We present the first orthogonalized-plane-wave band structures and corresponding densities of states for two reported crystal structures of polymeric surfur nitride, ${\left(\mathrm{SN}\right)}_x$, and compare our results with experiment. We examine the band structures in light of the low-temperature stability of the metallic and superconducting states in ${\left(\mathrm{SN}\right)}_x$ and conclude that this stability derives from closed Fermi surfaces introduced by electronic interchain coupling.

We report x-ray photoemission (XPS) measurements on polymeric sulfur nitride, ${\left(\mathrm{SN}\right)}_x$. Both valence-band states and core-level binding energies have been studied. The charge transfer $\delta$ in the ${\mathrm{S}}^{+\delta }{\mathrm{N}}^{-\delta }$ bond is estimated to be 0.30-0.42 electrons. The XPS spectra are compared with densities of states derived from a single-chain tight-binding calculation and also with three-dimensional orthogonal-plane-wave (OPW) calculations based on the two reported ${\left(\mathrm{SN}\right)}_x$ crystal structures. Good quantitative agreement is found with the OPW density of states.

A new two-dimensional diode simulation code is used to show the possibility of using hemispherical diodes to produce converging ion beams in the 1-10-MA range. The pinched electron flow enhances ion emission, while suppressing electron emission, allowing $\frac{I_i}{I_e}>1\mathrm{}$. Such focused ion beams are of considerable interest for use in ablatively driven implosions of fusion targets.

A method of discriminating between rapidly moving electric and magnetic charges is proposed. The scheme relies on detection of the polarization of Cherenkov radiation.

We calculate the critical behavior of systems having a multicritical point of a new type, hereafter called a Lifshitz point, which separates ordered phases with $\overrightarrow{\mathrm{k}}=0\mathrm{}$ and $\overrightarrow{\mathrm{k}}\ne 0$ along the $\lambda$ line. For anisotropic systems, the correlation function is described in terms of four critical exponents, whereas for isotropic systems two exponents suffice. Critical exponents are calculated using an $\epsilon$-type expansion.

Rates of high-energy cosmic-ray muon pairs have been measured for separations up to 70 m. Detailed calculations imply that the mean transverse momentum $〈p_T〉$ of mesons with $x>\mathrm{}0.01\mathrm{}$ is 0.66 ± 0.10 GeV/c at laboratory energies of ≳ 10 000 GeV. We find that the high-$p_T$ muons result mostly from decay of abundantly produced particles with lifetimes ≳ ${10}^{-8\mathrm{}}$ sec, such as pions and kaons.

No definite evidence for structure is found in the $\overline{p}p\to \overline{n}n$ cross section between 276 and 963 MeV/c. From these results limits are deduced on properties of the narrow enhancement reported in the $\overline{p}p$ total cross section at 475 MeV/c.

We have studied the angular distribution for the reactions $e^{+}{e}^{-}\to e^{+}{e}^{-}$ and $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ at beam energies of 1.55, 3.1, and 3.7 GeV at SPEAR II. At a beam energy of 3.7 GeV a significant azimuthal asymmetry was observed indicating that the electron and positron beams are strongly polarized. The angular distribution of the $\mu$ pairs was found to be in good agreement with the predictions of quantum electrodynamics. The equilibrium value of the polarization and the polarization time constant are found to be $P_0=0.76\mathrm{}\pm 0.05$ and $\tau ={10}_{-5\mathrm{}}^{+20\mathrm{}}$ min.

In ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}(p, n){}_{}{}^{90}{}_{}{}^{}\mathrm{Nb}$ spectra for $E_p=35\mathrm{} \mathrm{and} 45$ MeV, we observe a strong enhancement of the $T=4\mathrm{}$ continuum over a range of excitation energies (full width at half-maximum of 4.2 ± 0.4 MeV) centered at 8.4±0.3 MeV. The data are consistent with an interpretation of the broad peak as a ${(\pi g_{\frac{7}{2}}, \nu {g_{\frac{9}{2}}}^{-1\mathrm{}})}_{1^{+}}$ excitation wich corresponds to the giant magneticdipole resonance. Similar structure is observed near the isobaric analog state of ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$, ${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$, and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$.

