Absolute ${\mathrm{\pi }}^{\pm }$d differential cross sections and charge asymmetries have been measured at incident pion energies of 30 and 50 MeV, using an active target of scintillator plastic to detect recoil deuterons in coincidence with scattered pions. In addition, a small set of data at 65 MeV was collected for comparision with the results of an earlier experiment performed by this group. Measurements at 50 MeV from the earlier experiment are compared with the results of the present experiment.

Measurements of the polarization observables for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(p,p${)}^3$He elastic scattering have been obtained using a polarized proton beam in conjunction with polarized and unpolarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ targets. An unpolarized target was used to make high precision measurements of the proton analyzing power ${\mathit{A}}_{\mathit{y}0}$ at the energies of 4.01, 5.54, 7.03, 8.52, and 10.1 MeV. A total of 135 data points were obtained with accuracies of typically ±0.005 or better. A newly developed polarized ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ target was then used to make measurements of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ analyzing power ${\mathit{A}}_{0\mathit{y}}$, and the spin correlation coefficient ${\mathit{A}}_{\mathit{y}\mathit{y}}$ at the same five energies. A total of 48 data points were obtained for each observable. Finally, measuremments of the spin correlation coefficients ${\mathit{A}}_{\mathit{x}\mathit{x}}$, ${\mathit{A}}_{\mathit{x}\mathit{z}}$, ${\mathrm{A}}_{\mathrm{zx}}$, and ${\mathit{A}}_{\mathit{z}\mathit{z}}$ were made at the single energy of 5.54 MeV. The accuracy of the spin-correlation and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ analyzing power measurements is typically on the order ±0.01–0.03.

We have used a modified effective range expansion to parametrize the phase shifts for p${\mathrm{-}}^3$He elastic scattering over the energy range of 0 to 12 meV. Energy-dependent phase shifts were determined by fitting a database consisting of 1085 measurements, including 68 new measurements of the spin correlation coefficients ${\mathit{A}}_{\mathit{y}\mathit{y}}$, ${\mathit{A}}_{\mathit{x}\mathit{x}}$, ${\mathit{A}}_{\mathit{z}\mathit{z}}$, ${\mathit{Z}}_{\mathit{x}\mathit{z}}$, and ${\mathit{A}}_{\mathit{z}\mathit{x}}$. The addition of the new second order polarization observables has made it possible to uniquely determine the low energy phase shifts. The final fit has a ${\mathrm{\chi }}^2$ per degree of freedom of 0.966, corresponding to a confidence level of 0.778. The global phase shift uncertainties obtained in the present work represent a significant improvement over the results of previous analyses.

The study of the dynamics of intermediate mass fragment emission in fusion-fission processes has been carried out. The average kinetic energies and relative yield ratio of different fragments are calculated and compared with experimental values.

Hill, Wohn, Schwellenbach, and Smith have recently measured very large electromagnetic dissociation cross sections in the collisions of very heavy nuclei. Weizsacker-Williams (WW) theory predicts that these cross sections should be even larger. It has recently been shown that WW theory fails for these reactions because the associated probabilities are too large. However, WW theory is based on first order perturbation theory and an electric dipole approximation. Calculations are presented which show that for those cases where WW theory and experiment disagree, higher order perturbation plus electric quadrupole corrections improve the agreement between theory and experiment. These corrections also imply that multiple electromagnetic excitations occur.

Confirming our previous proposal, we show within a continuum random-phase approximation calculation that the ratio of proton-to-neutron neutrino-induced quasielastic yield is a sensitive way to determine the strange quark axial form factor of the nucleon. Particularly, we find that the ratio is virtually independent of final state interactions (accounted for by a finite-range force derived from the Bonn meson-exchange potential) and nuclear structure effects. We present the ratio calculated for the neutrino beam available in an experiment currently approved at LAMPF.

An energy-dependent and set of single-energy partial-wave analyse have been completed for the reaction ${\mathrm{\pi }}^{+}$d→pp. Amplitudes are presented for pion laboratory kinetic energies from threshold to 500 MeV. These results are compared with those found in other recent analyses. We comment on the present database and make suggestions for future experiments.

Left-right asymmetries for pion elastic scattering and charge exchange from polarized ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$ are calculated and compared with the available data. It is shown for elastic scattering that the quadrupole spin-flip contribution is dominant in the determination of the asymmetry at forward angles. The distorted wave impulse approximation and optical model treatments are compared and a qualitative discussion of the underlying physics of the sign of the asymmetry in the first diffraction minimum is presented.

