Inclusive velocity spectra of heavy ions produced in the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${+}^{28}$Si reaction at 22, 26, 30, and 35 MeV per nucleon were measured and decomposed into peripheral and central components using an analytical moving-source parameterization. The persistence of incomplete fusion followed by evaporation has been observed over the entire bombarding energy range. Ratios of parallel and perpendicular momentum widths for fusion events show a growth of preequilibrium emission with increasing beam energy. The evaporation-residue data are consistent with a limit of 6 MeV per nucleon excitation energy beyond which conventional evaporation becomes significantly less probable. This limiting value is compatible with what one can expect from the balance between nuclear relaxation times and times for particle evaporation.

Two-fragment correlation functions observed in central collisions of ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$${+}^{197}$Au at E/A=50 MeV are compared to many-body trajectory calculations. For the present reaction, ambiguities between source size and lifetime can be reduced by employing directional emission cuts and describing observed differences between longitudinal and transverse correlation functions. For fragments emitted above the Coulomb barrier, E/A≥6 MeV, many-body Coulomb-trajectory calculations with a surface emission model indicate emission from an extended source of short lifetime.

The collision term has been deduced based on the effective Skyrme interactions in addition to the mean field. The effective elastic nucleon-nucleon cross sections are calculated for different densities, energies, and temperatures in nuclear matter. Because of the limitation due to zero-range forces used, the calculated results are expected to be limited to nucleon energy E≤120 MeV and nuclear temperature T≤10 MeV.

We obtain a local but angular momentum dependent potential ${\mathit{V}}_{\mathit{L}}$ which is phase equivalent to a Hartree-Fock nonlocal potential for the description of nucleon-nucleus scattering. We first identify two different pieces of the microscopic effective nucleon-nucleon interaction, guided by an analysis of the L-dependent properties of the conventional microscopic direct and exchange matrix elements of the n-n interaction. By separately folding these two pieces of the effective n-n interaction over the nucleons in the target nucleus we obtain two different microscopic local potentials. We finally obtain ${\mathit{V}}_{\mathit{L}}$ from the superposition of these two potentials with L-dependent coefficients, determined such that the deviation of the scattering wave function from the exact solution of the nonlocal Schrödinger equation, with the Hartree-Fock potential, is as small as possible. We provide a numerical example for n${\mathrm{-}}^{16}$O scattering at 20 and 50 MeV. We find that the deviation of the wave functions for ${\mathit{V}}_{\mathit{L}}$ is only a little smaller than the deviation for a local L-independent potential obtained by inversion of the scattering phase shifts. Hence the latter provides a nearly optimum local description of the exchange nonlocality.

We present the results of our calculations for the inelastic scattering of 800 MeV/c charged pions from the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nucleus within a strong absorption framework in the adiabatic approximation. For this purpose we extend and generalize our previous model which has been successfully applied to the description of pion-nucleus elastic scattering at 800 MeV/c. This has been achieved by introducing a phenomenological approach involving complex angular momenta in the spirit of Regge. The results of the present calculation are found to be in very good agreement with the experimental data. We also discuss the validity of this approximation within the context of high energy pion-nucleus inelastic scattering and the implications of the results obtained regarding the structure of the $2^{+}$(4.44 MeV) and $3^{\mathrm{-}}$(9.64 MeV) states of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$.

The transverse and longitudinal momentum distributions of projectile fragmentation of unstable nuclei are studied by using a peripheral direct reaction model. We found that the transverse momentum distribution is affected by absorptive cutoff of the fragmentation process, and the width becomes narrower than that of the longitudinal one which remains almost unaffected. The momentum distributions of fragments from unstable projectiles ${}_{}{}^{11}{}_{}{}^{}\mathrm{Be}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ are studied for various microscopic wave functions. Calculated results with halo wave functions show good agreement with experimental data. We discuss also the difference among various models, the spectator model, Friedman model, and Serber model, for predicting the momentum distribution.

