A new technique for the monochromatic detection of ${10}^{12}$-Hz phonons is applied to the study of 20-${\mathrm{cm}}^{-1\mathrm{}}$ phonons in ruby. The resolution of the phonon detector in space and time allows the observation of the local imprisonment of 29-${\mathrm{cm}}^{-1\mathrm{}}$ phonons in a ruby crystal that contains variable concentrations of ${\mathrm{Cr}}^{3+}$ ions in the excited $\overline{E}\left({}_{}{}^2{}_{}{}^{}E\right)$ state. The application for the determination of the lifetime of ${10}^{12}$-Hz phonons is discussed.

Transitions to the states of ${\mathrm{Cr}}^{3+}$ pairs where both ions are excited to the ${}_{}{}^2{}_{}{}^{}E_g^{}{}_{}{}^{}$ levels have been observed in LaAl${\mathrm{O}}_3$:${\mathrm{Cr}}^{3+}$. Of the predicted eight pair levels, three of the $S=0\mathrm{}$ and one of the $S=1\mathrm{}$ levels have definitely been identified at approximately twice the ${}_{}{}^2{}_{}{}^{}E_g^{}{}_{}{}^{}$ energy absorption. The remaining transitions either are obscured by the strong vibronic spectrum or are very weak. The polarization of the lines agrees with a model based on the mechanism of exchange-induced electric dipole moment.

The frequency-wave-vector dispersion relation $\nu \left(\overrightarrow{\mathrm{q}}\right)$ for the normal vibrations of a CuCl single crystal at room temperature has been measured for the [100]-, [110]-, and [111]-symmetric directions using inelastic neutron scattering.

In the NMR measurements reported here, it is found that the amplitude of the electron-density oscillation, $\alpha$, around manganese and chromium impurities in aluminum is temperature dependent. Between 180 and 400°K the temperature dependence can be represented by $\alpha \mathrm{}\left(T\right)=\alpha \mathrm{}\left(0\right)[1-{\left(\frac{T}{\tilde{\Theta }}\right)}^2]$, with $\tilde{\Theta }\sim 740$°K for manganese and $\tilde{\Theta }\sim 960$°K for chromium impurities. We suggest that this temperature dependence is brought about by the localized spin fluctuations at the impurity sites.

Torque measurements have been performed on flux-grown magnetic garnets exhibiting strong noncubic anisotropies. The observed orthorhombic anisotropies are interpreted in terms of a growth-induced pair-ordering model.

The pair anisotropy model is extended to include the next-nearest-neighbor tetrahedral-iron ions. An anisotropy model based on growth-induced preferential site occupation is derived using the pair model. With the site model the nearest-neighbor tetrahedral- and nearest-neighbor octahedral-iron ions lead solely to a uniaxial anisotropy under both growth facets. Inclusion of the next-nearest-neighbor tetrahedral-iron ions results in the experimentally observed orthorhombic anisotropies.

The use of auxiliary single-particle potentials permits the inclusion of the dispersion effect in the energy of a many-Fermion system calculated in the independent-pair approximation of the Iwamoto-Yamada cluster expansion.

Inelastic ${\pi }^{-}-\mathrm{C}$ scattering from 120 to 280 MeV is calculated in the distorted-wave Born approximation using the Kisslinger optical potential and treating the $2^{+}$ (4.44 MeV and $3^{-}$ (9.64 MeV) levels as rotational states. Agreement with experimental data is good, especially in the forward hemisphere. Fairly consistent values for the deformation parameters are obtained.

The reaction $\mathrm{D}(n,2n)p$ has been measured at $E_{\mathrm{inc}}=14.1\mathrm{}$ MeV, ${\theta }_{n\mathrm{}\left(3\right)\mathrm{}}={\theta }_{n\left(4\right)\mathrm{}}={30}^{\circ }$, $\varphi ={180}^{\circ }$, and the results are compared with the predictions of two separable-potential models. Neutron-proton and proton-proton quasifree scattering from nucleon + deuteron reactions at 14 MeV are also compared with the predictions of the same models. The upper limit of 2 ${\mathrm{m}\mathrm{b}/\mathrm{s}\mathrm{r}}^2$ is determined for the reaction $\mathrm{D}(n,n\gamma )d$.

