Statistical calculations to predict the neutron spectrum resulting from the decay of giant resonances are discussed. The dependence of the results on the optical potential parametrization and on the level density of the residual nucleus is assessed. A Hauser-Feshbach calculation is performed for the decay of the monopole giant resonance in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ using the experimental levels of ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}$ from a recent compilation. The calculated statistical decay is in excellent agreement with recent experimental data, showing that the decay of this resonance is dominantly statistical, as predicted by continuum random phase approximation calculations.

Excitation functions for the yields of all the residual nuclei from the ${}_{}{}^{28}{}_{}{}^{}{+\mathrm{}}^{28}$,30Si and ${}_{}{}^{30}{}_{}{}^{}$Si${+\mathrm{}}^{30}$Si reactions have been measured via the gamma-ray technique for center of mass energies in the region within one and two times the Coulomb barrier, using steps of 500 keV in the laboratory system. Thirteen nuclides were identified for the first reaction and ten for the other two. While no structure is shown by the data for the ${}_{}{}^{28}{}_{}{}^{}$Si${+\mathrm{}}^{28}$Si reaction, we have found evidence for intermediate width structure in the 2α and αpn channels in ${}_{}{}^{28}{}_{}{}^{}$Si${+\mathrm{}}^{30}$Si, and for broad structure in the total fusion cross section for ${}_{}{}^{30}{}_{}{}^{}$Si${+\mathrm{}}^{30}$Si. Calculations using a barrier penetration model with one free parameter reproduce the average behavior of the fusion cross sections quite well.

The one-nucleon transfer reactions ${}_{}{}^{28}{}_{}{}^{}\mathrm{O}$${,}^{17}$O${)}^2$ ${}_{}{}^9{}_{}{}^{}\mathrm{Si}$ and ${}_{}{}^{28}{}_{}{}^{}\mathrm{O}$${,}^{19}$F${)}^2$ ${}_{}{}^7{}_{}{}^{}\mathrm{Al}$ have been studied at 352 MeV bombarding energy. Several strong transitions were identified in each reaction and analyzed using the distorted-wave Born approximation. A shallow, surface-transparent optical potential of E-18 type did not give acceptable results, but deeper, more conventional potentials fitted the data without any need for renormalization. Data on the same reactions taken earlier at 56 MeV were reanalyzed and the results compared to the present experiment. The use of the distorted-waves approximation is examined critically.

Yields for isotopes of Rn through Pu have been measured in the reaction ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$${+}^{248}$Cm at an energy of 248–263 MeV (1.04–1.10 times the Coulomb barrier). Despite the low bombarding energy, high and essentially constant integral yields of about 1 to 2 mb for the elements Rn through U were observed. There is evidence that these nuclides are produced with little excitation energy.

Lifetimes of high-spin states in ${}_{}{}^{157}{}_{}{}^{}$,158,159Er have been measured following the reaction ${}_{}{}^{128}{}_{}{}^{}\mathrm{Te}$${(}^{34}$S,xn) induced by 155-MeV ${}_{}{}^{34}{}_{}{}^{}\mathrm{S}$ ions. A Doppler-shift recoil-distance device was used and γ-γ coincidences were recorded between five germanium detectors at 90° to the beam direction and a Compton-suppressed Ge detector at 0° to record the shifted and unshifted γ-ray peaks. The results for the ground band of ${}_{}{}^{158}{}_{}{}^{}\mathrm{Er}$ clearly show increasing collectivity with spin, an effect probably arising from centrifugal stretching for this N=90 nucleus. In the s band, formed by the alignment of a pair of $i_{13/2}$ neutrons, there is a significant reduction in the collectivity, which appears to have a rotational-frequency dependence similar to that found earlier for ${}_{}{}^{160}{}_{}{}^{}\mathrm{Yb}$ and interpreted as possibly arising from movement toward triaxiality in the nuclear shape. Four states each in the yrast bands of ${}_{}{}^{157}{}_{}{}^{}\mathrm{Er}$ and ${}_{}{}^{159}{}_{}{}^{}\mathrm{Er}$ were also measured, and here, too, a similar reduction of collectivity at higher rotational frequencies is observed.

The polarization of the lambda hyperons, produced in proton- and nucleus-induced interactions over a wide range of incident energies and target masses, is examined. The persistence and con- stancy of the polarization up to the highest energy measured is consistent with the absence of quark-gluon plasma in these reactions. It is suggested that, in ultrarelativistic heavy ion collisions, the formation of quark-gluon plasma in the central region will result in the diminishing of the polarization of central rapidity lambdas.

The double scattering correction to the ion-ion double folding interaction is calculated for the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ system. The multiple scattering theory was employed for the purpose. The effect of this correction on the total reaction cross section at intermediate energies (∼100 MeV/nucleon) was found to be less than 10%.

