We present electron diffraction data from amorphous silicon which cannot be reconciled with the intensity profiles derived from small-crystallite models based on the diamond structure. Our diffraction patterns do reveal a pronounced low-angle scattering which anneals out on progressive heating and is indicative of actual void spaces, or regions of distinctly deficient density, in the films. These regions may be responsible for the recent observations of Brodsky and Title on surface states within the bulk of amorphous Si.

A small magnetic cluster is shown to exist around an isolated Fe atom in ${\mathrm{Cu}}_{1-X}{\mathrm{Ni}}_X$ alloys with a magnetic moment and saturation hyperfine field depending on the number $n$ of Ni near neighbors. This small cluster changes abruptly from moments of $\mathrm{}(2.85+0.6n)\mathrm{}\times {\mu }_{\mathrm{B}}$ to large moments [$\left(\sim 17 \mathrm{to} 20\right){\mu }_{\mathrm{B}}$] for Ni concentrations near the critical composition. The moment compensation (Kondo effect) found for isolated Fe in Cu appears to persist in Cu-Ni up to at least 10 at.% Ni.

Comparisons of the electromagnetic and proton inelastic-scattering reduced transition probabilities for the even nickel isotopes are made. It is found that the values obtained for high multipole transitions in the inelastic scattering are extremely sensitive to the nuclear density distribution. This sensitivity is investigated for various phenomenological models of the nuclear density distribution.

Gamma-gamma directional correlations have been measured in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Gd}$ with a Ge(Li) detector in one channel. The $M1\mathrm{}$ admixtures in the ${3_{\gamma }}^{+}-2^{+}$, ${3_{\gamma }}^{+}-{4_{\gamma }}^{+}$, and ${4_{\gamma }}^{+}-4^{+}$ transitions were measured to be <1, (3.0±0.3), and (4.8±0.8)%, respectively. The $M3\mathrm{}$ admixture in the ${2_{\beta }}^{+}-4^{+}$ and ${2_{\gamma }}^{+}-4^{+}$ transitions is (0.1±0.1)%.

Evidence for broad resonances in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and the three-proton system has been observed in the continuum neutron spectra from the reactions ${}_{}{}^3{}_{}{}^{}\mathrm{H}(p, n)$ and ${}_{}{}^3{}_{}{}^{}\mathrm{He}(p, n)$ at 30 and 50 MeV. The positions and widths of possible resonances in the three-nucleon system have been calculated using a variational method. A comparison is made with data from photonuclear reactions.

Spherically symmetric initial solutions of the coupled gravitational-massless scalar field-"charged particle" system are exhibited. For a given set of coupling constants, there are generally either no or two nonsingular solutions. In the latter case, one of these has essential singularities in the scalar and gravitational constants at zero coupling. Other properties of the solutions are listed. The corresponding results in tensor-scalar gravitation are also outlined.

The inelastic scattering of muons has been measured using positive muons of momentum 10 GeV/c incident upon a liquid-hydrogen target. We present values of the differential cross section and of the virtual photon-photon absorption cross section for $\mathrm{}\left|q\right|\mathrm{}$ in the range 0.05 to 1.2 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and for equivalent photon laboratory energies of 0.6 to 6.5 GeV.

Results from muon-proton inelastic scattering are used to investigate the form of ${\sigma }_{\exp }(q^2, K)$, the quantity commonly called the "virtual photon-proton total cross section." Fits to ${\sigma }_{\exp }$ have been made for photon energies 0.6≤6.5, and 4-momentum transfer squared $\left|q^2\right|$ up to 1.2 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. Measurements of the real photon-proton total cross section ${\sigma }_{\gamma p}\mathrm{}\left(K\right)\mathrm{}$ have been included in the fits. The forms of rho-dominance theory which predict ${\sigma }_{\exp }(q^2, K)=\frac{{\sigma }_{\gamma p}\mathrm{}\left(K\right)\mathrm{}}{(1+\frac{\left|q^2\right|}{{m_{\rho }}^2})}$ are in agreement with the data.

