A simple weak coupling model previously applied to the analysis of the yrast spectrum of ${}_{}{}^{143}{}_{}{}^{}\mathrm{Nd}$ is extended to yrast spectra of odd-A N=82 and 83 isotopes of Z=58–61 nuclei. The model generally provides a good description of these spectra; however, yrast 19/$2^{+}$ states expected to arise in ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$ and ${}_{}{}^{143}{}_{}{}^{}\mathrm{Pm}$ from the coupling of π${\mathit{g}}_{7/2}$ holes to the $6_1^{+}$ states of the even-even cores are not observed experimentally. The absence of these states can be explained using a simple microscopic argument.

We have performed a microscopic calculation for the reaction ${}_{}{}^3{}_{}{}^{}\mathrm{He}$${+}^3$H→d+α with special emphasis on recent measurements by Rai et al. of the analyzing power. A detailed comparison is given with the d→+α${\to }^3$He${+}^3$H reaction. The dynamics responsible for deviations from isospin symmetry in the two reactions manifests indeed in different ways. A comparative analysis seems to allow for a better determination of a specific matrix element responsible for the apparent isospin breaking effects in the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$${+}^3$H→d+α reaction.

Using a coupled-channel model (NN-ΔΔ) as a dynamical model for the deuteron it is found that a small amount of the ΔΔ state in the deuteron (0.36%) compatible with the recent experimental limit (<0.4%) accounts to a large extent for the shifting of the diffraction minimum in the B(q) structure function. The A(q) structure function is well described within this model.

Intranuclear cascade calculations are found to provide a good description of the various features of subthreshold ${\mathrm{\pi }}^0$ production in nucleon-nucleus collisions.

The quasifree production of hyperons by ${\mathit{K}}^{\mathrm{-}}$ on C and Li has been calculated. A purely kinematical model has been used to correlate experimental N(${\mathit{K}}^{\mathrm{-}}$,${\mathrm{\pi }}^{+}$)Y cross sections with the reaction amplitude of the kaon with a bound nucleon. In all cases one observes experimental points at lower missing mass values than the computed quasifree production cutoff. This is interpreted that a bound hypernucleus state exists.

Large-angle excitation functions for ${\mathrm{\pi }}^{+}$ scattering on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ are calculated by using the theoretical optical potentials based on the α-particle model of nuclei. The results show that considerably improved agreement with the experimental data over the Kisslinger-type optical model calculations is obtained.

We study the effects of coupling between the fission coordinate and bosonic intrinsic excitations on the fission width by using a path integral method. We assume a general coupling form factor and discuss how the decay width at high temperature changes from that of the extended Kramers formula recently obtained in the bilinear coupling model. Applying the results to two different types of bosonic spectra we show a possibility to represent the effects of nonlinearity of the coupling in terms of a suitable renormalization of the friction and the mass for the fission coordinate.

The scaling behavior of the observed fragment yields in the reactions induced by high-energy proton and relativistic heavy ions can be explained in terms of a rate equation. In the mean field approximation we have been able to show that the solution of the rate equation after a large time develops a scaling form that can then be compared with experiments.

We performed the coupling of a quasiparticle to an even-even core described by the microscopic-macroscopic Kumar-Baranger solution of the Bohr Hamiltonian. The coupling was made in the usual way, directly in the laboratory frame, and also in a new fashion, in the intrinsic reference frame, with subsequent transformation to the laboratory coordinates. The states occupied by the quasiparticle were taken from the microscopic part of the solution for the core. This model was applied to describe the low-lying levels of ${}_{}{}^{133}{}_{}{}^{}\mathrm{Xe}$. The results are compared to the experimental data, showing good agreement.

Azimuthal distributions of fragments with respect to the reaction plane are studied in the Ar+V system as a function of beam energy. Light charged particles are found to exhibit an enhanced emission in the reaction plane which increases with the mass of the detected particle. As the beam energy is increased, the asymmetry decreases. Possible mechanisms behind the asymmetry, such as rotational collective motion and directed transverse momentum, are discussed.

We present data for small-angle particle-particle correlations from the reactions 80, 140, 215, and 250 MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$${+}^{27}$Al→p-p or p-d. The main features of these data are anticorrelations for small relative momenta (≤25 MeV/c) that strengthen with increasing bombarding energy. Statistical model calculations have been performed to predict the mean lifetimes for each step of evaporative decay, and then simulate the trajectories of the particle pairs and the resulting particle correlations. This simulation accounts very well for the trends of the data and can provide an important new test for the hypothesis of equilibration on which the model is built.

