Double differential cross sections and analyzing powers over the quasielastic region have been measured using the (p→,n) reaction on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Pb}$. The data were obtained at proton energies of 495 and 795 MeV and cover momentum transfers from 1.0–2.1 ${\mathrm{fm}}^{\mathrm{-}1}$ at 495 MeV data and from 0.0–3.5 ${\mathrm{fm}}^{\mathrm{-}1}$ at 795 MeV. The cross section data are compared to results from a nonrelativistic reaction model that includes contributions from two-step scattering. The analyzing power measurements are compared to a recent relativistic plane-waves model.

Fission and evaporation residue cross sections and fission fragment angular distributions have been measured for the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{208}$Pb in small energy steps spanning the barrier region. Fission fragment anisotropies have been calculated using the transition state model, making use of spin distributions more accurately determined from the new cross-section data, and a more realistic calculation of the nuclear temperatures at the saddle point. Comparison of these calculations with the new experimental anisotropies show no evidence for anomalously large fission fragment anisotropies at beam energies below the average fusion barrier. Thus, the standard models of fusion and fission are able to describe the new data.

We have developed an extended direct-semidirect (DSD) model for fast-nucleon capture to virtual single-particle configurations that subsequently damp into the compound nucleus or (at sufficiently high excitation energies) escape into the continuum. The inclusion of final-state fluctuation effects is an important feature of this model. To test the model we have measured the spectra of gamma rays from approximately 10 MeV to the endpoint in the ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$(p→,γ) reaction with 19.6 MeV polarized protons from the TUNL tandem accelerator. Gamma spectra were measured with a pair of 25.4 cm×25.4 cm anticoincidence-shielded NaI detectors at angles of 30°, 55°, 90°, 125°, and 150° with respect to the incident beam. The spectra show significant analyzing powers and forward peaking of the angular distributions. These features allow for the discrimination between compounds processes and direct processes. Analyzing powers and fore-aft asymmetries were observed for gamma energies below those associated with direct-semidirect transitions to known bound final states. We have also performed Hauser-Feshbach calculations of the statistical component of the gamma emission, which dominates below approximately 15–16 MeV. The extended DSD model reproduces the spectral shapes and analyzing powers above this energy quite well. There is no evidence in the present reaction that additional mechanisms, such as multistep compound or multistep direct emission, are required.

The energy spectrum of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ ions emitted from ${}_{}{}^{223}{}_{}{}^{}\mathrm{Ra}$ sources implanted at ISOLDE has been measured with the spectrometer SOLENO. The highest statistics (899 events) and the best energy resolution (90 keV) obtained so far in cluster decay allow a real spectroscopic study. Hindrance factors for transitions to the ground state and first excited state in ${}_{}{}^{209}{}_{}{}^{}\mathrm{Pb}$, and limits for the next three low-lying states, hae been determined. The data can be explained by a parent wave function containing mainly a ${\mathit{i}}_{11/2}$ spherical component.

In this work, we investigate the possibility of occurrence of a critical behavior related to a liquid-gas phase transition in a finite classical system. The equation of state of such a classical system resembles that of nuclear matter. Through a study of mass distributions, scaled factorial moments, anomalous fractal dimensions, and moments of cluster mass distributions, we find evidence for the presence of a critical behavior of our finite system. Such a critical behavior is connected, by the use of Fisher’s droplet model and Campi analysis, to a liquid-gas phase transition.

We use the two time influence functional method of the path integral approach in order to reduce the dimension of the coupled-channels equations for heavy-ion reactions based on the no-Coriolis approximation. Our method is superior to other methods in that it easily enables us to study the cases where the initial spin of the colliding particle is not zero. It can also be easily applied to the cases where the internal degrees of freedom are not necessarily collective coordinates. We also clarify the underlying assumptions in our approach.

Elastic and inelastic differential cross sections and analyzing powers are presented for the scattering of 650 MeV protons from ${}_{}{}^{206,207,208}{}_{}{}^{}\mathrm{Pb}$. Five phenomenological optical potential sets with comparable ${\mathrm{\chi }}^2$ values are obtained. The volume integrals and root-mean-square (rms) radii of these potential sets are compared with those expected from the impulse approximation. The agreement is close for the imaginary, but not the real central potentials. The potential rms radii are ∼3% smaller than those from the impulse approximation indicating a ‘‘shrinking’’ of the effective nuclear density. The inelastic data for ${}_{}{}^{206,208}{}_{}{}^{}\mathrm{Pb}$ are analyzed using collective transition densities. The results are then compared with electromagnetic matrix elements to obtain neutron-proton transition matrix element ratios. These are in fairly good agreement with earlier determinations and indicate large core polarization contributions to the low-lying ‘‘two neutron hole’’ states in ${}_{}{}^{206}{}_{}{}^{}\mathrm{Pb}$.

