Soft x-ray emission spectra of TiN, excited by monochromatized synchrotron radiation, have been recorded in a grazing-incidence spectrometer. The tunability of the excitation energy has allowed the pure N K and Ti $L_{\mathrm{III}}$ emission spectra to be isolated for the first time. A new type of resonance is observed in the Ti L emission spectrum, and interpreted as due to the decay of a quasiatomic intermediate state. The results call for a reinterpretation of Ti L spectra and a revision of the interpretation of 3d-metal L-emission spectra in general.

We have observed in experiments with a driven nonlinear electrical resonator that the fluctuations in the ‘‘noisy precursor’’ to a period-doubling bifurcation are phase dependent and that the noise is deamplified in one of the phases. This is a classical effect analogous to ‘‘squeezing’’ which normally refers to deamplification of quantum noise. Preceding the period-doubling bifurcation a ‘‘noise rise’’ similar to that observed in Josephson-junction parametric amplifiers evolves and the noise deamplification ceases. This phenomenon and the ‘‘noise rise’’ appear to be related as successive stages in the development of bifurcation in a nonlinear system in the presence of noise.

Unusually high ionization energies have been observed for Cs-O clusters having certain sizes and composition, namely for ${\mathrm{Cs}}_{2\mathrm{n}+\mathrm{z}}$${\mathrm{O}}_{\mathrm{n}}$ with z=8, 18, 34, 58, and 92. The anomalies are well defined for clusters containing from 1 to 7 oxygen atoms. The indicated values of z are identical to the number of electrons in closed shells of angular momentum.

We have developed a novel simulation method that combines a multigrid technique with a stochastic blocking procedure. Our algorithm eliminates critical slowing down completely, as demonstrated by simulations of the two-dimensional Ising model at criticality.

We explicitly provide, in a simple way, the form of the conserved quantities of the one-dimensional Hubbard model. The method developed is based in a newly found factorization property of the local transition matrices, which is satisfied by several spin and fermion chain models. In this way, we have shown a systematic method for deriving the conserved quantities of integrable quantum systems.

The groups Pin(n,m) and Pin(m,n) are not isomorphic, and the obstruction classes to their respective bundles are different. It follows that for nonorientable superstring theories the contributions to a Polyakov path integral from surfaces with positive metric are different from the contributions from those with negative metrics.

A scheme is proposed to explain the hierarchy of fermion masses. In the model presented, which has no horizontal symmetry, generations pick up masses one by one through radiative corrections as we go to higher orders in perturbation theory. An extra generation of isosinglet heavy fermions play an important role in implementing the scheme.

The semileptonic decay rate of a heavy lepton is shown to be rigorously calculable by use of perturbative QCD. Even the τ lepton is heavy enough for the perturbative approximation to be accurate. The prediction for the ratio R=Γ(τ→${\mathit{v}}_{\mathrm{\tau }}$+hadrons)/Γ(τ→${\mathit{v}}_{\mathrm{\tau }}$+${\mathit{e}}^{\mathrm{-}}$+v${\mathrm{¯}}_{\mathit{e}}$) is 3.29, with an uncertainty of about 1% due to the uncertainty in the Λ parameter of QCD. Nonperturbative corrections to this prediction are estimated to be on the order of 1%. More importantly, these corrections are shown to be negative because of a fortuitous cancellation of the leading contribution from the gluon condensate. The resulting prediction is significantly smaller than the present experimental result R=3.65±0.13.

We report the first result of a search for highly ionizing particles in $e^{+}$$e^{\mathrm{-}}$ annihilations at the KEK storage ring TRISTAN. CR-39 and UG-5 dielectric track detectors were exposed to 4.8 ${\mathrm{pb}}^{\mathrm{-}1}$ integrated luminosity at total energies of 50–52 GeV in the center of mass. This search is sensitive to Dirac magnetic monopoles and yields 95% confidence-level upper limits of 8×${10}^{\mathrm{-}37}$ and 1.3×${10}^{\mathrm{-}35}$ ${\mathrm{cm}}^2$ on the cross section for production of monopoles with magnetic charges g=68.5e≡$g_D$ and g=2$g_D$ and respective maximum masses 24.1 and 22.0 GeV/$c^2$.

We report on a search for charm-changing neutral-current decays and lepton-family-number–nonconserving decays of charmed hadrons using inclusive and exclusive decays of charmed hadrons into oppositely charged dileptons. We find no evidence for such interactions. The upper limits on the branching ratio for inclusive charm decay to dileptons are B(c→X${\mu }^{+}$${\mu }^{\mathrm{-}}$)<1.8×${10}^{\mathrm{-}2}$, B(c→${\mathrm{Xe}}^{+}$$e^{\mathrm{-}}$)<2.2×${10}^{\mathrm{-}3}$, and B(c→X${\mu }^{\pm }$$e^{\mp }$)<3.7×${10}^{\mathrm{-}3}$ at 90% confidence level. Upper bounds are also presented for the branching ratios of several exclusive modes.

