Angle-resolved photoelectron spectroscopy and surface-core-level chemical shifts have been used to study electronic structure and derive structural models of the Al, Ag, and Ni metal-induced reconstructions on Si(111). We show, for the first time, the connection between the Ni-stabilized $\sqrt{19}\times \sqrt{19}$ and clean 7×7 surfaces, and report a new Si(111)-$(\sqrt{7}\times \sqrt{7})\mathrm{Al}$ structure at <0.5 monolayer coverage of Al.

A global two-dimensional simulation of a substormlike process occurring in Earth's magnetosphere is presented. The results are consistent with an empirical substorm model—the neutral-line model. Specifically, the introduction of a southward inter-planetary magnetic field forms an open magnetosphere. Subsequently, a substorm neutral line forms $\lesssim 15 R_E$ in the magnetotail, and plasma sheet thinning and plasma acceleration occur. Eventually the substorm neutral line moves tailward toward its presubstorm position.

A novel type of neutron interferometer was constructed and tested employing a split cylindrical zone plate with neutrons of 20 Å wavelength. Its performance and relative merits are discussed.

A very general cosmological solution to Einstein's equations exhibiting sensitive dependence on initial data is analyzed as a dynamical system. The metric and topologic entropies of the one-dimensional Poincaré map are determined and various results in number theory employed to calculate other invariants of the "chaotic" cosmological dynamics.

Measurements on niobium spheres which show unambiguously the existence of fractional charges of $\frac{1}{3}e$ are reported. Charge changes of $\frac{1}{3}e$ on particular spheres when they contact other surfaces are continually observed. Of 21 new measurements, four charges of $+\frac{1}{3}e$, four of $-\frac{1}{3}e$, and thirteen of zero are found. Extensive measurements and critical analyses have assured us that the background forces are either negligible or have been measured and taken fully into account.

Results are presented of a search for strange, doubly charged, narrow [full width at half maximum ≤0.2 ${(\mathrm{G}\mathrm{e}\mathrm{V}/{\mathit{c}}^2)}^2$] meson states produced in the baryon-exchange reaction ${\pi }^{+}p\to {{\Lambda }_f}^0{S}^{++}$ at 9.8 GeV/c. No evidence is found for such states. The 95%-confidence-level limit for the production cross section is < 20 nb for $M\left(S^{++}\right)<~2$ GeV/${\mathit{c}}^2$. Limits on $\sigma B$ from a kinematic reconstruction of final states with $S^{++}\to K^{+}{\pi }^{+}$ are ≤ 10 nb for $M\left(K^{+}{\pi }^{+}\right)<~2.0$ GeV/${\mathit{c}}^2$.

Evidence for the backward production of the $B\left(1235\right)\mathrm{}$ meson in the final state ${\pi }^{+}p\to p_f{\pi }^{+}\omega$ at 11.46 GeV/c with $\sigma \mathrm{}\left(\right|\mathrm{}{u}^{\prime }|<\mathrm{}1.5\mathrm{} \mathrm{Ge}{\mathrm{V}}^2)=1.28\mathrm{}\pm 0.26$ μb is presented. When nucleon exchange is assumed to dominate, estimates for the SU(3) mixing parameter $\frac{F}{D}$ as well as the $B$ coupling to the nucleon-antinucleon are given. Some indication of a narrow enhancement at $M\left({\pi }^{+}\omega \right)\simeq 1.03$ ${\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c}}^2$ is seen, but confirmation of this as a resonant state is not yet possible.

Interpretations of the $E$ meson (1420 MeV) in the radiative decay of the $\frac{J}{\psi }$ are discussed. Information on the spin and parity assignment, and the two-photon decay rate of the $E$ meson, will be sufficient for one to decide whether it is an ordinary quark-antiquark or a gluonic bound state.

Evidence is presented that there are at least two states near 1.4 GeV which decay to $\overline{K}K\pi$. One is $E\mathrm{}\left(1420\right)\mathrm{}$, an axial vector, and the other is $G\mathrm{}\left(1440\right)\mathrm{}$, probably a pseudoscalar. The pseudoscalar is likely to be a glueball.

Effects arising from the existence of lower-$l$ cutoff ($l_{min}$) in heavy-ion fusion processes are discussed within the framework of the statistical theory. Both the fluctuation cross section as well as the angular cross-correlation function are seen to be affected qualitatively by $l_{min}$.