We develop an approach for incorporating both medium and off-shell effects in the calculation of full-folding nucleon-nucleus optical potentials for elastic scattering. The approach is based on a flexible scheme for calculating the nucleon-nucleon effective interaction in the nuclear medium. Using this scheme, we calculate a fully off-shell, energy-dependent effective force which includes effects arising from Pauli blocking and the nuclear mean field via an interacting nuclear matter model. Calculations of the elastic scattering observables for p${+}^{40}$Ca and for p${+}^{208}$Pb at energies between 30 and 400 MeV are presented and discussed. We also study total cross sections for neutron scattering off ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ in the 5–400 MeV energy range. The theory gives a reasonable overall description of the data in the energy range under study.

The intermediate energy (p,p′x) reaction is studied with antisymmetrized molecular dynamics (AMD) in the cases of ${\mathrm{Ni}}^{58}$ target with ${\mathrm{E}}_{\mathrm{p}}$=120 MeV and ${\mathrm{C}}^{12}$ target with ${\mathrm{E}}_{\mathrm{p}}$=200 and 90 MeV. Angular distributions for various ${\mathrm{E}}_{\mathrm{p}\prime }$ energies are shown to be reproduced well without any adjustable parameter, which shows the reliability and usefulness of AMD in describing light-ion reactions. Detailed analyses of the calculations are made in the case of ${\mathrm{Ni}}^{58}$ target and the following results are obtained: Two-step contributions are found to be dominant in some large angle region and to be indispensable for the reproduction of data. Furthermore, the reproduction of data in the large angle region θ≳120° for ${\mathrm{E}}_{\mathrm{p}\prime }$=100 MeV is shown to be due to three-step contributions. Angular distributions for ${\mathrm{E}}_{\mathrm{p}\prime }$≳40 MeV are found to be insensitive to the choice of different in-medium nucleon-nucleon cross sections ${\mathrm{\sigma }}_{\mathrm{NN}}$ and the reason for this insensitivity is discussed in detail. On the other hand, the total reaction cross section and the cross section of evaporated protons are found to be sensitive to ${\mathrm{\sigma }}_{\mathrm{NN}}$. In the course of the analyses of the calculations, comparison is made with the distorted wave approach.

Two standard molecular dynamics approaches, differing in their treatment of Pauli blocking effects, are analyzed in terms of their predictions of intermediate mass fragment production and radial flow. Although the time evolution of the system is different when described in the two treatments, they converge to similar asymptotic results. However, both approaches fail to reproduce, in some cases, the experimental radial flow and intermediate mass fragment multiplicities.

Measurements of spectra from the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(${\mathrm{\pi }}^{\mathrm{-}}$,${\mathrm{\pi }}^0$) reaction with a 500 MeV beam have been made from near zero degrees to 90 degrees. A peak corresponding to breakup or quasielastic scattering is observed, and its width, maximum, and differential cross section are reported. Peak shape determinations were also made with the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^0$) reaction. Results are compared to recent pion charge exchange data on deuterium at lower pion beam energies. A simple impulse approximation calculation accounts for the data at all angles.

The model-independent method for evaluating the intensity of the emission of fast nucleons in hadron-nucleus reactions as formulated by Strugalski is applied to the multiplicity distribution of fast protons in collisions of protons at 300 and 400 GeV/c and negative pions at 300 GeV/c with emulsion nuclei. It is shown that the production of pions does not influence significantly the emission of protons.

We have measured the charge-changing cross sections of 10.6 GeV/nucleon ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ nuclei interacting in targets of ${\mathrm{CH}}_2$ (polyethylene), C, Al, Cu, Sn, and Pb. Cross sections for H are calculated from those measured in C and ${\mathrm{CH}}_2$. The total charge-changing cross sections are higher than those measured at energies of ≤1 GeV/nucleon. The measured cross sections for the heavier targets are somewhat larger than those predicted by a model based on data taken at lower energies with lighter targets. Partial charge-changing cross sections for the production of fragments from the incident Au projectiles were measured for charge changes (ΔZ) from ΔZ=+1${,}_{80}$Hg, down to approximately ΔZ=-29${,}_{50}$Sn. In comparison to lower energy measurements, these partial cross sections are found to be smaller for small ΔZ and larger or the same for large ΔZ. The H partial cross sections are found to follow a power law in ΔZ similar to that for heavier targets, instead of the exponential form observed at lower energies. Factorization is found to hold for all partial cross sections with ΔZ greater than two. In the heavier targets, the cross sections for one and two proton removal have significant contributions from electromagnetic dissociation. The electromagnetic dissociation contribution to the total cross section is derived and found to be relatively small, but with a strong dependence on the charge of the target nuclei of the form ${\mathit{Z}}_{\mathit{T}}^{1.75\pm 0.01}$.

