Plasma heating by fast $\theta$ compression has been studied using an initial plasma with $T_i>T_e$ and $n\sim {10}^{14}$ ${\mathrm{cm}}^{-3\mathrm{}}$, which is produced by collision of two plasma streams ejected from $\theta$-pinch guns. Both ions and electrons are heated up to 3-4 keV with a maximum heating rate of 20 eV/nsec. After the magnetic field becomes maximum, two-temperature distributions are observed for the ions.

We present experimental evidence for the occurrence of energy-gap structure and microwave-assisted tunneling in the $\mathrm{IV}$ curves for superconducting thin-film weak links. From measurements of the power and the temperature dependence of the Josephson steps we argue that also the Riedel peak is observable in weak links.

The dispersion of surface plasmons at an air-metal interface has been studied experimentally using the method of attenuated total reflection. In the vicinity of the surface plasmon energy the dispersion curve was found to bend back toward the light line instead of increasing asymptotically to the surface plasmon energy at infinite momentum. We conclude that surface plasmon interactions must be characterized by a complete response-function surface rather than by a single dispersion curve.

By means of computer simulation of a copper lattice, we have found two resonance modes of the (split) interstitial configuration. The low frequencies of about $\frac{{\omega }_{max}}{7}$ are due to the strong negative "leaf springs" typical for the strongly compressed lattice around the interstitial atom. It seems very likely that many longstanding problems associated with point defects can be explained in terms of such modes.

Bounds on the exponents of the many-electron x-ray threshold anomaly are obtained, and a relationship between soft- and hard-x-ray threshold shapes is derived. The spectra of ${\mathrm{Mg}}_x{\mathrm{Sb}}_{1-x}$ alloys and Al metal are shown to be inconsistent with the many-electron theory of threshold exponents.

The long-range order parameter of the {100} surface of ${\mathrm{Cu}}_3$Au has been determined as a function of temperature by low-energy electron diffraction. The order parameter of the surface, unlike the bulk order parameters, appears to be a continuous function of temperature, and the disordering process at the surface begins about 60°K below a common critical temperature. A Monte Carlo calculation of the order parameter in terms of a model incorporating nearest- and next-nearest-neighbor interactions reproduces the experimental results.

The temperature dependence of the electrical conductivity and Seebeck coefficient for the polymer chain system ${\left(\mathrm{SN}\right)}_x$ has been measured along the chain axis from 4.2 to 300°K. The data show the system to be metallic over the entire temperature range studied, with a small conductivity maximum at ∼33°K.

In the bombardment of ${}_{}{}^{96}{}_{}{}^{}\mathrm{Mo}$ by proton beams with energies between 22 and 28 MeV, a definite structure is observed in the proton spectra of the reaction products, extending from about 3.0 to 4.2 MeV. The characteristics of this structure indicate that it arises from the isospin-allowed two-neutron decay (experimentally unobserved) of $T_{>}$ ($T=\frac{13}{2}$) levels in ${}_{}{}^{97}{}_{}{}^{}\mathrm{Tc}$ to low-lying $T_{>}$ ($T=\frac{11}{2}$) ${}_{}{}^{95}{}_{}{}^{}\mathrm{Tc}$ levels which then undergo proton decay (experimentally observed) to the low-lying levels of ${}_{}{}^{94}{}_{}{}^{}\mathrm{Mo}$. The ${}_{}{}^{97}{}_{}{}^{}\mathrm{Tc}$ levels whose decay modes produce this structure have excitation energies between 27 and 33 MeV and they are from 16 to 22 MeV above the lowest-lying $T_{>}$ state in ${}_{}{}^{97}{}_{}{}^{}\mathrm{Tc}$.

The members of the ground and $\beta$ bands in ${}_{}{}^{154}{}_{}{}^{}\mathrm{Gd}$ have been identified to spin 18. Plots of $\frac{2\mathcal{I}}{{\hslash }^2}$ versus ${\omega }^2$ yield backbending curves for both the $\beta$ and yrast states. It is shown that the backbending in the yrast sequence results from a band crossing and it is speculated that the twin backbending may arise from the intersection of the ground and $\beta$ bands by a third "intersecting band."