New results are presented on the reaction ${\pi }^{+}p\to {\eta }^0{\Delta }^{++}$ between 1.2 and $2.67 \frac{\mathrm{GeV}}{c}$. The data above $2 \frac{\mathrm{GeV}}{c}$, when combined with some existing data, give evidence for a dip in the $t$ distribution near $t=-1.5\mathrm{} {\left(\frac{\mathrm{GeV}}{c}\right).\mathrm{}}^2$ This dip, and other features of the data, are adequately described by an $A_2$ Regge-pole model. The effective $A_2$ trajectory is calculated and found to disagree with that obtained from the reaction ${\pi }^{-}p\to {\eta }^{0}n$.

We present a new sum rule which relates the nucleon form factor to the integral over energy of the inelastic cross section of nucleons by charged vector currents.

It is shown that light-cone dominance ideas apply to exclusive processes as well. These processes must include a photon of large virtual mass, as for example deep pion electroproduction. The method provides for a new general parametrization for amplitudes in the Bjorken limit. If correct, it will lend strong support to the ideas of light-cone expansions of operator products and provide a way to study the structure, at short distances, of the commutators of electromagnetic currents and strong sources.

It is shown that the algebra generated by the space integrals of the fourth components of the electromagnetic current and the weak-interaction current is that of an $\mathrm{SU}\mathrm{}\left(2\right)\mathrm{}\otimes \mathrm{U}\mathrm{}\left(1\right)\mathrm{}$ group. Let $\overrightarrow{\mathrm{K}}$ be the generator of this SU(2) group. By requiring the $\left|\Delta \overrightarrow{\mathrm{K}}\right|=1\mathrm{}$ part of these current operators, including their respective coupling constants, to form a $\overrightarrow{\mathrm{K}}=1\mathrm{}$ triplet, one finds that the semiweak coupling constant $g$ is related to the fine-structure constant $\alpha$ by ${\left(4\mathrm{}\pi \right)}^{-1\mathrm{}}{g}^2=\frac{1}{8}\alpha$; therefore, in the absence of radiative corrections, the mass of the (hypothetical) spin-1, charged intermediate boson is 37.29 GeV.

Using many-body perturbation theory a value of -76.48 a.u. is calculated for the non-relativistic energy of ${\mathrm{H}}_2$O in the Born-Oppenheimer approximation. The perturbation expansion is based on a set of orbitals calculated in a neutral-oxygen single-particle potential.

The amplitude for the one-photon transition $2{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}\to 1{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ in helium is shown, from quantum electrodynamics, to be computable in terms of the nonrelativistic wave functions. Numerical evaluation gives a decay rate of 1.2×${10}^{-4\mathrm{}}$ ${\sec }^{-1\mathrm{}}$.

The observation of x-ray parametric conversion is reported. Results are in accord with the calculated nonlinear x-ray susceptibility. The appropriate nonlinear mechanisms are described in terms of classical free electrons.

Experiments demonstrating resonant nonlinear electromagnetic wave excitation of electron-plasma and ion-acoustic waves in a plasma column are described. Direct verification of the wave-number selection rule and indirect measurements of the mode power levels are shown.

A spin-wave calculation of the thermodynamic properties of antiferromagnetically ordered solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in a magnetic field has been carried out. A cooling effect with isentropic magnetization is predicted for fields near the ($T=0\mathrm{}$) critical value $H_c=\frac{2zJI}{{\gamma }_n\hslash } \left(\cong 74 \mathrm{kG}\right)$. In a second calculation a field $H\sim H_c$ is found to displace the melting curve $P\left(T\right)\mathrm{}$ to significantly lower pressures; it follows that a two-phase mixture of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ can be isentropically solidified (and thus cooled) by application of a field from starting temperatures $T\sim 5$ mdeg K as a useful adjunct to the Pomeranchuk cooling method.

Strong current-driven turbulence is observed in high-$\beta$ collisionless shock waves under $T_e\sim T_i$ and $v_d\ll v_e$ conditions. The level and the frequency and wave-number spectra of this turbulence are measured by scattering light from the shock. The turbulence is probably due to an electron-cyclotron drift instability.

A simple, empirical connection between electronic and lattice ionicity is reported for $45 A^N{B}^{8-N}$ compounds. The Szigeti charge per effective ionic valence is found to be equal to the ratio of Phillips' electronegativity difference $C$ and the plasma energy of the free-valence-electron gas. Deviations are most prominent for low-ionicity compounds containing first-row elements.