We discuss a simple model for the metal-insulator transition in Eu-rich EuO. Trap states associated with the O vacancies act as donor states. The transition is driven by the exchange field generated by the long-range magnetic order. We obtain results which are in fair agreement with the experimental results for values of the parameters of the model appropriate for EuO.

Using a general formulation we show that by using surface electromagnetic waves in an attenuated-total-reflection prism configuration it should be possible to enhance the intensity of Raman scattering by a thin overlayer on a Ag surface by two orders of magnitude and that the use of surface electromagnetic waves may in fact make it possible to observe coherent anti-Stokes Raman scattering by the overlayer.

We consider the role of electron-phonon mass enhancement in impurity-dominated dc electronic transport and conclude that such mass enhancement should be observed in the thermoelectric effects. We also present new experimental evidence in support of this conclusion.

The evolution of the singlet character of correlated ion radical pairs, prepared by high-energy impact in alkane solutions, is monitored by nanosecond-time-resolved solute-recombination fluorescence. Results obtained in the presence and absence of magnetic fields ($B<~4$ kG) show evidence for damped periodic modulations ($\omega \approx 10$ MHz) of fluorescence intensity. They are explained in terms of hyperfine-interaction-induced coherent singlet-triplet mixing, and of field-dependent spin-lattice relaxation.

A spherical model of a spin-glass is solved in the limit of infinite-ranged interactions with a Gaussian probability distribution. We use the known properties of a large random matrix, and show that the results are identical to those obtained by the $n\to 0$ trick. We believe that the solution is exact.

Using two models, we study the relaxation to a Maxwell distribution in the context of classical kinetic theory. For the first model, an exact solution of the nonlinear Boltzmann equation is derived. For the second model, an asymptotic solution exhibits the remarkable feature of a transient tail population sometimes much larger than the equilibrium Maxwell distribution. This phenomenon may be of importance for calculating rates of fast chemical reactions and for controlled thermonuclear fusion.

We have measured large-transverse-momentum ($p_{\perp }$) inclusive ${\pi }^0$ production at c.m. angles centered near 90° for ${\pi }^{\pm }p$ and $\mathrm{pp}$ interactions at 100 and 200 GeV/c. This is the first such measurement using a pion beam. The ratio $\frac{\sigma (pp\to {\pi }^{0}X)}{\sigma (\pi p\to {\pi }^{0}X)}$ decreases with increasing $p_{\perp }$ and is independent of energy when expressed as a function of $x_{\perp }=\frac{p_{\perp }}{p_{max}}$. We compare the data with predictions of various models.

${\Lambda }^0$ polarization has been observed in $p+\mathrm{Be}\to {\Lambda }^0+\mathrm{anything}$ at 300 GeV. A total of 1.2 × ${10}^6$ ${\Lambda }^0$ decays were recorded at fixed lab angles between 0 and 9.5 mrad, covering a range of kinematic variables $0.3<~x<~0.7$ and $0<~p_{\perp }<~1.5$ GeV/c. The observed polarization was consistent with parity conservation and increased monotonically with increasing $p_{\perp }$, independently of $x$, reaching $P_{\Lambda }=0.28\mathrm{}\pm 0.08$ at 1.5 GeV/c.

We show that in an SU(2) quantum gauge field theory, with isospin symmetry broken spontaneously by a triplet of scalar mesons, isospinor degrees of freedom are converted into spin degrees of freedom in the field of a magnetic monopole.

It is argued that magnetic monopoles in an SU(2) gauge theory may bind with an ordinary boson with isospin, to give bound states with spin. If the isospin of the free boson is integer or half-odd-integer, the total angular mometum of the bound state is integer or half-odd-integer, respectively. According to the spin-statistics theorem we can obtain fermions this way in a theory that started off with bosons only.

An object composed of a spinless electrically charged particle and a spinless magnetically charged particle may bear net half-integer spin, but the wave function of two such clusters must be symmetric under their interchange. Nevertheless, a careful study of the relative motion of the clusters shows that this symmetry condition implies the usual connection between spin and statistics.