Using the Ward-Takahashi (WT) identity and the Bethe-Salpeter wave equation, we investigate the dynamical requirements imposed by electromagnetic gauge invariance on Compton scattering from relativistic composite systems. The importance of off-shell rescattering in intermediate states, which is equivalent to final state interactions in inclusive processes, is clarified in the context of current conservation. It is shown that, if the nuclear force is nonlocal, there will be both two-photon interaction currents and rescattering contributions to terms involving one-photon interaction currents. We derive the two-body WT identity for the two-photon interaction currents, and obtain explicit forms for the interaction current operators for three illustrative models of nuclear forces: (a) two-pion exchange forces with baryon resonances, (b) covariant separable forces, and (c) charged one-pion exchange.

An energy-dependent phase shift analysis of ${\mathrm{\pi }}^{\pm \mathrm{-}4}$He elastic scattering data up to an energy ${\mathit{T}}_{\mathrm{\pi }}$=260 MeV was carried out. Using a careful treatment of Coulomb effects to describe the Coulomb nuclear interference we reexamined the constraints to the π${\mathrm{-}}^4$He forward scattering amplitude ${\mathit{f}}_0$ by dispersion relations. This allows a stringent consistency check of the data. A satisfactory description of the data could only be achieved assuming large error bars of the total cross section measurements and allowing normalization factors for the differential cross section data.

We consider the dependence of collective flow on the nuclear surface thickness in a Boltzmann-Uehling-Uhlenbeck transport model of heavy ion collisions. Well-defined surfaces are introduced by giving test particles a Gaussian density profile of constant width. Zeros of the flow excitation function are as much influenced by the surface thickness as the nuclear equation of state, and the dependence of this effect is understood in terms of a simple potential scattering model. Realistic calculations must also take into account medium effects for the nucleon-nucleon cross section, and impact parameter averaging. We find that balance energy scales with the mass number as ${\mathit{A}}^{\mathrm{-}\mathit{y}}$, where y has a numerical value between 0.35 and 0.5, depending on the assumptions about the in-medium nucleon-nucleon cross section.

We derive simple expressions for the effect of medium modifications (or distortions) on the propagation of a pion between two nucleons in a nucleus. Our results are applicable to pion reactions in a variety of situations, but we are particularly interested in the influence of distortions on pion double charge exchange at low energy. We are able to calculate these distortions for a finite nucleus using a realistic choice of optical potential. We represent their effect as a modification of the S- and P-wave pion-nucleon scattering amplitudes that occur at the location of the first (or last) nucleon to be struck. We illustrate our method by showing numerical results for a shematic optical potential.

High-energy photon-hadron interactions in relativistic heavy ion collisions are studied in the impulse approximation. This leads to an explicit treatment of the spatial distribution of the constituents in the volume of the nucleus struck by the equivalent photon. Relevant changes in the high-energy tail of the equivalent photon spectrum compared to the conventional method are obtained. Total fragmentation cross sections due to photon-hadron interactions which contribute to the luminosity decrease at colliders like the Brookhaven Relativistic Heavy Ion Collider or the CERN Large Hadron Collider (heavy ions) are also studied. As an important application we study the γg fusion into quark-antiquark pairs. This gives a handle to determine the gluon distribution function of nucleons inside the nucleus.

We calculate the total electromagnetic dissociation cross section in peripheral heavy-ion collisions ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$${+}^{208}$Pb for the planned Brookhaven Relativistic Heavy Ion Collider, the CERN Large Hadron Collider, and the Superconducting Super Collider. The two nuclei interact via their Lorentz contracted electromagnetic fields leading to nuclear disintegration. We employ an impact parameter dependent version of the equivalent photon method with experimental photon-nucleus dissociation cross sections. The hadronic structure of the photon at large equivalent photon energies has been taken into account. In particular, we stress unitarity conservation of the dissociation probability for small impact parameters.

Deep-inelastic structure functions ${\mathit{F}}_2^{\mathit{A}}$(x) are investigated in a ${\mathit{Q}}^2$ rescaling model with parton recombination effects. We find that the model can explain experimentally measured ${\mathit{F}}_2^{\mathit{A}}$(x) structure functions reasonably well in the wide Bjorken-x range (0.005<x<0.8). In the very small x region (x<0.02), recombination results are very sensitive to input sea-quark and gluon distributions.

