistic complex optical potentials are utilized in finite nucleus, fully-off-shell, momentum space calculations to represent the final state interactions in an approach which has been shown to provide realistic descriptions of the separate response functions in the inclusive reaction. Analyses of the effects of Dirac dynamical degrees of freedom and final state interactions upon the separate longitudinal and transverse scaling functions are presented along with a discussion of the high momentum transfer dependence.

In the present paper we give the explicit expressions for the ground state of a many boson system in different mean field approximations, such as Hartree-Bose, Bogoliubov, the particle-hole random phase approximation (RPA), and its coupling with the particle-particle (RPA). The ground states obtained satisfy the requirement that the annihilation operators of the ‘‘elementary excitations’’ annihilates them. In all cases the ground state wave functions can be understood as a condensate of pairs of bosons.

The cross section and vector analyzing power for transitions to the ground and low-lying states in the ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$(p→,γ${)}^{90}$Zr reaction have been studied over the angular range θγ=38.8°–130° at ${\mathit{E}}_{\mathit{p}}$=22.5 MeV and over the energy range ${\mathit{E}}_{\mathit{p}}$=18.5–28.5 MeV at ${\mathrm{\theta }}_{\gamma }$=90°. Angular distributions for the ${\gamma }_0$ and ${\gamma }_{1+2+3}$ transitions (i.e., to the first three strong single-particle excited states) reveal large asymmetries about ${\mathrm{\theta }}_{\gamma }$=90° in both σ(θ) and σ(θ)${\mathit{A}}_{\mathit{y}}$(θ), suggesting E1/E2 interference effects. Legendre polynomial fits to these data yield nonzero coefficients of order k=3,4, thus confirming interference between the dominant E1 radiation and opposite parity E2 radiation. A transition-matrix element analysis of the ${\gamma }_0$ angular distribution data, including E1 and E2 radiation, suggests a 28% E2 contribution, while a pure direct capture calculation predicts only 12% E2 strength. The energy dependence of ${\mathit{A}}_{\mathit{y}}$(90°) for the ${\gamma }_{123}$ data is adequately described using the direct-semidirect model by including isovector quadropole resonances at ${\mathit{E}}_{\mathrm{GQR}}$=27.5 MeV, built on each of the three states, with widths of ${\mathrm{\Gamma }}_{\mathrm{GQR}}$=7.0 MeV and strengths which exhaust 100% of the isovector E2 energy-weighted sum rule for each state. These results provide strong evidence for collective E2 strength built on excited states in ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, approximately at the energy predicted for the isovector giant quadrupole resonance, but are inconclusive concerning the ground-state transition.

Alpha-alpha coincidence measurements have been made in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^{16}$O,α${)}^{24}$${\mathrm{Mg}}^{\mathrm{*}}$→α${+}^{20}$${\mathrm{Ne}}^{\mathrm{*}}$ at the bombarding energy of E${(}^{16}$O)=63 MeV corresponding to the resonance in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{16}$O system at ${\mathit{E}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=26.9 MeV leading to the compound nuclear state at 43.7 MeV in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$. The coincidence alphas are detected, one at 0° to the beam and the other at 20° to 80° in steps of 10°. The spins of the states in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ at 20.2 and 21.4 MeV are fed strongly at this resonance are inferred to be J≥8 from the branching of these states to the states in the ground state band of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$. From the result it is deduced that these states of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ do not correspond to the near Coulomb barrier resonances in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{12}$C system. In addition, the coincidence measurements also lead to the result that the states of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ in the 20–22 MeV region fed at the resonance preferentially decay to the eight-particle–four-hole states of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ near 7.2 MeV. These results establish the structural connection of highly deformed shape isomeric states in the region of ε=1.17 to 1.35 and γ=50° to 60° in ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ expected from the Nilsson-Strutinsky calculations of Leander and Larsson.

The cross section for the capture ${\mathrm{reaction}}^2$H(α,γ${)}^6$Li was measured in the energy range of about ${\mathit{E}}_{\mathrm{\alpha },\mathrm{l}\mathrm{a}\mathrm{b}}$≊2 MeV corresponding to the $3^{+}$ resonance in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ at ${\mathit{E}}_{\mathit{x}}$=2186 keV. Calculations in a direct-capture model using double-folded α-d potentials reproduce strength and width of this resonance as well as the nonresonant capture cross section at lower and higher energies.

