We have measured the strange-quark content of the nucleon, ${\mathrm{\eta }}_{\mathit{s}}$${=}_{\mathrm{-}0.08}^{+0.012\mathrm{}}$, and the Kobayashi-Maskawa matrix element ‖${\mathit{V}}_{\mathit{c}\mathit{d}}$‖=0.${220}_{\mathrm{-}0.018}^{+0.015\mathrm{}}$ using a sample of 1797 ${\nu }_{\mathrm{\mu }}$- and ν${\mathrm{¯}}_{\mathrm{\mu }}$-induced ${\mathrm{\mu }}^{\mathrm{-}}$${\mathrm{\mu }}^{+}$ events with ${\mathit{P}}_{\mathrm{\mu }}$≥9 GeV/c and 30≤${\mathit{E}}_{\nu }$≤600 GeV. The data are consistent with the slow-rescaling hypothesis of charm production in ν-N scattering and within this formalism yield a value of the charm-quark mass parameter ${\mathit{m}}_{\mathit{c}}$=1.${31}_{\mathrm{-}0.48}^{+0.64\mathrm{}}$ GeV/${\mathit{c}}^2$. .AE

Using isolated leptons reconstructed in the Mark II detector to tag bb¯ events, we measure the fraction of bb¯ events in hadronic ${\mathit{Z}}^0$ decays to be 0.${23}_{\mathrm{-}0.09}^{+0.11\mathrm{}}$, in good agreement with the standard-model prediction of 0.22. We find Γ(Z→bb¯)=0.${43}_{\mathrm{-}0.17}^{+0.21\mathrm{}}$ GeV.

We reexamine the unitarity constraints on the high-energy scattering of longitudinal W ’s and Z’s and Higgs bosons in the standard model including one-loop corrections, and make an Argand-diagram analysis of the j=0 scattering amplitudes. We find that the theory is approximately unitary and weakly interacting at O(${\lambda }^2$) for Higgs-boson couplings λ<${\lambda }_{\mathit{c}}$=1.5–2 (equivalent to ${\mathit{M}}_{\mathit{H}}$<350–400 GeV), but that O(${\lambda }^3$) or higher corrections must be included to restore perturbative unitarity for larger values of λ or ${\mathit{M}}_{\mathit{H}}$.

Collisions of ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$+Al, Cu, Pb at ${\mathit{E}}_{\mathrm{lab}}$/A=14.6 GeV were studied in a calorimetry-based experiment at the BNL Alternating Gradient Synchrotron. Transverse-energy production was measured for pseudorapidities -0.5<η<0.8. Correlations with the spectra and multiplicity of neutrons and protons emitted into a forward 0.8° cone demonstrate quantitatively the large amount of nuclear stopping observed in these reactions. Calculations in hadronic-fireball or nucleon-nucleon based models underpredict the measured transverse-energy production for Si+Pb and indicate the need to include rescattering of secondaries and /or contributions from target fragmentation.

We report here the first observation of ${\mathrm{Na}}_2$ Rydberg states with an excited ${\mathrm{Na}}_2^{+}$ 1 ${}_{}{}^2{}_{}{}^{}\mathrm{\Pi }_{\mathit{u}}^{}{}_{}{}^{}$ The principle of our experiment is to prepare a Rydberg state associated with the ion in its ground state and then to excite the ${\mathrm{Na}}_2^{+}$ core with a tunable laser. The autoionization processes occurring in these states as well as the internal energy redistribution of the singly excited Rydberg states are discussed. Finally, the energy levels of the 1 ${}_{}{}^2{}_{}{}^{}\mathrm{\Pi }_{\mathrm{u}}^{}{}_{}{}^{}$ state of ${\mathrm{Na}}_2^{+}$ are deduced.

Relative differential cross sections for elastic scattering of 5–50-eV positrons by argon atoms at angles from 30° to 134° are measured in a crossed-beam experiment. These measurements provide strong evidence that the positronium formation channel (threshold=9.0 eV) is having a significant ‘‘absorption’’ effect on the elastic-scattering channel, as is observed by the ‘‘washing out’’ of clear structure (a maximum and minimum) present in the measured elastic differential cross section below 9.0 eV (where good agreement is found with theory) when the positron energy is increased to higher energies.

Theoretical analysis is made of an intense relativistic electron beam moving through a plasma of increasing density, but density always less than that of the beam (underdense). Analysis is made of the beam radiation energy loss and it is noted that the focuser is insensitive to the beam energy spread due to radiation loss. Furthermore, because of the scaling behavior in the nonclassical regimes, the radiation limit on lenses (the Oide limit) can be exceeded.

We report experimental results for wave-number selection in Taylor-vortex flow with slow spatial ramps of the Reynolds number. The accessible range of wave numbers is always much smaller than the Eckhaus-stable range, but the selected wave number depends on the detailed nature of the ramp. For a particular ramp, wave numbers outside the Eckhaus-stable band were selected, leading to a periodic state of traveling vortices. The selected wave numbers and the frequencies of the periodic state agree well with a phase-dynamical calculation by Riecke and Paap.

