The fusion cross sections for the ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{152}$Sm system in the near- and sub-barrier region are calculated on the basis of a direct reaction description for fusion by introducing a dynamic polarization potential which reproduces coupled-channels effects in a one-channel optical model. It is found that this method explains data as well as coupled-channels results very well. The calculated spin distributions of the compound nucleus again agree well with those from coupled-channels calculations.

In this paper we study some aspects of the ${\mathrm{K}}_{\mathrm{L}}^0$ elastic scattering as well as of the ${\mathrm{K}}_{\mathrm{S}}^0$ regeneration on nuclei. In particular, the radial localization of these processes and their sensitivity to neutron densities are discussed.

Fusion cross sections for ${}_{}{}^{16}{}_{}{}^{}$O${+\mathrm{}}^{16}$O and ${}_{}{}^{40}{}_{}{}^{}$Ca${+\mathrm{}}^{40}$Ca reactions are calculated in the classical microscopic equations of motion approach. Calculated fusion cross sections are sensitive to the long-range nature of the effective nucleon-nucleon (NN) potential. It is shown that with a proper choice of the parameters of the NN potential, the model calculations give good agreement with experiments over a wide range of energies above the fusion barrier.

We predict a narrow resonance structure (Γ≃10 MeV) in the excitaton function of (${\pi }^{+}$,${\pi }^{\mathrm{-}}$) double-charge-exchange reactions at a pion kinetic energy of ∼419 MeV. This structure is due to the interference between the usual ${\pi }^{+}$→${\pi }^0$→${\pi }^{\mathrm{-}}$ double-charge-exchange amplitudes, which have a smooth energy dependence, and a resonant ${\pi }^{+}$→${\eta }^0$→${\pi }^{\mathrm{-}}$ high-energy double-charge-exchange amplitude associated with the formation of a strongly bound η-nucleus system. The latter process leads to a novel feature of the pion-nucleus interaction, the mesonic compound nucleus resonance.

The $S^2$ factors of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$${+}_{\mathrm{\Lambda }}^9$Be and α${+\mathrm{}}_{\Lambda }^8$Be decays from the S-substitutional state of ${}_{{\mathrm{}}^1{\mathrm{}}_{\mathrm{\Lambda }}^2}{}^{}{}_{}{}^{}\mathrm{C}$ are evaluated by assuming ${\mathrm{SU}}_3$ wave functions. The unknown hypernucleus, the lifetime of which was measured, is identified as ${}_{\mathrm{\Lambda }}{}^9{}_{}{}^{}\mathrm{Be}$.

It is shown that the energies and strengths of states at high excitation energy in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ which are strongly excited at high q by inelastic electron scattering may be understood in terms of $p_{3/2}^{\mathrm{-}1}$×$d_{5/2}^2$ weak-coupling configurations, and that the spin assignments suggested by Manley et al. are unlikely to be correct. Also, it is pointed out that a problem can arise in the interpretation of observed M4-like strength since M4 and E3 form factors from the magnetization current are known to be identical in shape for 0p→0d transitions (in addition, M2 and E1 form factors can also peak at high q). Comments are also made on states observed in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$.

Some possible problems in Millener’s suggested spin assignments for states at high excitation energy in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ are pointed out.

The level structure of ${}_{}{}^{139}{}_{}{}^{}\mathrm{Pm}$ has been investigated. The yrast band, based on a decoupled $h_{\frac{11}{2}}$ proton orbital, was observed up to $J^{\pi }={\frac{59}{2}}^{-}$. A sharp backbend with a surprisingly large gain in alignment $\Delta i=14\mathrm{}\hslash$ was observed at a frequency $\hslash \omega =0.43\mathrm{}$ MeV. This large increase in alignment, which is twice that observed in the ${}_{}{}^{137}{}_{}{}^{}\mathrm{Pm}$ isotope, is due to the simultaneous alignment of both a pair of $h_{\frac{11}{2}}$ protons and $h_{\frac{11}{2}}$ neutrons. A $\Delta J=1\mathrm{}$ sideband based on the neutron-aligned configuration $\pi h_{\frac{11}{2}}\otimes {\left(\nu h_{\frac{11}{2}}\right)}^2$ with a large negative $\gamma$ deformation ($\gamma \sim -60\mathrm{}°$) was also observed. The observation of both $\pi h_{\frac{11}{2}}$ and $\nu h_{\frac{11}{2}}$ alignments is consistent with cranked-shell model calculations.

