Neutron-production spectra from (p,n) reactions on ${}_{}{}^{204,206,207,208}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ measured previously by a Russian group were analyzed to extract numerical values for the level densities of the residual nuclei up to excitation energies of 5–6 MeV with uncertainties of 20–50%. Comparisons with the Gilbert-Cameron form and various parametrizations of the Ignatyuk formulation indicate that the Ignatyuk model with original parameters describes the results well whereas the other forms yield lower level densities. The agreement with the results of the first analysis by the experimenters themselves varies over the range of nuclei considered, being poorest for ${}_{}{}^{204,206}{}_{}{}^{}\mathrm{Bi}$.

The fission cross sections for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{138}$Ba and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$${+}^{122}$Sn in the regoin of the fusion barrier have been measured. These results are combined with evaporation residue cross sections from another measurement to obtain the total fusion excitation functions for these systems at energies near and below the barrier. Coupled channels calculations easily reproduce the experimental results.

In order to explore the possibility that previously observed anomalous mean angular momenta are related to the mass asymmetry of the entrance channel, we have studied three systems, ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ + ${}_{}{}^{142}{}_{}{}^{}\mathrm{Ce}$, ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ + ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}$, and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$ + ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$, all of which lead to the same compound nucleus, ${}_{}{}^{170}{}_{}{}^{}\mathrm{Hf}$. Gamma ray multiplicities for fusion have been determined using an electrostatic deflector and time of flight to identify the evaporation residues. Results have been obtained for bombarding energies from approximately 20% above the Coulomb barrier down to nearly 10% below the barrier. The mean angular momenta deduced from the gamma ray multiplicities are generally well reproduced by coupled channels calculations employing known deformation parameters and an estimate of the transfer strength and do not show any evidence of an unexpected effect related to the mass asymmetry of the entrance channel.

The elastic and inelastic scattering of 35.4 MeV alpha particles by ${}_{}{}^{90,92,94,96}{}_{}{}^{}\mathrm{Zr}$ have been measured to investigate the isospin mixing of transitions to the $2_1^{+}$ and $3_1^{\mathrm{-}}$ states. The data have been analyzed using a deformed optical model potential and a folding model assuming transition densities of either the standard collective model type or resulting from random-phase approximation calculations. For the $2_1^{+}$ states of ${}_{}{}^{90,92,94}{}_{}{}^{}\mathrm{Zr}$, both models give B(E2)↑ values which are in excellent agreement with those determined from Coulomb excitation or lifetime measurements. Both models of analysis suggest a sharp drop in the B(E2)↑ at ${}_{}{}^{96}{}_{}{}^{}\mathrm{Zr}$ relative to the value at ${}_{}{}^{90,92,94}{}_{}{}^{}\mathrm{Zr}$, in agreement with an earlier measurement of alpha-particle scattering. Deduced ${\mathit{M}}_{\mathit{n}}$/${\mathit{M}}_{\mathit{p}}$ ratios for ${}_{}{}^{92,94,96}{}_{}{}^{}\mathrm{Zr}$ are considerably larger than their respective ratios of N/Z. General agreement is found between folding model calculations for alpha-particle scattering and ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ scattering when using the same random-phase approximation (RPA) transition densities. A small shift in phase is observed between the oscillations in the calculated inelastic angular distributions and the measured ones. A possible means to reproduce this shift is presented, but the changes required appear to be too large to be physically meaningful.

Angular distributions of the cross section and the first complete set of analyzing powers for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${(}^6$Li→,α${)}^{14}$N have been measured over the range 4°≤${\mathrm{\theta }}_{\mathrm{lab}}$≤29° at a bombarding energy of 33 MeV. The ${}_{}{}^{\mathit{T}}{}_{}{}^{}$${\mathit{T}}_{20}$ analyzing power data are shown to distinguish between natural and unnatural parity states in ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ as observed earlier in (d→,α) reactions. General rules are presented for tensor analyzing powers for transfers to $0^{\pm }$ and $1^{\pm }$ states that are derived assuming only conservation of parity and total angular momentum. Finite-range deuteron cluster transfer DWBA calculations which allowed coherent multiple L transfers were carried out and compared with the data. The analyzing powers exhibited sensitivity to L mixing including the presence of D states in both ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ but had limited success in describing the data.

We present results of measurements of the forward-angle cross sections for pion double charge exchange on ${}_{}{}^{40,44}{}_{}{}^{}\mathrm{Ca}$ to the nonanalog ground states of ${}_{}{}^{40,44}{}_{}{}^{}\mathrm{Ti}$ at incident pion energies from 35 to 80 MeV. The data indicate that a substantial contribution to these cross sections arises from core polarization and/or cross-shell transitions.

