The probability of simultaneously photoexciting and photoionizing helium has been measured near threshold at a wavelength of 186 Å. It was found that about (8 ± 2)% of the ions formed at that wavelength were excited into the $n=2\mathrm{}$ state.

The attenuation of first sound in liquid helium was measured with an acoustical interferometer. Two results are of particular interest: the temperature dependence of the attenuation in the critical behavior region near the lambda point, and contrary to recent Brillouin scattering measurements, agreement with a theory of Khalatnikov and Chernikova in the region below about 2 K.

We have measured the elastic response of niobium in the region of the critical point of hydrogen in niobium. The elastic susceptibility exceeds commonly observed values by two or three orders of magnitude and follows a Curie-Weiss relation over the temperature range investigated. The diffusion coefficient of hydrogen shows "critical slowing down" behavior but no anomaly in the transport coefficient.

The effect of stress on contact potential has been measured semiquantitatively in Al, Cu, Au, steel, and brass using a high-sensitivity version of the Kelvin method. The observed shifts are in all samples positive (i.e., the electric field outside the sample is more positive when pressure is applied) and the magnitude is a few microvolts per kg/${\mathrm{cm}}^2$ applied stress. Both sign and magnitude agree with the theories of Dessler, Michel, Rorschach, and Trammell, and of Herring, provided one assumes that gravitationally produced stress is equivalent to hydraulically produced stress.

The position of a solute atom in a lattice can be detected by the nature of its x-ray fluorescence excitation during a diffraction process.

It is shown that dielectrically defined average covalent and ionic energy gaps, $E_h$ and $C$, respectively, can be used to predict crystal structures and absolute band energies in crystals of formula $\mathrm{AB}$ with eight valence electrons per atom pair.

Excitation of surface charge waves (surface plasmons) produces intensity anomalies in the light reflected from a metal grating. We demonstrate that coupling occurs for both $s$- and $p$-polarized light if the grating lines are oblique to the plane of incidence, provided there is a component of the incident electric field along the direction of surface-wave propagation. We have measured the magnitude, phase, and direction of the plasmon electric field, and find Fano's theory confirmed. Underlying the coherent radiation we observe a small incoherent component resulting from spontaneous emission by the surface plasmons.

The direct $L_{2^{\prime }}\to L_1$ transition is very apparent in photoemission data from pure Cu; however, as might be expected, there is no evidence for this transition in 87% Cu-13% Ni alloys. In contrast, structure in ${\epsilon }_2$ for $h\nu >~2.1$ eV for the alloy and pure Cu is qualitatively similar. These observations support the assignment of major structure in ${\epsilon }_2$ of pure Cu to nondirect transitions from the $d$ states and argue against the 5.0 eV peak being due principally to the $L_{2^{\prime }}\to L_1$ transition.

A general method for calculating spectra of solids is developed, and the analytical expressions required for it are obtained and given. This procedure gives high resolution in the computed spectra, is at the same time also rapid and accurate, and has a wide range of applicability in fields of solid-state physics.

In EuO we observe no critical attenuation of sound near $T_c$, but a corresponding critical change in sound velocity is noticeable. These experiments can be explained by the experimentally verified fact that the sound wave couples to the energy of the spin system.

The quasielastic magnetic scattering from ${\mathrm{K}}_2$Ni${\mathrm{F}}_4$ over the temperature range from 97.2°K to at least 200°K is found to correspond to reciprocal lattice rods rather than points thus giving the first concrete evidence of the two-dimensional character of ${\mathrm{K}}_2$Ni${\mathrm{F}}_4$. At 97.1°K the crystal undergoes an extremely sharp phase transition to long-range order in three dimensions. From 97.0°K to 5°K the sublattice magnetization follows a ${\mathrm{}(97.1-T)\mathrm{}}^{\beta }$ law with $\beta =0.15\mathrm{}$.

