In 1.0×${10}^9$ collisions of 11.4A GeV ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ on a 1.27-cm Pb target we found no nuclear products with charge >84 emitted within an angle of 140 mrad to the beam direction, allowing us to set an upper limit of 20 nb on the production cross section at 90% confidence level for abnormal nuclei with lifetime ≥${10}^{\mathrm{-}9}$ s.

Angular distributions and inclusive energy spectra of isotopes with masses 23–41 were measured for the reaction ${}_{}{}^{\mathrm{nat}}{}_{}{}^{}\mathrm{Si}$${(}^{16}$O,X) at bombarding energies of 96.4, 112.4, and 127.8 MeV. Complete and incomplete projectile momentum transfer components of the resulting velocity distributions were separated by kinematic transforms which rely on an angular distribution function fitted to the data using center-of-mass frame symmetry conditions. Characteristics of the extracted complete momentum transfer component spectra, mass distributions, and laboratory frame angular distributions are consistent with fusion-evaporation models. Comparison with the Glas-Mosel parametrization and predictions for the angular momentum barrier to fusion indicate that at 112.4 and 127.8 MeV, competing entrance channel processes, rather than compound nucleus formation limits, restrict the fusion cross section. Spectra and cross sections of the incomplete momentum transfer component are consistent with sequential two-body breakup/fusion calculations.

Absolute pp-elastic-differential cross sections were measured at incident energies 492, 576, 642, 728, and 793 MeV from about 30° to 90° c.m. The total uncertainty was determined to be less than 1%, made possible by particle counting for beam normalization and extensive cross-checks of systematic effects. These new data are consistent with previous data above 600 MeV but have uncertainties about a factor of 10 smaller. Near 500 MeV these data are consistent with 90° data from TRIUMF, but differ significantly from similar data from PSI; the cause of this discrepancy is discussed.

Charged-particle correlations were measured for the reactions ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$${+}^{197}$Au and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$${+}^{27}$Al at E/A=75 MeV and for ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$${+}^{27}$Al and ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$${+}^{122}$Sn at E/A=31 MeV. Relative populations of widely separated states in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^5{}_{}{}^{}\mathrm{Li}$, and ${}_{}{}^8{}_{}{}^{}\mathrm{Be}$, only weakly affected by side feeding, indicate emission temperatures of T=4–5 MeV for the ${}_{}{}^{14}{}_{}{}^{}\mathrm{induced}$ reactions and values about 1 MeV lower for the ${}_{}{}^{129}{}_{}{}^{}\mathrm{induced}$ reactions.

The asymptotic D-state to S-state ratio of the ${}_{}{}^3{}_{}{}^{}\mathit{n}$+d cluster wave function (${\mathrm{\eta }}_{\mathit{t}}$) has been determined from measurements of sub-Coulomb (d→,t) tensor analyzing powers. New measurements of the tensor analyzing power ${\mathit{T}}_{20}$ for (d→,t) reactions on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{119}{}_{}{}^{}\mathrm{Sn}$ at several different energies are presented. These data, along with previous measurements of ${\mathit{T}}_{20}$ and ${\mathit{T}}_{21}$ for several additional reactions and energies, are used in a distorted-wave Born approximation analysis that includes nuclear tensor potentials as well as long-range tensor potentials that arise from Coulomb interactions. A weighted mean of all fourteen statistically independent values gives the result ${\mathrm{\eta }}_{\mathit{t}}$=-0.0431±0.0025, where the quoted uncertainty includes statistical and systematic contributions. This result is compared with previous measurements and with predictions obtained from Faddeev calculations.

The quasielastic breakup of an ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nucleus at 32.5 MeV/nucleon on a ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ target has been investigated by measuring the projectilelike fragments in coincidence with the emitted light charged particles. It is found that the breakup proceeds via sequential, two-step processes in which inelastic scattering and one-neutron pickup are the most significant components in the formation of the primary fragment. This is followed by statistical decay of the highly excited primary fragment. A Monte Carlo simulation was used to identify these processes and to deduce differential and total cross sections for the breakup of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ into the α${+}^{12,13}$C channels.

Double differential cross-section angular distributions were measured for the ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ (n,p${)}^{32}$P charge exchange reaction in the 0°≤${\mathrm{\theta }}_{\mathrm{lab}}$≤14° angular range. All data presented here were measured simultaneously covering indicent neutron energies between 60 and 220 MeV using the white neutron source at Los Alamos Meson Physics Facility–Weapons Neutron Research. The Gamow-Teller strengths obtained from a multipole decomposition analysis of these ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$(n,p${)}^{32}$P data are compared to previously reported ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$(p,n${)}^{32}$Cl results as well as to calculated Gamow-Teller strengths obtained using the shell-model code oxbash and random phase approximation (RPA) calculations. The resultant gian dipole and giant spin-dipole cross sections obtained from this multipole decomposition analysis are also compared with distorted-wave impulse approximations calculated with densities obtained from a simple one-particle–one hole shell model and also densities obtained from RPA calculations.

