The spontaneous magnetization in the critical region of the uniaxial, dipolar-coupled ferromagnet LiTb${\mathrm{F}}_4$ has been measured using sensitive optical techniques. These measurements provide a quantitative comparison between the predicated logarithmic corrections to mean-field theory and the experimentally observed magnetization of a ferromagnet at marginal dimensionality. We conclude that the spontaneous magnetization in LeTb${\mathrm{F}}_4$ is described by the relation $\frac{M_c\mathrm{}\left(T\right)\mathrm{}}{M_c\mathrm{}(T=0\mathrm{})\mathrm{}}=B{\mathrm{}\left|t\right|\mathrm{}}^{\frac{1}{2}}{\left|\ln \right|\frac{t_0}{t}\mathrm{}\left|\right|\mathrm{}}^{\frac{1}{3}}$ over the range $0.002<~t<~0.09$ with $B=1.77\mathrm{}\pm 0.06$, $T_c=2.8700\mathrm{}\pm 0.002$ K, and $t_0=0.53\mathrm{}\pm 0.06$.

The pion double-charge-exchange reaction ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}({\pi }^{+}, {\pi }^{-}){}_{}{}^{18}{}_{}{}^{}\mathrm{Ne}$ has been observed. A value of $\left(\frac{d\sigma }{d\Omega }\right)\left(0\mathrm{}°\right)=1.78\mathrm{}\pm 0.30$ μb/sr was obtained at a pion energy of 139 MeV for the $\Delta T_z=2\mathrm{}$ isobaric analog transition from the ground state of oxygen-18 to the ground state of neon-18.

${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ elastic electron scattering data have been extended to large momentum transfer ($q=3.7\mathrm{}$ ${\mathrm{fm}}^{-1\mathrm{}}$). The present data combined with previous electromagnetic data allow a precise determination of the charge density. It shows a small central depression and density fluctuations much less pronounced than theoretically predicted.

New detailed angular distribution measurements are presented for ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}(p, {\gamma }_0){}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ above the giant dipole resonance ($14 \mathrm{MeV}<~E_p<~27 \mathrm{MeV}$), which show pronounced effects of higher multipoles. Direct-semidirect calculations provide a good description of the data by including $E2\mathrm{}$ and $E3\mathrm{}$ as well as $E1\mathrm{}$ radiation. The sensitivity of the reaction to a $T=1\mathrm{}$ giant quadrupole resonance is demonstrated.

We have observed Ramsey's interference fringes in the optical region using saturated-absorption techniques in a fast atomic beam. We discuss their physical origin and describe an optical configuration that guarantees fringes of high symmetry. This technique, with its high-resolution potential, should lead to dramatic improvements in spectral measurements.

Stability of the runaway electrons in tokamaks is analyzed. The distinction between high-density and low-density operation of tokamak discharges is interpreted in terms of the stability condition obtained. In the unstable case, the temporal evolution of the distribution function of the runaway electrons is obtained by solving the quasilinear equation. Time-dependent synchrotron emission from the runaway electrons is calculated.

Measurements are reported of NMR linewidth, $\frac{1}{T_2}$, for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ atoms adsorbed on Grafoil at 1 K for various quantities of gas adsorbed. The data show three well-defined regions corresponding to a two-dimensional fluid, a two-dimensional solid, and a region where a second layer of adsorbed atoms is forming. A sharp minimum in $T_2$ gives a precise indication of monolayer completion. A theory for tunneling in the two-dimensional solid is presented.

Transition-matrix-element effects are shown to predict the angular variations in the valence-band x-ray-photoemission-spectroscopy (XPS) spectra of copper and gold, while a recently proposed direct-transition model does not. The angular dependence of XPS spectra is directly related to the symmetry properties of the initial-state wave functions. In particular, the $t_{2\mathrm{g}}$ and $e_{\mathrm{g}}$ projections of metal $d$ bands can be obtained directly from angle-resolved photoemission.

It is shown that the calculation of quantum effects associated with the classical four-dimensional pseudoparticle can be carried to completion in the one-loop, lowest-order-in-source approximation, with size effects calculated exactly. The result is finite, and leaves symmetry-breaking results intact. For the case of two flavors the theory reduces to a particularly simple form which suggests that the pseudoparticle acts as a source of zero-mass bosons which, in turn, are made of fermion pairs.

I construct the supergravity theory for a supersymmetry algebra whose spinor generators carry SO(3) internal symmetry. Spins ½, 1, $\frac{3}{2}$, and 2 are unified in one gravitational multiplet. The method used should be applicable to theories based on other internal symmetry groups.