The relative widths for the proton ($\tilde{p}$) decay of the isobaric analog of the ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ ground state have been remeasured with significantly improved accuracy using the charge-exchange reaction ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}\mathrm{}(p,n)\mathrm{}$ rather than ${}_{}{}^{207}{}_{}{}^{}\mathrm{Pb}\mathrm{}(p,p)\mathrm{}$ and ($p,p^{\prime }$) excitation functions to populate the isobaric analog level. For the first time the sequential process ($p,n\tilde{p}$) has been observed both with a heavy ($A\sim 200$) target nucleus and also with a target nucleus which is even-even rather than even-odd. The total cross section for the isobaric-analog-state reaction ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}\mathrm{}(p,n)\mathrm{}{}_{}{}^{208}{}_{}{}^{}\mathrm{Bi}$ has also been measured for the range of proton bombarding energies between 25.2 and 47.3 MeV.

Very large quantities of low-frequency electromagnetic radiation will be produced by the rotating, magnetic, neutron stars favored for pulsar models. It is shown that this radiation will accelerate particles injected into the wave field to energies in excess of ${10}^{18}$ eV (adopting parameters derived from the Crab object), that the spectral dependence accords with cosmic-ray observations, and that the total energy available is consistent with the observed density of these very high-energy particles. The maximum energy a proton can attain by this mechanism is of order ${\left(\frac{e^2}{Gm_p^{}{}_{}{}^2}\right)}^{\frac{1}{3}}\times \left(\mathrm{rest}\mathrm{mass}\right)$ or ≅${10}^{21}$ eV.

Two different peripheral quasi three-body final-state processes are studied in the reaction $K^{-}p\to K^{-}p{\pi }^{+}{\pi }^{-}$ Near-threshold mass enhancements are observed in both the ${\overline{K}}^{*0\mathrm{}}\mathrm{}\left(890\right)\mathrm{}{\pi }^{-}$ and ${\Delta }^{++}\mathrm{}\left(1238\right)\mathrm{}{\pi }^{-}$ systems. In both cases the data are suggestive of a production mechanism involving inelastic diffraction scattering. For each case a comparison is made with the predictions of a double-Regge-pole exchange model.

Demanding the consistency of finite-energy sum rules at high energies, we predict that Regge trajectory $\alpha \mathrm{}\left(s\right)\mathrm{}$ increases at large energies as ${\left(s\ln s\right)}^{\frac{1}{2}}$ and the elastic widths of resonances go as $\frac{s^{{\alpha }_t\mathrm{}\left(0\right)-\frac{1}{2}}}{\ln s}$ for large $s$.

It is shown that the connection between even scattering lengths and $\sigma$ terms of current algebra depends strongly upon dynamics. The $\sigma$ terms for $\pi \Lambda$ and $\pi \Sigma$ scattering are evaluated and shown to be consistent with a model algebra of current divergences in which the SU(3)-symmetry breaking parameter is not small.

We make a systematic test of soft-meson theorem predictions for both elastic and inelastic $P-B$ threshold scattering amplitudes. The predictions are obtained by using an extrapolation procedure developed by Fubini and Furlan and by ourselves. Our results are in reasonable agreement with a theory of SU(3) ⊗ SU(3)-symmetry breaking proposed recently by Gell-Mann, Oakes, and Renner.

The structure functions for inelastic electron-nucleon scattering are studied in the Bjorken limit in the framework of canonical field theory. The "parton" model of Feynman is derived and the structure functions' asymptotic behavior for large energy transfers is computed.

By considering the decay reactions $\omega \to 3\pi$ and $\eta \to \pi +\pi +\gamma$ within the framework of the Veneziano model and the $\rho$ dominance of the isovector electric current, we fix certain coupling constants and are able to obtain zero parameter relations among others.

Transfer of spin polarization from optically pumped metastable helium atoms to the ions of Cd, Sr, and Zn following Penning collisions has been demonstrated indicating that a component of spin angular momentum is conserved. The ion polarization, detected optically, exceeds 10% at ion concentrations on the order of ${10}^{10}$-${10}^{11}$ ${\mathrm{cm}}^{-3\mathrm{}}$.