The spectral function in the Jost-Lehmann-Dyson representation of causal commutators is determined for the nonrelativistic limit of inclusive lepton scattering from nuclei. From this an extrapolation of the Coulomb sum rule to higher-momentum transfers is performed which is consistent with the requirement of causality.

In the conventional coupled channels resonating group approach it is difficult to investigate the convergence of the solution with increasing number of distortion channels because of the nonorthogonality (and linear dependency) of channel spaces and because of nonuniqueness of the coupled channels solution. The orthogonalized version of the resonating group method allows us to study convergence. It is presently done for the n-channels case with one open channel and n-1 (closed) distortion channels. It is found that the relative motion solutions and distortion amplitudes determined by the approximate equations converge pointwise towards values determined by the Schrödinger equation. The converged set of equations defines the effective interaction of two clusters in the elastic energy region; if one cluster is a single particle this definition goes over into Feshbach’s definition of the optical potential in the elastic energy region.

We have used the ${}_{}{}^{148}{}_{}{}^{}(\mathit{p}$,t${)}^{146}$Gd reaction with protons of 34.6 and 24.9 MeV to study levels in ${}_{}{}^{146}{}_{}{}^{}\mathrm{Gd}$ below $E_x$=5.6 MeV. The radioactive target material was deposited on the carbon support foil from an isotope separator. Triton spectra were analyzed by a magnetic quadrupole-dipole-dipole-dipole spectrometer (Q3D) at 11 angles between 10° and 60°. By comparing the angular distributions with the results of distorted-wave Born approximation calculations we obtained definitive L-transfer values for 11 excited states, including a strongly populated $0^{+}$ state at 4534 keV, and approximate L values for about 50 additional states. A search for members of the two-octupole-phonon quartet of states expected to occur at ∼3.2 MeV of excitation (twice the single-phonon energy) revealed no convincing evidence of the $0^{+}$ component, but the $2^{+}$ component could be one of the four new $2^{+}$ states identified in this region. A comparison between the most strongly populated low-lying states of ${}_{}{}^{142}{}_{}{}^{}\mathrm{Sm}$ in the ${}_{}{}^{144}{}_{}{}^{}(\mathit{p}$,t) reaction and states in the pairing-vibrational region of ${}_{}{}^{146}{}_{}{}^{}\mathrm{Gd}$ reveals a possible set of states whose energies and (p,t) cross sections are in reasonable agreement with predictions of the harmonic pairing-vibration model.

Two-neutron-hole excitations have been investigated via the (p,t) reaction at 168 MeV on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$ targets, up to ∼25 and ∼17 MeV excitation energy, respectively. The kinematic conditions strongly favor high L transfer values (L∼10 for Sn and L∼13 for Pb). High-spin stretched states are found to dominate the spectra with an even stronger enhancement for J=[($l_1$+(1/2)($l_2$-1) & states. Angular distributions and standard local zero-range distorted-wave Born approximation analysis have been performed for ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$. Such analysis has been extended to the ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$ data taken at two angles. The zero-range normalization constant $D_0^2$ is found to be significantly smaller than that usually adopted at low incident energy, $D_0^2$∼6 instead of ∼22. The high-spin stretched states of the valence multiplets are distributed from 2.2 MeV up to 6.1 MeV in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$, whereas they are clustered between ∼3.0 and 3.7 MeV in ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$. New spectroscopic information gained for $J^{\pi }$≥6 levels or structures in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$ is discussed together with that of previous studies, especially the (α${,}^6$He) results at high incident energy. Such comparisons show that configuration mixing is larger than predicted for the higher-energy transitions in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$. No significant concentration of valence plus deep hole states could be found in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$, whereas the previously known one valence plus one deep bump in ${}_{}{}^{114}{}_{}{}^{}\mathrm{Sn}$ exhibits a maximum at ∼7.3 MeV here mainly attributed to the & state in agreement with the prediction of the quasiparticle phonon model.

Mass and velocity distributions have been measured for the evaporation residue and fusion-fission products from the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{40}$Ca reaction at 214 MeV. Comparisons of Monte Carlo statistical evaporation simulations to the observed angle and mass dependences of the evaporation-residue velocity distributions were used to set limits on the maximum complete-fusion cross section and to extract information about the magnitude and character of incomplete-fusion processes. The extracted value of the complete fusion evaporation-residue cross section is discussed in the framework of previous results and existing models.

We used CR39 plastic nuclear track detectors (${\mathrm{C}}_{12}$${\mathrm{H}}_{18}$${\mathrm{O}}_7$) in combination with automatic track measurement techniques to determine total charge changing and partial cross sections for the production of fragments of charge $Z_F$=6 to $Z_F$=13 in collisions of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ beam nuclei at 14.5 GeV/nucleon in targets H, C, CR39, (${\mathrm{C}}_{18}$${\mathrm{H}}_{38}$O), Al, Cu, Ag, and Pb. By application of factorization rules, measured partial cross sections are separated into pure nuclear and electromagnetic components. The cross sections for electromagnetic dissociation agree with theoretical models. The results are consistent with a $Z^2$ dependence of virtual photon spectra.