Differential cross sections for quasielastic transfer were measured for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ beams bombarding ${}_{}{}^{92,98,100}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ targets at laboratory energies of 109, 116, and 125 MeV. Distorted-wave Born approximation calculations are in good agreement with the one-nucleon transfer data at all energies. Large transfer cross sections were observed for ${}_{}{}^{98,100}{}_{}{}^{}\mathrm{Mo}$ and ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$ targets which is consistent with the large sub-barrier fusion enhancement observed in the same systems. The transfer probability for one-nucleon transfer at large reaction distances is well described by the semiclassical model. There is a slope anomaly for two-proton stripping at energies just above the barrier but no anomaly for two-neutron pickup.

Angular distributions of the differential cross sections and analyzing powers have been measured for the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(p→,${\mathrm{\pi }}^{+}$) ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(p→,${\mathrm{\pi }}^{+}$${)}^5$He reactions at proton bombarding energies between 240 and 507 MeV. These new results provide a comprehensive set of data spanning the region of the ${\mathrm{\Delta }}_{1232}$ resonance and are compared with a phenomenological model that incorporates the amplitudes for the pp→d${\mathrm{\pi }}^{+}$ reaction, and with calculations from a microscopic (p,${\mathrm{\pi }}^{+}$) model. A ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ final state interaction calculation based upon the low energy n+α elastic phase shifts indicates that the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(p,${\mathrm{\pi }}^{+}$${)}^5$He spectra are nearly independent of pion angle and proton energy. Comparisons made with the time reversed charge symmetric reaction ${}_{}{}^3{}_{}{}^{}\mathrm{H}$(n,${\mathrm{\pi }}^{\mathrm{-}}$${)}^4$He reaction indicate substantial Coulomb effects are still present at 300 MeV.

A phenomenological pp→d${\mathrm{\pi }}^{+}$ model of A(p→,${\mathrm{\pi }}^{+}$)B reactions is developed that incorporates the full spin dependence of the former reaction. The model makes predictions of analyzing powers and differential cross sections and is applied to an investigation of the (p→,${\mathrm{\pi }}^{+}$) reaction on ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. The general trends of the predicted observables agree reasonably well with experiment for the helium isotopes. Much greater sensitivity due to effects of absorption and interference between different amplitudes is observed for carbon. Nevertheless, characteristic features of the analyzing powers and differential cross sections for single-particle and two-particle–one-hole states are clearly discerned. Consistent cross section normalization factors between the model and experiment, of the order of unity, are found in nearly all cases over the whole range of nuclei and energies investigated.

An analysis of the observed double-strangeness-exchange (${\mathit{K}}^{\mathrm{-}}$,${\mathit{K}}^{+}$) inclusive cross sections at 1.65 GeV/c on nuclear targets is presented. The ${\mathit{K}}^{+}$ momentum spectrum displays a low momentum peak centered around 600 MeV/c, which we interpret as due to the first order ${\mathit{K}}^{\mathrm{-}}$p→φΛ, ${\mathit{a}}_0$Λ, and ${\mathit{f}}_0$Λ processes, followed by φ, ${\mathit{a}}_0$, ${\mathit{f}}_0$→${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{-}}$ decays. This hypothesis is shown to be approximately consistent with the shape of the ${\mathit{K}}^{+}$ spectrum, its integrated cross section, and the ${\mathit{A}}^{\mathrm{\alpha }}$ dependence observed for the (${\mathit{K}}^{\mathrm{-}}$,${\mathit{K}}^{+}$) cross section on targets of mass number A. We predict a rapid energy dependence for the nuclear (${\mathit{K}}^{\mathrm{-}}$,${\mathit{K}}^{+}$) process in the momentum region 1.4–1.8 GeV/c near the two-body thresholds for producing scalar (${\mathit{a}}_0$,${\mathit{f}}_0$) and vector (φ) mesons in ${\mathit{K}}^{\mathrm{-}}$p collisions.