We use the quasiclassical nuclear model and the recently proposed early cluster recognition algorithm to investigate the dynamical evolution of the fragmentation pattern for suitably excited finite spherical spin-isospin symmetric system of 80 nucleons. We find that the asymptotic fragment structure (when clusters are far away from each other) is strongly related to the early most bound density fluctuations (MBDF) in phase space (when the system is dense). We focus on the evolution of the microscopic structure of this MBDF, finding that the constituents of the MBDF are strongly correlated in time. Our calculations indicate that not only the final fragment spectra but also the microscopic structure of the final clusters carry information about the early stages of the evolution.

We describe how multiple preequilibrium emission can be included in the Feshbach-Kerman-Koonin (FKK) theory. By analyzing ($p,xn$) and ($p,xp$) reactions on zirconium, at incident energies of 80 and 160 MeV, the importance of multiple preequilibrium emission can be clearly seen. This mechanism accounts for much of the emission spectra and its importance extends to relatively high emission energies. We show that multiple preequilibrium must be included in FKK analyses at these incident energies in order to simultaneously satisfy unitarity and account for inclusive nucleon emission spectra. The importance of multistep processes is reduced in comparison to analyses which omit multiple preequilibrium. Our calculated angular distributions account for measurements except at the highest backward angles, where we underpredict the data. We compare our results with other analyses at these energies.

Measurements of the transverse momenta (${\mathit{p}}_{\mathit{T}}$) of medium and heavy mass projectile fragments for a range of projectile nuclei ${(}^{40}$Ar, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$, ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$) have been carried out. It is found that the width of the transverse momentum distributions increases more rapidly with projectile and fragment mass than predicted by models based on nucleon momenta in the projectile nuclei. The distributions can be fit by including an additional transverse momentum, ${\mathit{p}}_{\mathit{B}}$ (for Bounce). The extracted values of ${\mathit{p}}_{\mathit{B}}$/${\mathit{A}}_{\mathit{F}}$ increase with decreasing ${\mathit{A}}_{\mathit{F}}$, and extrapolations to small ${\mathit{A}}_{\mathit{F}}$ appear to be consistent with the mean values of reaction-plane-projected ${\mathit{p}}_{\mathit{T}}$ per nucleon for light particle (e.g., nucleon) ‘‘bounce-off.’’

Unfavored components of doubly decoupled bands are reported. They can be interpreted as having the pseudospin flipped relative to the orientation in the favored components, i.e., antialigned with respect to the rotation axis. In addition, the differences in consecutive transition energies along the favored and unfavored sequences are strikingly similar among them up to ${\mathit{I}}^{\mathrm{\pi }}$=${15}^{+}$ and ${14}^{+}$, respectively. This feature arises from a cancellation of differences in alignments and moments of inertia.

States in neutron-deficient ${}_{}{}^{110}{}_{}{}^{}\mathrm{Te}$ have been studied with the ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$${+}^{58}$Ni reaction at 250 MeV. An unusual feature is that, above spin $8^{+}$, negative parity states become yrast. These states are interpreted in terms of a ν[${\mathit{h}}_{11/2}$⊗${\mathit{d}}_{5/2}$] structure (Δl=Δj=3). For spins above ${15}^{\mathrm{-}}$, strong (E1) dipoles are seen linking another band into the negative-parity states. This is taken as evidence for octupole correlations in ${}_{}{}^{110}{}_{}{}^{}\mathrm{Te}$ at high spin.

The total cross section for η production in deuteron-deuteron interactions has been measured at four different kinetic energies, from 0.7 MeV to 3.7 MeV above threshold. The squared amplitude is consistent with a constant value of ‖f${\mathrm{\Vert }}^2$=(24.6±1.2±1.7) nb/sr close to threshold (14<${\mathit{p}}_{\mathrm{\eta }}$<40 MeV/c). Assuming that the ${\mathrm{\pi }}^0$-η mixing reaction mechanism is dominant, this result allows a prediction of (dσ/dΩ${)}_{{\mathrm{\pi }}^0}$=(8.3±0.5 ±0.6) pb/sr for the cross section of the isospin-forbidden reaction d+d→α+${\mathrm{\pi }}^0$ at the η-threshold energy.

