Charged particles have been observed in collisions of Au on Au at an incident energy of 150A MeV using a high-granularity detector system covering approximately the forward hemisphere in the center-of-mass system. Highly central collisions have been studied using a double selection criterion which combines large charged-particle multiplicities with small transverse-momentum directivities. In this class of events about one quarter of the total nuclear charge emerges as intermediate-mass fragments with nuclear charges Z>2. These fragments are centered at midrapidity and are produced with large transverse velocities.

We apply a recently computed nucleation rate to a first-order deconfinement/chiral-symmetry restoring phase transition in a set of rate equations to study the time evolution of expanding quark-gluon plasma as it converts to hadronic matter. At energies of the BNL Relativistic Heavy Ion Colliders, the system must supercool about 20% below ${\mathit{T}}_{\mathit{c}}$ before nucleation of hadronic bubbles is sufficiently rapid to overcome the expansion rate. The system reheats to near ${\mathit{T}}_{\mathit{c}}$, nucleation turns off, and the transition is completed by the growth of previously nucleated bubbles. Based on Bjorken hydrodynamics and on current parameter values, we estimate that the transition generates 30% extra entropy.

It is shown that self-similar behavior in multiplicity fluctuations exists in the Ginzburg-Landau description of second-order phase transitions. Furthermore, there exists a numerical exponent that characterizes the intermittency properties in the hadronic phase and is independent of the specific values of the coefficients in the Ginzburg-Landau potential. Current data on intermittency are only 2σ away from the critical exponent.

The mass, energy, and centrality dependence of rapidity density distributions of relativistic, charged particles, produced in heavy-ion interactions in the energy range 4A–200A GeV, are investigated. The results indicate that the rapidity density distributions show systematic variations, which are used to predict distributions for Au+Au and Pb+Pb interactions in a model-independent way.

Results from a complete set of polarization-transfer observables for quasifree (p→,n→) scattering at 495 MeV are reported. Measurements were carried out on ${\mathrm{CD}}_2$, carbon, and calcium targets at a laboratory scattering angle of 18° using the new neutron time-of-flight facility at LAMPF. The ratio of spin-longitudinal to spin-transverse responses at a momentum transfer of approximately 1.72 ${\mathrm{fm}}^{\mathrm{-}1}$ is extracted from the data and compared to distorted-wave calculations incorporating a random-phase approximation description of the nuclear response. No enhancement is observed in the experimental ratio.

An unusual optimum pair basis exists in the nuclear shell-model wave function for an even system of like particles. This prompts the proposal of a generalized pair mean-field method, in which the desired goal of avoiding the dimensional difficulty in the traditional shell-model approaches may be possible.

High-energy γ rays have been measured in coincidence with heavy fragents in deeply inelastic reactions of ${}_{}{}^{136}{}_{}{}^{}\mathrm{Xe}$${+}^{48}$Ti at 18.5 MeV/nucleon. The giant dipole resonance (GDR) strength function is deduced from an analysis of the photon spectra within the statistical model. The GDR width Γ is studied as a function of the fragment excitation energy ${\mathit{E}}^{\mathrm{*}}$. A saturation at about Γ=10 MeV is observed for ${\mathit{E}}^{\mathrm{*}}$/A≥1.0 MeV/nucleon.

We have perfromed high-precision measurements of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ charge and magnetic form factors up to ${\mathit{Q}}^2$=1 (GeV/c${)}^2$. These measurements combined with previous data on ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ allow us to separate the three-nucleon isospin charge and magnetic form factors up to ${\mathit{Q}}^2$=1 (GeV/c${)}^2$. A large discrepancy between experiment and theory occurs for the T=1 charge form factor.

We give a parameter-free microscopic description of the α decay of the ground state of ${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$ by expanding the parent wave function over a basis containing shell-model- as well as cluster-model-type elements. The resulting decay width agrees with experiment well within the range of the uncertainty inherent in the input of the model. The amount of core +α clustering in the parent state is found much higher (30%) than former microscopic estimates (∼1%), which shows the soundness of assuming the existence of preformed α particles with appreciable probability in the initial state.

Inclusive electron scattering cross sections for ${}_{}{}^{3,4}{}_{}{}^{}\mathrm{He}$ have been measured in the quasielastic region at electron energies between 0.9 and 4.3 GeV, and scattering angles of 15° and 85°. Longitudinal (${\mathit{R}}_{\mathit{L}}$) and transverse (${\mathit{R}}_{\mathit{T}}$) response functions have been extracted using a Rosenbluth separation at constant ‖q‖ of 1.050 GeV/c. The ratio of the longitudinal to the transverse reduced response functions in the negative y region reaches unity.

Nuclear fragmentation may show specific features such as intermittency which induces self-similarity at all scales in final mass or charge distributions. We test this property on specific rate-equation models which are aimed at describing sequential decay processes. We use analytical arguments which are corroborated by numerical calculations in order to show that the generic structure of these equations does not allow for the presence of intermittency.

