Velocity distributions of mass-identified evaporation residues produced in the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${+}^{40}$Ca reaction have been measured at bombarding energies of 309, 397, and 452 MeV using time-of-flight techniques. These distributions were used to identify evaporation residues and to separate the complete-fusion and incomplete-fusion components. Angular distributions and upper limits for the total evaporation-residue and complete-fusion evaporation-residue cross sections were extracted at all three bombarding energies. The complete-fusion evaporation-residue cross sections and the deduced critical angular momenta are compared with earlier measurements and the predictions of existing models. The ratios of the complete-fusion evaporation-residue cross section to the total evaporation-residue cross section, along with those measured for the ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${+}^{12}$C and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$${+}^{28}$Si systems at the same energies, support the entrance-channel mass-asymmetry dependence of the incomplete-fusion evaporation-residue process reported earlier.

Double differential cross-section angular distributions covering 0°≤${\mathrm{\theta }}_{\mathrm{lab}}$≤40° have been measured for the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(n,p${)}^{40}$K charge exchange reaction. With the white neutron source at LAMPF-WNR, we were able to study not only the angular distribution but also the energy dependence of this charge exchange reaction covering simultaneously incident neutron energies between 60 and 260 MeV. The identification of Gamow-Teller (GT) transitions and L=1 dipole resonance was carried out using a multipole decomposition technique. The empirically deduced GT strength in the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(n,p${)}^{40}$K reaction evaluated up to 15 MeV excitation energy is compared to theoretical values. We have used a simple one-particle–one-hole shell model calculation to study the excitation of the giant dipole resonance and the giant spin-dipole resonance, which are compared with empirical results.

Elastic scattering and ${(}^9$Be${,}^6$He) reaction data have been taken at a ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$ bombarding energy of 40 MeV. The reaction data are consistent with ${(}^9$Be${,}^6$He) being a direct ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ cluster transfer, so that population of ${\mathit{T}}_{>}$=3/2 final states from T=0 targets is unlikely. Contributions to the elastic scattering arising from the identity of the target and projectile have been calculated. Large deviations from standard optical model calculations do not occur until scattering angles are larger than 90° c.m.

Energy spectra and angular distributions have been measured for high energy gamma rays (${\mathit{E}}_{\gamma }$≥20 MeV) from the p+d reaction at 145 and 195 MeV. Gamma rays were observed up to the maximum energy allowed by kinematics. A comparison is made with previous measurements for the p+d system at 140, 197, and 200 MeV. Below the free pnγ threshold the general shape of the energy spectra and angular distributions are in reasonable agreement with a recent calculation of the free pnγ elementary process. However, the magnitude of the predicted cross section is not in good agreement with the present data.

Energy spectra and angular distributions have been measured for high energy gamma rays (${\mathit{E}}_{\gamma }$≥20 MeV) from proton-nucleus reactions at 104, 145, and 195 MeV on targets of C, Zn, and Pb. Gamma rays were observed with energies up to 170 MeV. The spectra showed differences from the typical exponential shape that is observed in gamma ray production from heavy-ion reactions. The angular distribution of the gamma ray is forward peaked in the laboratory, which is consistent with emission from a moving source. A comparison is made with previous measurements at 72, 140, 168, and 200 MeV. The experimental evidence indicates that first-chance incoherent proton-neutron bremsstrahlung is the main production mechanism.

Extraction of spin-longitudinal and -transverse response functions from polarization transfer measurements of nucleon-nucleus quasifree scatterings is discussed. The method proposed by Carey et al. is reconsidered and more general formulas are presented. Spin-longitudinal and -transverse interactions are well defined in the nucleon-nucleon scattering t matrix in the nucleon-nucleon center-of-mass frame. However, observed data are given in the nucleon-nucleus laboratory frame and theoretical analysis based on the distorted-wave and plane-wave impulse approximations is carried out in the nucleon-nucleus center-of-mass system, in which the t matrix in a certain optimum frame of the nucleon-nucleon system is used. Careful consideration is paid for transformations among these reference frames relativistically.

