Cross sections for the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(n,p) reaction were measured at angles of 2.7°, 7.5°, 14.4°, 28.2°, and 34.9° (c.m.) at an incident beam energy of 288 MeV. Outgoing protons were observed to energies corresponding to a Q value of -40 MeV. The reduced cross section for the Gamow-Teller component of the ground-state isobaric-analog transition was determined to be σ^=σ(q=0)/${\mathit{B}}_{\mathrm{GT}}$=6.9±0.2 mb/sr. This value is significantly smaller than that observed for nuclei in the mass range 6≤A≤13. A multipole analysis of the data indicates that the cross section of the continuum up to a Q value of -20 MeV involves mainly ΔL=1 spin dipole transitions. The analysis determines an upper limit of 0.06 units of Gamow-Teller strength in transitions to excited states between 7 and 16 MeV, but is consistent with no Gamow-Teller strength in this region. Distorted wave impulse approximation calculations using transition amplitudes from a large-scale shell model calculation provide a good fit to the measured ground-state cross section, but fail to account for the magnitude of the measured cross sections to the continuum below 30 MeV excitation.

Highly excited neutron hole states in ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ have been studied via the (d→,t) reaction at ${\mathit{E}}_{\mathit{d}}$=200 MeV using for the first time a polarized beam, with both vector and tensor components. The determination of overlapping neutron hole response functions takes advantage of the strong characteristic features of ${\mathit{j}}_{\mathrm{-}}$=l-1/2 versus ${\mathit{j}}_{+}$=l+1/2 level analyzing powers and of the good distorted wave Born approximation (DWBA) description of the reaction. A least-squares fit analysis of the σ, ${\mathit{A}}_{\mathit{y}}$, and ${\mathit{A}}_{\mathit{y}\mathit{y}}$ angular distributions has allowed a determination of the high j transition spectroscopic factors contributing to the excitation energy bins up to ${\mathit{E}}_{\mathit{x}}$=14.5 MeV. The results are compared in details with those relying only on l identification, previously obtained in the 1${\mathit{i}}_{13/2}$ and 1${\mathit{h}}_{9/2}$ valence state fragmentation up to ${\mathit{E}}_{\mathit{x}}$=6.7 MeV and on the 1${\mathit{h}}_{11/2}$ strength up to ∼10 MeV. Several previous conclusions are unambiguously confirmed, in particular, the attribution of the bump around ${\mathit{E}}_{\mathit{x}}$=8.2 MeV to the 1${\mathit{h}}_{11/2}$ strength. In addition, the present experiment settles the attributions of several ${\mathit{j}}_{\mathrm{-}}$ versus ${\mathit{j}}_{+}$ valence groups and indicates that the 1${\mathit{h}}_{9/2}$ strength is spread up to ∼10.8 MeV.

The analysis performed up to ${\mathit{E}}_{\mathit{x}}$=14.5 MeV gives the first determination of the 1${\mathit{h}}_{11/2}$ strength beyond the bump, and a first reliable evidence for the 1${\mathit{g}}_{7/2}$ strength, with the maximum around ${\mathit{E}}_{\mathit{x}}$=11 MeV. ∼85% of these inner hole state sum rules are exhausted in the studied excitation energy range. The spin-orbit splitting of 1h orbitals in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ deduced from the strength centroids is 5.2 MeV. The experimental strength distributions and the integral characteristics of the 1${\mathit{i}}_{13/2}$, 1${\mathit{h}}_{9/2}$, 1${\mathit{h}}_{11/2}$, and 1${\mathit{g}}_{7/2}$ hole states are compared with the results from different theoretical approaches, i.e., microscopic calculations of the fragmentation and phenomenological calculations of spectral functions in a modified mean field. The comparison reports on the sharing of the valence strengths between each quasihole level and the other fragments, characterized by their centroids and widths, and on the shape of the inner hole strength distributions, the centroids and spreading widths.

Mass, angular, and total-kinetic-energy distributions for symmetric mass division products of the compound nucleus (CN) ${}_{}{}^{105}{}_{}{}^{}\mathrm{Ag}$ formed in the ${}_{}{}^{37}{}_{}{}^{}\mathrm{Cl}$${+}^{68}$Zn and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{89}$Y reactions have been measured with a time-of-flight telescope. The characteristics of the products are consistent with those of the fission products obtained in the heavier mass systems. A remarkable angular momentum effect on the width of the mass and total kinetic energy distributions is observed. The features of symmetric mass division products in nuclei with mass numbers around ${\mathit{A}}_{\mathrm{CN}}$=100 are summarized and systematically examined in terms of the corresponding angular momentum.