The interaction of a $K^{\pi }=5^{-}$ two-quasiproton band with a $K^{\pi }=5^{-}$ two-quasineutron band in ${}_{}{}^{250}{}_{}{}^{}\mathrm{Cf}$ has been observed using proton and neutron transfer reactions and radioactive-decay measurements. Configuration-mixing calculations using a two-body neutron-proton force give an interaction matrix element in good agreement with the value derived from our measurements.

Several new isomeric states above the well-known ${\left(h_{\frac{9}{2}}\right)}^2$ $8^{+}$ level have been observed in ${}_{}{}^{202,204,206}{}_{}{}^{}\mathrm{Po}$. They can be accounted for by simple weak coupling between two-particle or two-quasiparticle states found in the closed-shell nuclei ${}_{}{}^{210}{}_{}{}^{}\mathrm{Po}$ and ${}_{}{}^{200,202,204}{}_{}{}^{}\mathrm{Pb}$.

Multiphoton ionization of krypton has been experimentally investigated for the first time with a single-mode tunable ${\mathrm{Nd}}^{3+}$: glass laser producing an electric field of $E=8\mathrm{}\times {10}^7$ V/cm. In the range 10 585 Å to 10 605 Å, two resonances have been found, shifted towards the high-energy side from the nearest states $5d{\left[\frac{1}{2}\right]}_1$ and $4d^{\prime }{\left[\frac{5}{2}\right]}_3$ by 39.5 ${\mathrm{cm}}^{-1\mathrm{}}$ and 42 ${\mathrm{cm}}^{-1\mathrm{}}$, respectively. Far from resonances, the dependence of the ionization rate on the laser intensity agrees with the lowest-order perturbation-theory prediction.

Differential gain and large hysteresis have been seen in the transmission of a Fabry-Perot interferometer containing Na vapor irradiated by light from a cw dye laser. Non-linear dispersion, neglected in earlier work, dominates over nonlinear absorption in Na. The apparatus uses only optical inputs and outputs. Similar apparatus may be useful as an optical amplifier, memory element, clipper, and limiter.

A direct method of measuring the Fokker-Planck velocity diffusion coefficient in plasma turbulence is developed. The method is consistent with, but more general than, the quasilinear approximation. The velocity variance $〈\Delta v^2〉$ is measured by integrating the space-time potential correlation function along unperturbed particle orbits. Correlation times and velocity diffusion coefficients are measured as a function of velocity in ion-beam-plasma turbulence and the experimental results are compared with the Fokker-Planck theory requirements.

The decay of a right-hand polarized (whistler) wave is considered in the presence of a spatial gradient of the pump amplitude. It is shown that the low-frequency ion wave can be trapped in the vicinity of the gradient and sufficient conditions are derived for the threshold electric field and ion-wave frequency. The results of the calculation are in good agreement with experimental results.

This paper gives preliminary experimental results on synchronous injection of electron packets in the potential trough of an electrostatic plasma wave, and the trapped-particle modes which are generated. The initial conditions, wave amplitude, electron packet density, and phase of the packets with respect to the wave, may be varied independently and lead to detailed comparison with a recently developed theory.

Stereo electron microscopy of gold bombarded at room temperature with atomic and molecular ions shows that the nature of damage clusters is sensitive to the density of deposited energy. Both the total number of defects and their distribution in space show that vacancy loops are formed preferentially at high density of deposited energy and interstitial loops at low density. Calculations indicate that the limiting density corresponds to ∼ ${10}^{-2\mathrm{}}$ point defects per atom.

Leggett's investigation of the superfluid density of solids has been extended. By employing plane waves as a basis set, one can obtain the superfluid fraction $\frac{{\rho }_s}{{\rho }_0}$ as a function of the localization parameter. Solid ${\mathrm{He}}^4$ is estimated to have a $\frac{{\rho }_s}{{\rho }_0}$ between 0.05 and 0.2 at zero temperature. This approach also sheds light on the superfluidity of thin films and the "index of refraction" of fourth-sound chambers.