The finite size effect of interacting heavy ions on the strong absorption radius of the heavy-ion potential is examined. The inclusion of the finite size contribution to the dynamic moment of inertia yields smaller values for the strong absorption radius for a given value of the grazing angular momentum. The weak energy dependence seems to be an inherent property of the strong absorption radius parameter irrespective of the size consideration of the interacting heavy ions. The finite size effect has been quantitatively demonstrated for the ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$${+}^{40}$Ca heavy-ion system. The interaction potential for the system is a sum of the Coulomb interaction term and the nuclear interaction part obtained from the unified nuclear potential approach of Krappe, Nix, and Sierk. The strength of the potential is calculated for separation distances greater than the contact radius of interacting heavy ions with sharp spherical ion shapes. The Coulomb interaction term outside the contact radius corresponds to two point charge interacting ions.

Fusion barriers are calculated within the sudden approximation, using the Skyrme interaction energy-density model. Both the closed and unclosed shell nuclei are considered and the role of spin-density term is studied in detail. For unclosed shell nuclei, the fusion cross sections are found to decrease by as much as ∼50 mb when spin-density effects are included. Very accurate, simple analytical expressions, in terms of only the masses and charges of the reacting nuclei, are obtained for the barrier heights and positions. This introduces a great simplification for the fusion barrier calculations.

A Green’s function method is developed to derive quantal zero point motion formulae for the barrier transmission probability in heavy ion fusion reactions corresponding to various nuclear intrinsic degrees of freedom. In order to apply to the decay of a hot nucleus, the formulae are then generalized to the case where the intrinsic degrees of freedom are in thermal equilibrium with a heat bath. A thermal zero point motion formula for vibrational coupling previously obtained through the use of influence functional methods naturally follows, and the effects of rotational coupling are found to be independent of temperature if the deformation is rigid.

We extend the semiclassical approach which was implemented successfully for the one-step direct reaction to the two-step process. Using essentially the same approximations as in a previous paper by Luo and Kawai, we obtain a closed parameter-free formula for the two-step cross section. This formula contains experimental nucleon-nucleon cross sections and distorted-wave intensities, and is physically interpreted.

Predictions relevant for exploring color transparency in (p,2p) nuclear reactions are often made by using simplified treatments of nuclear dynamics. We examine the extent to which the earlier predictions are valid by carrying out calculations using an improved treatment of the proton scattering wave functions, nucleon Fermi motion, and the effects of long- and short-range nuclear correlations. The consequences of two existing models of color transparency are also presented.

We study several aspects of a two-color delta model of interacting quarks, with the purpose of extracting information of relevance to real quark models of nuclei. We first describe a BCS treatment of the quark pair correlations that arise in the model at low densities and demonstrate that the rms radius of the dominant correlated pairs increases in the presence of the medium. We then consider the application of a Dyson boson mapping to the model and show that it incorporates, at the level of the Hartree-Bose approximation, the pair clustering dynamics of quark BCS. However, the collective bosons that emerge do not have the same structure as the correlated BCS pairs. The mapping also leads to a short-range repulsive interaction between the collective bosons, which we derive in both momentum and coordinate space. The additional correlations that result from this repulsive boson interaction can in principle be incorporated through a Brueckner treatment of the mapped boson Hamiltonian.

Quark and gluon condensates in nuclear matter are studied. These in-medium condensates may be linked to a wide range of nuclear phenomena and are important inputs to QCD sum-rule calculations at finite density. The Hellmann-Feynman theorem yields a prediction of the quark condensate that is model independent to first order in the nucleon density. This linear density dependence, with slope determined by the nucleon σ term, implies that the quark condensate is reduced considerably at nuclear matter saturation density—it is roughly 25–50 % smaller than the vacuum value. The trace anomaly and the Hellmann-Feynman theorem lead to a prediction of the gluon condensate that is model independent to first order in the nucleon density. At nuclear matter saturation density, the gluon condensate is about 5% smaller than the vacuum value. Contributions to the in-medium quark condensate that are of higher order in the nucleon density are estimated with mean-field quark-matter calculations using the Nambu–Jona-Lasinio and Gell-Mann–Lévy models. Treatments of nuclear matter based on hadronic degrees of freedom are also considered, and the uncertainties are discussed.

