Experimental results are presented which show the stabilization of the drift-dissipative instability in an afterglow plasma. Stabilization was achieved by means of an applied azimuthal rf magnetic field perpendicular to the main containing axial magnetic field or, alternatively, by an applied rf axial electric field parallel to the dc magnetic field. The results obtained at various applied frequencies are compared with a previous theory, and some points of agreement and disparity are noted.

The first moments of a series of Kramers-Kronig-transformed experimental electro-reflectance spectra are calculated in order to estimate critical-point contributions to the second- and third-order nonlinear optical susceptibilities, ${\chi }^{\mathrm{}\left(2\right)\mathrm{}}$ and ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$. Analysis of data for Ge and GaAs provides the first direct experimental evidence that the electronic resonant processes responsible for electroreflectance contribute negligibly to ${\chi }^{\mathrm{}\left(2\right)\mathrm{}}$, but significantly affect the value of ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$.

We have performed a self-consistent nonlinear calculation of the modifications of the contact potential due to the degenerate doping of the semiconductor. For sufficiently small $r_s (r_s<~1.5)$ the resulting potential is of sufficient strength to support a bound state. The implications of this for the validity of the use of linear-response theory near the surface is briefly considered.

The Rayleigh line scattered by succinonitrile is studied by means of a Fabry-Pérot interferometer having a resolving power of 5 × ${10}^5$. The line is found to be Lorentzian with a 5.4-GHz width and a depolarization ratio 0.77. The experimental data are in good agreement with the orientational relaxation theory in liquids.

The electron spin-resonance spectrum of Mg:Gd single-crystal alloys in the concentration range 50-1000 ppm exhibits a single anisotropic line. Both the field for resonance and the angular variation of linewidth can be described in terms of unresolved fine structure, but with substantially different values for the axial crystalline field constant. We propose a possible explanation for this difference. We discuss discrepancies between our conclusions and those of Salamon on a similar system.

The Phillips—Van Vechten dielectric theory of binary tetrahedral compounds and Levine's bond-charge model are formulated in terms of macroscopically defined linear and nonlinear bond polarizabilities. This formulation allows the determination of the linear and nonlinear optical properties of tetrahedral solids. As an illustration, the case of ternary compounds with chalcopyrite structure is considered. Theoretical and experimental results are in good agreement.

The magnetostatic modes of a ferromagnetic film including the uniform mode are absent when the spins are pinned and the exchange interaction is included. New modes, the magnetoexchange modes, occur with dispersion intermediate between the magnetostatic and exchange dispersions. Formulas and detailed results are presented for both the pinned cases. Experimental tests for deducing the effective boundary conditions are discussed.

The reactions ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$(${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^3{}_{}{}^{}\mathrm{He}$)${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}({}_{}{}^6{}_{}{}^{}\mathrm{Li},t){}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$ have been performed at an incident energy of 24 MeV. The observed strong selectivity of these reactions suggests a predominantly direct-reaction mechanism and allows the identification of several isobaric analogs in ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ and ${}_{}{}^{19}{}_{}{}^{}\mathrm{Ne}$.

The results from a neutrino experiment deep underground are used to set upper limits on the energy flux of muon neutrinos which might be associated with the gravitational pulses described by Weber.

We present the results of a wire spark-chamber experiment studying the reaction ${\pi }^{-}p\to {\pi }^{+}{\pi }^{-}n$ at 15 GeV/c. The differential cross section, $\pi -\pi$ mass distribution, and density-matrix elements have been determined from 10 000 $\pi \pi n$ events ($M_{\pi \pi }<1.0\mathrm{}$ GeV) produced with $-t<\mathrm{}0.30\mathrm{}$ ${\mathrm{}(\mathrm{G}\mathrm{e}\mathrm{V}/\mathrm{c})\mathrm{}}^2$. Both the density-matrix elements and the differential cross section exhibit structure in the forward direction ($-t<\mathrm{}{m_{\pi }}^2$).