Quasicontinuum γ-decay studies of ${}_{}{}^{144}{}_{}{}^{}\mathrm{Gd}$ have been performed using the ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$${(}^{28}$Si, 4n)reaction at 125, 135, 145, and 155 MeV bombarding energies. Angular distribution and multiplicity measurements have been done at the above energies. At 145 MeV bombarding energy, a lifetime measurement has also been performed. Although a collective behavior has been observed, the present data do not give evidence for population of superdeformed rotational bands. Theoretical interpretation using the cranking model with the Woods-Saxon field is given. The effects of temperature and pairing on the superdeformed configuration are discussed; superdeformation effects are predicted to disappear below I∼60–70 ħ when temperature exceeds ∼500 keV.

The fusion of the heavy asymmetric systems of ${}_{}{}^{16}{}_{}{}^{}$O,${\mathrm{}}^{18}$O${+\mathrm{}}^{208}$Pb and ${}_{}{}^{15}{}_{}{}^{}$N,${\mathrm{}}^{16}$O${+\mathrm{}}^{209}$Bi was studied at bombarding energies near and below the Coulomb barrier. The fusion-fission, transfer, and elastic angular distributions were measured for all four systems. The evaporation residue component of the fusion was measured for only the ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{208}$Pb→${\mathrm{}}^{224}$Th reaction; in agreement with statistical model calculations, the cross section for the evaporation residues was found to be negligible compared to the fission, and hence can be ignored in all the systems. The shapes of the fission fragment angular distributions are then a direct measure of the entrance channel spins which lead to fusion. The experimental sub-barrier fusion cross sections are underpredicted by the one-dimensional barrier penetration model in all cases. However, if the zero point motion of the targets is included in the barrier penetration model, the energy dependence of both the total fusion and the fission angular distributions can be explained for the ${}_{}{}^{15}{}_{}{}^{}$N${+\mathrm{}}^{209}$Bi system alone. To fit the low-energy fusion of the oxygen reactions requires considerably more zero point motion—this being inconsistent with the fact that this effect should be the same in all the reactions. Also, the cross sections measured for the transfer channels were found to exhibit the same trend as the fusion at the lower energies. This correlation suggests that some of the sub-barrier fusion in the oxygen-induced reactions may be due to transfer-related processes.

A projection operator method is presented for the extraction of resonance energies, shifts, and widths of bound states embedded in the continuum for potentials that have a repulsive core. The procedure is applicable for heavy ion as well as nucleon-nucleus collisions. The original potential is modified beyond the radius where the repulsive core merges into the attractive part of the potential by a harmonic oscillator potential whose shape is determined primarily by the harmonic oscillator frequency. The method requires that the size of the modified well be fixed for only one particular l value. It is then automatically determined for a range of other l values. The extracted bound states can be used reliably in ensuing diagonalization procedures and in treating continuum-continuum coupling. The method is readily applicable to the determination of widths in those situations where the normal phase shift procedure cannot be employed. As a test case the procedure is applied to ${}_{}{}^{12}{}_{}{}^{}$C${+\mathrm{}}^{12}$C for l=0 to 8 and yields resonance energies and widths in very good agreement with a phase shift analysis.

The theory of excitation of the giant quadrupole resonance in E/Q=0.5–2.1 GeV heavy ion collisions is studied. Karol’s soft spheres model based on nucleon-nucleon cross sections is generalized to deal with collective excitations in deformed nuclei. The giant quadrupole resonance cross sections are calculated in several cases. The results are shown to be in close agreement with the prediction of Blair’s simple diffraction model except for excitation in the light nuclei ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. Comparison with ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ fragmentation yield data is made.

I present a macroscopic model for the energy of rotating nuclei which has several refinements relative to the rotating-liquid-drop model. Of most importance are the inclusion of finite-range effects in the nuclear surface energy by means of a Yukawa-plus-exponential potential, finite surface diffuseness effects in the Coulomb energy and in the rotational moments of inertia, and an improved specification of nuclear shapes. With this model I calculate the properties of points of equilibrium corresponding to nuclear ground states and fission saddle points. The results are qualitatively similar to those of the rotating-liquid-drop model, but there are significant quantitative differences in fission-barrier heights and moments of inertia. Fission barriers for nonrotating nuclei are calculated for nuclei with atomic numbers varying from 14 to 117. For rotating nuclei, detailed results are given for the entire range of angular momentum for which a fission barrier exists, for nuclei with atomic numbers from 20 to 100, and for mass numbers which exceed the range of known nuclei. The calculated barriers are lower than liquid-drop-model barriers for lighter nuclei and are consistent with those deduced from experimental fission-fusion data over a wide range of nuclear species. The present calculations indicate that super-deformed rotating ground states, which are predicted in the liquid-drop model, would not survive fission long enough to undergo electromagnetic decay. Multiparameter functions which approximately reproduce the calculated results for barrier heights and moments of inertia are described.