We have measured the differential cross sections for the associated-production reactions ${\pi }^{-}p\to K^0{\Lambda }^0$ and ${\pi }^{-}p\to K^0{\Sigma }^0$ at 3, 4, 5, and 6 GeV/c, with a total of over 40 000 events. We find that both reactions have exponential forward peaks for $-t\lesssim 0.4$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$, with no indication of forward-direction flattening or turnover; the slopes of the forward peaks show little if any variation with momentum; and the two cross sections are equal within experimental error from $-t=1.2\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ out to at least $-t=2.0\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$.

The application of simple dimensional counting to bound states of pointlike particles enables us to derive scaling laws for the asymptotic energy dependence of electromagnetic and hadronic scattering at fixed c.m. angle which only depend on the number of constituent fields of the hadrons. Assuming quark constituents, some of the $s\to \infty$, fixed-$\frac{t}{s}$ predictions are ${\left(\frac{d\sigma }{\mathrm{dt}}\right)}_{\pi p\to \pi p}\sim s^{-8\mathrm{}}$, ${\left(\frac{d\sigma }{\mathrm{dt}}\right)}_{\mathrm{pp}\to \mathrm{pp}}\sim s^{-10\mathrm{}}$, ${\left(\frac{d\sigma }{\mathrm{dt}}\right)}_{\gamma p\to \pi p}\sim s^{-7\mathrm{}}$, ${\left(\frac{d\sigma }{\mathrm{dt}}\right)}_{\gamma p\to \gamma p}\sim s^{-6\mathrm{}}$, $F_{\pi }\left(q^2\right)\sim {\left(q^2\right)}^{-1\mathrm{}}$, and $F_{1p}\left(q^2\right)\sim {\left(q^2\right)}^{-2\mathrm{}}$. We show that such scaling laws are characteristic of renormalizable field theories satisfying certain conditions.

Unitarity implies a rapid variation (singularity) in an amplitude usually assumed to be slowly varying in simple pairwise final-state-interaction fits to three-body final states. Neglect of this singularity casts doubts on recent analyses of $\pi +N\to \pi +\pi +N$, among others. Tentative suggestions for including the singular term are offered.

The microwave absorption spectrum of a tetrahedral molecule in its ground vibronic state has been observed for the first time. By using a conventional Stark spectrometer with a signal averager, four lines with strengths≲5×${10}^{-11\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ have been detected in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$${\mathrm{H}}_4$ between 7.8 and 14.2 GHz and identified as $\Delta J=0\mathrm{}$ transitions resulting from the distortion electric dipole moment.

We report a large angular variation in the Orbach relaxation rate for ${\mathrm{Ti}}^{3+}$ in methylammonium alum. This anisotropy is due to the dynamic Jahn-Teller effect, which modifies the spin-phonon interaction by the Ham vibronic reduction factor.

The unstable modes on a low-density, cold-electron-beam-plasma system are treated as an ensemble of Van der Pol oscillators. This model predicts the observed amplitude limiting of unstable waves at the neighboring frequencies of a launched wave that traps the beam electrons.

We report measurements of the reflection coefficient $R$ for electron plasma waves propagating into a density gradient on a narrow column. Within experimental error, $R$ is proportional to $\exp (-\delta )$ when $R$ is less than 0.25 and is equal to $\exp (-0.23\mathrm{}\delta )$ for $R$ greater than 0.25, where $\delta$ is the inverse of the WKB parameter.

Results of a numerical simulation model are presented. Internally generated megagauss magnetic fields are produced which tend to impede and deform the heat flow into the target plasma beyond the laser-energy deposition layer. Two new instabilities are also discussed.

An anisotropic ultrasonic velocity in smectic-$A$ diethyl 4,4′-azoxydibenzoate was measured at 2, 5, 12, and 20 MHz. The material was aligned by slowly cooling through the phase transition point in a magnetic field of 12.4 kOe. An accuracy of ±0.08% in the relative velocity was provided by the phase-matching technique, and three elastic constants were calculated.

Densities of states and $K$ x-ray emission and absorption spectra from both components of a 50-50 intermetallic compound TiFe were calculated using results of self-consistent energy-band calculations. The calculated x-ray spectra agree well with experiment.

In the linear Jahn-Teller effect of an electronic $E$ state, we report on the distinction between coupling with one set of doubly degenerate vibrational modes, and coupling with several such sets of different frequencies (the multimode Jahn-Teller effect) as is the case for an impurity in a solid. Whereas the combination of the reduction factors $2q-p$ is exactly unity in the former case, it is shown to be less than unity in the latter. Also, the value of $q$ may decrease below ½.