Target residues from the interaction of copper with 15, 25, and 45 MeV/nucleon ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions have been studied by off-line γ-ray spectroscopy. Cross sections, average ranges, and forward-to-backward ratios were measured for some 35 products. The data were used to obtain the isobaric yield distribution, the mass yield distribution, the mean longitudinal momentum transfer, and the mean excitation energy. The evolution of these quantities with energy is examined in conjunction with our previous results for 35 MeV/nucleon ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions.

The g factor of the 10 995 keV, $J^{\pi }$${=(59/2\mathrm{}}^{\mathrm{-}}$, and $T_{1/2}$=0.8 ns level in ${}_{}{}^{147}{}_{}{}^{}\mathrm{Gd}$ has been determined by the transient field method for ions recoiling through a magnetized Gd foil at a temperature of 100 K. The ${}_{}{}^{76}{}_{}{}^{}\mathrm{Ge}$${(}^{76}$Ge,5n${)}^{147}$Gd reaction at E${(}^{76}$Ge)=310 MeV was used to provide high recoil velocity. A 100 ps flight time in vacuum between the target and the ferromagnet of 100 ps ensured that the γ-ray cascades fed the (59/2 level before the recoil ions traversed the Gd foil. The g factor was extracted from standard double ratios with the known parametrization of the transient field, yielding g=0.38(7). This value is in agreement with the predicted wave function and experimental single-particle moments in this mass region. Results for levels in ${}_{}{}^{146}{}_{}{}^{}$,148Gd were also obtained.

The lattice Hamiltonian method for solving the Vlasov equation with exact energy conservation is developed, with a view to understanding low-energy phenomena in heavy-ion collisions. An accurate method of creating initial nuclear ground states is presented, and breathing mode excitations in these states are studied. Heavy-ion collisions are simulated using classical and Thomas-Fermi time-dependent mean field theory to study the effects of the quantum Fermi motion in such collisions.

The level scheme of ${}_{}{}^{132}{}_{}{}^{}\mathrm{La}$ was obtained with in-beam gamma spectroscopy techniques using fusion evaporation reactions with ${}_{}{}^{10}{}_{}{}^{}$,11B, ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ beams and isotopic targets of Te and Sn. Two rotational band structures were seen. One band, assigned to the π$h_{11/2}$⊗ν$h_{11/2}$, shows a smaller signature splitting as compared to the isotones ${}_{}{}^{134}{}_{}{}^{}\mathrm{Pr}$ and ${}_{}{}^{136}{}_{}{}^{}\mathrm{Pm}$, indicating a slight reduction of triaxiality. The other band has been tentatively assigned the π${\left[422\right](3/2\mathrm{}}^{+}$⊗ν$h_{11/2}$ configuration, and shows no signature splitting indicating a near prolate shape.

The reactions of 6 MeV/nucleon ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ ions on ${}_{}{}^{51}{}_{}{}^{}\mathrm{V}$ have been studied by measuring the yields and projected recoil range distributions of radioactive reaction residues and the inclusive spectra of emitted projectile-like fragments. Modelling of the reaction mechanism in terms of contributions from complete fusion and various incomplete fusion processes, on the hypothesis that the observed projectile-like fragments are essentially all due to incomplete fusion, leads to good agreement with the observed yields and recoil distributions. The results are discussed in the context of the sum rule model of incomplete fusion.

New pre-scission neutron multiplicity (${\nu }_{\mathrm{pre}}$) data for ${}_{}{}^7{}_{}{}^{}\mathrm{-}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{-}$, and ${}_{}{}^{20}{}_{}{}^{}\mathrm{induced}$ fission are presented, spanning a fissility range from 0.60 to 0.85. Fission time scales have been deduced for two extreme assumptions regarding the mean excitation energy during fission. It is found for fusion-fission reactions that the fission time scale is independent of fissility, within a factor 1.5. A comparison of time scales deduced from ${\nu }_{\mathrm{pre}}$ measurements for fast-fission with quasifission time- scales deduced from the rotation angle of the composite system allows a minimum fusion-fission time scale of 30×${10}^{\mathrm{-}21}$ s to be determined. For the most fissile system, fast-fission (fission without barrier) is shown to be up to three times faster than fusion-fission. Using a model to interpret the fusion-fission time scales, it is concluded that motion in the fission direction is strongly overdamped. This means that the dynamics of fission are dominated by a slow diffusion towards scission, and not by the potential energy surface. It is shown that such a picture can explain the observed lack of dependence of the fission time scale on fissility.

