The coupled channel method for heavy ion scattering is greatly simplified by suitable transformations of wave functions in the case of large reduced mass.

In ${}_{}{}^{70}{}_{}{}^{}\mathrm{Zn}$${(}^{16}$O${,}^{14}$C${)}^{72}$Ge, at 110 MeV, the first-excited $0^{+}$ state at 0.69 MeV (commonly thought to be a two-proton excitation) has vanishingly small transfer strength–the upper limit is less than one percent of the ground state strength.

We present a model based on the direct reaction concept which is able to describe the fusion cross section consistently throughout the entire range of the measured energies from the sub-barrier region to the very high energies where the cross section decreases linearly as the inverse of the center of mass energy. The model is applied to the fusion reaction of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ with ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ where Harmon et al. measured the cross section at energies up to three times the Coulomb barrier.

Experimental neutron multiplicities and spectral slope parameters are compared with evaporation calculations for the damped ${}_{}{}^{165}{}_{}{}^{}$Ho${+\mathrm{}}^{56}$Fe reaction as a function of $E_{\mathrm{loss}}$ for different degrees of energy relaxation of the dinuclear system. These calculations indicate that the popular direct interpretation of the slope parameters in terms of the nuclear temperature of the emitter is poorly justified. Detailed comparisons for two different primary reaction fragment distributions show that the energy partition of the primary fragments is energy-loss dependent and, for small energy losses, far from thermal equilibrium. For $E_{\mathrm{loss}<100\mathrm{}}$ MeV, the ratio $E_L$(Fe-like)/$E_H$(Ho-like)>0.5 and for $E_{\mathrm{loss}=150\mathrm{}}$ MeV, this ratio is given by $A_L$/$A_H$.

A new iterative method is used to solve the self-consistent periodic mean field equations governing nuclear fission. A general filter method is introduced to interactively refine an initial approximation, and its stability and convergence are analyzed. The basic ideas are illustrated for the familiar static Hartree equations and generalized to address the unique aspects of the mean field tunneling problem. The method is applied to an illustrative self-consistent fission problem.

We have used the (${\pi }^{\mathrm{-}}$,${\pi }^0$) reaction at a beam energy of 475 MeV on targets of ${}_{}{}^1{}_{}{}^{}\mathrm{H}$, ${}_{}{}^2{}_{}{}^{}\mathrm{H}$, C, and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ to examine excitations near 300 MeV. At this excitation energy, delta production is expected to occur by charge exchange on a nucleon. Our (${\pi }^{\mathrm{-}}$,${\pi }^0$) results for delta production in complex nuclei are compared to those for photoabsorption, (p,n), and ${(}^3$He,t) reactions. The target mass dependence of the absorption for the three charge-exchange reactions is found to be similar.

We study the p¯${+\mathrm{}}^{12}$C→n¯+X reactions within the nuclear cascade model, where the free space antiproton reaction data are used as inputs and the Pauli effect is taken into account. It is found that the energy dependence of the annihilation cross sections reduces the (p¯,n¯) cross sections and the Pauli effect further cuts down the (p¯,n¯) cross sections at small angles, and hence the cascade model largely underestimates the (p¯,n¯) cross sections.

Target nucleon correlation contributions to intermediate energy proton-nucleus elastic scattering observables are explored within the context of a semirelativistic multiple scattering model. A general, nonlocal expression for this second-order relativistic optical potential model is derived and discussed. Use is made of the local, projectile-target nucleon interaction given by the relativistic impulse approximation together with a shell model target nucleus wave function represented in a suitable, four-component form. For this initial investigation a simplified model is then assumed in which only the scalar and time-like vector components of the projectile-nucleon interaction are retained and in which the lower components of the target wave function are omitted. Intermediate propagation of positive and negative energy projectile states are included, as are important nonlocalities arising from the Dirac propagator for the projectile. Numerical estimates are provided for several cases of interest. Individual terms in the correlation contribution to the optical potential are fairly large; significant cancellations occur, however, resulting in relatively small changes in the calculated proton-nucleus elastic scattering observables. The differential cross section predictions are increased in magnitude at forward angles, although to a lesser degree than in nonrelativistic models of correlation effects. Analyzing powers and spin rotation functions, which are generally described quite well by the first-order relativistic impulse approximation model, are not significantly affected by these corrections, except at large scattering angles. These results indicate that the semirelativistic impulse approximation model considered here is stable with respect to higher-order multiple scattering contributions, at least to the level of two-body target nucleon correlations. The erroneous target mass dependence of the first-order relativistic impulse approximation model is not corrected by these effects, however.

The ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ charge form factor is investigated based on the Reid soft-core potential model and the relativistic harmonic oscillator quark model. A reasonable agreement with the experimental data is obtained for the momentum transfer up to ∼1.0 GeV/c with 2.7% six-quark compound state confined within a radius of ∼0.9 fm.

Inclusive cross sections for the proton and nuclear targets of A=4, 9, 12, and 16 were measured for 537 and 730 MeV electrons scattered at 37.1 deg. Systematic features of the continuum scattering data are compared with other electron scattering data and with photoabsorption measurements. A model calculation based on the isobar-hole formalism is compared with the data in the delta resonance region.

A nonrelativistic nucleon-nucleon interaction potential model containing explicit coupling to NΔ(1232 MeV) and /or ${\mathrm{NN}}^{\mathrm{*}}$(1440 MeV) channels is developed and used to describe empirical elastic scattering phase shifts from 0–1000 MeV. The theoretical Feshbach-Lomon meson exchange potential provides the starting point for describing the interaction between the two nucleons. NNπ and NNNN¯ intermediate states are implicitly included through the two-pion exchange portion of the Feshbach-Lomon interaction. Short range phenomenological NN-NN potentials are used along with empirical short range and one pion exchange coupling potentials between the nucleon-nucleon and nucleon-isobar channels. Quantitative fits to the Arndt phase shifts and inelasticity parameters from 0–1000 MeV for J≤6 are obtained. The resulting potentials are obtained in a local, coordinate space representation, convenient for use in many-body calculations at intermediate energies.

Cross section and analyzing power angular distribution measurements are reported for the ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$(p→,${\pi }^{\mathrm{-}}$${)\mathrm{}}^{49}$Ti reaction at two bombarding energies ($T_{\mathrm{p}=166\mathrm{}}$ and 205 MeV) and for ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$(p→,${\pi }^{\mathrm{-}}$${)\mathrm{}}^{43}$Ti at $T_{\mathrm{p}=205\mathrm{}}$ MeV. Also presented for comparison are single-angle spectra for (p,${\pi }^{\mathrm{-}}$) on other $f_{7/2}$-shell targets and for ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ti}$(p,${\pi }^{+}$${)\mathrm{}}^{49}$Ti. The (p, ${\pi }^{\mathrm{-}}$) spectra show a strong selectivity for population of high-spin (${\mathrm{}(15/2)\mathrm{}}^{\mathrm{-}}$ and ${\mathrm{}(19/2)\mathrm{}}^{\mathrm{-}}$) 2p-1h [(π$f_{7/2}$${)}^2$(ν$f_{7/2}$${)}^{\mathrm{-}1}$] states, which are not prominent in the (p,${\pi }^{+}$) spectrum. Supporting evidence for the high-spin identification comes from comparisons with simple (p,${\pi }^{\mathrm{-}}$) model calculations and the results of other reaction studies. Characteristic features of the data for the high-spin states and for the continuum portions of the (p,${\pi }^{\mathrm{-}}$) spectra are discussed in the context of a two-nucleon (NN→NNπ) pion production mechanism. All of the main systematic features observed are at least qualitatively consistent with expectations for such a mechanism.

Inelastic scattering of 163 MeV ${\pi }^{\mathrm{-}}$ and ${\pi }^{+}$ to the collective states of ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$ was used to determine the neutron-proton composition of the transitions. The lowest $2^{+}$ and $3^{\mathrm{-}}$ states were examined for both targets, as were the low-energy octupole, giant quadrupole, and giant monopole excitations. Only slight deviations from the features expected for a hydrodynamic model are observed for the low-lying $3^{\mathrm{-}}$ and $2^{+}$ states of ${}_{}{}^{118}{}_{}{}^{}\mathrm{Sn}$, but these states are observed to be proton-like in ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$. The giant quadrupole resonances and giant monopole resonances in both targets show a significantly greater ${\pi }^{\mathrm{-}}$ than ${\pi }^{+}$ strength, while the low-energy octupole resonance is excited symmetrically.

