Infrared radiation has been found to cause a redistribution of the clusters of traps for valence-band holes in doped silver-halide crystals. This new effect was found by monitoring the concentration of trapped holes by the equivalent concentration of free electrons in the conduction band. Reciprocity failure was also found at low irradiation levels. In addition to their relevance to solid state physics, these new effects extend the analogies between normal and complementary photographic images.

A simple one-dimensional model of an oxide film on the surface of a semiconductor is used to calculate the surface-state energy as a function of the film width. As this width increases above a critical value, the surface state disappears from the semiconducting gap. Application is made to the Si-Si${\mathrm{O}}_2$ system, and a semiquantitative estimate of the critical width is given.

The spin-wave dispersion relation for the $c$ direction of dysprosium metal in the ferro-magnetic phase at 78°K and in the helical magnetic phase at 98°K has been measured by triple-axis neutron spectrometry. The energy gap measured in the ferromagnetic phase at $\overrightarrow{\mathrm{q}}=0\mathrm{}$ is in poor agreement with that calculated from the macroscopic magnetostriction and crystal-field anisotropy constants. The Fourier-transformed exchange interaction $J\left(\overrightarrow{\mathrm{q}}\right)-J\left(0\right)\mathrm{}$ in the ferromagnetic phase posses a peak near the wave vector that gives the periodicity of the helical structure just above the Curie temperature.

The three experimentally known $M1\mathrm{}$ transition rates among the $f_{\frac{7}{2}}d_{\frac{3}{2}}^{}{}_{}{}^{-1\mathrm{}}{2}^{-}$, $3^{-}$, $4^{-}$, and $5^{-}$ quartet of ${}_{}{}^{40}{}_{}{}^{}\mathrm{K}$ are calculated to first order using the one-particle, one-hole wave functions of Perez. The calculations are in qualitative agreement with experiment and illustrate that the effective moment method is not valid when used with a zeroth-order (i.e., the pure $f_{\frac{7}{2}}d_{\frac{3}{2}}^{}{}_{}{}^{-1\mathrm{}}$ configuration) calculation. This is expected since the effective moments correct for second-order effects and cannot simulate the first-order correction due to the presence of $f_{\frac{5}{2}}d_{\frac{3}{2}}^{}{}_{}{}^{-1\mathrm{}}$ and $f_{\frac{7}{2}}d_{\frac{5}{2}}^{}{}_{}{}^{-1\mathrm{}}$ impurities.

The kinetic energy distribution of coincident fragments from spontaneous fission of ${}_{}{}^{257}{}_{}{}^{}\mathrm{Fm}$ has been measured with silicon detectors. The data reveal two significant features: (1) The mass-yield distribution is markedly more symmetric than for slightly lighter nuclei (e.g., ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$, ${}_{}{}^{254}{}_{}{}^{}\mathrm{Cf}$); (2) the average total kinetic energy increases monotonically with the approach to symmetric fission.

We have measured the cross section for the photoproduction of di-pions in the mass range 0.9-2.2 $\frac{\mathrm{BeV}}{c^2}$. The experiment was performed with a 16-BeV bremsstrahlung beam on a Be target. Upper limits on the cross section for photoproduction of high-mass vector mesons are determined.

$\omega$-meson photoproduction cross sections, summed over elastic ($\gamma N\to \omega N$) and inelastic ($\gamma N\to \omega N^{*}$) channels, have been measured from hydrogen and deuterium targets. The results agree with a calculation which includes only elastic and $N^{*}\mathrm{}\left(1236\right)\mathrm{}$ channels, suggesting that photoproduction of higher resonances is small. No evidence is found for $I=1\mathrm{}$ natural-parity (e.g., $A_2$) exchange.

Using only the general factorization and nondegenerate threshold properties of multiperipheral models, we demonstrate the existence of damped oscillatory components for both the total cross section and the rate of growth of average multiplicity, with identical frequencies and relative amplitudes. For weak oscillation, however, they are shown to be 180° out of phase. Relevant experimental information on this fine structure is also discussed.

Using hard-meson current algebra with single meson dominance of currents and the $\sigma$ commutator, it is deduced that (a) the $0^{\pm }$ mesons must occur in nonets, and (b) chiral symmetry is broken by only $(3,3^{*})\oplus (3^{*},3)$ terms (which then implies a small $\xi$ parameter). Recent calculations which obtain a large negative $\xi$ with only (3,$3^{*}$) terms are seen to imply a violation of the current-algebra constraints. However, the large experimental $\xi$ can be obtained by including additional nonpole $(1,8)\oplus (8,1)$ breaking terms.