In a sample of 670 000 charged-current neutrino events, 101 ${\mu }^{\mathrm{-}}$${\mu }^{\mathrm{-}}$ events have been observed, with 30 GeV<$E_{\nu }$<600 GeV and $P_{\mu }$>9 GeV/c for both muons. After background subtraction, 18.5±13.9 events remain, yielding a prompt rate of (5.5±4.1)×${10}^{\mathrm{-}5}$ per charged-current event. A sample of 124 000 antineutrino events yields 15 ${\mu }^{+}$${\mu }^{+}$ events, giving 6.4±4.2 events after background subtraction and a prompt rate of (1.0±0.7)×${10}^{\mathrm{-}4}$ per charged-current event. The numbers and kinematic distributions of these events are consistent with standard model sources.

The transverse momentum of charged particles produced within the pseudorapidity range η=-0.36 to +1.0 has been measured in p¯p collisions at √s =1.8 TeV. The charged-particle multiplicity of each event was measured with a 240-element cylindrical hodoscope system covering the range -3.25<η<3.25. The average transverse momentum as a function of the average charged-particle density per unit of pseudorapidity is presented. Events are observed with average charged-particle density as high as 32 per unit of pseudorapidity.

A discrete superdeformed band was found in ${}_{}{}^{148}{}_{}{}^{}\mathrm{Gd}$, and was produced both in Ca- and Si-induced compound-nucleus reactions. It is the third band found in the mass-150 region and its properties provide the clearest indication that ${}_{}{}^{152}{}_{}{}^{}\mathrm{Dy}$ is a ‘‘magic’’ superdeformed nucleus.

Photons with energies from 2 to 60 MeV have been measured in coincidence with binary fragments in the reaction ${}_{}{}^{92}{}_{}{}^{}$Mo${+}^{92}$Mo at an incident energy of 19.5A MeV. The rapid change of the γ-ray spectrum and multiplicity with the fragment total kinetic energy in the exit channel indicates that the γ rays are emitted statistically by the highly excited fragments. Temperatures as high as 6 MeV are inferred.

It is shown that product ratios in photodissociation differential cross sections can be controlled experimentally by variation of the polarization of the exciting laser. For M-selected initial states, where M is the angular momentum projection quantum number of the initial bound level, control can be complete insofar as one can totally eliminate production of a selected product-arrangement channel. Further we show that control survives M averaging for ${}_{}{}^1{}_{}{}^{}\to _{}^1{}_{}{}^{}$Π systems. The method is applied to model diatomic ${}_{}{}^1{}_{}{}^{}\to _{}^1{}_{}{}^{}$Σ and ${}_{}{}^1{}_{}{}^{}\to _{}^1{}_{}{}^{}$Π photodissociation.

It is shown analytically, in a suitable limit, that a sharp pattern selection mechanism exists in driven explosive crystallization: After the onset of a morphological instability of the steady-state crystallization front, nonlinear effects cause the front to develop a spatial pattern with a definite wavelength. The amplitude, wavelength, and shape of the selected pattern are calculated analytically.

When a magnetosonic wave packet crosses the second-harmonic gyroresonance layer, it linearly excites an ion-pressure–anisotropy wave packet, which propagates only in k space. The latter wave in turn excites a second magnetosonic wave packet which appears as a time-delayed reflection from the resonance layer. We call this phenomenon a linear ion-cyclotron echo.

A 2D quasicrystal with a twelvefold rotational axis has been found in rapidly solidified ${\mathrm{V}}_3$${\mathrm{Ni}}_2$ and ${\mathrm{V}}_{15}$${\mathrm{Ni}}_{10}$Si alloys by means of transmission electron microscopy. The electron diffraction pattern taken along this axis shows no periodicity but a clear twelvefold orientation symmetry. The corresponding high-resolution electron-microscopic image agrees well with an aperiodic pattern consisting of squares and equilateral triangles. A structural model for this dodecagonal quasicrystal has been proposed.

Atoms with energies of several electronvolts are ejected if small metal particles are illuminated with low-intensity visible laser light. The desorption rate exhibits a resonant behavior with its maximum at λ=490 nm for particles of 50 nm average radius. The novel process is explained by a mechanism of laser-induced desorption that is based on surface-plasmon excitation.

We have made the first direct measurements of the critical current density of individual grain boundaries and their adjoining grains in ${\mathrm{Y}}_1$${\mathrm{Ba}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ superconducting films. The critical current of the boundary was always found to be less than either of the two grains. The magnetic field dependence of the critical current of the grain boundaries indicates that they are comprised of regions of weak and strong Josephson coupling. A single grain boundary was also used to build and operate a simple dc SQUID. Current-voltage curves of a grain-boundary junction n the finite voltage range show subgap structure.