The first measurements of γ rays following the decays of ${}_{}{}^{134}{}_{}{}^{}\mathrm{Sn}$ and the $0^{\mathrm{-}}$ isomer of ${}_{}{}^{134}{}_{}{}^{}\mathrm{Sb}$ are reported. The decay schemes have been constructed using the γ-ray data in combination with results from delayed neutron spectroscopy. Both decays are dominated by the first forbidden ground state β transitions. All observed levels can be interpreted in terms of the shell model. The energy of the (ν${\mathit{h}}_{9/2}$π${\mathit{h}}_{11/2}$)$1^{+}$ state in ${}_{}{}^{134}{}_{}{}^{}\mathrm{Sb}$ was found to be 3.85 MeV, implying a n-p interaction energy which is less than that of the g orbitals in very neutron-rich isotopes of In.

States in doubly odd ${}_{}{}^{216}{}_{}{}^{}\mathrm{Fr}$ have been studied using in-beam α, γ, and ${\mathit{e}}^{\mathrm{-}}$ spectroscopy techniques through the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$${(}^{11}$B3n) fusion-evaporation reaction. ${}_{}{}^{216}{}_{}{}^{}\mathrm{Fr}$ shows a band structure with interleaved states of alternating parities connected by enhanced B(E1) transitions. It represents the lowest-mass corner of the region (Z≥87,N≥129) in which this phenomenon is observed.

Reports that fusion of hydrogen isotopes may occur at room temperature during the electrolysis of ${\mathrm{D}}_2$O led us to investigate possible d-t fusion reactions in an electrolysis cell with a tritiated Ti cathode. A searc for 14-MeV neutrons from this reaction, using an NE213 scintillator detector and pulse shape discrimination techniques, showed no significant deviations from background levels. We derive an upper limit of ${10}^{\mathrm{-}23}$ ${\mathrm{s}}^{\mathrm{-}1}$ for the fusion rate per d-t pair.

We have measured γ rays in coincidence with ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ fragments from the fission of ${}_{}{}^{56}{}_{}{}^{}\mathrm{Ni}$ produced with the ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$${+}^{24}$Mg reaction at ${\mathit{E}}_{\mathrm{lab}}$=140 MeV. These data provide insight into the fission process in this light system by giving information about the energy and spin sharing between the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ fragments, and the spin alignment of the lighter, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ fragment. The spin transfer and the nuclear ‘‘temperature’’ at scission deduced from this measurement can be related to the compound-nucleus spin and potential energy at scission. The results indicate a statistical decay process consistent with the predictions of the transition-state model employing newer estimates of the spin- and mass-asymmetry-dependent saddle-point energies and corresponding shapes. No evidence is found for the spin alignment of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ fragments, contrary to what might be expected for a deep-inelastic scattering origin of the fully energy damped yields.

Microscopic calculations of the energy shifts and widths of kaonic atoms are carried out using a low-energy kaon-nucleon T matrix which is parametrized by a single Yukawa function. The Λ(1405) resonance is not included explicitly but only via its influence on the T matrix at threshold. The experimental values for the shifts and widths are approximately reproduced using a range of 0.66 fm for both the real and imaginary parts of the T matrix, although the use of different ranges for the two parts may result in an improvement of the fit. Medium corrections are negligibly small.

We show that it is possible to obtain a quantitatively excellent description of low energy NN scattering, including the deuteron, using a relativistic equation with a simple one boson exchange kernel consisting of the exchange of only π,σ,ρ, and ω mesons. Relativistic properties of the meson-nucleon couplings play an essential role in the success of the description. A second model which includes ${\mathrm{\sigma }}_1$ and η mesons in addition to those in the four-meson model has also been constructed and is virtually equivalent to the four-meson model on shell. Since these two models differ off shell and are the same on shell, the low energy on-shell NN data cannot completely determine the off-shell NN amplitudes.

We have studied the reaction p+p→p+p+${\mathrm{\pi }}^0$, near threshold, at five energies between 320 and 500 MeV, by detecting the decay γ rays of the ${\mathrm{\pi }}^0$ in coincidence in two large NaI crystals. The ${\mathrm{\pi }}^0$ energy and angular distributions were measured from which we determine that the s-wave contribution to the total cross section is ${\mathrm{\sigma }}_{\mathit{T}\mathit{s}}^{\mathit{S}}$(μb)=(15.2±3.0)${\mathrm{\eta }}_0^2$. This is somewhat lower than results of previous experiments.

The dependence of excitation-energy sharing on the direction of the net transfer of mass, observed by Viola and co-workers, is interpreted in terms of the participant-spectator model of Wilczynski and Wilschut. It is demonstrated that the division of the excitation energy in fully damped collisions (proportional to the mass numbers of the fragments) is a natural consequence of the participant-spectator kinematics and therefore it does not necessarily imply temperature equilibration prior to scission.