The reported 330-keV electron line in positron scatterings on a Th target has been reinvestigated by using the positron emitter ${}_{}{}^{82}{}_{}{}^{}\mathrm{Sr}$ in place of ${}_{}{}^{118}{}_{}{}^{}\mathrm{Te}$, employed in previous experiments. We have observed the same line with an energy of 330.1±0.4 keV and a cross section of 158±0.22±0.25 mb. The full width at half maximum is less than 2.1±0.3 keV, which is limited by the instrumental resolution. The experimental results agree with the previous ones.

Deuteron electrodisintegration cross sections near 180° have been measured near breakup threshold for the four-momentum transfer squared ${\mathit{Q}}^2$ range 1.21–2.76 (GeV/c${)}^2$. Evidence for a change of slope in the cross section near ${\mathit{Q}}^2$=1 (GeV/c${)}^2$ has been obtained. The data are compared to nonrelativistic calculations, which predict a strong influence of meson-exchange currents. The data are also compared to a hybrid quark-hadron model. None of these calculations agrees with the data over the entire measured range of ${\mathit{Q}}^2$. The ratio of inelastic structure functions ${\mathit{W}}_1$(${\mathit{Q}}^2$,${\mathit{E}}_{\mathit{n}\mathit{p}}$)/${\mathit{W}}_2$(${\mathit{Q}}^2$,${\mathit{E}}_{\mathit{n}\mathit{p}}$) is extracted from the present results and previous forward angle data. No prediction is in good agreement with the deduced ratios at small relative energy ${\mathit{E}}_{\mathit{n}\mathit{p}}$.

Differential cross sections and analyzing powers for scattering of 200 MeV protons have been measured for states of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ up to 14.4 MeV and for states of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ up to 7.2 MeV of excitation. The data cover c.m. momentum transfers from approximately 0.4 ${\mathrm{fm}}^{\mathrm{-}1}$ to 3.0 ${\mathrm{fm}}^{\mathrm{-}1}$. Calculations were performed using several density-dependent effective interactions in the local density approximation. Empirical effective interactions from isoscalar normal-parity transitions were fitted to elastic and inelastic scattering data for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ either individually or simultaneously. Transition densities from electron scattering were used to minimize uncertainties due to nuclear structure. The fitted interactions were iterated to generate optical potentials self-consistently. We find that the empirical interaction, although strongly dependent on the local density, is essentially independent of target or state. We also find that the empirical interaction is reduced in strength at zero density. Finally, the results were compared with a relativistic impulse approximation model and with a recent global optical potential from Dirac phenomenology.

Target residues from the interaction of copper with 90 MeV/nucleon ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions have been studied using thick-target, thick-catcher recoil range techniques. Cross sections, average ranges, and forward-to-backward ratios have been measured. Isobaric and mass yield distributions, along with mean longitudinal momentum transfer and mean excitation energy, have been obtained from these data. Comparisons with previous 15–45 MeV/nucleon ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$+Cu results and with intranuclear cascade and evaporation models are presented.

Double differential cross sections were measured for neutron emission induced by 256 MeV and 800 MeV protons incident on Li, Al, Zr, and Pb targets. The experimental spectra obtained are almost exclusively attributable to a preequilibrium emission mechanism and are compared to predictions made by several preequilibrium reaction models. The intranuclear cascade model reproduces the data quite well at both incident energies. Other approaches—the statistical multistep direct model and the hybrid model—reach the limit of applicability in their present form as the pion production threshold is crossed.

Bose-Einstein correlations of negative pions in heavy ion collisions have been investigated for the reaction ${}_{}{}^{139}{}_{}{}^{}\mathrm{La}$${+}^{\mathrm{nat}}$La→2${\mathrm{\pi }}^{\mathrm{-}}$X at 12.6 GeV/nucleon at two acceptances, centered at laboratory observation angles of approximately 0° and 45° with respect to the beam axis. A scintillation counter array downstream of the target was used to sample the charged particle multiplicity of each event and hence give some information on the impact parameter of the collision. Including results from previous experiments, space-time dimensions of the pion source are now available for mass-symmetric collisions in the mass range of A=40 to 139. The sources are oblate for nearly all systems, except for La+La central collisions viewed near 45° in the laboratory (90° in the center of mass) where the source is spherical. The perpendicular radius ${\mathit{R}}_{\mathrm{\perp }}$ is never less than 4 fm, regardless of the centrality of the La+La collision. Furthermore, ${\mathit{R}}_{\mathrm{\perp }}$ seems independent of the mass of the collision system.

