Neutral pion production has been studied in the ${}_{}{}^{36}{}_{}{}^{}\mathrm{Ar}$${+}^{27}$Al reaction at 95 MeV/nucleon with the aim to get a quantitative estimate of its impact-parameter dependence. A near 4π multidetector has been used to detect both the gamma rays originating from the ${\mathrm{\pi }}^0$ decay and the associated charged particles. The charged particle multiplicity has been used in the present analysis as a global variable to extract the impact parameter scale. A comparison with a Boltzmann-Nordheim-Vlasov calculation, whcih takes into account the effect of pion reabsorption in the nuclear medium, has been performed.

Tensor and vector analyzing powers for the ${}_{}{}^2{}_{}{}^{}\mathrm{H}$(d,γ${)}^4$He reaction have been obtained as a function of angle at ${\mathit{E}}_{\mathit{d}}$(lab)=20, 30, and 50 MeV. Differential cross sections were extracted at 30 and 50 MeV. Data for ${\mathit{A}}_{\mathit{y}\mathit{y}}$(θ) and ${\mathit{A}}_{\mathit{y}}$(θ) were obtained at all three energies, while ${\mathit{T}}_{20}$(θ) was also measured at ${\mathit{E}}_{\mathit{d}}$(lab)=50 MeV. A direct capture calculation was performed and compared to the data. This calculation assumes point deuterons and that the reaction proceeds primarily via $E2$ radiation in this region. A value of 4% for the D state probability arising from two-deuteron relative motion in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ wave function was extracted by fitting the predictions of this model to the data. This calculation indicates that g-wave capture is significant at the energies of the present experiment, a result which is supported by a transition-matrix element analysis of the data. The results of a microscopic 7-channel resonating group model (MCRGM) calculation are also compared to the data. This model takes all amplitudes having incoming angular momenta l≤2 into account as well as the couplings to the n${\mathrm{-}}^3$He and p-T channels. This microscopic calculation, which has produced reasonable agreement with the previous low energy data, predicts a value of 2.2% for the two-deuteron component of the D state in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. There is qualitative agreement with the present data.

Angular distributions of differential cross-section and vector analyzing power have been measured for the ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$${(}^6$Li→${,}^6$He${)}^{26}$Al reaction, populating four states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$, at an incident energy of 60 MeV. Distorted-wave Born approximation (DWBA) calculations were performed for the ${(}^6$Li→${,}^6$He) process using shell-model spectroscopic amplitudes and microscopic form factors derived from the M3Y interaction. Sequential contributions to the charge-exchange reaction mechanism via the ${(}^6$Li→${,}^7$Li)${(}^7$Li${,}^6$He) and ${(}^6$Li→${,}^7$${\mathrm{Li}}^{\mathrm{*}}$)${(}^7$${\mathrm{Li}}^{\mathrm{*}}$${,}^6$He) processes were calculated using the coupled-channels Born approximation (CCBA). The effects of inelastic couplings in ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ were also examined.

The absolute cross section of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$(n,γ${)}^4$He reaction was measured at five energies between ${\mathit{E}}_{\mathit{n}}$=0.14–2.0 MeV to an accuracy of ∼±10%. The ∼21 MeV gamma rays produced in a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ gas target were detected at 90° with respect to the beam direction. The results are discussed in light of previous measurements of the two-body photodisintegration of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$.

Three structure functions have been determined in the reaction ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(e,e’p${)}^{15}$N at ${\mathit{Q}}^2$=0.20 (GeV/c${)}^2$ for 1${\mathit{p}}_{1/2}$ and 1${\mathit{p}}_{3/2}$ knockout and for the excitation of the (5/$2^{+}$,1/$2^{+}$) doublet at ${\mathit{E}}_{\mathit{x}}$=5.3 MeV in ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$. The longitudinal-transverse interference structure function ${\mathit{W}}_{\mathit{L}\mathit{T}}$ is enhanced by a factor 2.05±0.06±0.12 for 1${\mathit{p}}_{3/2}$ knockout and by a factor 1.50±0.10±0.08 for 1${\mathit{p}}_{1/2}$ knockout with respect to a calculation that gives a proper account of data taken in parallel kinematics. The longitudinal structure function ${\mathit{W}}_{\mathit{L}}$ is also enhanced, albeit less with respect to these calculations.

The ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$($1^{+}$0)${\to }^4$He+d virtual decay vertex constant ${\mathit{G}}_0$ and the respective asymptotic coefficient ${\mathit{C}}_0$ of the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ wave function in the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$+d channel are found using the analytic continuation of the solution of a novel energy-dependent phase-shift analysis of elastic d${\mathrm{-}}^4$He scattering to the pole corresponding to the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ ground state. The reliability and accuracy of the method used have been corroborated independently by three other ways: by directly solving the inverse problem for d${\mathrm{-}}^4$He scattering and by two different methods for finding a solution for the three-body (α+n+p) problem. The values ${\mathit{G}}_0^2$=0.42±0.02 fm and ${\mathit{C}}_0$=2.93±0.15 have been found, which seem to be the most accurate and reliable among the values obtained so far.

We study pion-induced single- and double-charge exchange reactions in nuclei at energies above the Δ(3/2,3/2) resonance using a microscopic, parameter-free Glauber approach. We introduce corrections in the amplitudes due to the medium polarization from an isospin-flip spin-nonflip source which dominates the reaction in the transitions studied and which has not previously been identified. Using an effective force derived from the study of electromagnetic transitions we obtain sizable reductions of the cross sections in both single- and double-charge exchanges, which bring the results of both reactions into close agreement with experiment. Predictions for angular distributions for both reactions on ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, and ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$ targets are made which should serve as guidelines for experiments planned in this region and as further tests of the proposed isovector renormalization.

We have derived a general formula for the coalescence model that expresses the formation cross sections for various kinds of composite particles consisting of an arbitrary number of particles with different interaction ranges and masses. We have studied the formation of light nuclei to confirm the validity of this model. We have also studied the formation of a double-lambda hypernucleus ${(}_{\mathrm{\Lambda }\mathrm{\Lambda }}^{6\mathrm{H}\mathrm{e}}$) and a pineut (${\mathrm{\pi }}^{\mathrm{-}}$${\mathit{n}}^2$) as examples. This formula is extremely useful for studying the formation cross sections of composite particles.

The present model describes the exotic decay of nuclei by considering the molecular phase of the fragments in an effective liquid drop description of the process. Shell corrections are included via experimental values of energy released in the disintegration (Q value), which is used to define the effective surface tension of the drop. The Coulomb potential energy is the exact solution of the Poisson equation for a uniform charge distribution in the nuclear volume. The inertial coefficient of the barrier penetrability problem is determined by using the Werner-Wheeler approximation for the velocity field of the nuclear flow. The model is successful in calculating the half-life for both the exotic decay and the α disintegration processes.

We examine effects of the energy dependence of the elementary nucleon-nucleon cross section on extracting the so-called in-medium cross section by studying the beam energy dependence of the flow parameter. The reliability of a recently inferred in-medium cross section using a Boltzmann-Uehling-Uhlenbeck transport model with a constant cross section is discussed.

The first uniform semiclassical (SC) calculations of Regge pole positions and residues have been carried out for four complex optical potentials, which have been used to fit ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{28}$Si elastic-scattering data at ${\mathit{E}}_{\mathrm{lab}}$=55 MeV. In particular, we have extended a SC formalism developed for atomic and molecular scatterings to allow for the presence of a long-range Coulomb potential. The SC Regge poles and residues are compared with quantum results of Takemasa and Tamura [Phys. Rev. C 18, 1282 (1978)], who numerically integrated the radial Schrödinger equation. The SC computations show that Takemasa and Tamura missed ten poles. Using a modified version of the quantum computer code regge, due to Takemasa, Tamura, and Wolter [Comput. Phys. Commun. 18, 427 (1979)] we have located five of these poles—the remaining poles have residues of modulus <${10}^{\mathrm{-}8}$. For low values of the Regge pole quantum number, n, the SC and quantum pole positions are in close agreement, with larger differences for the residues. As n increases, the SC results become less accurate. However at high values of n, the quantum results also lose accuracy due to numerical instabilities in the regge code. It is demonstrated that the choice of Coulomb interaction—charged sphere or pure Coulomb—can significantly effect the properties of the Regge pole positions and residues.