We present a Skyrme model with modified kinetic-energy terms. The baryon current of the model supports both fractional and integer baryon number solutions. Chiral symmetry breaking renders the fractional baryon number states absolutely confined. In the unbroken phase the solutions bear resemblance to the constitutent quarks of the nonrelativistic quark model. The model predicts correctly the nucleon and delta resonance masses using a value for the pion decay constant ${\mathit{F}}_{\mathrm{\pi }}$ very close to experiment. The model yields an attractive central potential between nucleons.

In this paper we describe the role of instantons in a model of the nucleon called the chiral confining model (CCM). The effect of instantons is included through the ’t Hooft interaction. In general, confining models tend to give for the product of nucleon mass and quark rms radius, ${\mathit{M}}_{\mathit{N}}$〈${\mathit{r}}^2$${\mathrm{〉}}^{1/2}$, values in the range 6–8, while the experimental value is 3.48. In the CCM, in principle, the gluons have been integrated out in favor of mesons. Hence the N-Δ mass splitting must be understood in terms of the spin-isospin dependent forces generated by pion exchange. Unfortunately, one-pion exchange contributes only about 50 MeV or less to the N-Δ mass splitting. The ’t Hooft interaction is capable of resolving both these problems. The passage from QCD to the CCM modifies the strength of the ’t Hooft interaction and, at present, we do not know what it is. We fix it by fitting ${\mathit{M}}_{\mathit{N}}$-${\mathit{M}}_{\mathrm{\Delta }}$. With the strength so fixed we obtain values of ${\mathit{M}}_{\mathit{N}}$〈${\mathit{r}}^2$${\mathrm{〉}}^{1/2}$ in the range 4.4–5.1. A simple estimate of the correction for the motion of the center of mass of the nucleon, always present in any mean field calculation, reduces the value to 3.8–4.4. One hopes that the remaining discrepancy will be largely resolved when the mean-field approximation is improved by including quark-quark correlations.

The total cross section for the ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$(d,n${)}^{14}$${\mathrm{O}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ reaction has been measured with ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ radioactive beams at laboratory energies of 8.2, 12.0, 16.2, and 28.5 MeV. A spectroscopic factor of 0.9 is obtained from a distorted-wave Born approximation analysis of this transfer reaction. The astrophysical S factor for the ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$(p,γ${)}^{14}$O reaction is calculated using the experimentally known resonance parameters for the resonant contribution and the direct-capture model with the experimental spectroscopic factor for the nonresonant contribution.

Cross sections for forming ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$ and ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ by the interactions of 13.6-GeV/nucleon ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ ions with Al and for forming ${}_{}{}^{24}{}_{}{}^{}\mathrm{Na}$ in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ interactions with Cu have been measured relative to the cross section for forming ${}_{}{}^{11}{}_{}{}^{}\mathrm{C}$ from carbon. The results are generally consistent with energy-independent inclusive cross sections (limiting fragmentation) for heavy ions between ∼2 and 13.6 GeV/nucleon. However, comparison of the heavy-ion data with those for high-energy protons indicates a significantly weaker dependence on projectile size than that predicted by the factorization hypothesis for ${\mathrm{\sigma }}_{\mathrm{C}}$${(}^{11}$C), ${\mathrm{\sigma }}_{\mathrm{Al}}$${(}^{18}$F), and ${\mathrm{\sigma }}_{\mathrm{Al}}$${(}^{24}$Na). The dependence is slightly stronger in the case of ${\mathrm{\sigma }}_{\mathrm{Cu}}$${(}^{24}$Na).

Inclusive neutron spectra from the decay of ${}_{}{}^{156}{}_{}{}^{}\mathrm{Er}$ compound nucleus populated at ${\mathit{E}}_{\mathit{x}}$=47 MeV excitation energy by the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${+}^{144}$Sm and ${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$${+}^{92}$Zr reactions have been measured. The neutron spectra from the ${}_{}{}^{64}{}_{}{}^{}\mathrm{induced}$ reaction are strongly contaminated by other reactions different from fusion evaporation so that inclusive spectra cannot be used to test nonstatistical or entrance channel effects in the compound nucleus decay.