The elastic magnetic form factor of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ has been measured up to $q^2=32\mathrm{}$ ${\mathrm{fm}}^{-2\mathrm{}}$. Fewbody theory fails to explain the location of the diffraction minimum unless nonnucleonic degrees of freedom are explicitly introduced.

$K^{+}$ meson production by 2.1-GeV/nucleon Ne, $d$, and $p$ projectiles on NaF and Pb targets has been measured. The cross sections depend exponentially upon the kaon energy in the nucleon-nucleon c.m. frame, with an inverse slope $T_0$ larger than the values obtained from comparable proton and ${\pi }^{-}$ spectra. The angular distribution in this frame is approximately isotropic. We find that $\frac{\sigma (\mathrm{Ne}+\mathrm{Pb}\to K^{+}X)}{\sigma (\mathrm{Ne}+\mathrm{NaF}\to K^{+}X)}>\frac{\sigma (d+\mathrm{Pb}\to K^{+}X)}{\sigma (d+\mathrm{NaF}\to K^{+}X)}$. Data are compared with theoretical predictions.

New higher precision measurements of the hyperfine Zeeman transitions in the ground state of muonium have been performed with use of the high-stopping-density surface ${\mu }^{+}$ beam at the Clinton P. Anderson Meson Physics Facility. The results are $\Delta \nu =4\mathrm{}463-302.88\left(16\right)\mathrm{}$ kHz (0.036 ppm) and $\frac{{\mu }_{\mu }}{{\mu }_p}=3.183\mathrm{}3461\left(11\right)\mathrm{}$ (0.36 ppm). The current theoretical value of $\Delta \nu$ agrees well with experiment within the 0.77-ppm error of $\Delta {\nu }_{\mathrm{theor}}$, which is due principally to inaccuracy in evaluation of the nonrecoil radiative correction term. The most precise current value of $\frac{m_{\mu }}{m_e}$ is obtained from our value of $\frac{{\mu }_{\mu }}{{\mu }_p}$.

The attenuation of longitudinal ultrasound in smectic-$A$ liquid crystals departs markedly from the quadratic frequency dependence predicted by hydrodynamics. The experimental results are compared to recent theoretical predictions of the breakdown of conventional hydrodynamics in smectic-$A$ liquid crystals and other "one-dimensional crystals."

Some new, powerful, and very simple Bell inequalities are derived. They establish that for two spin-$s$ particles in the singlet state, the quantum-theoretic Einstein-Podolsky-Rosen correlations for spin measurements along all pairs of directions from a set of $N$ axes are incompatible with local realism for any set of distinct coplanar axes when $N=3\mathrm{}$, and for any set of distinct axes whatever when $N=4\mathrm{}$, with the possible exception of sets restricted by one of the constraints $\hat{a}\pm \hat{b}\pm \hat{c}\pm \hat{d}=0\mathrm{}$. These results hold for any value of the spin.

Delicacies in quantum physics for magnetic sources carrying electric charge, recently exposed by Wilczek, are studied further, with emphasis on the meaning of angular momentum for these systems, and the nature of phases which affect the statistics of indistinguishable objects. Wilczek has uncovered a remarkable two-body interaction which leads to a many-body system in two dimensions changing from Bose gas to Fermi gas as the interaction parameter is varied. A nontrivial realization of these notions might occur in a thin sheet of superconductor with many magnetic vortices.

The electric polarizability of the deuteron has been determined by measuring deviations from the Rutherford scattering formula for deuteron elastic scattering from ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at energies from 3.0 to 7.0 MeV. The measured value of the electric polarizability, $\alpha =0.70\mathrm{}\pm 0.05$ ${\mathrm{fm}}^3$, is in fair agreement with theoretical predictions.

It is argued that the recently measured (${\pi }^{-}, {\pi }^0$) and (${\pi }^{+}, {\pi }^0$) reactions on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ exciting the two components of the giant dipole provide new information about the density distribution of protons and neutrons. The large difference in the (${\pi }^{-}, {\pi }^0$) and (${\pi }^{+}, {\pi }^0$) cross sections is mainly due to the effect of Coulomb polarization in the nucleus.

An approach to the study of electromagnetic wave propagation in a random medium, based on coupled-mode theory, is presented. As an example of the general formalism, the statistical distribution of the angle of arrival and the mutual coherence function of an initially plane wave traversing a given distance are evaluated.

