The muonic x-ray cascade in Fe has been measured with Ge detectors. The intensities of 103 x-ray lines from the $K$, $L$, $M$, $N$, and $O$ series were determined and compared with cascade calculations. The best "initial distribution" at principal quantum number $n=20\mathrm{}$ does not strongly depend on the angular momentum.

The first observation of destructive interference of imaginary contributions to ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$ from different resonances is reported. Destructive and constructive interferences were obtained between Raman and two-photon absorption (TPA) contributions in organic liquids. Accurate TPA and two-photon dispersion spectra of C${\mathrm{S}}_2$ obtained by using these interferences in ${\chi }^{\mathrm{}\left(3\right)\mathrm{}}$ are reported. The TPA experiment described is superior to the classical TPA experiments in its accuracy and in the fact that it lacks the uncertainties originating from scattering processes which compete with true TPA.

A multicoil, internal magnetic probe is used to follow the development of the plasma current profile through the disruptive instability. The initial perturbation of the current channel is localized between the singular surfaces $q=1, 2$ present within the plasma. Subsequently, during the main disruption, peak toroidal electric fields ≳10 times the quiescent value are observed near axis. It is suggested that microturbulence is responsible for this extreme resistivity anomaly.

Steady-state electrotransport measurements were performed for H and D interstitials in V, Nb, and Ta. The measurements were made in the temperature range between 49°C and 245°C and with hydrogen concentrations up to an atom ratio of 0.054. The results yield strong experimental evidence for the existence of a direct field force.

Heat-capacity (2-400 K) and inelastic-neutron-scattering studies of the phonon spectra are reported for superconducting, high-critical-field, Chevrel-phase, lead and tin molybdenum sulfides ($T_c\sim 11-15$ K). Nine phonon modes per unit cell are identified whose frequencies are in the immediate region Bergmann and Rainer indicate is necessary to optimize $T_c$. Acoustic-phonon softening on cooling is observed. A molecular-crystal model is proposed for the lattice dynamics of these materials.

We have measured the melting temperatures of crystallized suspensions of polystyrene spheres as a function of concentration. By analyzing the data on the basis of a simple model we can estimate the heat of melting and the entropy change.

The Compton scattering of circularly polarized $\gamma$ rays was used for studying the linear momentum distribution of electrons with unpaired spins in ferromagnetic iron metal. The observed Compton profile shows a broad minimum around zero momentum. The results are discussed in comparison with those calculated by Wakoh, Kubo, and Yamashita using the augmented-plane-wave method.

We have calculated the ground-state energy as a function of density for a recently suggested condensed phase of lithium impurities in silicon. The temperature-density phase diagram of this system has been determined and it is found that the critical temperature and density are 3.0×${10}^2$ °K and 3.5×${10}^{19}$ ${\mathrm{cm}}^{-3\mathrm{}}$, respectively.

The temperature dependence of the electric field gradient $\mathrm{eq}\left(T\right)\mathrm{}$ in noncubic metals is calculated within a pseudopotential approach including the influence of lattice vibrations. The resulting $\mathrm{eq}\left(T\right)\mathrm{}$ factorizes into a Debye-Waller factor and a lattice sum over screened ions. The accurately measured $\frac{\mathrm{eq}\left(T\right)\mathrm{}}{\mathrm{eq}\left(0\right)\mathrm{}}$ values for In, Cd, Zn, Sb, and Sn are quantitatively reproduced using known data for the lattice constants and for the mean-square atomic displacements.

We apply the self-consistent theory of lattice vibrations to calculate ${\alpha }^{2}F$, which is of central importance in the theory of strong-coupling superconductors. Neglecting the effects of alloying on the electron states and the electron-phonon interaction, it is found that the low-frequency dependence of ${\alpha }^{2}F$ changes from ${\omega }^2$ in the mass-defect case to $\omega$ if one includes force-constant fluctuations. Numerical results for ${\alpha }^{2}F$ show a shift in weight from the longitudinal to the transverse peak in qualitative agreement with experiment.