We have studied the pre-yrast $\gamma$ decay of high-spin states in Yb isotopes excited highly above the yrast line in oxygen-induced $\mathrm{xn}$ reactions on Sm targets. We measured energy spectra, $\gamma$-ray multiplicities, angular correlations, and feeding times. The multiplicities increase with the $\gamma$ de-excitation energy. The $\gamma$-ray anisotropy indicates a dominant quadrupole character of the de-excitation $\gamma$ continuum. Hindered feeding times into the ground-band states were observed for ${}_{}{}^{158}{}_{}{}^{}\mathrm{Yb}$ but not for the decoupled states in ${}_{}{}^{159}{}_{}{}^{}\mathrm{Yb}$.

We have studied the properties of the four rotational bands developed in ${}_{}{}^{165}{}_{}{}^{}\mathrm{Tm}$ for high spin values. The ${\mathrm{½}}^{-}$[541] is the only one which does not show the backbending effect. These results are in agreement with other recent experiments showing the role of the $h_{\frac{9}{2}}$ protons in the backbending effect. A strong $\Delta K=3\mathrm{}$ coupling between ${\mathrm{½}}^{+}$[411] and ${\frac{7}{2}}^{+}\mathrm{}\left[404\right]\mathrm{}$ bands has been found.

Energy spectra and angular distributions have been measured of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ fragments emitted from Ag and U targets, bombarded with 2.7-GeV protons, and 1.05-GeV/nucleon $\alpha$ particles and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ions. All cross sections increase dramatically with projectile mass. No narrow peaks are found in the angular distributions or in the energy spectra.

Quasibound Rb-He Van der Waals molecules have been observed through their influence on the electron spin relaxation of optically pumped ${\mathrm{Rb}}^{85}$ and ${\mathrm{Rb}}^{87}$. The natural lifetime of the complex has been measured to be 6×${10}^{-10\mathrm{}}$ sec.

Large-amplitude lower-hybrid wave bursts at ${\omega }_0>{\omega }_{\mathrm{LH}}$ are excited from a grid and propagate into a density gradient perpendicular to ${\overrightarrow{\mathrm{B}}}_0$. The evolution of the internal rf fields and the plasma parameters is investigated. Above threshold localized field maxima appear ($E_{\mathrm{int}}\gg E_{\mathrm{appl}}$) and, simultaneously, strong density perturbations are formed. The nonlinear phenomena are interpreted by ponderomotive-force and space-charge separation effects.

A phase-sensitive, differential, light-scattering method is used to measure the shape of correlated regions in the isotropic phase of nematics. In MBBA ($p$-methoxybenzylidene $p-n$-butylaniline) these regions are elongated along the molecular-axis direction and the critical behavior is close to that predicted by mean-field theory; de Gennes's parameter $\frac{L_2}{A}$ is positive. In the isotropic phase of the smectic OBBA ($p$-octoxybenzylidene $p-n$-butylaniline) the correlated regions are flat and cannot be described by a constant $L_2$.

We have used the ion-vortex interaction to measure the drift velocity of the vorticity present in turbulent counterflow, and find that it moves in the direction of normal-fluid flow. The result is in direct conflict with a central assumption of the presently accepted model of the turbulent state.

Heat capacity and vapor-pressure measurements indicate a higher-order phase transition in nitrogen monolayers adsorbed on basal-plane graphite. The transition coincides with finite jumps in three experimental quantities: the two-dimensional compressibility, the isosteric heat of adsorption, and the heat capacity at constant area. Thermodynamics implies that the heat capacity at constant two-dimensional spreading pressure also has an abrupt jump and hence the transition is suggestive of a second-order Ehrenfest type.

An exact expression is derived for the isotopic difference of jump rates in diffusion processes and is used to examine several topical difficulties in the theory.

The new variational-principle, density-functional theory of the spin susceptibility $\chi$ is used to make a priori calculations of $\chi$ for the alkalis. Crystalline effects are calculated by the spherical-cell method and the local spin-density approximation is used for the exchange-correlation functionals. The excellent agreement between the results and recent experiments establishes the validity of this new theory and the correctness of the theoretical values for the exchange-correlation enhancement of $\chi$ for a homogeneous electron gas for ${\mathcal{r}}_s\lesssim 5$.

Photoemission spectra show that atomic hydrogen reacts near room temperature with Si(111)1×1 to form a trihydride phase, Si(111): Si${\mathrm{H}}_3$. The new phase, clearly to be distinguished from the monohydride Si(111): H obtained from Si(111)7×7, has been identified by theoretical calculation of the photoemission spectrum. Formation of Si(111): Si${\mathrm{H}}_3$ suggests that the vacancies that exist on clean Si(111)7×7 are disordered on Si(111)1×1.