The derivation of the nucleon-nucleon force from the Skyrme model is reexamined. Starting from previous results for the potential energy of quasistatic solutions, we show that a calculation using the Born-Oppenheimer approximation, properly taking into account the mixing of nucleon resonances, leads to substantial central attraction. We obtain a potential that is in qualitative agreement with phenomenological potentials.

Levels in ${}_{}{}^{184}{}_{}{}^{}\mathrm{Pt}$ were studied from the decay of mass-separated ${}_{}{}^{184}{}_{}{}^{}\mathrm{Au}$ by gamma-ray and conversion-electron spectroscopy and by gamma-ray angular distributions from low-temperature nuclear orientation. In addition to coexisting ${\mathit{K}}^{\mathrm{\pi }}$=$0^{+}$ bands, coexisting ${\mathit{K}}^{\mathrm{\pi }}$=$2^{+}$ bands are observed at low energy. String interband electric monopole transitions are observed between states of the two ${\mathit{K}}^{\mathrm{\pi }}$=$0^{+}$ bands and also between states of the two ${\mathit{K}}^{\mathrm{\pi }}$=$2^{+}$ bands. The coexistence of ${\mathit{K}}^{\mathrm{\pi }}$=$2^{+}$ bands at low energy represents a new type of collective structure.

Green’s-function Monte Carlo methods are used to determine the Euclidean proton response of light nuclei from a realistic Hamiltonian containing two- and three-nucleon potential models. Final-state interactions are exactly included in this approach. The calculated Euclidean proton response functions for the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ nucleus are found to be in excellent agreement with those obtained from an analysis of the longitudinal response functions measured in (e,e’) experiments at the Bates and Saclay laboratories.

For each of several proposed π-meson cutoff masses (${\mathrm{\Lambda }}_{\mathrm{\pi }}$) in the πNN form factor, we obtained ρ-meson cutoff mass (${\mathrm{\Lambda }}_{\mathrm{\rho }}$) in the ρNN form factor so that the three-body force with these form factors may reproduce the triton binding energy. We calculated the wave function and the exchange current in the Gamow-Teller matrix element for the triton beta decay, consistently using these form factors. The most favorable set ${\mathrm{\Lambda }}_{\mathrm{\pi }}$=0.81 GeV and ${\mathrm{\Lambda }}_{\mathrm{\rho }}$=1.13 GeV yielded a triton binding energy of 8.485 MeV (experimentally, 8.482 MeV) and a Gamow-Teller matrix element divided by √3 0f 0.955 (experimentally, 0.961).

Polarization asymmetries observed in elastic tagged photon scattering at excitations between 16 and 30 MeV were used to identify the isovector giant electric quadrupole resonance in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ through its interference with underlying electric dipole strength. Resonance parameters reflecting the distribution of E2 (T=1) transition strength were extracted in a manner that has minimal sensitivity to uncertaintities in the Delbruck amplitudes or in the q dependence of the modified Thomson amplitudes. The isovector E2 resonance was found at an excitation of 20.2±0.5 MeV, with a width of 5.5±0.5 MeV, and a strength corresponding to 1.4±0.3 times the isovector quadrupole sum rule.

A two-degrees-of-freedom Hamiltonian system is constructed and serves as a toy model for compound-nucleus scattering. The model contains both direct reactions and isolated and/or overlapping resonances. All its properties are in good agreement with the random matrix theory of compound-nucleus reactions. We attribute this agreement to the chaotic character of the process and its universality.

We develop a relativistic density-dependent Hartree approach for finite nuclei, where the coupling constants of the relativistic Hartree Lagrangian are made density dependent and are obtained from the relativistic Brueckner-Hartree-Fock results of nuclear matter. The calculated results on binding energies and root mean square radii of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ agree very well with experiment. The charge densities from electron scattering are also calculated and their dependence on the nucleon-nucleon interaction is discussed in relation with nuclear matter properties.

Secondary beams of radioactive heavy ions have been stored and cooled in a storage ring for the first time. Relativistic beams of bare ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ ions were produced by fragmentation of 310 MeV/nucleon ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ at the heavy-ion synchrotron at GSI. They were separated in flight with the high-resolution forward spectrometer and injected into the storage-cooler ring. The feasibilities of in-flight lifetime and direct mass measurements for radioactive beams are demonstrated.

Using the (lowest-order) perturbative QCD, we argue that high energy heavy-ion collisions proceed via two stages: equilibration of gluons takes time ${\mathrm{\tau }}_{\mathit{g}}$∼1/2 fm/c, while production and equilibration of quarks needs time at least ${\mathrm{\tau }}_{\mathit{q}}$∼2 fm/c. If so, the initial gluon plasma is much hotter than usually estimated, ${\mathit{T}}_{\mathit{g}}$∼400 MeV, which leads to enhanced charm production and significant modifications of other proposed signals.