$K\alpha \alpha$ absolute energies and energy shifts relative to twice the $K\alpha$ energy have been measured in ion-atom collisions at MeV energies in the region from $Z=12\mathrm{} \mathrm{to} 26$. For $Z=12\mathrm{} \mathrm{to} 22$ good agreement is obtained with Hartree-Fock energy calculations assuming an $E1\mathrm{}$ transition with two $L$-shell vacancies in the initial state. $K\alpha \alpha$ to $K\alpha$ intensity ratios are also presented.

Polarization labeling is a new method for studying excited states of molecules. Lightinduced anisotropy is used to label a molecular ground-state level, and all optical transitions which share this common lower level are detected. Polarization labeled spectra of ${\mathrm{Na}}_2$ were recorded using pulsed dye lasers. These spectra are easier to interpret than absorption spectra. Collision processes and perturbations of the $A$ state of ${\mathrm{Na}}_2$ were also observed.

The Zeeman effect in ${}_{}{}^1{}_{}{}^{}\Sigma {\mathrm{CO}}_2$ and ${\mathrm{N}}_2$O molecules arising from small rotational magnetic moments is observed in several infrared rotation-vibration bands using Doppler-free resonances in gas samples subjected to a magnetic field. Utilizing entire rotation-vibration bands allows measurements of the excited-state molecular $g$ factors and a precise determination of the small dependence [(1-2)%] of the $g$ factors on vibrational states which gives rise to an anomalous Zeeman effect. The signs of the $g$ factors are also determined.

An exact solitary Alfvén wave is found using kinetic theory. The wave has a long structure in the direction of an ambient magnetic field and a short structure with a size comparable to an ion gyroradius in the perpendicular direction. It propagates in a direction oblique to the ambient magnetic field.

Nonlinear wave propagation in inhomogeneous media is studied analytically in the model of the nonlinear Schrödinger equation. Exact solutions in the form of multisolitons, accelerated in the nonuniform medium, are obtained.

The tightly pinched electron beam of a pulsed electron accelerator is used to generate an intense beam of ions. A foil anode and vacuum drift tube are used. The space-charge field of the pinched beam in the tube accelerates ions from the foil anode. Ion currents of 10 kA at a density of 5 kA/${\mathrm{cm}}^2$ with pulse length of 50 nsec are obtained using a 5 kJ, 450 kV, $3-\Omega$ diode.

A lower-hybrid instability with ion cyclotron harmonics is observed to be resonantly driven by an ion beam injected obliquely to the confining magnetic field, in agreement with a linear, warm-plasma theory. Quasilinear velocity-space diffusion of the beam is observed.

Spatial and ten poral origins of three distinct neutron emission peaks observed in the University of Maryland turbulently heated high-voltage theta pinch machine have been identified. They are the result of fusion reactions involving reflected hot deuterium ions, pinched plasma, and energetic ions colliding with deuterium absorbed on the vacuum vessel wall, respectively. Studies of the wall-interaction neutron peak further reveal that the particle end loss in the reversed-field case is substantially slower than in the parallel-field case.

Debye-Waller factors $\exp \mathrm{}(-2W)\mathrm{}$ of monolayer films of butadiene iron tricarbonyl molecules adsorbed on basal-plane graphite surfaces have been measured in the surface-normal and surface-parallel directions. For each coverage $x=0.3, 0.7, \mathrm{and} 1.0$, the normal exponent $2W_{\perp }$ indicates strong substrate binding at all temperatures, while the parallel one $2W_{\parallel }$ increases abruptly at a definite temperature, indicating a first-order melting transition in the plane of the film.

The first observation of magnetic quantum effects in Auger recombination is reported. Experiments were carried out with the semiconducting compounds ${\mathrm{Hg}}_{1-x}{\mathrm{Cd}}_x\mathrm{Te}$. In addition to significant oscillations, the lifetime increases strongly with the magnetic field, as a result of the magnetic-field-induced spin polarization. The effect provides a very sensitive method for the determination of band parameters and may give valuable information on the electron-electron interaction in magnetic fields.

It is shown that a space-charge-neutralized intense ion beam can be focused down to diameters of ∼${10}^{-1\mathrm{}}$ cm by injection into a magnetic mirror through the combined action of the magnetic field and nonadabatic radiative energy losses. These intense tightly focused beams may be important for the eventual ignition of thermonuclear microexplosions.