Recent experiments have found the existence of ‘‘photon bands’’ in periodic dielectric structures analogous to the electron bands in the solid. Using a plane-waves method, we study in the scalar-wave approximation the nature of the photon bands in structures where spherical ‘‘atoms’’ of dielectric constant ${\mathrm{\epsilon }}_{\mathit{a}}$ are periodically arranged in a background dielectric ${\mathrm{\epsilon }}_{\mathit{b}}$. The scalar-wave calculation predicts gaps in the spectrum for ${\mathrm{\epsilon }}_{\mathit{a}}$/${\mathrm{\epsilon }}_{\mathit{b}}$ or ${\mathrm{\epsilon }}_{\mathit{b}}$/${\mathrm{\epsilon }}_{\mathit{a}}$≳3 or so. The nature and symmetry of the wave functions is also discussed.

By means of an asymptotic analysis, two distinct approaches to incompressibility are found for a low-Mach-number ideal fluid, distinguished according to the relative magnitudes of temperature, density, and pressure fluctuations. For heat-conduction-dominated-fluids, temperature and density fluctuations are predicted to be anticorrelated, and the classical passive scalar equation for temperature is recovered, whereas a generalized ‘‘pseudosound’’ relationship for the fluctuations is found for heat-conduction-modified fluids, together with a modified thermal equation. The full set of nearly incompressible dynamical equations is described.

Fast waves or MHD surface waves of m=-1 (poloidal mode number of left-hand rotation) have been observed to be mode converted on the Alfvén resonance layer. The converted waves are a quasielectrostatic form of the shear Alfvén waves, i.e., kinetic Alfvén wave and/or the resistive mode.

The absorption of 250-fs KrF laser pulses incident on solid targets of aluminum and gold has been measured as a function of polarization and angle of incidence for the intensity range of ${10}^{14}$–2.5×${10}^{15}$ W ${\mathrm{cm}}^{\mathrm{-}2}$. Maximum absorption of over 60% occurs for p-polarized radiation at angles of incidence in the range of 48°–57°. The measured results are in agreement with absorption on a steep density gradient.

Magnetic feedback control has been used in the DITE tokamak to substantially reduce saturated m=2, n=1 instabilities in both Ohmic discharges and discharges with lower hybrid current drive (LHCD). Feedback has been used for the first time to significantly increase the disruptive density limit in a tokamak. LHCD on DITE stabilizes the sawtooth instability but generates a large m=1,2, n=1 instability. Both components of this mode have been controlled for the first time with feedback. Open loop experiments with LHCD show that mode locking occurs and allow detailed study of this phenomenon.

Fast-wave and slow-wave current drive near the mean gyrofrequency were compared in the Irvine Torus. The slow-wave current drive density limit observation was extended by an order of magnitude in wave frequency compared to previous tokamak results. At low densities, the fast-wave antenna was observed to launch slow waves which drove currents that suffered from the current drive density limit identical to waves launched from the slow-wave antenna. At higher densities, current was driven by the fast-wave antenna while none was driven by the slow-wave antenna.

We study growing interfaces by the numerical simulation of several three-dimensional systems: the Kardar-Parisi-Zhang equation, a discrete variant of that model, and a solid-on-solid model with asymmetric rates of evaporation and condensation. Growth exponents in the rough phase are calculated, and we estimate the kinetic roughening transition temperature, its dependence on driving force, and analyze the transition by finite-size scaling. We find the transition depends strongly on driving force, which could be investigated experimentally.

The ordering kinetics in a two-dimensional dilute Ising antiferromagnet near the percolation threshold, ${\mathrm{Rb}}_2$${\mathrm{Co}}_{0.60}$${\mathrm{Mg}}_{0.40}$${\mathrm{F}}_4$, 4, are studied. The random magnetic field created by the uniform external field destroys the long-range order; after removing the field the development of order in the system with a fractal geometry can be observed. Both neutron scattering and magnetic measurements give the first observation of a logarithmic growth law with a temperature dependent power below the Néel temperature.

We propose a new electron holographic scheme for the three-dimensional imaging of the atomic environment of disordered adsorbate atoms on a crystal surface, in which the object acts as its own beam splitter. The technique may be regarded as a direct method in low-energy electron diffraction, or even, in a sense, as a form of ‘‘lensless electron microscopy.’’

Diffusion of interstitial iron in silicon could be observed on an atomic scale for the first time: Coulomb-excited ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$ nuclei were implanted into high-purity n-type silicon Mössbauer spectra were recorded at temperatures between 300 and 850 K. The diffusional broadening of one spectral component identified as interstitial Fe could be observed. The isomer shift of interstitial Fe in Si was determined and the assumption that one single mechanism is governing the diffusion of Fe in Si between 300 and 1500 K is confirmed.

Computer-simulation studies of the crystallization and melting of a model of sodium have been carried out to determine the (001) steady-state velocity versus temperature relation in the temperature region 81 to 497 K. Using a form of transition-state theory there is an apparent slope discontinuity in the velocity versus temperature relation at the melting point, which is correlated with slope discontinuities in averaged order parameters for planes buried in the crystal; planes appear to soften more per unit temperature increase above the melting point leading to larger melting velocities.

I consider edge states of a quasi-one-dimensional Bloch electron in a magnetic field. They have irregular energy gaps and lead, at progressively low temperatures, to increasingly higher resolution of chaotic quantum oscillations and phase transitions. This situation is characteristic of open-orbit edge states in any dimensionality.