By integrating the classical formula for fusion of two charged spheres with a flat distribution of barriers extending down to a threshold barrier the fusion cross sections of heavy nuclei at energies near and below the Coulomb barrier have been successfully parametrized by P. H. Stelson. The systematics of the threshold barriers derived from the data are examined in terms of a simple picture in which the onset of free neutron flow between the collision partners promotes fusion at a large distance. A consistent correlation between observed barrier shifts and the conditions necessary to maintain free neutron flow has emerged.

This work investigates the interference in radiative nucleon capture reactions between the giant resonances and the doorway configurations mixed in compound nucleus levels. A unified formalism has been established by which it is possible to study the interference among the four parts in the capture amplitude: the potential capture, valence capture, semidirect capture, and fine resonance capture stemming from doorway configurations. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,${\gamma }_0$) data in the excitation energy region of 10–30 MeV in ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ were analyzed by means of this formalism with an emphasis on investigating the dips and peaks superimposed on the pigmy resonance. These structures are interpreted as destructive or constructive interferences in doorway configurations. Parameters for both the giant resonances and fine levels were extracted by fitting the measured data. We extend the study to discuss the potential of observing similar interferences in the reactions ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(n,${\gamma }_0$) and ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(p,${\gamma }_{\mathit{n}}$${)}^{13}$${\mathrm{N}}^{\mathrm{*}}$, leading to excited states of the final nucleus.

In the linear chiral perturbation theory, both kaon and antikaon masses decrease in dense matter. There is also a repulsive vector potential for the kaon and an attractive one for the antikaon. With these effects included in the relativistic transport model, it is found that the slope parameter of the kaon kinetic energy distribution is larger than that of the antikaon. This is consistent with the experimental data from heavy-ion collisions in the Alternating Gradient Synchrotron experiments at Brookhaven.

We present a dynamical analysis of deep inelastic collisions between two ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ ions at ${\mathit{E}}_{\mathrm{c}.\mathrm{m}.\mathrm{}}$=14.7 MeV/nucleon using two different models. The first, a microscopic model, is based on the Landau-Vlasov equation which includes a two-body residual-interaction collision term. The second model is based on a macroscopic approach which uses collective shape degrees of freedom and a one-body dissipation mechanism. The results of our microscopic calculations show good qualitative agreement with experimental data.

On the basis of recent progress in our ability to predict cross sections for pair transfer, the interesting possibility of observing multipair transfer in collisions between heavy nuclei is reexamined. The results indicate that 3–4 pair transfer between pairing vibrational and pairing rotational states should be observable at low bombarding energies.

We have used the relativistic impulse approximation (RIA) to study the newly measured neutron total cross section data for ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$. In particular, we are interested in what we can learn from the RIA in order to build up a phenomenological optical potential. A complete set of scattering observables would be required in order to study the details of the neutron-nucleus interaction. In the absence of any such data at intermediate energy, the present study of total cross sections provides useful preliminary information on the isovector part of a generalized nucleon-nucleus interaction. We used the NN amplitude calculated by McNeil, Ray, and Wallace (MRW) and the relativistic Love-Frany NN amplitude developed by Murdock and Horowitz (MH). We found that the use of MH’s amplitude in the RIA gives a good description to the neutron total cross section from 200 to 400 MeV, while the use of MRW’s amplitude provides a good description from 500 MeV and above. The energy dependence of the volume integrals of the total optical potential is consistent from both calculations, but there is a large difference in the energy dependence of the volume integral of the isovector part of the potential.

