The analysis of the cross section and the tensor analyzing power of the reaction $p+\overrightarrow{d}\to {}_{}{}^3{}_{}{}^{}\mathrm{He}+\eta$ provides us with the most direct, and the strongest, signature of the meson double-scattering three-body mechanism in $\mathrm{pd}$ capture reactions.

Evidence is presented for a $\pi h_{\frac{9}{2}}$ band crossing at surprisingly low rotational frequency in the odd-neutron ${}_{}{}^{185}{}_{}{}^{}\mathrm{Pt}$ and odd-proton ${}_{}{}^{183}{}_{}{}^{}\mathrm{Ir}$ nuclei. The proton nature of the crossing is indicated by measured $\frac{B(M1;I\to I-1)}{B(E2;I\to I-2)}$ ratios, strongly supported by theoretical values from both the semi-classical Dönau and Frauendorf approach and a variable-core particle-rotor calculation employing cranked-shell-model matrix elements. However, the actual crossing frequency is greatly overestimated by the cranking method using generally accepted model parameters.

A new formula for the neutron separation energy at high nuclear excitations and nuclear spin is derived. The statistical theory of the superfluid nucleus is used to obtain the neutron emission probability at high spins $>50\mathrm{}\hslash$. The results obtained here agree very well with the recent experimental data of Henss et al. for ${}_{68}{}^{156}{}_{}{}^{}\mathrm{Er}$. The nature and consequences of the structural transitions for the isotones $N=88\mathrm{}$ have been investigated comprehensively. A shape transition from prolate to oblate at $I\simeq 47\hslash$ is predicted for ${}_{68}{}^{156}{}_{}{}^{}\mathrm{Er}$.

We have measured the differential cross sections for coherent Compton photon scattering in the reaction ${}_{}{}^4{}_{}{}^{}\mathrm{He}(\gamma ,\gamma ){}_{}{}^4{}_{}{}^{}\mathrm{He}$ at laboratory angles of 24°, 30°, 45°, and 60° with an average laboratory photon energy of 320 MeV, at 22° with 358 MeV, and at 30° with 260 MeV. These measurements are the first unambiguous test of the $\Delta$-hole formalism for this reaction near the peak of the cross section for the $\Delta$ resonance. The results are compared to theoretical calculations in the isobar-hole model. Agreement is good for data at the energy corresponding to the $\Delta$ peak.

A macroscopic approach to giant dipole resonances (GDR's) in hot rotating nuclei is presented. It is based on the Landau theory of nuclear shape transitions and provides a unified description of thermal fluctuations in all quadrupole shape degrees of freedom. With all parameters fixed by the zero-temperature nuclear properties the theory shows a very good agreement with existing GDR measurements in hot nuclei. The sensitivity of the GDR peak to the shape of hot nuclei is critically examined. Low-temperature experimental results in Er show clear evidence for changes in the nuclear energy surface, while higher-temperature results are dominated by the fluctuations.

In the microscopic approach the decay constant of cluster radioactivity is determined by the preformation probability for the open channel multiplied with the Gamov penetrability. The preformation probability is found to possess a simple mass dependence on the emitted cluster. This observation leads to a formula for order-of-magnitude estimates of absolute decay constants. The estimates are in excellent agreement with available experimental data. Predictions for as-yet unmeasured decay rates are made.

Longitudinal response functions for ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ have been obtained from inclusive electron scattering cross sections, for $200\le q\le 550$ MeV/c. The response functions are compared with several theoretical calculations, all of which use exact three-body ground-state wave functions. The response functions are found to be more similar than the calculations predict. When a direct calculation of the Coulomb sum rule is compared with our data, the agreement is good and evidence for two-proton correlations in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is clear.

The distribution of $M1\mathrm{}$ strength in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ has been measured between 5.8 and 7.4 MeV with highly polarized tagged photons. $\Sigma \frac{{\Gamma }_0^2\mathrm{}\left(M1\mathrm{}\right)\mathrm{}}{\Gamma }={14.6}_{-1.3\mathrm{}}^{+1.5\mathrm{}}$ eV corresponding to $\Sigma B\left(M1\mathrm{}\uparrow \right)=\left({10.7}_{-0.9\mathrm{}}^{+1.1\mathrm{}}\right){\mu }_N^2$ was found, and can fully account for the much discussed "missing" $M1\mathrm{}$ in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$. When the present result is combined with known $1^{+}$ transitions above neutron threshold, an $M1\mathrm{}$ giant resonance emerges at 7.3 MeV, 1 MeV wide, with $\Sigma B\left(M1\mathrm{}\uparrow \right)\approx 15.6{\mu }_N^2$. Smaller $1^{+}$ resonances are also seen at both 5.85 and 6.24 MeV. The total $M1\mathrm{}$ strength below 6.4 MeV amounts to $\Sigma B\left(M1\mathrm{}\right)\mathrm{}=\left({1.9}_{-0.4\mathrm{}}^{+0.7\mathrm{}}\right){\mu }_N^2$.