We use the (3+1)-dimensional string-parton model to study relativistic collisions of heavy ions at CERN energies. Various inclusive hadronic observables, such as transverse energy, ${\mathit{dE}}_{\mathit{T}}$/dη, and rapidity distributions, are calculated and compared with WA80 and NA35 data. We study secondary interactions that occur during the dynamical evolution, and show that these interactions tend to fill the midrapidity region. The dynamical evolution of the energy density of produced mesons and their thermodynamic properties are also studied.

We study elastic proton-nucleus scattering at intermediate energies. The nucleon-nucleus optical potential is derived from the Bonn nucleon-nucleon potential and the Dirac-Brueckner approach for nuclear matter. Our calculations, which do not contain any adjustable parameters, yield good agreement with experiment.

We argue that the ratio of cross sections of quasielastic electron scattering for heavy and light nuclei at x>1 and ${\mathit{Q}}^2$>1 (GeV/c${)}^2$ should exhibit simple scaling relations which are ultimately expressed through the ratio of the light-cone nucleon distributions in nuclei. We extract these cross section ratios from existing data in a practically model independent way. The results are found to be in reasonable agreement with our x-scaling relations for the region of 2>x≥1.4 where the contribution of two-nucleon short-range correlations are expected to dominate. The ratios exhibit scaling in the light-cone fraction, α, of the struck nucleon for the range 2>x≥0.9. The α scaling is in agreement with the expectations of the light-cone quantum mechanics of nuclei, providing further evidence for the dominance of short-range correlations in nuclei at k>0.3 GeV/c. An extension of this analysis to the interpretation of color transparency experiments is discussed.

We develop a complete and consistent description for the hadron spectra from heavy ion collisions in terms of a few collective variables, in particular temperature, longitudinal, and transverse flow. To achieve a meaningful comparison with presently available data, we also include the resonance decays into our picture. To disentangle the influences of transverse flow and resonance decays in the ${\mathit{m}}_{\mathit{T}}$ spectra, we analyze in detail the shape of the ${\mathit{m}}_{\mathit{T}}$ spectra.

Non-Abelian induced bremsstrahlung associated with multiple scattering of high-energy parton in a quark-gluon plasma is investigated in the context of semiclassical gauge-covariant kinetic theory. New collisions terms are derived involving the scattering of virtual gluons by the self-charge of the high-energy parton (Compton bremsstrahlung) as well as by dynamical polarization (nonlinear bremsstrahlung).

The surface tension of a quark nugget is calculated at zero temperature by taking into account the dynamical effects due to an increase in the effective color coupling and the quark confinement at the surface. Assuming a Woods-Saxon shape for the baryon density, the surface tension is calculated in two different approximations, namely the local density approximation and the quark cluster approximation. It is found that, in the former case, the surface tension depends sensitively on the rate of increase of the effective color coupling strength and in the latter case it depends on the rate of change of the cluster size at the surface. The surface tension also depends strongly on the choice of the skin thickness and the minimum baryon density at the surface.

We have derived an expression for the cross section for the γd→pn reaction at small momentum transfers t and u in the framework of the quark-gluon model and Regge phenomenology. Our predictions reproduce very well the few data available at energies between 1.5 and 4.2 GeV, where our approach can be applied. Moreover, we found a good agreement also with the forward- and backward-angle data in the intermediate-energy region.

The kinetic energy of the Skyrmion-Skyrmion system is calculated in the product ansatz. The energy is expanded in a set of rotationally invariant quadratic functions of translational and isorotational velocities in the product ansatz and all inertial parameters are evaluated. Most of the isospin dependent parameters are small at separations larger than 1 fm. However, some parameters of the coupling between the isorotational velocities of the Skyrmions decay slowly, as 1/R, when zero pion mass is used. Otherwise we find that the results are not sensitive to the addition of the pion mass term.

A direct measurement of the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$(γ,${\mathit{p}}_0$) reaction was performed using 34 MeV end-point bremsstrahlung photons. Photoprotons were simultaneously detected at nine angles. The magnitude of the deduced cross section is at variance with the results from recent experiments but is in perfect agreement with the previously recommended values. Consequently, as yet no definite conclusion can be drawn about the validity of charge symmetry of the nuclear force.