We study $K^{+}$N low-energy scattering using the effective Lagrangian approach. The scattering mechanism model consists of hyperon and meson exchanges (this model is borrowed from π-N scattering calculations). We limit ourselves to the tree level, motivated by nuclear physics applications. Canonical values of the required coupling constants give rise to scattering parameters which disagree strongly with experiment. Kaon photoproduction (γ+p→$K^{+}$+Λ) studies using a similar model also yield coupling constants which differ from standard compilations values. Using these values in the $K^{+}$N scattering calculations, we find a better agreement with experiment (the level of agreement is still only within a factor of 2–3, however). We discuss the role of ω and ρ t-channel mesonic exchanges in the scattering process and elaborate on the implications to some recent work in the current literature. Possible reasons for the results and discrepancies found in the present work, as well as possible implications, are discussed.

Scattering amplitudes for the pion photoproductions have been derived on the chiral bag model by taking into account pion cloud effects, pion-pole term, and antiquark propagation. The differential cross section for ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(γ,${\pi }^{+}$${)}^{13}$B has also been calculated.

A procedure for extracting electromagnetic exchange-current operators from a given nucleon-nucleon potential is developed on the basis of the continuity-equation constraint. The present method is applied to the one-boson-exchange nucleon-nucleon potential to yield exchange-current operators. It is shown that the proposed formulas reproduce, up to divergence-free four-currents, both the contact current and the mesonic current derived consistently within the one-boson-exchange model including meson retardation and nucleon recoil.

We study quantization of meson fluctuations about the soliton with a view to obtaining covariant meson exchange as a first step to an effective meson-‘‘nucleon’’ field theory. We illustrate our method with one-dimensional models. We show that Dirac quantization of the soliton and two-soliton systems can give a covariant meson-soliton interaction to the one-meson range and to the leading nonstatic order. Achieving this goal requires careful choice of two-soliton static configuration.

A technique for calculating electron-inclusive threshold electroproduction cross sections on the nucleon in the case of positive kaons is detailed. The study is extended to the analogous calculation of subthreshold kaon electroproduction on nuclei using several models of the nucleon momentum distribution. In anticipation of the forthcoming analysis of an experiment, results for positive kaon electroproduction on Cu for incident electrons of 700 MeV are given for both Gaussian and modified Chew-Goldberger momentum distributions.

Cross sections of radionuclides in the A≊72 mass region produced by the interaction 800 MeV protons with ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{92}{}_{}{}^{}$,96,100Mo, and ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}$ were measured. Particular emphasis was paid to the measurement of short-lived products far from β stability. The cross sections were used to generate isobaric yield curves at A=72. Precise characterization of these curves showed that the distribution parameters (mean, standard deviation, skewness) vary in a regular fashion with target N/Z. For ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, relative isobaric curves produced by 500 and 800 MeV protons were found to be identical within experimental error. The yield distributions for the ${}_{}{}^{92}{}_{}{}^{}$,96,100Mo targets also scaled with those from an earlier alpha-induced spallation study. These findings lend strong support to the argument that the spallation mechanism is independent of projectile energy and target composition.

We investigate some important theoretical issues associated with the treatment of the spin-(3/2 baryons in the effective Lagrangian theory. These are the form of the spin-(3/2 particle propagator, off-shell parameters involving the spin-(3/2 field; strategies of implementing gauge invariance, and unitarity. We comment on previous works by Peccei, Nath et al., Williams, and Adelseck et al., the last three works being in the context of recent revival of interest of baryon resonance structure in quantum chromodynamics. Our experience on the Δ(1232) resonance is invoked as a concrete example of dealing with these problems. Examples of some related problems in theories of massive vector and spin-(3/2 particles, in pion decay and supersymmetry, respectively, are also discussed. These discussions should trigger new theoretical and experimental investigations in the study of baryon resonances excited from free hadrons and in complex nuclei.

We examine radiative muon capture in a nuclear medium using mean field theory and a relativistic Fermi gas model for the nucleus to obtain the single nucleon states. The aim is to explore, in a simple model, effects of the medium which are characterized primarily by a nucleon effective mass $m^{\mathrm{*}}$, as well as other relativistic effects. The relative rate, i.e., the photon spectrum divided by the nonradiative rate, and the photon asymmetry relative to the muon spin are calculated. The most important effect turns out to be the Fermi motion which reduces the relative rate by a factor of 2–3 in the experimentally accessible region, compared to the static case. The $m^{\mathrm{*}}$ effect further reduces the result by 10–50 %, depending on the photon energy. The relativistic nature of this calculation, unlike usual nonrelativistic calculations, allows these effects to be incorporated to all orders in 1/m. As a consequence some interesting effects can be studied in the small k region. We conclude that both relativistic kinematic and medium effects may be significant and thus that it is worthwhile investigating this reaction in more realistic relativistic nuclear models.