The magnetization density of $5f$ electrons in PuSb has been measured by use of a single crystal and polarized neutrons. The spatial extent of the spin and orbital densities is such that the form factor has a maximum at $\frac{sin\theta }{\lambda }\simeq 0.2$ ${\mathrm{\AA }}^{-1\mathrm{}}$. The ground-state wave function is deduced. Evidence for anisotropic interactions is presented.

Simulations of the two-dimensional ferromagnetic Ising model in a random magnetic field with spin-flip dynamics are reported. After the system is deeply quenched into the unstable region of the phase diagram, novel dynamical behavior for the average size of the growing domains is observed.

A new class of Bethe lattices formed by two or more chemical elements of fixed but usually different coordinations is presented. The atoms are randomly bonded. The Green's function of the system is governed by a probabilistic equation, which can be solved by an iterative numerical procedure. Hydrogenated $a$-Si is modeled by a random Bethe lattice in which Si has coordination four and H has coordination one. Comparison with experiment shows that this model incorporates the main attributes of the real material.

A two-series approach to partial differential approximant analysis of power series is presented. Instead of double series, $f(x,y)=\Sigma c_{\mathrm{ij}}{x}^i{y}^j$, our approach uses two one-variable series in $x$, $f$ and $\frac{\partial f}{\partial y}$, and has the efficiency and stability of one-variable methods. 21-term high-temperature series are analyzed for the susceptibility and correlation length squared for double-Gaussian Ising models on the bcc lattice. Critical exponents are $\gamma =1.2378\mathrm{}\left(6\right)\mathrm{}$, $2\nu =1.2623\mathrm{}\left(6\right)\mathrm{}$, and $\eta =0.0375\mathrm{}\left(5\right)\mathrm{}$; correction-to-scaling exponents are ${\theta }_{\chi }=0.52\mathrm{}\left(3\right)\mathrm{}$ and ${\theta }_{{\xi }^2}=0.49\mathrm{}\left(4\right)\mathrm{}$; and the subdominant critical amplitude ratio is $\frac{a_{\xi }}{a_{\chi }}=0.83\mathrm{}\left(5\right)\mathrm{}$.

The design and performance of a superconducting induction detector with two 60-cm-diam superconducting loops is presented. During eight months of data taking, no candidate events were observed and an upper limit on the flux of cosmic-ray magnetic monopoles $F_m\lesssim 6.7\times {10}^{-12\mathrm{}}$ ${\mathrm{cm}}^2$ ${\mathrm{sr}}^{-1\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ (90% C.L.) is set. The detector demonstrates the possibility of operating large induction detectors in ambient magnetic fields greater than 1 mG.

The three-dimensional ${\left({\overrightarrow{\Phi }}^2\right)}^3$ theory is studied at large $N$. A complete mapping of the phase diagram and a detailed analysis of the renormalization-group flows is given. The recently found uv fixed point of Bardeen, Moshe, and Bander is investigated and it is pointed out that its characteristics seem to be somewhat nongeneric and might disappear at finite $N$. Our analysis is restricted to infinite $N$ and hence no definitive conclusions are yet possible.

It is much harder to flip the spin of a proton by flipping a $d$-quark spin than by flipping a $u$-quark spin. This gives very strong flavor dependence which can be used in tests of QCD models. For example, the ratio of the spin-flip transitions $\frac{\sigma ({\pi }^{-}p\to {\rho }^{-}p)}{\sigma ({\pi }^{+}p\to {\rho }^{+}p)}$ is predicted to be 1 if the mechanism is flavor-independent gluon exchange, to be 16 if the mechanism is quark-antiquark annihilation and pair creation, and to be $\frac{1}{16}$ if the mechanism is quark exchange.

Calculations are presented for the reaction ${}_{}{}^{71}{}_{}{}^{}\mathrm{Ga}\mathrm{}(p,n)\mathrm{}{}_{}{}^{71}{}_{}{}^{}\mathrm{Ge}$ at $E_p=35\mathrm{}$ MeV. Differential cross sections to the ground state and the 0.175- and 0.500-MeV states are estimated and compared with experimental results. It is shown that the 0° ($p$, $n$) cross section at $E_p=35\mathrm{}$ MeV is not directly proportional to the Gamow-Teller strength and thus the experimental results cannot be used to used to estimate the absorption of solar neutrinos.

We have observed a multitude of resonance phenomena in the photoelectron spectrum of atomic calcium excited in the $3p$ threshold region. Their detailed interpretation needs extensive theoretical insight; nevertheless, we distinguish some systematic connections between resonant intermediate levels and final-state photoelectron distributions. Finally, the lowest $3p$-ionization threshold, at 30.8 eV, is measured here, for the first time, from Auger lines observable only under resonant excitation conditions.