The ratio of the total charge bound in fragments with Z between 2 and 15 to the hydrogen yield, (${\mathit{tsum}}_2^{15}$${\mathit{M}}_{\mathit{i}\mathit{Z}\mathit{i}}$)/${\mathit{M}}_{\mathit{H}}$, has been measured, and the neutron-to-proton ratio n/p has been estimated from the data of central Au + Au reactions between 100 and 400A MeV, measured with the phase I setup of the detector system FOPI and GSI, Darmstadt, in the polar-angle range between 7° and 30°. These two quantities were used to determine the entropy per nucleon S/A by comparing them with the predictions of the freesco code. The analysis allows the simulataneous extraction of the values of the baryonic entropy, temperature, and collective flow. The extracted values are in good agreement with the values obtained in earlier FOPI studies, and, for the baryonic entropy, with recent hydrodynamic calculations.

Target and centrality dependence of pion and proton distributions is studied in C+C and C+Ta collisions at 4.2 GeV/c per nucleon using the 2-m propane bubble chamber. The experimental data are compared with the predictions of the Monte Carlo quark-gluon string model (QGSM). The pion and proton transverse momentum spectra at midrapidity are well described by the two-component thermal model. The shape of the proton rapidity distribution strongly depends on the collision centrality and reflects the stopping power of colliding nuclei. The pion rapidity distribution is Gaussian in shape regardless of the target mass number and collision centrality. The QGSM completely reproduces main features of pion and proton rapidity spectra as well as pion transverse momentum spectra. The model does not fully reproduce the features of the proton transverse momentum spectra.

The Monte Carlo parton string model for multiparticle production in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions at high energies is described. An adequate choice of the parameters in the model gives the possibility of recovering the main results of the dual parton model, with the advantage of treating both hadron and nuclear interactions on the same footing, reducing them to interactions between partons. Also the possibility of considering both soft and hard parton interactions is introduced. Comparison to the available experimental data on nucleon and nuclear collisions, together with predictions for mean multiplicities, net baryon rapidity distributions, and the temporal evolution of meson densities for heavy ion collisions at the CERN Super Proton Synchrotron (194A) GeV) and the BNL Relativistic Heavy Ion Collider (200A GeV) are presented. Furthermore, predictions for charm production at these energies are given.

The problem of hadronic cluster production in quark-hadron phase transition in heavy-ion collisions is studied by cellular automata. Previous result on the scaling behavior is extended to include variations in the drift speed. It is also shown that coalescence is more important than growth in generating scaling. A new set of rules is adopted to free the clusters from being rigid. It is found that the scaling exponent is independent of not only the shapes of the clusters, but also the probability of the breakup of the clusters. The universality of the scaling behavior is now extended to a wide range of physical properties characterizing the geometry and dynamics of the phase transition process.

By using a nonrelativistic quark cluster model to describe baryonic systems, we generate a nucleon-Δ potential from the elementary interaction between constituents. The basic quark-quark potential used provides, when applied to the nucleon-nucleon system, an adequate description of the scattering phase shifts, the deuteron properties and the nonstrange baryonic spectroscopy. Special attention is paid to the short-range behavior of the interaction and its connection to the quark Pauli principle. This establishes a conceptual difference with meson-exchange models where the interaction, due to the lack of data, is not even well defined.

The effective masses and the screening masses of hadrons at finite temperature and density for the quantum hadrodynamics two (QHD-II) model have been investigated under the one-loop approximation. The nucleon-nucleon interaction through pion, sigma, omega, and rho mesons exchange in hot nuclear matter is given. We have found that the potential well of the nucleon-nucleon interaction becomes shallow as the temperature and/or density increases. At a critical temperature and/or a critical density, the potential well disappears.

The effects of the initial state interactions on the ${\mathit{K}}^{\mathrm{-}}$-p radiative capture branching ratios are examined and found to be quite sizable. A general coupled-channel formalism for both strong and electromagnetic channels using a particle basis is presented, and applied to all the low energy ${\mathit{K}}^{\mathrm{-}}$-p data with the exception of the 1s atomic level shift. Satisfactory fits are obtained using vertex coupling constants for the electromagnetic channels that are close to their expected SU(3) values.