The perturbative vacuum for models in which fermions are coupled to scalar bosons and contain no derivative coupling for the scalar is shown to be unstable at the one-loop level. The instability is due to fluctuations at a sufficiently short-distance scale and is caused by the fermion loop contributions. Possible instabilities in models, which couple fermions to vector bosons only, are also discussed.

Configuration mixing calculations based on a first-order perturbation theory are carried out to study higher-shell mixing effects on the stretched $1\hslash \omega$ particle-hole excitations. It is shown that the suppression of the transition strengths which has been observed in electron scattering and in hadronic reactions can be obtained theoretically in all the closed shell nuclei, being in qualitative agreement with experiments.

We have found in the neutron-deuteron scattering a correlation of $Kcot{}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ with the doublet scattering length (${}_{}{}^2{}_{}{}^{}a$) which is roughly linear for energies above the threshold. We predict the value of $Kcot{}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ for the accepted experimental ${}_{}{}^2{}_{}{}^{}a$ value at the energies of 5.6 and 9.4 MeV. Our calculations reproduce the ${}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ p-d experimental data of Arvieux, but are in disagreement with the experimental n-d ${}_{}{}^2{}_{}{}^{}\delta _0^{}{}_{}{}^{}$ data of Van Oers and Seagrave.

Good fits to the magnetic moments of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ are obtained when the nucleonic bags consisting of three quarks each are assumed to be deformed. Expressions for the magnetic dipole strengths residing in the low-energy and the $\Delta$ sectors are obtained. If, as manifested in the European Muon Collaboration effect, the bags expand in the nuclear medium, then the net deformation of a bag must also decrease in nuclei.

Semiclassical kinematic arguments and optimum Q value considerations together with phase space considerations allow the theoretical disentanglement of direct stripping reactions and preequilibrium reactions from fragmentation phenomena.

New levels at high excitation in ${}_{}{}^{110}{}_{}{}^{}\mathrm{Sn}$ have been determined using a γ-ray multiplicity filter and the reaction ${}_{42}{}^{94}{}_{}{}^{}\mathrm{Mo}$${(}^{19}$F, p2nγ${)}_{{\mathrm{}}^1{\mathrm{}}_{50}^{10}}$Sn at 83 MeV. Evidence is presented for a ΔJ=2 band with spins from ${10}^{+}$ to ${20}^{+}$. The behavior of this band suggests that it arises from the ν($h_{11/2}$${)}^2$ configuration in ${}_{}{}^{110}{}_{}{}^{}\mathrm{Sn}$ rather than the known 2p2h proton configuration structure present in other even heavier tin isotopes.

We have measured excitation functions for elastic and inelastic scattering of the nonsymmetric alpha-particle system of ${}_{}{}^{24}{}_{}{}^{}\mathrm{Si}$, in the energy range 90.95 MeV<$E_{\mathrm{lab}<106.25\mathrm{}}$ MeV. We observe narrow structures similar to those seen in the nearby ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ systems. Elastic scattering angular distributions reflect the contribution of two or three l values for structures at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=50.51\mathrm{}}$ and 52.53 MeV, with the dominant partial waves in the range of l=33 to 38 ħ. A statistical fluctuation analysis of the data for the low lying excitations confirms the nonstatistical nature of these resonances.

The contribution of the spin density term in the Vautherin-Brink energy density functional to the real part of the heavy-ion potential is estimated. The explicit expression involving Hartree-Fock orbitals given by Vautherin and Brink is used to calculate the spin density where, instead of self-consistent orbitals, shell model orbitals have been used. Results are presented for target projectile combinations such that (a) one of the nuclei is spin unsaturated and (b) both are spin unsaturated. The contribution of the spin density term to the heavy-ion potential is found to be appreciable.

We analyze the phase structure of the nonlinear mean-field meson theory of baryonic matter (nucleons plus delta resonances). Depending on the choice of the coupling constants, we find three physically distinct phase transitions in this theory: a nucleonic liquid-gas transition in the low temperature, $T_c$<20 MeV, low density, ρ≃0.5${\rho }_0$, regime, a high-temperature (T≃150 MeV) finite density transition from a gas of massive hadrons to a nearly massless baryon, antibaryon plasma, and, third, a strong phase transition from the nucleonic fluid to a resonance-dominated ‘‘delta-matter’’ isomer at ρ>2${\rho }_0$ and $T_c$<50 MeV. All three phase transitions are of first order. It is shown that the occurrence of these different phase transitions depends critically on the coupling constants. Since the production of pions also depends strongly on the coupling constants, it is seen that the equation of state cannot be derived unambiguously from pion data.