$\gamma$-ray out-of-plane anisotropy and multiplicity are determined for the ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}$ + ${}_{}{}^{165}{}_{}{}^{}\mathrm{Ho}$ reaction at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=450\mathrm{}$ MeV. The measurements are made as functions of $Q$ value and ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}$ for the coincident quasi or deeply inelastically scattered ions. Strong correlations of the aligned angular momentum with both energy loss and scattering angle are observed.

Our experiments on doubly periodic wavy vortex flow show that the second spectral frequency corresponds to a modulation of the $m$ azimuthal traveling waves. We use spacetime symmetry to classify the possible modulation patterns and to predict a basic period $\tau$ such that in the frame rotating with the angular velocity of the waves the wave pattern at times $t$ and $t+\tau$ will differ only by a rotation through an integral multiple of $\frac{2\pi }{m}$. Measurements on the twelve observed modulation patterns agree with this prediction.

The problem of the neutralization of one-dimensional ion beams moving through a source of cold electrons into free space has been studied with the use of a computer simulation of the electron dynamics. The results indicate that neutralized high-intensity beams of ions appropriate for inertial-confinement fusion may be able to propagate to a focus through vacuum with negligible limits imposed by the electron pressure.

Radio-frequency plugging of a streaming plasma was observed in experiments in which the applied electric fields were too weak for plugging by the ponderomotive effect on ions. The experimental parameters met two requirements for the electron ponderomotive effect: (a) the electron thermal speed $v_0\ll \omega L$, the product of the frequency and scale length of the rf field; and (b) the field amplitude $E\gtrsim \left(\frac{2\omega }{e}\right){\left[mk\right(T_e+T_i\left)\right]}^{\frac{1}{2}}$. The plugging observed was the result of the ponderomotive effect on electrons.

The exponents for large branched dilute polymers (which are also connected with the exponents of the lattice animals) are related in $D$ dimensions to the exponents of the Lee-Yang edge singularity of the Ising model in $D-2\mathrm{}$ dimensions. From the exact solution of the Ising model in zero and one dimension, one gets the polymer exponents in two and three dimensions, $\theta \mathrm{}(D=2\mathrm{})=1\mathrm{}$ and $\theta \mathrm{}(D=3\mathrm{})=\frac{3}{2}$.

It is shown that the color of a single, classical pole particle can change only if the gauge group contains two generators $a$ and $b$ such that $\mathrm{}[a,b]=a\ne 0$ and the particle is unaccelerated. If the gauge group is compact and semisimple, then color is constant, but there is transfer of energy by the Yang-Mills field, in complete analogy with the situation in electrodynamics described by the Liénard-Wiechert potentials.

The magnetic moment of the ${\Xi }^0$ hyperon has been measured to be ${\mu }_{{\Xi }^0}=-1.253\mathrm{}\pm 0.014$ nuclear magnetons. A new measurement of ${\mu }_{\Lambda }$ is also reported.

Under certain simplifying assumptions, an analysis is made of the embedding of color ${\left[\mathrm{SU}\mathrm{}\right(3\left)\right]}_c$ in the SU(8) of extended supergravity. It is shown how reality under ${\left[\mathrm{SU}\mathrm{}\right(3\left)\right]}_c$ as required by parity conservation forces the massless SU(8) supermultiples to combine into massive Sp(16) supermultiplets; this, together with naturalness, would necessitate superheaviness for all composites.

High-energy $\gamma$ rays from the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$($\alpha$,$\gamma$) have been observed decaying from states between 32 and 39 MeV in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$. A narrow unexpectedly strong line, corresponding to decay to a state at 14.8±0.1 MeV in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, was observed with an angular distribution suggesting a strong $E2\mathrm{}$ component. Structure in the excitation function of this transition favors a resonant rather than direct-capture mechanism. Comparisons with SU(3)- and shell-model calculations suggest a giant quadrupole excitation built on the $6_1^{+}$ state in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$.

Out-of-plane angular distributions have been measured for sequential $\alpha$-particle decay from targetlike fragments produced in fully damped heavy-ion collisions. Fragment spins, extracted from the angular distributions, and $\gamma$-ray multiplicity data are consistent with rigid rotation of an intermediate complex composed of two substantially deformed spheroids. Over the limited range of asymmetries populated, $l$ fractionation appears to play a minor role.