Velocity spectra and angular and mass distributions for the evaporation residues of the ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{12}$C system at ${\mathit{E}}^{32}$S=145 MeV in the angular range 3°≤${\mathrm{\vartheta }}_{\mathit{L}}$≤12° have been measured. In order to separate compound nucleus evaporation residues from other heavy reaction products, a kinematic analysis based on simple statistical assumptions relative to the velocity spectra was performed. The structures in the mass distribution are compared with the lilita code predictions. The fusion excitation function of the existing results is compared with theoretical models. The total reaction cross section has been extracted by means of the modified sum of differences method.

We discuss the physical meaning of the spatial source parameters obtained from two-pion interferometry. We propose that the average radius 〈r〉 of the source is a suitable quantity to describe the spatial extent of the source under various assumptions about the source density distribution, and demonstrate that the average radius is more appropriate than the root-mean-square radius proposed by Bartke and Kowalski. The mean square radius 〈${\mathit{r}}^2$〉 of the source can be estimated using a correlation function for small relative momenta, and more detailed information about the source density distribution can be inferred from the value of k=〈${\mathit{r}}^2$〉/〈r${\mathrm{〉}}^2$. Studies of central collisions of 1.5A GeV Ar+KCl and 1.8A GeV Ar+Pb at the Bevalac streamer chamber show that the data are consistent with a phenomenological Gaussian model for the density distribution at the present level of experimental accuracy.

Differential cross sections and analyzing powers for low-lying states of ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ were measured using 318 MeV protons. The data were analyzed using an empirical effective interaction previously fitted to inelastic scattering data for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ at the same energy. Transition densities for many states were fitted to the data using general expansions which permit evaluation of uncertainties due to statistical and normalization errors, penetrability and distortion, and incompleteness in momentum space. The accuracy of the procedure was tested by comparing isoscalar densities fitted to (p,p’) data for ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ with proton densities fitted to (e,e’) data. The good agreement between these analyses supports the quantitative accuracy of densities fitted to (p,p’) data. Isoscalar densities were also fitted to data for several states of ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ for which no (e,e’) data exist. We find that the experimental densities agree well with the shell model for the first $2^{+}$ state, but that the neutron density for the second $2^{+}$ state is distinctly different in shape. Good qualitative agreement between the data and the shell model is obtained for the first two $4^{+}$ states of ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$. Transition densities were also fitted to the data for the lowest $1^{\mathrm{-}}$, $3^{\mathrm{-}}$, and $5^{\mathrm{-}}$ states in ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$. The shape of the $1^{\mathrm{-}}$ transition density is complicated, but the very small matrix element agrees with the approximate selection rule that suppresses isoscalar E1 moments.

Differential cross sections and analyzing powers for low-lying states of ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ were measured using 318 MeV protons. Neutron transition densities for the $2_1^{+}$ and $2_2^{+}$ states were fitted to the data using general expansions which permit evaluation of uncertainties due to statistical and normalization errors, penetrability and distortion, and incompleteness in momentum space. We find that the experimental densities agree well with the shell model for the first $2^{+}$ state, but that the neutron density for the second $2^{+}$ state is distinctly different in shape. We also find ${\mathit{M}}_{\mathit{n}}$/${\mathit{M}}_{\mathit{p}}$=+0.27(6) for the $2_2^{+}$ state, in qualitative agreement with electromagnetic results for A=34 but in marked disagreement with the shell-model prediction of ${\mathit{M}}_{\mathit{n}}$/${\mathit{M}}_{\mathit{p}}$=-0.61. A detailed analysis of earlier data for 650 MeV, originally described as qualitatively consistent with the shell model, is also presented and shows that these data are more consistent with the present results. The shape of the isoscalar density for the $2_2^{+}$ state of ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ cannot be reproduced with the sd shell, supplemented by surface-peaked core polarization, but can be reproduced if an empirical (1f${)}^2$ contribution is admitted. Shell-model calculations were performed for other $2^{+}$ and $4^{+}$ states of ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$, but give cross sections well below the (p,p’) data for all but the lowest $2^{+}$ state. The data for the lowest $1^{\mathrm{-}}$, $3^{\mathrm{-}}$, and $5^{\mathrm{-}}$ states in both ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ and ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ are very similar.