A ‘‘super-radiant’’ state emerges when, under certain conditions, one or a few ‘‘internal’’ states acquire a large collective decay width due to the coupling to one or a few ‘‘external’’ decay channels. The rest of the internal states are ‘‘stripped’’ of their decay width and become long lived quasistationary states. The essentials of such mechanism and its possible role in intermediate energy nuclear physics are discussed in this work.

A new model approach to preequilibrium α emission is presented which does not contain a preformation parameter or hypothesis. It takes explicit account of a pickup type of emission process. The correlation requirement proposed for the nucleons forming the emitted cluster is solely based on the cluster binding energy, and it fits readily into the framework of the exciton model. Numerical calculations are shown to be in good agreement with experimental data.

We use the Boltzmann-Uehling-Uhlenbeck model to simulate the dynamical evolution of heavy-ion collisions and to ocmpare the effects of two parametrizations of the momentum-dependent nuclear mean field that have identical properties in cold nuclear matter. We compare with recent data on nuclear flow, as characterized by transverse momentum distributions and flow (F) variables for symmetric and asymmetric systems. We find that the precise functional dependence of the nuclear mean field on the particle momentum is important. With our approach, we also confirm that the difference between symmetric and asymmetric systems can be used to pin down the density and momentum dependence of the nuclear self-consistent one-body potential, independently. All the data can be reproduced very well with a momentum-dependent interaction with an equilibrium nuclear matter compressibility K=210 MeV.

The transparency of nuclei to propagating protons in the (e,e’p) reaction has been calculated within the distorted-wave impulse approximation. This framework is commonly employed to describe the final-state interaction in knockout reactions, using phenomenologically determined optical-model potentials. The calculations reproduce measured transparencies for a range of nuclei. This lends support to the treatment of the final state interaction in (e,e’p) analyses, and therefore to the spectroscopic factors derived from such analyses. Since the transparency data can also be described by many-body calculations which include correlations of the struck proton with the remaining nucleons and other medium effects, it is also concluded that such many-body effects are effectively included in the optical-model calculations.

The dynamical motion of a classical particle in a potential taken as the sum of harmonic oscillator and time-independent or time-dependent multipolar Legendre function was investigated. Starting from various initial conditions, with increasing strength of the Legendre potential, which broke down the rotational invariance of the system, the dynamical behavior of the particle changed from regular to chaotic type. Meanwhile the local curvature of the potential surface may change from positive to zero, and negative sign. This negative curvature was demonstrated to be responsible for the local instability of a trajectory. Only via the mechanism of chaotic particle motion could the time-dependent potential permanently exchange energy with the particle. Contrasting this phenomenon with properties of independent particle model of nucleus with spherical or deformed shape would shed light on the foundation of significant property of the corresponding quantum system and the mechanism of the energy dissipation during nuclear reaction process.

The Δ excitations in nuclei induced by pion and photon scattering are analyzed within the isobar-hole model. The results are compared to those of intermediate energy charge exchange reactions. The similarities and differences between the various probes due to their kinematics and spin-structure are discussed. It is shown that the experimental cross sections for pion and photon induced reactions as well as for the inclusive charge exchange reactions can be consistently described within the isobar-hole model. Of special interest is the coherent pion decay of the Δ resonance which is studied by means of the exclusive reaction ${\mathrm{C}}^{12}$(${\mathrm{He}}^3$,t${\mathrm{\pi }}^{+}$)${\mathrm{C}}^{12}$ (g.s.), by elastic pion scattering, and by pion photoproduction. It turns out that the coherent pion decay of the ${\mathrm{C}}^{12}$(${\mathrm{He}}^3$,t${\mathrm{\pi }}^{+}$)${\mathrm{C}}^{12}$ (g.s.) reaction is intimately related to elastic pion scattering. Most interestingly, both the peak energy and the magnitude of the coherent pion production cross section depend very sensitively on the strength of the Δ-hole residual interaction. The observed energy shift is directly proportional to the nuclear density ρ. This shows that the coherent pions propagate through the nuclear interior. The coherent pion cross section can be used to determine the Landau-Migdal parameter ${\mathrm{g}}_{\mathrm{\Delta }\mathrm{\Delta }}^{\prime }$.