${\mathit{K}}^{+}$-nucleus double-differential cross sections in the quasielastic region have been measured using a kaon beam with an incident laboratory momentum of 705 MeV/c. Data are presented for D, C, Ca, and Pb at fixed three-momentum transfers of 290, 390, and 480 MeV/c. Measurements of the effective number of nucleons are compared with calculations predicted from a semiclassical attenuation model based on the eikonal approximation, and the long nuclear mean free path expected for positive kaons is found, even for lead. An exclusive (K,K’p) spectrum for C at 480 MeV/c is shown. The characteristics of the exclusive data suggest that protons with zero orbital angular momentum have been detected in coincidence. The inclusive data are described well by local density random phase approximation calculations which include isoscalar N-N correlations in the σ-ω model.

Using a kinematical coincidence setup with ΔE-E identification two-body reactions between medium heavy nuclei were studied in the vicinity of the Coulomb barrier. The measured angular distributions for transfer of up to four protons with additional transfer of neutrons show maxima at large c.m. angles of 120–140°. For one- and partially for two-proton transfers the angular distributions are consistent with a one-step transfer mechanism, described by a distorted-wave Born approximation (DWBA) approach. The angular distributions of the three- and four-proton transfers show components in the forward angular region which cannot be described by DWBA. These contributions are interpreted as originating from the decay of a dinuclear complex; for this complex a lifetime of r=$6_{\mathrm{-}2}^{+6\mathrm{}}$×${10}^{\mathrm{-}22}$ s is deduced from the angle of rotation.

The inelastic scattering of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{12}$C to states above the decay threshold into 6α particles has been studied at center-of-mass energies in the range 25–40 MeV. We observe strong resonant behavior in the $0_2^{+}$+$3_1^{\mathrm{-}}$ and $0_2^{+}$+$0_2^{+}$ channels around 32.5 MeV with strikingly enhanced cross sections at 90° in the center of mass. Further measurements suggest that the $0_2^{+}$+($0_3^{+}$) channel also resonates in this energy region. These data are compared to recent band crossing model calculations and the shape eigenstate interpretation.

The partial widths for ground-state alpha-particle decay of selected excited states in ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ have been determined by measuring the production cross section and the ground-state alpha-particle decay cross section in the reaction ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$${(}^{12}$C${,}^{15}$${\mathit{N}}^{\mathrm{*}}$→α${+}^{11}$${\mathrm{B}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$)α at a bombarding energy of 90 MeV. Decay cross sections are determined by making use of a symmetry property of the decay angular correlation. The method produces agreement within experimental uncertainties for the one state for which a partial width measurement already exists, ${\mathit{E}}_{\mathit{x}}$${(}^{15}$N)=11.44 MeV. Reduced widths for some states place restrictions on J values previously reported.

The multifragment emission for central collisions of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ (25–150 MeV/nucleon) on ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ was studied via the quantum molecular dynamics model. The distribution of intermediate mass fragments (IMFs) can be described by a power-law function with the parameter τ or an exponential function with the parameter λ. By increasing the beam energy, the mean multiplicity of IMFs and relative cross sections emitting multifragment first increase to their maximum values and then decrease; while the extracted τ, λ parameters and relative cross section for single IMF emission show the converse tendency. The calculation and relevant experiment suggest that the reactions have a critical energy point where the onset of multifragmentation takes place.

Conditions under which compression occurs and collective expansion develops in energetic symmetric reactions of heavy nuclei are analyzed, together with their effects on emitted light baryons and pions. Within transport simulations, it is shown that shock fronts perpendicular to beam axis form in head-on reactions. The fronts separate hot compressed matter from normal matter and propagate into the projectile and target. As the impact parameter increases, the angle of inclination of the fronts relative to beam axis decreases, and in between the fronts a weak tangential discontinuity develops. Hot matter exposed to the vacuum in directions perpendicular to shock motion (and parallel to fronts) starts to expand sideways early within the reactions. Expansion in the direction of shock motion follows after the shocks propagate through nuclei, but due to the delay does not acquire the same strength. Expansion affects angular distributions, mean-energy components, shapes of spectra, and mean energies of different particles emitted into any one direction and further particle yields. Both the anisotropy in the expansion and a collective motion associated with the weak discontinuity affect the magnitude of sideward flow within the reaction plane. Differences in mean particle energy components in and out of the reaction plane in semicentral collisions depend sensitively on the relative magnitude of shock speed in normal matter and speed of sound in hot matter. The missing energy, considered in the past in association with low measured pion multiplicity in central reactions, may be identified with the energy of collective expansion. Relations are established which govern approximately the behavior of density and entropy in the compressed region in reactions with beam energy and impact parameter.