The possible near degeneracy in mass of recently detected massive neutral boson states with opposite charge conjugation allows for the possibility that a relatively weak $C$-nonconserving interaction is enhanced in mixing these states. Some observable $C$-nonconserving effects that are consequences of this mixing are discussed.

We propose that both SU(3) and broken nonchiral SU(2) ⊗ SU(2) internal symmetries are relevant for classification of hadronic states. The theory explains the $A_2$ splitting while predicting the existence of at least one abnormal meson with $(I^G, J^P)=(2^{-}, 2^{+})$ degenerate in mass with the $A_2$.

It is shown that the wave function for three particles interior to the finite volume where all force ranges overlap completely determines the exterior wave function via the solution of a one-variable integral equation with a compact kernel. A unitary parametrization of the interior wave function therefore would supply the equivalent of a phase-shift analysis for three-particle final states, including the exact description of overlapping resonances throughout the Dalitz plot.

The small discrepancy between experimental and theoretical values for the dissociation energies of ${\mathrm{H}}_2$, HD, and ${\mathrm{D}}_2$ has been resolved by new measurements of the ultraviolet absorption limits of these molecules. In addition, the ionization potential of ${\mathrm{H}}_2$ has been more accurately determined from Rydberg series. The agreement between theory and experiment must be considered very satisfactory.

Optical and infrared emission spectra of electron-bombarded liquid helium reveal the presence of a number of excited singlet and triplet states of the ${\mathrm{He}}_2$ molecule, including the $a{{}_{}{}^3{}_{}{}^{}\Sigma _{\mathrm{u}}^{}{}_{}{}^{}}^{+}$ metastable state. The observed liquid spectra show vibrational and unresolved rotational structure. There is also preliminary evidence that excited atomic states, including the metastable $2{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}$ state, are populated in the liquid.

Comparable one-, two-, and three-dimensional simulations of electrostatic two-beam instabilities show major qualitative differences between one and two dimensions, and only small quantitative differences between two and three dimensions. In particular, the well-known persistence of vortex structure is lost in going from one dimension to two and three dimensions.

Capture and escape of negative ions by vorticity resulting from a supercritical heat current in liquid He II are demonstrated in the temperature range between 1.6 and 1.8°K. The vorticity is identical to that produced by rotation except for configuration of the individual lines. The escape probability was measured between 1.7 and 1.8°K and is in agreement with the theory of Donnelly.

A negatively charged plasma with energetic magnetic-mirror-confined electrons may provide a suitable environment for long-term ion confinement and for intense multiple ionization of heavy ions. Classical rates for ion loss from the negative potential well are low compared with the comparable ion mirror-loss rates. It is proposed to maintain the plasma by steady electron injection together with cyclotron acceleration for electron trapping and heating.

We examine the application of a parametric equation of state to several magnetic and fluid systems near the critical point. An attractively simple form represents the experimental data very closely and this suggests there may be a functional relationship between the critical exponents and coefficients.

Critical-field measurements of silver layers sandwiched between two superconducting layers indicate that supercooling appears below a temperature $T^{*}$ and that the supercooling field stays constant at low temperatures. We propose a simple theoretical model which correctly predicts the temperature of saturation as well as the observed amount of supercooling, and leads to an estimate of 0.1 for $\mathrm{NV}$ for silver. This model further suggests that a $\frac{1}{x}$ spatial dependence of the order parameter in the silver should be observed in the ${\mathrm{He}}^3$ temperature range and below.

Electrical resistivity measurements on bulk specimens of very-short-coherence-distance [${\left(l{\xi }_0\right)}^{\frac{1}{2}}\approx 50$ Å] type-II superconducting alloys suggest the presence of fluctuation superconductivity at temperatures up to at least $2T_c$, where $T_c$ approximates the bulk superconducting transition temperature. Apparent magnetic field quenching of fluctuation superconductivity is observed up to 50 kG both above and below $T_c$.

The electron-phonon contribution to the resistivity of a dilute metal alloy at low temperatures is drastically different from that of the ideally pure host metal if the conduction-electron cross section for impurity scattering varies with energy on a scale comparable with or less than the Debye energy of the host metal. Experimentally the effect should be of particular importance for magnetic or nearly magnetic transitional impurities in appropriate nontransitional hosts.