Forward differential cross sections for isospin-1 bosons produced in $p+p\to d+x^{+}$ were measured using a deuteron missing-mass spectrometer at a small angle between 4.0- and $12.3-\frac{\mathrm{GeV}}{c}$ incident momentum. Differential cross sections for ${\pi }^{+}$ and ${\rho }^{+}$ were extracted from the spectra using phase-space backgrounds. They range from 10.4 to 0.4 μb/sr for ${\pi }^{+}$ and from 1.4 to 0.3 μb/sr for ${\rho }^{+}$. A bump near 6 $\frac{\mathrm{GeV}}{c}$ appears in both $d\pi$ and $d\rho$ channels. No clear evidence is seen for higher-mass bosons. The possible ${\delta }^{+}$ cross sections average less than 0.01 μb/sr.

We present a class of scattering amplitudes which are dual and crossing symmetric, have Regge asymptotic behavior and second-sheet poles for resonances in all channels, and satisfy a Mandelstam representation with correct double-spectral-function boundaries. The Regge trajectories and residues are essentially arbitrary.

We have performed experiments with very low-frequency parallel resonance circuits which, subject to some questions of theoretical validity, set a new upper limit for the photon rest mass of ${10}^{-49\mathrm{}}$ g. This value is more than an order of magnitude smaller than the previous limit established by satellite measurements of the Earth's magnetic field.

Experimental evidence is presented that the observed depolarized scattering of light from gaseous argon is due to two processes. It is suggested that the broader and weaker component with intensity proportional to the square of the density is due to the "electronic overlap effect" proposed by Levine and Birnbaum and that the sharper and less density-dependent component first observed by McTague and Birnbaum is due to the "dipole-induced dipole" effect proposed by Thibeau, Oksengorn, and Vodar.

Polarized muons were stopped in a single crystal of CaS${\mathrm{O}}_4$ · 2${\mathrm{H}}_2$O placed in a magnetic field. Muon precession displayed a beat behavior and a "slow" -μsec-decrease of the muon spin polarization; these effects were found to be strongly dependent on crystal orientation in the field. Consistent explanation of the results was achieved by assuming that the muon occupied a normal proton site, and by considering the local field effects due to the dipole-dipole interaction of muon-proton pairs.

We report a calculation of the $\left(\frac{m_e}{m_{\mu }}\right){\alpha }^2\ln {\alpha }^{-1\mathrm{}}$ corrections to the hyperfine splitting (${\nu }_m$) of the muonium ground state. The result, $\Delta {\nu }_m=24\mathrm{}{\left(\frac{m_e}{m_{\mu }}\right)}^2{[1+(\frac{m_e}{m_{\mu }}\left)\right]}^{-5\mathrm{}}c{\alpha }^4{R}_{\infty }\ln {\alpha }^{-1\mathrm{}}=0.0252\mathrm{}$ MHz (5.6 ppm), shifts the theoretical value for ${\nu }_m$ to within one standard deviation of the most recent experimental determination of the muonium hyperfine interval by the Chicago-Illinois group.

A theory of the motion of ions in He II which takes into account ion-vortex-ring nucleation and escape probabilities is described. Predictions of the theory are compared with available experimental data and suggestions are made for further experiments.

Light scattering by ion-acoustic waves has been investigated in a $z$-pinch plasma. The asymmetry of the observed spectra varies with the angle between scattering wave number and longitudinal electron-drift velocity in a way which is in qualitative accord with light-scattering theory. However, the magnitudes of electron-drift velocities which were evaluated from these spectra are greatly at variance with values derived from the Doppler shift of the electron feature of light scattering.

The thermal conductivity of a gas becomes infinite at the critical point. It is shown that the experimental data for the thermal conductivity of C${\mathrm{O}}_2$ satisfy scaling-law relations very similar to those previously established for equilibrium properties near the critical point. The analysis also suggests that the values reported in the literature for the critical exponent of the Rayleigh linewidth should be revised downwards.

The asymptotic decay of the general two-point correlation function $G_{\mathrm{AB}}\left(\overrightarrow{R}\right)$ at high temperatures is analyzed on the basis of the $d$-dimensional, spin-½ Ising model in general field $H$. For $H\ne 0$ the Ornstein-Zernike form $\approx \frac{D_A{D}_B{e}^{-\kappa R}}{R^{\frac{\mathrm{}(d-1\mathrm{})\mathrm{}}{2}}}$ is found for general $\hat{A}$ and $\hat{B}$. However for certain operators, including the energy, the amplitude of the Ornstein-Zernike term vanishes as $H^2$ and in zero field only the higher order decay $\sim \frac{e^{-2\mathrm{}\kappa R}}{R^d}$ remains. The relation to approximate treatments and to critical-point phenomena is discussed briefly.

It is shown that in a system of two counterstreaming plasmas, the growth rates of the ordinary-mode electromagnetic instability can be several times the plasma frequency even for nonrelativistic velocities. The electromagnetic instability therefore grows faster than the coexisting electrostatic instabilities of the two-stream type, contrary to the common belief that electromagnetic instabilities are only of interest if electrostatic ones are absent.