Complex fragments with atomic numbers between those of the target and the projectile have been detected from the reactions of 26 and 31 MeV/nucleon ${}_{}{}^{129}{}_{}{}^{}\mathrm{Xe}$+C, Al, Ti, and Cu. Angular distributions, cross sections, and velocity spectra of these fragments were extracted from the inclusive data. The velocity of the emitting source and Z-total distributions were reconstructed from the twofold coincidence data. These results are used to characterize the emission source of the complex fragments. The results are compared to a geometric incomplete fusion model calculation. Agreement between the model and the data is good.

Transverse elastic and inelastic form factors for low-lying levels in ${}_{}{}^{117}{}_{}{}^{}\mathrm{Sn}$ have been measured by 180° electron scattering in the momentum transfer range ${\mathit{q}}_{\mathrm{eff}}$=1.1–2.4 ${\mathrm{fm}}^{\mathrm{-}1}$. The simple independent-particle model fails to account for these data, predicting form factors that are much too large. In better quantitative agreement with the data are the results of more detailed calculations that allow for configuration mixing of valence nucleons, as well as first-order core polarization. As in the similar case of ${}_{}{}^{205}{}_{}{}^{}\mathrm{Tl}$, these calculations successfully predict the presence of a deep diffraction minimum observed in the intermediate q region of the elastic M1 form factor. Nevertheless, the overall description of the data by the detailed calculations remains quantitatively unsatisfactory. A more complete understanding of these data may rely upon the consideration of multiparticle-multihole configurations outside the 0ħω basis space.

Coincident cross sections were measured for the reaction ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$(p,p’p’’) at an incident energy of 200 MeV. The protons emitted from the continuum were detected at primary laboratory angles of -40°, -50°, and -60°, for secondary angles ranging between 20° and 150°. The theoretical model which was used to interpret the coincident spectra describes the reaction mechanism in terms of a quasifree nucleon-nucleon interaction between the projectile and a bound target nucleon, folded with a probability for emission of the quasifree knocked-on nucleon after inelastic rescattering off the residual target nucleus. The validity of the distorted-wave impulse approximation which describes the initial quasifree interaction was confirmed by measuring the quasifree knockout of valence-orbital protons from ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$. The measured coincident continuum cross sections were then compared with model calculations for primary proton energy cuts around 90, 70, and 40 MeV. The reasonable agreement found between the calculated and measured cross sections indicates that the signature of quasifree scattering persists in the continuum emission from a nucleus as heavy as ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, and is not obscured by multiple scattering efects.

Double- and triple-coincidence data for pion absorption on ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ are analyzed using a multistep reaction model with Monte Carlo calculations. The cross sections far from the two-nucleon absorption region could be reproduced very well using only well-known reaction mechanisms and nuclear data. Clear evidence for the two-step process is also shown.

A previous νp elastic scattering experiment at BNL is reanalyzed, taking into account the strange vector and axial-vector form factors of the proton ${\mathit{F}}_1^{\mathit{s}}$, ${\mathit{F}}_2^{\mathit{s}}$, and ${\mathit{G}}_1^{\mathit{s}}$. Values for these form factors are obtained, although with large errors due to correlations between ${\mathit{F}}_1^{\mathit{s}}$ and ${\mathit{F}}_2^2$ and between ${\mathit{G}}_1^{\mathit{s}}$ and the axial vector dipole mass ${\mathit{M}}_{\mathit{A}}$. Future νp elastic scattering experiments could significantly improve the knowledge of these form factors.

A parameter-free geometric model for nuclear absorption is derived from microscopic theory. The expression for the absorption cross section in the eikonal approximation taken in integral form is separated into a geometric contribution, described by an energy-dependent effective radius, and two surface terms which are shown to cancel in an asymptotic series expansion. For collisions of light nuclei, an expression for the effective radius is derived using harmonic-oscillator nuclear density functions. A direct extension to heavy nuclei with Woods-Saxon densities is made by identifying the equivalent half density radius for the harmonic-oscillator functions. Coulomb corrections are incorporated and a simplified geometric form of the Bradt-Peters type obtained. Results spanning the energy range of 1 MeV/nucleon to 1 GeV/nucleon are presented. Good agreement with experimental results is obtained.

The algebraic-eikonal approach to the medium-energy hadron-nucleus scattering is generalized to arbitrary interactions and boson types using the 1/N expansion technique for the interacting boson model. The results are used in a comparative study of proton scattering from deformed nuclei in the sd and sdg boson models. The two models give almost identical results for a pure quadrupole interaction but widely differ when a hexadecapole interaction is included.