The energy dependence of the polarization transfer coefficient ${\mathit{K}}_{\mathit{y}}^{\mathit{y}}$ for the ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$(p→${,}^{31}$S→)n and ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$(p→${,}^{35}$A→r)n reactions has been determined from measurements of the positron asymmetry in the decay of ${}_{}{}^{31}{}_{}{}^{}$ S and ${}_{}{}^{35}{}_{}{}^{}\mathrm{Ar}$. The ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$(p→${,}^{23}$M→g)n reaction was also studied, but the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Mg}$ asymmetry was consistent with zero over the energy range investigated. The minimum proton energy for each reaction was near the respective (p,n) threshold. Thin targets of NaI and of red phosphorous were used for the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$(p→${,}^{23}$M→g)n and ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$(p→${,}^{31}$S→)n measurements, with maximum proton energies of ${\mathit{E}}_{\mathit{p}}$=7.0 and 9.1 MeV, respectively. The ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$(p→${,}^{35}$A→r)n reaction was investigated to a maximum proton energy of ${\mathit{E}}_{\mathit{p}}$=10.3 MeV for gas targets with one atmosphere of pure ${\mathrm{Cl}}_2$ or a mixture of ${\mathrm{CCl}}_4$ and He. The polarization transfer coefficients for the ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$(p→${,}^{31}$S→)n and ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$(p→${,}^{35}$A→r)n reactions show considerable variation over the energy ranges studied, with maxima of ${\mathit{K}}_{\mathit{y}}^{\mathit{y}}$=-0.091±0.003 for ${}_{}{}^{31}{}_{}{}^{}\mathrm{P}$(p→${,}^{31}$S→)n at 7.3 MeV and ${\mathit{K}}_{\mathit{y}}^{\mathit{y}}$=0.143±0.012 for ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$(p→${,}^{35}$A→r)n at 8.1 MeV.

The ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$(e,e’α) reaction has been measured in parallel kinematics. The ${\mathit{Q}}^2$ dependence of both the two-body and three-body breakup of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ has been studied at fixed recoil momentum. In addition, the recoil momentum dependence of the two-body α-d breakup has been investigated. The data indicate that the reaction mechanism is quasielastic in these kinematics.

High-accuracy measurements of ${\mathit{A}}_{\mathit{y}}$(θ) data for elastic scattering and inelastic scattering to the first excited state for n${+}^{208}$Pb have been performed at 6, 7, 8, 9, and 10 MeV. In addition, σ(θ) was measured at 8 MeV. These data provide an important subset for the growing database for the n${+}^{208}$Pb system from bound-state energies to energies above 40 MeV, the limit of the range of interest here. This database has been interpreted via several approaches. First, a conventional Woods-Saxon spherical optical was used to obtain three potential representations for the energy range from 4 to 40 MeV: ‘‘best fits’’ at each energy, constant-geometry global fit with linear energy dependences for the potential strengths for the range 4.0–40 MeV, and an extension of the latter model to allow a linear energy dependence on the radii and diffuseness. A preference for a complex spin-orbit interaction was observed in all cases. Second, the dispersion relation was introduced into the spherical optical model to obtain a more ‘‘realistic’’ representation. In our approach, the strength and shape of the real potential was modified by calculating the dispersion-relation contributions that originate from the presence of the surface and volume imaginary terms. Two potentials were developed, one based only on the scattering data (from 4.0 to 40 MeV) and another based additionally on single-particle and single-hole information down to a binding energy of 17 MeV. In addition, the σ(θ) and ${\mathit{A}}_{\mathit{y}}$(θ) measurements were compared to earlier conventional and dispersion-relation models. One of the latter of these included an l dependence in the absorptive surface term, and we applied this model in the 6- to 10-MeV region to describe all the σ(θ) and the new ${\mathit{A}}_{\mathit{y}}$(θ). A reasonably good overall description was obtained by all the models; however, only the l-dependent model came close to giving a detailed agreement to the data around 7 MeV, a region where some abnormal angular dependences occur in the data.

The mass dependence of cross sections for double-isobaric-analog states from pion-induced double-charge-exchange reactions is examined with small-angle data taken at 450 and 500 MeV incident pion energies for several targets. New (${\mathrm{\pi }}^{+}$,${\mathrm{\pi }}^{\mathrm{-}}$) cross sections are reported for ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$,${\mathrm{}}^{46,50}$Ti, ${}_{}{}^{54,56}{}_{}{}^{}\mathrm{Fe}$,${\mathrm{}}^{52}$Cr, ${}_{}{}^{80}{}_{}{}^{}\mathrm{Se}$,${\mathrm{}}^{90}$Zr, ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. The (${\mathit{f}}_{7/2}$${)}^{\mathit{n}}$ data are fitted to a two-amplitude model which contains expressions for cross sections for transitions to the DIAS and to nonanalog ground states in the residual nucleus.