The leading nonperturbative correction to the gluon propagator is derived. The Breit-Fermi-type one-gluon exchange potential with the above-mentioned nonperturbative correction is formulated in the nonrelativistic scheme. The result shows that, except for the regular color Coulomb, color electric, and color magnetic terms, both linear confinement and ${\mathit{r}}^3$ deconfinement terms can automatically be obtained.

A transport theory with chiral symmetry is developed from the quark level to describe the chiral dynamics in high-energy heavy-ion collisions. The strong interaction is treated effectively by the Nambu–Jona-Lasinio model. A set of generalized Boltzmann equations of constitutent quarks and mesons is derived by using the closed time-path Green’s function technique and a loop expansion approach. Chiral symmetry, energy spectrum and dissipation, and density distributions of constitutent quarks and mesons can then be studied self-consistently in the nonequilibrium dynamical processes. In particular, the discussion for exploring chiral symmetry breaking and its restoration and for studying dynamics of meson production (as collective qq¯ excitations) in heavy-ion collisions is presented.

Motivated by the Nambu–Jona-Lasinio model of light mesons, we introduce a covariant separable interaction to model the structure of relativistic quark-antiquark systems. The Schwinger-Dyson equation for the quark self-energy is solved analytically, generating a dynamical quark mass through spontaneous breaking of chiral symmetry, and yielding a pion which has zero mass in the chiral limit. The Bethe-Salpeter vertex function for this qq¯ pion, which has a momentum distribution and composite structure associated with the interaction, is obtained analytically. Using this vertex function, and a similar one for the ρ meson, we calculate the electromagnetic observables of this composite Nambu-Goldstone boson, including effects from ρ-meson dominance processes. Our calculation takes the composite structure of the mesons into account. The ρ-meson effects are found to be very small in the pion charge form factor, but substantial in the charge radius. Using the model, predictions are made for ${\gamma }^{\mathrm{*}}$${\mathrm{\pi }}^0$→γ and ρπγ transition form factors.

Experimental limits on the second class induced tensor weak current are reviewed. A method, involving the measurement of the β-ν-α angular correlations in ${}_{}{}^8{}_{}{}^{}\mathrm{Li}$ and ${}_{}{}^8{}_{}{}^{}\mathrm{B}$ decays is proposed to test for this current with improved precision.

Asymmetries for the scattering of electrons from a polarized deuterium target are investigated to study the isoscalar weak neutral current. Sensitivities of the asymmetries to the vector- and axial-vector-type strange quark current matrix elements have been found to depend on the direction of the polarization of the target. One can study both the vector- and axial-vector-type strange quark current matrix element of the nucleon by changing the direction of the polarization of the target.

For nearly 100 nuclei, the rms expectation values of three neutron transmission observables sensitive to parity violation are predicted. Total enhancement factors ∼${10}^{2–}$${10}^4$ in comparison to related observables in nucleon-nucleon scattering are found. To this end, a model of parity violation in the framework of statistical scattering theory is formulated and worked out in detail. General expressions are deduced from it, which connect the expectation values of parity forbidden S-matrix elements to average input parameters, namely, level densities, transmission coefficients, and spreading widths. The general results are discussed in terms of the relevant nuclear time scales, and the numerical predictions in terms of a ‘‘parity forbidden strength function’’ and several enhancement factors. Additionally, the role of finite energy resolution, crucial for energy averaging experiments, is studied.

Charged- and neutral-current neutrino cross sections for deuterium have been calculated for the Bonn, Paris, and Hamada-Johnson potentials in order to estimate event rates (and their uncertainties) for solar and supernova neutrino detection in the Sudbury Solar Neutrino Observatory. Tests of the wave functions are provided by calculations of the j=1/2 hyperfine-state muon capture rate and of the total cross section for absorbing ${\nu }_{\mathit{e}}$s from stopped muon decay. Detailed tables of the Paris potential results are given, and comparisons are made to the work of Doi and Kubodera.