Formulas are derived for cross sections for inclusive (p,${\mathrm{\Delta }}^{++}$) and (p,p′ ${\mathrm{\pi }}^{+}$) reactions; these are shown to depend on the pion self-energy in the nucleus, and the production and decay vertices of the ${\mathrm{\Delta }}^{++}$. The pion self-energy includes both nucleon excitation (${\mathrm{NN}}^{-1\mathrm{}}$) as well as delta excitation (Δ${\mathrm{N}}^{-1\mathrm{}}$) in the nucleus. The pion-nucleon couplings in the transition vertex as well as in the self-energy are written using relativistic pseudovector coupling; results are compared with a nonrelativistic reduction. The distortions of the continuum particles are included in a “distorted-wave Fermi gas” approximation. Calculations are made for the excitation spectrum of the nucleus, dσ/dω, and the angular distribution in the (p,${\mathrm{\Delta }}^{++}$) reaction, for proton beam energies from threshold to 3 GeV. For the (p,p′ ${\mathrm{\pi }}^{+}$) reaction cross sections are calculated for the proton spectrum and the distribution dσ/d${\mathrm{\Omega }}_{\mathrm{\pi }}$Ωp′${\mathrm{dE}}_{\mathrm{p}\prime }$${\mathrm{dE}}_{\mathrm{\pi }}$ at fixed values of the proton and proton angles and a fixed value of ${\mathrm{E}}_{\mathrm{p}\prime }$. The latter essentially gives the excitation energy spectrum of the nucleus. Many interesting features are seen in these spectra. The differences in results using relativistic pion-nucleon coupling and its nonrelativistic reduction are shown to increase with the beam energy. Around 400 MeV, there is little difference in the cross sections but at 1 GeV and beyond the difference becomes large, changing both the magnitude and shape of the distributions. The inclusion of distortions reduces the magnitude of the cross section but leaves the shape unchanged.

We have applied S(l)-to-V(r) inversion to S matrices from coupled channel and CDCC calculations of Kamimura and co-workers in order to establish the local and l-independent dynamic polarization potential for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ scattering at 168, 216, and 311 MeV. The energy dependence and the character of the dynamic polarization potential (DPP) are discussed. It is shown that a consistent pattern of smooth DPPs can be found so long as no attempt is made to include within them a representation of S(l) where ‖S‖ is very small. Inclusion of further partial waves leads to wavy potentials, although information can be extracted from them by careful adjustment of the extent to which S(l) are fitted. The particular characteristics of the iterative perturbative (IP) inversion procedure play a key role in making these investigations possible. It turns out that certain aspects of the behavior we extract are very similar to those found previously for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ on ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at the Coulomb barrier. The particular characteristics of the IP inversion procedure which are important for this work are emphasized.

Cross sections for the electromagnetic dissociation of ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ targets by 1.7 GeV/nucleon ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ and 1 GeV/nucleon ${}_{}{}^{86}{}_{}{}^{}\mathrm{Kr}$, ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$, and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ beams have been measured by an activation method. We observe systematic discrepancies between the experimental data and a simple Weizsäcker-Williams calculation: For the heaviest projectiles, the calculation overpredicts the 1n cross sections, whereas the 2n and 3n cross sections are systematically underpredicted. The deviations can be significantly reduced, however, by calculations including isoscalar and isovector giant quadrupole excitations as well as the possibility to excite multiphonon states. The most important experimental result of the present study is the observation of large cross sections for three-neutron removal from ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ with ${}_{}{}^{197}{}_{}{}^{}\mathrm{Au}$ and ${}_{}{}^{209}{}_{}{}^{}\mathrm{Bi}$ projectiles which can only be explained by a dominant contribution from two-phonon giant dipole excitation. For an almost quantitative reproduction for all xn channels observed, we have to assume a higher excitation probability by roughly a factor of 2 for the double giant dipole resonance as compared to the harmonic approach.

After a long and controversial tradition of applications to high-energy hadron-hadron and hadron-nucleus collisions, relativistic hydrodynamics may finally become a convincing concept when applied to ultrarelativistic nuclear collisions with large projectiles and targets. We propose a new method, which we call global hydrodynamics, for solving the hydrodynamic equations, with two objectives in mind: first to make the calculations easier by using an approximate but very efficient scheme, and second to gain new insights into the dynamics by establishing the global expansion characteristics as a new viewpoint. The method consists of integrating the partial differential equations of hydrodynamics over an azimuthally symmetric region to obtain global conservation laws from the local ones. Assuming specific thermal and velocity profiles we derive ordinary differential equations for the most relevant dynamical quantities which are easy to solve. This enables us to do large numbers of runs easily and thus to perform a systematic scan of the whole range of possible initial conditions, following each case individually until freeze-out. By comparing the computed particle spectra to experiments it is possible to restrict the initial conditions and obtain quantitative information on the early dynamics of relativistic nuclear collisions.

Second-order radiative corrections to the nucleon axial vector coupling constant from gluon, pion, and sigma meson exchange are calculated in the chiral soliton quark model. Many apparent processes are found not to contribute. The soliton is elastically decoupled from meson radiative corrections which are dominated by a gluon exchange contribution equivalent to a gluonic hybrid component of the nucleon. A 30% radiative reduction of the axial coupling strength is indicated.