Inelastic scattering of 800 MeV protons has been studied for targets of ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$, and ${}_{}{}^{116}{}_{}{}^{}\mathrm{Sn}$. At excitation energies above particle emission threshold a spectrum of giant resonances is clearly in evidence. Angular distributions were extracted for the high-lying peaks (∼20 MeV excitation energy) in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ and ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$. Collective model distorted-wave Born approximation analyses of these data show that isoscalar octupole and dipole states dominate the spectra.

The spin observables in quasielastic proton scattering are calculated in a simple relativistic model where the NN interaction is assumed to depend on the enhancement of the lower components of nucleon wave functions (because of strong nuclear potentials). This enhancement is characterized by an average effective mass $M^{\mathrm{*}}$ of (0.8–0.9)M which is calculated in an eikonal model. The $M^{\mathrm{*}}$ dependence of the NN interaction is taken from relativistic impulse approximation calculations. The polarization is found to decrease by 40 percent compared to the free NN value at 500 MeV. Next, simple formulas are provided to estimate the effects of spin-orbit potential distortions on spin observables. At 500 MeV and 18.5° in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$, the polarization is decreased by 5 percent while $D_{l\mathcal{’}l}$ and $D_{s\mathcal{’}s}$ are decreased by 15 percent and $D_{\mathrm{nn}}$ is almost unchanged.

We study the production of ${\mathrm{K}}^{+}$ mesons in pA collisions at energies below the threshold for a stationary nucleon target. Using the picture of color flux tubes, the ${\mathrm{K}}^{+}$ production cross section on many-quark clusters is connected with that on a nucleon target at energies above the threshold. Comparison with experimental data yields upper estimates for the rate of many-quark-cluster states in nuclei.

We compare three different types of relativistic two-body equations, namely the Blankenbecler-Sugar equation, the Gross equation, and an equation derived from relativistic three-body equations. Regarding the one-boson-exchange, the corresponding potentials coincide on mass shell but differ off shell. The potential connected with the three-body equation even shows some cuts in the momentum plane. We analyze the differences for the example of the one-pion-exchange calculating half-off-shell functions and phase shifts. We also include strong πNN form factors and discuss the influence of some of their parametrizations on the phase shifts.

We present an approximate theoretical calculation of the cross section for the reaction p+${\mathrm{}}^{12}$C→${}^{13}$ C+${\mu }^{+}$ +${\nu }_{\mu }$ for center of mass proton energies from $E_{\mathrm{p}=1060\mathrm{}}$ MeV to $E_{\mathrm{p}=1085\mathrm{}}$ MeV. We make use of data from p${+\mathrm{}}^{12}$C→${\mathrm{}}^{13}$C+${\pi }^{+}$ and p${+\mathrm{}}^{12}$C→γ${+\mathrm{}}^{13}$N reactions to obtain approximate values for the form factors involved via the partially conserved axial current hypothesis and conserved vector current hypothesis, respectively. We discuss the utility of this process in studying the role of anomalous thresholds in the nuclear partially conserved axial vector current.

We examine the p-wave πN scattering at medium energies by means of the Low equation with a view to determining the form factor of the πN interaction. Solutions of the equation with and without a Castillejo-Dalitz-Dyson (CDD) pole are used. The solution with no CDD pole corresponds to the old Chew-Low model, whereas the one with a CDD pole corresponds to the quark version of the Chew-Low model. The πN interaction form factor is determined so that the Δ resonance is well reproduced. We find that the solution with a CDD pole leads to a softer form factor but is not as soft as those expected from the nucleon size in the quark model. Using the solutions and form factors thus determined, we also examine the pionic contributions to the nucleon magnetic moment and the nucleon mass.

The ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$(${\pi }^{+}$,${\pi }^0$${)\mathrm{}}^{14}$N reaction to the isobaric analog state has been studied at pion energies between 35 and 100 MeV as an extension of earlier measurements at 100 to 295 MeV. Absolute differential cross sections were measured over the 0°–25° angular range, except at 49.3 MeV, where the range was extended to 75°. A deep minimum was found in the 0° excitation function near 50 MeV, similar to that in the ${\pi }^{\mathrm{-}}$p→${\pi }^0$n excitation function due to the near cancellation of the S- and P-wave contributions. A comparison of the data with several theoretical models is presented.

The Bethe-Salpeter equation for coupled-channel N-Δ scattering is extended to satisfy unitarity in the NN and NNπ sectors. The procedure eliminates the unitarity violations characteristic of the standard ladder Bethe-Salpeter equation in the inelastic region, and improves the description of pion production near threshold. Results are presented for the NN phase shifts and a number of observables up to 1 GeV. In particular, the ${}_{}{}^1{}_{}{}^{}\mathrm{D}_2^{}{}_{}{}^{}$ inelasticity is found to be considerably smaller than found from phase shift analysis. In this context, the importance of the pion deuteron channel for the inelasticity parameter is pointed out.