We present new measurements of the analyzing power for $\mathrm{np}$ scattering at 10.03 MeV accurate to ± 1 × ${10}^{-3\mathrm{}}$. A new source of systematic error, related to resonances in $n-{}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ scattering in the neutron detectors, is discussed. The interaction of the neutron magnetic moment with the Coulomb field of the proton is found to make a significant contribution to the analyzing power at the present level of accuracy. The results are compared to predictions of nucleon-nucleon potential models. New, improved values are reported for the $p$ and $d$-wave spin-orbit phase-shift splittings.

The vector analyzing power for the $n+d\to n+n+p$ breakup reaction was measured at 12 MeV. Data for $n-p$ final-state interaction and $n-p$ quasifree scattering, along with elastic-scattering data, are compared to rigorous three-nucleon calculations using the Paris and Bonn $N-N$ potentials. Calculations agree with the quasifree data and with the elastic and $n-p$ final-state-interaction data except around ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=120\mathrm{}°$.

An alternative formulation of the extended mean-field equations proposed in 1981 by Balian and Vénéroni is presented, together with a numerical method of solution. The time evolution and approach to equilibrium of a spherically symmetric compressed nucleus are then investigated.

New data on the polarization observables $i{T}_{11}$, $T_{20}$, $T_{21}$, and $T_{22}$, supplemented by $\frac{d\sigma }{d\Omega }$ and information from reasonable theoretical models, are used to extract the pion-deuteron scattering amplitude at 256 and 294 MeV. Using these amplitudes, partial-wave components are calculated and the spin-transfer parameter $i\left(11\right|20)$ is predicted. Some observations on helicity phase patterns are also made.

Effects of final-state interactions on the nuclear structure functions of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ are calculated. In kinematics similar to regions experimentally explored for some light nuclei, the transverse and longitudinal structure functions are almost equally modified by final-state effects. However, decreasing the relative energy between the nucleon and the residual nucleus leads to a significant enhancement of the transverse-to-longitudinal strength ratio.

The magnetic form factor of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ has been measured by elastic electron scattering in the momentum-transfer range between 1.8 and 3.3 ${\mathrm{fm}}^{-1\mathrm{}}$. The $1f_{\frac{7}{2}}$-neutron-orbit radius inferred from these data definitely demonstrates that the explanation of the Coulomb-energy anomaly cannot be found in a reduction of the valence-orbit radius.

We show that SO(3) gauge potentials arise in the Born-Oppenheimer description of the interaction between the dipole and quadrupole vibrations in even-even spherical nuclei and derive the effective Hamiltonian for the quadrupole motion.

Fluctuation properties of positive-parity states in ${}_{}{}^{26}{}_{}{}^{}\mathrm{Al}$ from the ground state to the resonance region (0-8 MeV excitation energy) are found to be consistent with the Gaussian-orthogonal-ensemble version of random-matrix theory. Although isospin is an approximately good quantum number in this system, the fluctuation properties of the combined sequence ($T=0\mathrm{}$ and $T=1\mathrm{}$ states) are consistent with those of a single Gaussian-orthogonal-ensemble sequence. This agrees with earlier predictions by Dyson and Pandey and with recent analysis by Guhr and Weidenmüller.

The superdeformed band in ${}_{}{}^{149}{}_{}{}^{}\mathrm{Gd}$ has been populated with various input angular momenta and excitation energies. These, together with all other available data, indicate that the necessary criterion for populating superdeformed bands is to form cold residual nuclei at spins higher than those where the superdeformed states become yrast. In addition, the decrease in the superdeformed band intensity as it is gated by higher-energy $\gamma$ rays does not support the predictions based on a recently proposed feeding mechanism of these states.

Several examples of the production of electron-positron pairs were found in the interactions with emulsion of fragments resulting from the collision of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{22}{}_{}{}^{}\mathrm{Ne}$ projectiles of 4.5 and $4.2 \frac{\mathrm{GeV}}{c}$ per nucleon, respectively with emulsion nuclei. Taking into account the effect of the background, the results seem to suggest the existence of new neutral boson with mass $1.60\pm 0.59 \frac{\mathrm{MeV}}{c}$ and a lifetime (0.15 ± 0.01) × ${10}^{-14\mathrm{}}$ sec.

Electron-positron pairs apparently resulting from the decay of light intermediate neutral particles emitted in relativistic heavy-ion collisions have been reported by El-Nadi and Badawy. The events, observed in nuclear emulsions, are similar to data from 35 years ago that caused the ${\pi }^0$ lifetime estimate to be wrong by almost 2 orders of magnitude for about a decade. The data are consistent with the production and subsequent decay of short-lived neutral bosons with masses around 1.1, 2.1, and 9 MeV and with lifetimes of the order of ${10}^{-16\mathrm{}}$-${10}^{-15\mathrm{}}$ s.

Tagged-photon measurements of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(\gamma ,pn)$ reaction in the photon energy range 83-133 MeV are reported. The measurements have achieved a good angular resolution, ≃4°, and a better missing-energy resolution, ≃8 MeV, than any previous measurement. This has allowed events to be selected in which both the neutron and proton are ejected from the $1p$ shell of the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ nucleus. The correlation of the momenta of the outgoing nucleon pairs is quantitatively explained by the quasideuteron mechanism.