The generalized susceptibility of NbC, determined from its augmented plane wave energy band structure (with constant matrix elements), shows large maxima, arising in large part from Fermi surface "nesting," to occur at precisely those $\overrightarrow{\mathrm{q}}$ values at which soft modes have been found in the phonon acoustic branches by Smith. These maxima can be represented by a warped cube of dimension $\sim 1.2\left(\frac{2\pi }{a}\right)$ in momentum space, in striking agreement with the soft mode surface proposed by Weber.

The current-voltage characteristics of superconducting thin-film indium microbridges (Dayem bridges) and their microwave-induced constant-voltage steps have been investigated at several frequencies. The results are well described by a resistively shunted Josephson junction model, which differs from the usual resistively shunted Josephson junction model only in having a current-phase relation of the form $I=I_0\left(\dot{\varphi }\right) sin\varphi +I_1\left(\dot{\varphi }\right)\times cos\varphi +I_2\left(\dot{\varphi }\right)$, where the functions $I_0$, $I_1$, and $I_2$ are derived from time-dependent Ginzburg-Landau theory.

Using a simple model for the boundary scattering, it is shown that the Stoner model of an itinerant electron gas with a finite spin polarization exhibits a well-defined surface-spin-wave mode. This mode always lies above the maximum frequency of the corresponding bulk-spin-wave modes and its degree of localization strongly increases with the bulk exchange splitting.

A new theory in which the observed electronic states in N-doped $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x$ derive from the combination of a long-range disorder and strain-induced nitrogen-associated potential and the usual short-range isoelectronic nitrogen potential is compared with pressure measurements at $x\sim 0.30$ (and with earlier measurements at $x\gtrsim 0.45$). In the composition region $x\sim 0.3$ a strong ${\mathrm{N}}_{\Gamma }-{\mathrm{N}}_X$ interaction is predicted and is observed by pressure measurements.

A magnetron operating at a wavelength of 10 cm has been constructed with six resonant cavities cut in a cylindrical anode block. A graphite cylinder acting as a field-emission cathode delivers ∼12 kA in an accelerating radial potential of ∼360 kV. The magnetic field directed along the diode axis is ∼8 kG. Linearly polarized microwaves of 30 nsec duration at powers of ∼1.7 GW are achieved. The conversion efficiency of electron energy into microwave is ∼35%.

Various nonlinear evolution equations that have been solved by the two-component inverse-scattering method are shown to be associated with the motion of certain simple types of helical curves. The linear eigenvalue problem that is usually postulated for solving these equations is found to follow quite incidentally from the standard intrinsic equations that govern the motion of space curves.

We report on the first observation of Fresnel diffraction of a beam of unpolarized slow neutrons by individual ferromagnetic domain boundaries. The observed occurrence of destructive interference in the experiment demonstrates that the phase of a spinor wave function changes by a factor of - 1 when the particle described by that wave function is rotated by an odd multiple of $2\pi$ radians.

It is shown that the new features of large-$p_{\perp }$ phenomena observed in high-energy inclusive ${\pi }^{\pm }p$ and $\mathrm{pp}$ reactions can be understood in terms of a statistical model. Consequences of this model in other processes, for example, $K^{\pm }p$ and $\overline{p}p$, are also discussed.

We calculate final-muon polarizations and their collinear angular distributions in anomalous lepton production from $e^{-}{e}^{+}$ annihilation near and beyond threshold energies and discuss their experimental significance.

The invariant cross sections for direct positron production in $p-p$ collisions have been measured to be $E\frac{d^3\sigma }{d{p}^3}=(-3\mathrm{}\pm 2)\times {10}^{-32\mathrm{}} \mathrm{and} (-14\mathrm{}\pm 12)\times {10}^{-32\mathrm{}}$ ${\mathrm{cm}}^2$/sr ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ at 256 and 800 MeV, respectively. These results are consistent with zero ($\frac{e^{+}}{{\pi }^{+}}\lesssim 3\times {10}^{-6\mathrm{}}$ at 800 MeV) and are in marked contrast to results at higher energies.