A microscopic ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$${+}^4$He interaction potential has been constructed in a double-folding model with the M3Y interaction and a single-nucleon-exchange term. Elastic scattering calculations with this potential together with a deuteron exchange mechanism reproduce the α${+}^6$Li elastic-scattering data at 36.6, 50, and 166 MeV in the forward- and back-angle regions, without any reduction factor. The exchange mechanism explains the large back-angle cross sections without affecting the forward-angle predictions. A recently formulated microscopic potential of Kamal et al. is also found to give a good fit to the forward-angle data at 36.6 and 50 MeV without renormalization. The latter however fails at 166 MeV. Inclusion of the deuteron exchange mechanism in the potential of Kamal et al. is also necessary to account for the large back-angle cross sections. The significance of the results in the context of the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ target breakup reactions recently studied at low relative fragment energies is discussed.

We present a multienergy partial-wave analysis of all NN scattering data below ${\mathit{T}}_{\mathrm{lab}}$=350 MeV, published in a regular physics journal between 1955 and 1992. After careful examination, our final database consists of 1787 pp and 2514 np scattering data. Our fit to these data results in ${\mathrm{\chi }}^2$/${\mathit{N}}_{\mathrm{df}}$=1.08, with ${\mathit{N}}_{\mathrm{df}}$=3945 the total number of degrees of freedom. All phase shifts and mixing parameters can be determined accurately.

We present an analysis of the reaction A(γ,πN)B in the full distorted wave impulse approximation carried out in momentum space. The bound nucleon is in a single particle orbital while the outgoing pion and nucleon are described by appropriate optical potential wave functions. The pion photoproduction operator of Blomqvist and Laget is used. This reaction allows for more direct studies of Δ properties in the nuclear medium than the reaction A(γ,π)B since the final nucleon is no longer bound and the sensitivity to the nuclear structure of the target is thereby largely reduced. Kinematically, the reaction provides a great deal of flexibility because the target can take up a wide range of momentum transfer and little energy. Our calculations agree roughly with data from Tomsk but overestimate data from Bates. Nonlocal effects tend to enhance the total cross sections and in some cases are significant. For future experiments we propose kinematics that greatly reduce uncertainties from the optical potentials and expose information from the production vertex. We find that photon asymmetry contains such information in the cleanest way and it should be pursued. We suggest forward pion angles where discrepancies between data and theory exist should be studied more carefully by experiments.

We study the validity and convergence of the eikonal expansion for the calculation of total ${\mathrm{\sigma }}_{\mathit{t}}$ and total reaction ${\mathrm{\sigma }}_{\mathit{R}}$ cross sections in the case of low-energy heavy-ion collisions. Investigations are performed by considering a few typical optical potentials, varying the incident energy from 10 MeV/nucleon to 300 MeV/nucleon. At low energy, the eikonal expansion does not necessarily converge and faces a violation of flux conservation, especially at low-impact parameter. For well-behaved cases, we find the eikonal approximation to be a convenient starting point. Adding the first correction leads in general to an acceptable accuracy with respect to the quantum mechanical result.

Recent laboratory experiments have measured fusion cross sections at center-of-mass energies low enough that the effects of atomic electrons are important. To extract the cross section for bare nuclei from these data (as required for astrophysical applications), it is necessary to understand these screening effects. We present a model in which the evolution of the electron wave function is treated dynamically in the time-dependent Hartree-Fock scheme, while the motion of the nuclei is treated classically. We have calculated screening in the d${+}^2$H and d${+}^3$He reactions and give the effective screening energy ${\mathit{U}}_{\mathit{e}}$ at small internuclear separations as a function of E. The resulting ${\mathit{U}}_{\mathit{e}}$ values do not exceed the previously established adiabatic limits, and thus cannot explain the higher screening energies derived from experiment.

We investigate theoretical approaches to pion-nucleus elastic scattering at high energies (300≤${\mathit{T}}_{\mathrm{\pi }}$≤1 GeV). A ‘‘model-exact’’ calculation of the lowest-order microscopic optical model, carried out in momentum space and including the full Fermi averaging integration, a realistic off-shell pion-nucleon scattering amplitude and fully covariant kinematics, is used to calibrate a much simpler theory. The simpler theory utilizes a local optical potential with an eikonal propagator and includes the Coulomb interaction and the first Wallace correction, both of which are found to be important. Comparisons of differential cross sections out to beyond the second minimum are made for light and heavy nuclei. Particularly for nuclei as heavy as ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, the eikonal theory is found to be an excellent approximation to the full theory.