The nonlocal approximation to the correlation energy density functional proposed by Langreth and Mehl [Phys. Rev. B 28, 1809 (1983)] is applied to molecules. A substantial improvement over the local approximation is observed. However, the errors are larger than in the atomic case.

Measurements on a convecting dilute ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-superfluid-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ solution show a transition from periodic to chaotic behavior via intermittency. In a region near but below the onset of intermittency, injection of external noise greater than some threshold value induces chaos.

The stability of the hot-electron precessional mode is investigated in the presence of a relative $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$ precession between the end cell and the center cell, which is inherent to the tandem-mirror concept. It is found that a positive radial electric field in the end cell is favorable to stability. Under normal conditions, the stability of a hot-electron symmetric tandem mirror is not worse than a quadrupole tandem mirror with the same relative $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$ precession.

We derive a set of diffusion equations based on time-dependent Landau-Ginzburg theory, which is capable of describing the role of domains in stage transformations and intercalation in layered materials. As illustrations of the formalism we study stage decomposition in a quenched sample and the intercalation of a dilute sample. Staggered domains of intermediate stages are shown to arise naturally as a consequence of the interactions and the kinetic constraints even for a sample without dislocations. Further, we show that intercalation proceeds through the formation and migration of islands of intermediate stages.

The in-plane structure and dynamics of the intercalant Cs layer in Cs${\mathrm{C}}_{24}$ has been studied by ${}_{}{}^{133}{}_{}{}^{}\mathrm{Cs}$ quadrupole-perturbed NMR spectra and quadrupolar spin-lattice relaxation. The results show that the dominant excitations leading to the disordering of the mixed commensurate-incommensurate structure are phononlike shear modes interrupted by diffusion and displaying softening as the temperature approaches the deintercalation temperature.

The growth of order in a system with continuous symmetry is studied in the time-dependent Ginzburg-Landau model (in the large-$N$ limit), quenched below the coexistence curve. The dynamics are studied with and without conservation of the order parameter. The development of order in the longitudinal direction and the buildup of Nambu-Goldstone modes in the transverse directions are explicitly exhibited. Nontrivial scaling behavior and growth laws are obtained in the long-time regime.

We show that the dynamically selected velocity and tip radius of dendrites in the boundary-layer model of solidification have the special values which permit the existence of steady-state needle-crystal solutions. This result, in conjunction with considerations of stability, provides new insight concerning the validity of the marginal stability hypothesis.

The atomic geometry, chemical bonding, and surface-state eigenvalue spectra are predicted for saturated (1×1) ordered monolayers of Sb on the (110) surfaces of GaP, GaAs, GaSb, InP, InAs, and InSb. For GaAs and InP the predicted geometries are in good correspondence with those obtained from low-energy electron diffraction. The predicted electronic structure of these Sb-substrate systems reveals a novel type of bonding not found in either bulk III-V semiconductors or molecular III-V analogs.

In diluted $\mathrm{Pd}\mathrm{Fe}$ alloys the motion of hydrogen isotopes in the vicinity of substitutional iron atoms has been investigated in the temperature range $40 \mathrm{K}<T<\mathrm{}150\mathrm{} \mathrm{K}$ by means of magnetic-aftereffect and complex-susceptibility measurements. In the temperature ranges $100 \mathrm{K}<T<\mathrm{}\infty$ and $60 \mathrm{K}<T<\mathrm{}100\mathrm{} \mathrm{K}$ the relaxation rates of all three isotopes obey Arrhenius laws with an inverse isotope effect of the activation enthalpies in the high-temperature range, and a mixed isotope effect at low temperatures with 0.13 eV for H, 0.12 eV for D, and 0.16 eV for T.

A double-peak structure is observed in the Cu concentration profile after low-energy pulsed-laser irradiation of Cu-implanted Si. From the Cu surface segregation a primary melt depth is inferred. In addition, Cu segregation at the depth of the amorphous-crystal interface gives evidence for a secondary melt propagating through the amorphous layer towards the crystalline substrate. The results imply a large difference in melting temperature, heat of melting, and heat conductivity between amorphous Si and crystalline Si.

New experimental techniques, sensitive to crystal surface symmetry, for reflection high-energy-electron diffraction have been developed and applied to the (001) surface of MgO. The techniques map the variation of the intensity of one or more diffracted beams as a function of the incident-beam orientation. The symmetry of these surface zone-axis patterns has been studied theoretically and confirmed experimentally. The techniques are expected to provide a sensitive means of surface characterization.