We present a comparison of new data on ${\pi }^{-}p\to {\rho }^{0}n$ at 15 $\frac{\mathrm{GeV}}{c}$ with polarized and unpolarized single-pion photoproduction data. Particular emphasis is placed upon the behavior of the differential cross sections and asymmetries in the forward direction ($-t<\mathrm{}{m_{\pi }}^2$). Qualitative agreement with the vector-dominance model is found. Quantitative agreement is found for the unnatural-parity—exchange cross section and for the asymmetry at low momentum transfer. Elsewhere there are disagreements in detail which may not be explained by changes of normalization.

We have observed an additional $K^{*}$ resonance on the low-mass side of the $K^{*}\mathrm{}\left(1420\right)\mathrm{}$ in the reaction $K^{+}n\to K^{+}{\pi }^{-}p$ at 12 $\frac{\mathrm{GeV}}{c}$. This resonance has parameters $M\approx 1370$ MeV and $\Gamma <150\mathrm{}$ MeV, and is probably produced by a pion-exchange mechanism with $J^P=0^{+}$; but the alternative hypotheses of a $J^P=1^{-}$ or a $J^P=2^{+}$ resonance cannot be ruled out at this time.

The Fe $K\alpha$ x-ray spectrum produced by 30-MeV ${\mathrm{O}}^{5+}$ bombardment is found to consist of two major components which have been identified as $1s\to 2p$ transitions shifted 38 and 68 eV above the $K{\alpha }_{1,2}$ energy due primarily to one and two additional vacancies, respectively, in the $2p$ shell.

The photoionization cross section of the neutral iron atom is calculated from threshold at 7.90 eV to 36 eV. Results are presented for the Hartree-Fock approximation and correlations are included by many-body perturbation theory.

Comparison of deuteron and proton dynamic polarizations measured simultaneously in butanol samples doped with porphyrexide, a free radical, shows that these polarizations correspond to equal spin temperatures for these different nuclei, in agreement with effects of dynamic orientation of nuclei by cooling of electron interactions, and in disagreement with the solid-state effect.

Low-energy electron-diffraction spectra for three beams of Al {001} have been calculated from a complex static potential by a method of an accuracy comparable to modern band calculations. Despite the presence of strong attenuation, the spectra still show considerable structure which arises from the potential and which corresponds closely to experiment.

Introducing boson-like excitations to describe the fluctuation of the order parameter in a superconductor near the transition temperature, we have calculated the fluctuation-induced diamagnetism and found a result in excellent agreement with the recent experiment of Gollub, Beasley, and Tinkham. We find that the effective density of boson excitations just above the transition temperature is of order of ${10}^{-6\mathrm{}}N$, where $N$ is the density of electrons, and vanishes at high temperatures.

The predictions of the localized spin-fluctuation model and those of a theory of the low-temperature behavior of the multiorbital Anderson model we have recently developed are compared with respect to both the bulk properties (resistivity, specific heat, and magnetic susceptibility) and the microscopic properties (impurity nuclear-resonance shift and relaxation rate) for the dilute magnetic alloys $\mathrm{Au}\mathrm{V}$ and $\mathrm{Al}\mathrm{Mn}$.

Curves of KCl $F$ center versus dose, obtained by making absorption measurements during irradiation with ${\mathrm{Co}}^{60}$ $\gamma$ rays at 85°K, are accurately described by $\alpha \mathrm{}\left(t\right)=A_1[1-\exp (a_{1}t\left)\right]+{\alpha }_{L}t$. After irradiation, the coloring decays less than 1% in 8×${10}^4$ sec. $A_1$ is independent of, and $a_1$ and ${\alpha }_L$ are proportional to, the dose rate. These observations are in accord with a particularly simple phenomenological theory of radiation-induced color-center formation.

The problem of a system of classical spins of arbitrary dimensionality interacting through an arbitrary, isotropic nearest-neighbor-exchange Hamiltonian is solved exactly for the closed linear chain. The $2m$-uple spin-correlation function for spins a distance $k$ apart is shown to be the $k\mathrm{th}$ power of the ratio of the $m\mathrm{th}$ eigenvalue to the largest one. It is proposed that experimental data be used to find the general functional form of the exchange interaction.