The branching ratio of the electron-capture decay of ${}_{}{}^{81}{}_{}{}^{}\mathrm{Kr}_{}^{\mathrm{m}}{}_{}{}^{}$ (13 s) has been measured in order to obtain the rate of the neutrino capture reaction ${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$(ν,${\mathrm{re}}^{-}$${)}^{81}$Kr(190.6 keV). This quantity is needed to determine the properties of an ${}_{}{}^{81}{}_{}{}^{}\mathrm{Br}$ solar neutrino detector. A branching ratio of (3.14±0.58)×${10}^{\mathrm{-}5}$ was obtained, leading to a logft of ${5.10}_{\mathrm{-}0.07}^{+0.06\mathrm{}}$ for this transition.

The circular polarization of the 1.081 MeV γ rays from ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ has been measured to be (1.7±5.8)×${10}^{\mathrm{-}4}$. ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ was produced by a 4.05 MeV ${}_{}{}^3{}_{}{}^{}$${\mathrm{He}}^{+}$ beam impinging on a recirculating water target with a thin entrance window. The circular polarization was measured with four magnetic transmission polarimeters, each backed by a 150 ${\mathrm{cm}}^3$ n-type Ge detector. A fast data acquisition system limited overall peak losses to 30% at a count rate of 60 kHz per detector. Supplementary experiments were carried out to investigate the sensitivity of the circular polarization measurement to systematic variations of beam position and intensity. These effects were found to be negligible relative to the statistical uncertainty. The experimental result is interpreted in terms of an isovector parity-nonconserving matrix element between the ‖$0^{+}$,T=1,1.042 MeV〉 and ‖$0^{\mathrm{-}}$,T=0,1.081 MeV〉 states in ${}_{}{}^{18}{}_{}{}^{}\mathrm{F}$ that is dominated by the weak pion exchange contribution. The present result for the weak pion-nucleon coupling strength is ‖$f_{\pi }^1$‖=(0.$4_{-0.4}^{+1.4\mathrm{}}$)×${10}^{-7}$, which is significantly smaller than recent theoretical predictions based on the Weinberg-Salam model.

The effect of deuteron structure on the hyperfine structure of deuterium is reexamined by using several realistic nucleon-nucleon (NN) potentials. We find that the value of the Bohr-Low correction is almost the same for all the potentials considered, and is larger than the value obtained by Low and by Low and Salpeter by using much simpler potentials. Among other corrections to the hyperfine structure, the most important one is due to angular momentum (L) dependent terms in the NN potential. This correction is sensitive to the choice of the potential. When these other corrections are included, theory and experiment become compatible for some of the potentials, while the situation is worsened for others. However, there are remaining ambiguities related to mesonic and isobaric effects, the implications of which are discussed.

The apparent contradiction between alpha strengths of ${11/2}^{\mathrm{-}}$ states in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and their E2 decays to ${7/2}^{\mathrm{-}}$ states is removed by considering configuration mixing in both ${7/2}^{\mathrm{-}}$ and ${11/2}^{\mathrm{-}}$ states.

A model based on a static quadrupole and octupole deformation of the intrinsic nuclear shape gives an accurate description of the low-energy level spectrum and wave functions in ${}_{}{}^{227}{}_{}{}^{}\mathrm{Ac}$. Major discrepancies between strong-coupling theory and experiment are removed by taking into account the nonadiabaticity of the nucleonic motion.

Excitation functions at 175° (lab) for elastic scattering of ${\pi }^{+}$ from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been measured across the energy region of the pion-nucleon (3,3) resonance. Optical-model calculations with matter distributions deduced from electron scattering qualitatively reproduce the data, but better agreement can be obtained with suitable modifications. These modifications may indicate the effects of the nuclear medium on the basic pion-nucleon interaction.

Previous data for (${\pi }^{+}$,${\pi }^{\mathrm{-}}$) double charge exchange on ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ have been extended by measuring forward-angle cross sections at six additional energies.