In a series of experiments, differential cross sections for elastic scattering of ${\mathrm{\pi }}^{+}$ and ${\mathrm{\pi }}^{\mathrm{-}}$ from ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ were measured at the Clinton P. Anderson Meson Physics Facility (LAMPF). Data were taken at incident energies between ${\mathit{T}}_{\mathrm{\pi }}$=90 and 240 MeV using different experimental setups which covered the angular range from far forward (≊10°) to far backward angles (≊170°). A phase-shift analysis of the data was carried out. The experimental phase shifts are compared with values predicted by a first-order optical model program.

Complete spin-transfer observables for the two lowest $1^{+}$ levels in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been studied with incident protons of 500 MeV. Outgoing protons were detected with an energy resolution of 120 keV at laboratory angles of 3.5°, 5.0°, 7.5°, 9.5°, and 12.5°. Angular distributions of differential cross sections, analyzing powers, and the individual spin observables for each $1^{+}$ state are recombined into three transverse and one longitudinal partial differential cross section as well as the spin-sum and spin-difference functions. Results are compared with model calculations and electron-scattering data. Information about experimental quantities not accessible in electron scattering is also discussed.

Measurements of angular distributions for inelastic scattering in the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$${+}^{12}$C system with excitation of the $2^{+}$ (4.44 MeV) level of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and 1/$2^{\mathrm{-}}$ (2.12 MeV) and 5/$2^{\mathrm{-}}$ (4.44 MeV) levels of ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ nuclei were performed in the energy range from 15 to 40 MeV c.m. in ≃2.5 MeV steps in broad angular regions up to about 170° c.m. The cross section at forward angles was well described in the distorted-wave Born approximation by collective model with energy-independent deformation length. The rise of cross section at the backward angles was explained as inelastic proton transfer. The extracted values of the proton spectroscopic factors for the excited nuclei ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}_{4.44}^{\mathrm{*}}{}_{}{}^{}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}_{2.12}^{\mathrm{*}}{}_{}{}^{}$ are energy independent in contradiction to the previously found energy-dependent spectroscopic factor for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}_{\mathrm{g}.\mathrm{s}.\mathrm{}}^{}{}_{}{}^{}$=p${+}^{11}$${\mathrm{B}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$.

Differential cross sections were measured for pion elastic and inelastic scattering from ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at ${\mathit{T}}_{\mathrm{\pi }}$=120 and 250 MeV. Energy-dependent neutron- and proton-transition matrix elements for a range of excited states were extracted and tested for consistency, using several structure models.

Collisions between ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$ projectile and ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ target nuclei at E/A=35 MeV have been studied with a 4π phoswich array with a low detection threshold. Azimuthal distributions of light-charged particles and intermediate-mass fragments are extracted with respect to reaction planes determined from fission fragments or from the emission patterns of coincident light particles and intermediate-mass fragments. The internal consistency and sensitivity to particle detection thresholds are explored for the various techniques of reaction plane determination. For the present reaction, the reaction plane can be determined with comparable accuracy from the distribution of fission fragments as from the orientation of the major axis of the transverse momentum tensor constructed from the emitted light particles and intermediate-mass fragments. Monte Carlo calculations are performed illustrating the sensitivity of the transverse momentum tensor method to the azimuthal anisotropy of the single-particle distributions and the convergence of this method as a function of particle multiplicity. The extraction of experimental uncertainties in the determination of the reaction plane is discussed.

Very precise elastic cross sections have been measured in a very forward angular range (up to 1.6° laboratory) for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{12}$C system at six energies not too far above the Coulomb barrier. From these data the symmetrized nuclear scattering amplitude ${\mathit{f}}_{\mathit{N}}^{\mathit{s}}$(θ) for small angles and the total reaction cross section ${\mathrm{\sigma }}_{\mathit{R}}$ could be derived making use of the generalized optical theorem for charged particles. It was found that ‖${\mathit{f}}_{\mathit{N}}^{\mathit{s}}$(0)‖ exceeds zero significantly in all cases investigated. This means that a forward nuclear glory exists in the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{12}$C scattering. This is the first time that evidence for a forward nuclear glory is deduced from experimental data.