The nuclear photofissility of actinides, at intermediate and high energies, was studied by means of a formalism which makes salient the aspects of preequilibrium emissions, compound nucleus formation, and fission decay of the equilibrated system. This formalism was applied in the interpretation of the recently measured photofissilities of ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, in the energy range 300–1200 MeV, using (a) an intranuclear cascade Monte Carlo calculation to describe the preequilibrium and thermalization processes, and (b) the statistical model for the fission decay of the compound nucleus. It was found that the nonsaturation of the ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ photofissility, even at energies up to 1200 MeV, could be explained as a consequence of its higher nuclear transparency, when compared with heavier actinides. Also, the question about a possible competition between statical and direct fission in ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ was addressed.

Coupled-channels calculations are performed to predict fusion, elastic scattering, and inelastic scattering cross sections for the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{152,154}$Sm and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{186}$W systems at sub- and near-Coulomb barrier energies, taking into account the lowest rotational states of the target up to ${\mathit{I}}^{\mathrm{\pi }}$=$8^{+}$ explicitly. It is shown that experimental data of fusion cross sections taken recently with high precision, partial fusion cross sections, and also average spin values of compound nuclei formed after fusion are well reproduced by the calculations using optical potential parameters that can reproduce elastic and inelastic scattering data. The fusion-barrier distribution, defined as the second derivative of the fusion cross section ${\mathit{d}}^2$(Eσ)/${\mathit{dE}}^2$, is also calculated and compared with experimental data. Particular attention is focused on effects of the ${\mathit{Y}}_4$ deformation of the target on various physical quantities.

We present distorted-wave impulse approximation calculations for the polarization of outgoing protons resulting from (${\mathrm{\pi }}^{+}$,2p) reactions using a quasideuteron absorption model with phenomenological amplitudes for the πNN vertex. As an example of the interesting interference and distorted-wave effects that can be observed from such reactions, we study the case of a ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ target. Calculations are also compared to the recently published data for the nuclei ${}_{}{}^{3,4}{}_{}{}^{}\mathrm{He}$.

A calculation technique of spectroscopic amplitudes of the lightest virtually excited clusters d, t, and α in p-shell nuclei is presented. These amplitudes are incorporated into a cluster quasielastic knockout theory based on the Glauber-Sitenko multiple scattering formalism where deexcitation of virtual clusters is taken into account and the outgoing cluster distorted wave is described by means of an eikonal approximation. Numerical calculations for a few target nuclei and knocked-out clusters complement our previous results and show that the strong influence of deexcitation effects is a general property of the reactions investigated. It is exemplified by angular anisotropy of the recoil momentum distributions, etc.

Inclusive quasielastic response functions are calculated for electron scattering in a relativistic model including momentum dependent scalar and vector mean fields. The momentum dependence of the mean fields is taken from Dirac optical fits to proton nucleus scattering and is important in describing data at momentum transfers of 1 GeV/c or larger. Our simple model is applicable for quasielastic scattering over a large range of momentum transfers.

We present an analysis of the energy and angular distributions of nucleons following three-nucleon pion absorption. Three-nucleon absorption is treated as a one-step process whose transition matrix element is constant with respect to the energy of the final state nucleons. The inclusion of partial wave amplitudes for incident pions of angular momentum less than two shows good agreement with the experimental data in the Delta-resonance region.

Multifragmentation reactions without large compression in the initial state (proton-induced reactions, reverse kinematics, projectile fragmentation) are examined, and it is verified quantitatively that the high temperatures obtained from fragment kinetic energy spectra and lower temperatures obtained from observables such as level population or isotope ratios can be understood in a common framework.

We formulate ${\mathit{K}}^{+}$-nucleus quasielastic scattering in a manner that closely parallels standard treatments of ${\mathit{e}}^{\mathrm{-}}$-nucleus quasielastic scattering. For ${\mathit{K}}^{+}$ scattering, new responses involving scalar contributions appear in addition to the Coulomb (or longitudinal) and transverse (e,e’) responses which are of vector character. We compute these responses using both nuclear matter and finite nucleus versions of the relativistic Hartree approximation to quantum hadrodynamics including random-phase approximation (RPA) correlations. Overall agreement with measured (e,e’) responses and new ${\mathit{K}}^{+}$ quasielastic scattering data for ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at ‖q‖=500 MeV/c is good. Strong RPA quenching is essential for agreement with the Coulomb response. This quenching is notably less for the ${\mathit{K}}^{+}$ cross section even though the new scalar contributions are even more strongly quenched than the vector contributions. We show that this ‘‘differential quenching’’ alters sensitive cancellations in the expression for the ${\mathit{K}}^{+}$ cross section so that it is reduced much less than the individual responses. We emphasize the role of the purely relativistic distinction between vector and scalar contributions in obtaining an accurate and consistent description of the (e,e’) and ${\mathit{K}}^{+}$ data within the framework of our nuclear structure model.