New measurements of heat capacity for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ adsorbed on ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ films are presented. It is found that for the thinnest ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ film used, and starting at a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ coverage of 0.058 layer, 3.7 × ${10}^{-4\mathrm{}}$ ${\mathrm{\AA }}^{-2\mathrm{}}$, the data show a very sudden onset of degeneracy. It is found that these data are consistent with phase separation in the two-dimensional layer of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at the surface of the ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ film.

From an isothermal molecular-dynamics experiment of an unstable two-dimensional fluid undergoing phase separation, two principal growth regimes are observed: (1) spinodal decomposition with a wavelike morphology followed by (2) a transition to cluster formation and growth due to atomic condensation and cluster coagulation. The time-dependent power-law behavior for the second growth regime is 0.5, in contrast to a constant-energy simulation which yields a power-law behavior of 0.33. Details of the phase-separation dynamics are discussed and compared with theory.

The dynamics of a system of long polymer chains is investigated numerically with Monte Carlo dynamics. By use of a lattice model of polymers interacting via hard-core potentials, much longer polymers have been investigated than has been possible previously. The correlation functions calculated are in agreement with de Gennes's "reptation" hypothesis, and differ strongly from Rouse-like behavior.

Strong elastic scattering of laser light, up to 200 times background, is found at the exciton resonance of GaAs/AlGaAs multi-quantum-well structures. It is shown to be a consequence of spatial fluctuations of the refractive index due to inhomogeneous broadening of the resonance. The frequency and temperature dependence of the homogeneous linewidth can be obtained from the data.

Picosecond self-diffraction is observed from transient orientational gratings produced in germanium by an anisotropic (in $k$ space) filling of the optically coupled states by direct absorption of the nearly monochromatic polarized exciting radiation, the first direct observation of anisotropic state filling in semiconductors. A new theoretical model is presented briefly; agreement is found with all aspects of the experiment.

An inelastic scattering process is observed between 2.5 and 4.0 eV when clusters of 10- to 50-nm-diam aluminum spheres are excited by a 1-nm-diam probe of 100-keV electrons. This inelastic scattering is a maximum when the incident electron probe is positioned within 10 nm of the smaller of two touching spheres. The observed energy and the spatial variation of the scattering probability are consistent with a calculation for a two-sphere system immersed in aluminum oxide.

In dilute alloys, in contrast to pure metals, the measured Fermi-surface volume is too small to accommodate all the electrons. In dilute copper-based heterovalent alloys the discrepancy increases as the solute valence increases but the anisotropy of the Fermi-surface changes is found to be approximately rigid-band-like in all alloys. These results are explained quantitatively in terms of the Fermi surface being determined by only those electrons which are scattered coherently.

The de Gennes-Alexander theory of superconductive networks is used to study the upper critical fields of two-dimensional square lattices built from $N$ equally spaced infinite wires joined by transverse strands. Phase diagrams and current-flow patterns for representative cases are shown. A critical value is found of the magnetic flux per square below which the current flow resembles the Meissner state, and above which an ordered array of vortices appears, in general incommensurate with the underlying lattice. The critical flux decreases for increasing $N$.

Ultraviolet-photoelectron-spectroscopy experiments and a coherent-potential-approximation calculation of the density of states of ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te}$ show a clear deviation from virtual crystal behavior in bands ≃ 5 eV below the valence-band maximum where there is a 60% $s$-electron contribution. The large (≃ 1.4 eV) atomic $s$-state shift between Hg and Cd is responsible for this deviation, as well as for the decrease of the band gap (1.5 to 0 eV) with composition, the high electron mobility (${10}^6$ ${\mathrm{cm}}^2$/V s), and difficulties experienced with growth and mechanical properties.

The conductance of narrow (0.1-μm) silicon inversion layers has been measured at low temperatures. A divergent, nonmetallic decrease of conductance is observed below 30 K, in excellent quantitative agreement with the combined theories of weak localization and interaction effects in their one-dimensional form, if one assumes parameters comparable to those observed in wide (two-dimensional) inversion layers. In this novel experimental system both localization and interaction effects are present and comparable in size.

Considered here is a class of theories of gravity characterized by a set of equations which represent the gravitational and electromagnetic structure of the theories in a spherically symmetric and static gravitational field. If one demands that the weak equivalence principle (WEP) and the principle of universality of gravitational red shift (UGR) be satisfied, it is found that the theories under investigation must be metric. This result lends support to the current version of Schiff's conjecture that WEP+UGR→EEP, where EEP refers to the Einstein equivalence principle.