An excess of negative particles and depletion of positive particles in the backward hemisphere (c.m. system) is observed in ${\pi }^{+}$ and $p$ interactions on neutron target. $\frac{d{\sigma }^{-}}{\mathrm{dy}}$ is compared with $\mathrm{pp}$ interactions and the difference is related to the slow-proton spectrum produced in the $\mathrm{pn}$ interactions. A neutron fragmentation component is observed and the inclusive charge-exchange probability at the nucleon vertex is found to be about 0.4.

We have measured the production of ${\pi }^{+}$ and ${\pi }^{-}$ in 200-, 300-, and 400-GeV $p-p$ and 400-GeV $p-d$ collisions for transverse momenta ($p_{\perp }$) ranging from 0.77 to 7.67 GeV/c. At large values of $x_{\perp }=\frac{2p_{\perp }}{\sqrt{s}}$, where $\sqrt{s}$ is the c.m. energy, we have fitted the $p-p$ data to the form $A{(1-x_{\perp })}^b{p_{\perp }}^{-n}$; we obtain $n=8.2\mathrm{}\pm 0.5$ for ${\pi }^{+}$ and 8.5±0.5 for ${\pi }^{-}$. At $x_{\perp }>0.3\mathrm{}$ the $\frac{{\pi }^{+}}{{\pi }^{-}}$ ratio in $p-p$ collisions rises appreciably with increasing $x_{\perp }$ whereas the $\frac{{\pi }^{+}}{{\pi }^{-}}$ ratio obtained from the difference of $p-d$ and $p-p$ cross sections is ∼ 1.0 at all $x_{\perp }$.

The ratios of $K^{+}$, $K^{-}$, $p$, and $\overline{p}$ yields to pion yields at transverse momenta ($p_{\perp }$) ranging from 0.77 to 6.91 GeV/c arepresented for 200-, 300-, and 400-GeV $p-p$ and 400-GeV $p-d$ collisions. The dependences of the particle ratios on $p_{\perp }$ and the scaling variable $x_{\perp }=\frac{2p_{\perp }}{\sqrt{s}}$ are discussed.

We present measurements of inclusive anomalous muon production in $e^{+}{e}^{-}$ annihilations in three energy ranges. In all three ranges we observe a large anomalous muon production rate in two-prong events which is compatible with the expected decays of pairs of heavy leptons. In the highest energy range there is also appreciable anomalous muon production in multiprong events which, due to its magnitude and momentum dependence, must come in part from a source other than a heavy lepton.

I present some exact solutions of the Polyakov-Belavin-Schwartz-Tyupkin equation $F_{\mu \nu }={\tilde{F}}_{\mu \nu }$ for an SU(2) gauge theory in Euclidean space. My solutions describe a system with an arbitrary number of pseudoparticles, with arbitrary scale parameters and arbitrary separations, arranged along a line. The action for an $n$-pseudoparticle solution is precisely $n$ times the action for a single pseudoparticle.

The structureless $\exp \mathrm{}(1.8t)\mathrm{}$ behavior of recent $\mathrm{pp}$ data for $\mathrm{}\left|t\right|\mathrm{}\gtrsim 2$ Ge${\mathrm{V}}^2$, $\sqrt{s}=53\mathrm{}$ GeV, is shown to be in sharp disagreement with dip-structure predictions from popular models of diffraction. Flip amplitudes, real parts, and large-angle effects are quantitatively insufficient to resolve the discrepancy. Modifications of some familiar ideas on diffraction (like eikonalization) seem necessary.

We report the first observation of first-order nonzero time-averaged torques and solid-body spinning velocities in intense acoustic fields, which occur when the acoustic displacement amplitude exceeds the viscous penetration depth.

Results are reported on the generation of MeV, pulsed ion beams at a peak power level in excess of 2 × ${10}^{11}$ W that have an angular divergence of about 3°-4°. Such beams can be used in the formation of field-reversing proton rings.

A set of harmonic-oscillator-like standing spin-wave modes have been observed in superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-$B$ confined by a set of parallel plates. The frequencies and intensities of the modes are in close agreement with computer solutions of the theoretical equations. Their observation represents the first direct confirmation of the existence of spin-wave dispersion in either superfluid phase of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$.

Dielectric measurements have been carried out on the single crystals of DyV${\mathrm{O}}_4$, TbV${\mathrm{O}}_4$, and TmV${\mathrm{O}}_4$ through the Jahn-Teller transition temperatures. An anomalous increase of the dielectric susceptibility with temperature along the $c$ axis was observed for DyV${\mathrm{O}}_4$, but not for TbV${\mathrm{O}}_4$ and TmV${\mathrm{O}}_4$. This behavior is explained as due to the antiferroelectricity driven by the soft $B_{1\mathrm{g}}$ strain mode through the "sublattice piezoelectricity."