The ($H_x, H_y, H_z$) phase diagram of a cubic ferromagnet with three easy axes, in a field $\overrightarrow{\mathrm{H}}=(H_x, H_y, H_z)$, is studied by mean-field, scaling, and renormalization-group theories. For $T<\mathrm{}{T}_c\mathrm{}(H=0\mathrm{})\mathrm{}$ and $\overrightarrow{\mathrm{H}}\parallel \mathrm{}\left[111\right]\mathrm{}$ there is a phase transition at fields $\pm H_0\mathrm{}\left(T\right)\mathrm{}$, described by the three-component Potts model. By varying $\overrightarrow{\mathrm{H}}$ the full phase diagram of the three-dimensional Potts model is experimentally accessible and competing predictions of the multicritical behavior can be tested.

We report evidence for the production of a new narrow charged state in $e^{+}{e}^{-}$ annihilation at a center-of-mass energy of 4.03 GeV. This state, which has a mass of 1876± 15 MeV/${\mathit{c}}^2$, is observed in the exotic channel $K^{\mp }{\pi }^{\pm }{\pi }^{\pm }$, but not in the nonexotic channel $K^{\mp }{\pi }^{+}{\pi }^{-}$. It is produced primarily in association with a system of mass 2.01±0.02 GeV/${\mathit{c}}^2$. These characteristics are just those expected of a charged charmed meson.

We have measured the production of $\rho +\omega$ and $J$ vector mesons, through their dimuon decay modes, by high-energy neutrons on nuclear targets at Fermilab. We determined the $A$ dependence to be $A^{0.62\pm 0.03}$ for $\rho +\omega$, $A^{0.93\pm 0.04}$ for $J$, and $A^{0.85\pm 0.05}$ for the continuum of dimuons between the $\rho +\omega$ and $J$ masses.

We have measured the $p_{\perp }$ and $p_{\parallel }$ dependence of $J$ production by high-energy neutrons in comparison with the production of the conventional vector mesons. We also report values for total inclusive cross sections for resonance and continuum dimuons, and give an upper limit for ${\psi }^{\prime }$ production.

We have searched for charmed particles produced hadronically in coincidence with the $J$ particle by looking for muons from the leptonic or semileptonic decays of the charmed particles. In a sample of 2500 $J\text{'}\mathrm{s}$, we see no muons above the level expected from $\pi$ and $K$ decays.

The recent data on ${\nu }_{\mu }p\to {\nu }_{\mu }p$ are examined from the point of view of discriminating among models of the space-time structure of the neutral weak current. The value of the total cross section appears to exclude pure $S$, $P$ from the interaction and we describe tests to confirm this conclusion.

Evidence for the $\alpha$ decay of the giant quadrupole resonance is reported. Measurements of the reaction ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}(e, e^{\prime }, \alpha ){}_{}{}^{234}{}_{}{}^{}\mathrm{Th}$ in the region 9-24 MeV are presented. The results imply that the reaction goes dominantly through $E2\mathrm{}$ absorption. The amount of $E2\mathrm{}$ strength used by the $\alpha$ emission channel exhausts 50% of the isoscalar energy-weighted sum rule.

The linear polarization of the $E2-M1\mathrm{}$ 122-keV $\gamma$ ray of ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ following the electron capture decay of polarized ${}_{}{}^{57}{}_{}{}^{}\mathrm{Co}$ was measured with a Compton polarimeter. An average time-reversal-noninvariant counting asymmetry of (-0.4 ± 0.8) × ${10}^{-5\mathrm{}}$ was obtained. This corresponds to a phase angle between the $E2\mathrm{}$ and $M1\mathrm{}$ matrix elements of $sin\eta =(-3.1\mathrm{}\pm 6.5)\times {10}^{-4\mathrm{}}$, consistent with time-reversal invariance.

Electrons have been injected into a toroidal magnetic field to form an electron cloud of approximately uniform density. The injection process was accomplished at magnetic fields of several kilogauss and differs from the inductive charging technique used by previous researchers. Electron densities of ∼${10}^{10}$ ${\mathrm{cm}}^{-3\mathrm{}}$ were injected and confined for several hundred microseconds, creating potential wells of ∼300 kV. Measurements of the radiated microwave energy from the electron cloud are reported.