Pion production in Ne on Pb collisions at a beam energy of 800 MeV/nucleon is studied by solving a coupled set of transport equations for the phase-space distribution functions of nucleons, deltas, and pions. The experimentally observed preferential emission of pions away from the interaction zone towards the projectile side in the transverse direction is found to be due to the stronger pion absorption by the heavier target spectator. A model calculation of the pion transverse momentum distribution in the reaction plane agrees with that of the experimental data.

A discussion of relativistic microscopic models of deuteron-nucleus scattering at intermediate energies is presented. Calculations based on various relativistic models, which take into account explicitly the deuteron internal structure, and on the nonrelativistic folding model are compared with elastic-scattering data from ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ at 400 and 700 MeV. The same global nucleon-nucleus Dirac optical potentials were used throughout. We find that the direct impulse approximation, where the deuteron-nucleus T matrix is the expectation value of the sum of the nucleon-nucleus T matrices in the deuteron, gives a reasonable description of the data. However, the fact that the best agreement is provided by the nonrelativistic folding model indicates the need for a more realistic treatment of multiple scattering and off-shell effects in the relativistic microscopic models.

We investigate the onset of multifragmentation employing an improved version of the N-body ‘‘quantum’’ molecular-dynamics approach. We study in detail the reaction ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$${+}^{197}$Au at 84 MeV/nucleon and find good agreement between the calculated results and the data for the double-differential proton cross section, the mass yield, the multiplicity, the kinetic energy of the fragments, and even for the kinematic correlations between intermediate mass fragments (IMF’s), which have been measured in this experiment for the first time. We observe a strong correlation between the impact parameter and both the size of the target remnant as well as the average proton multiplicity. Hence both observables can be used to determine the impact parameter experimentally. The IMF’s come from the most central collisions. The calculations confirm the experimental result that they are not emitted from an equilibrated system. Although the inclusive energy spectra look thermal, we cannot identify an impact parameter-independent isotropically emitting source. Even in central collisions global equilibrium is not observed. We find that multifragment emission at this bombarding energy is caused by a process very similar to that proposed in the macroscopic cold multifragmentation model. Thus it has a different origin than at beam energies around 1 GeV/nucleon, although the mass yield has an almost identical slope.

We discuss the calculation of the hadronic tensor, which plays an essential role in the description of the interaction of a nucleus with an electromagnetic probe, in the kinematic regime where the concepts underlying the theory of y scaling may be used. In our previous work we determined the kinematic factors that relate the cross section to the scaling function, F(y), defined in the theory of y scaling. That study was carried out for a deuteronlike bound state of two scalar particles. In this work we extend our analysis to the case where the target is composed of spin one-half nucleons. The origin of various kinematic factors arising from the off-shell characterization of the struck nucleon and its motion in the nucleus is clarified. The target nucleus is described as a relativistic system and, in the scaling limit, we discuss how the terms which parametrize the relativistic density matrix determine the value of the cross section.

A path-integral (time-path) formulation is used to derive Feynman rules for relativistic many-body systems at finite temperature and density. The generating functional of propagators is written in a form that involves evolution along contours in the complex time plane. Controversies regarding the factorization of this generating functional into separate contributions from real and imaginary times are resolved. The time paths are generalized to manifestly covariant form, and the distinction between evolution in the canonical and grand-canonical Heisenberg pictures is discussed. This unified path-integral approach produces manifestly covariant Feynman rules for both real and imaginary times, which were applied to hadronic field theories of hot, dense nuclear matter in an earlier paper.

We examine the implications of the quark-cluster model for the proposed measurements of the spin-dependent structure functions of the deuteron and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. We find that the presence of six-quark clusters in the deuteron wave function can result in a value for ${\mathit{g}}_1^2$H, the first moment of the spin-dependent structure function of the deuteron, that is observably different from predictions obtained using the Bjorken sum rule and the measured value for ${\mathit{g}}_1^{\mathit{p}}$. Therefore, it may not be possible to obtain an unambiguous determination of the integral of the neutron’s spin-dependent structure function, ${\mathit{g}}_1^{\mathit{n}}$, in these experiments. For ${}_{}{}^3{}_{}{}^{}\mathrm{He}$, the dominant clusters are constrained by the Pauli principle at the nucleon level to be either S=1,I=0 or S=0,I=1. We find that the presence of S=0,I=1 clusters leads to a violation of the Bjorken sum rule for mass three nuclei. Arguing that clusters with these quantum numbers are suppressed at the quark level, we obtain a relation between ${\mathit{g}}_1^{\mathrm{He}}$ and ${\mathit{g}}_1^2$He that depends on the probability of finding six-quark clusters in the nuclear wave function, but is essentially independent of their detailed structure.