Multiple proton and pion electroproduction from nuclei are studied. Final states including at least two protons produced by the interaction of 14.5 GeV electrons and positrons with light nuclei (mainly ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$) have been measured, and compared with analogous data from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$. Scattered electrons and positrons were detected in the energy transfer range from 0.2 to 12.5 GeV, and four-momentum transfer squared range from 0.1 to 5.0 ${\mathrm{GeV}}^2$/${\mathit{c}}^2$. Phenomenological characteristics of the secondary hadron production cross sections such as temperature and velocity of the effective source of hadrons were found to be dependent on energy transfer to the nucleus and independent on the four-momentum transfer squared at energy transfers greater than 2 GeV.

We report a measurement of the asymmetry in spin-dependent quasielastic scattering of longitudinally polarized electrons from a polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ target. The neutron magnetic form factor ${\mathit{G}}_{\mathit{M}}^{\mathit{n}}$ has been extracted from the measured asymmetry based on recent PWIA calculations using spin-dependent spectral functions. Our determination of ${\mathit{G}}_{\mathit{M}}^{\mathit{n}}$ at ${\mathit{Q}}^2$=0.19 (GeV/c${)}^2$ agrees with the dipole parametrization. This experiment represents the first measurement of the neutron magnetic form factor using spin-dependent electron scattering.

We report preliminary results of our calculations on the central gross features of the ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$ nucleus considered as a three body, ${}_{}{}^9{}_{}{}^{}\mathit{n}$ system employing two-body separable potentials. Even with simple s-state binary interactions, the calculations to extract information on properties such as the binding energy, the momentum distribution of ${}_{}{}^9{}_{}{}^{}\mathrm{Li}$ and of the halo neutron through the spectator functions as well as the root mean square separations of n-n and n${\mathrm{-}}^9$Li pairs within the nucleus, give results which are encouraging enough to investigate the finer details of the system using more realistic two-body interactions.

Effects of the halo as well as meson exchange currents (MEC) are studied for the Gamow-Teller (GT) β transition ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$(3/$2^{\mathrm{-}}$)${\to }^{11}$Be(1/$2^{\mathrm{-}}$,0.32 MeV). They are found to be important to reduce transition matrix elements and remedy deviations from the observed logft value of the GT transition. This GT transition is shown to play an indispensable role in identifying the structure of two-neutron halo of ${}_{}{}^{11}{}_{}{}^{}\mathrm{Li}$. It is indicated that the two neutrons forming the halo consist of the ${\mathit{p}}_{1/2}^2$ configuration with 60–70 % probability.

We derive classically an expression for a hadron width in a two-phase region of hadron gas and quark-gluon plasma (QGP). The presence of QGP gives hadrons larger widths than they would have in a pure hadron gas. We find that the φ width observed in a central Au+Au collision at √s=200 GeV/nucleon is a few MeV greater than the width in a pure hadron gas. The part of observed hadron widths due to QGP is approximately proportional to (dN/dy${)}^{\mathrm{-}1/3}$.

We show that the momentum-dependent potentials employed in molecular dynamical models of nucleus-nucleus collisions to simulate the effects of the Pauli principle do not sufficiently restrict the nucleonic degrees of freedom. This leads to an overprediction of the nuclear heat capacity which is shown to strongly hinder the multifragmentation process.

The transfer and fusion reactions are studied for reactions between a stable and an unstable nucleus with neutron skin, taking as examples the reactions ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${+}^{16,28}$O. The two-dimensional time-dependent Hartree-Fock method is used. It is shown that, in such reactions, the nucleon transfer is enhanced enormously for both protons and neutrons. The neutron skin does not enhance the fusion cross section contrary to the usual expectation.

Starting from a general, microscopic fermion-to-boson mapping that preserves Hermitian conjugation, we discuss truncations of the boson Fock space basis. We give conditions under which the exact boson images of finite fermion operators are also finite [e.g., a (1+2)-body fermion Hamiltonian is mapped to a (1+2)-body boson Hamiltonian] in the truncated basis. For the most general case, where the image is not necessarily exactly finite, we discuss how to make practical and controlled approximations.