Convoy electrons produced by 1-8.5 MeV/u ${\mathrm{O}}^{q^{+}}$ ions traversing polycrystalline C, Al, and Au targets and $〈110〉$ and $〈100〉$ axial channels in Au are detected in coincidence with emergent ions of charge state $q_e$. The yield integrated over electron velocity for channeled ions depends strongly on $q_e$, but the shape is found to be independent of $q_e$, $v$, and target material. For polycrystalline and randomly oriented monocrystalline targets, the yield is found to be independent of emergent-ion charge state $q_e$. The data suggest that convoy-electron production is a bulk process.

A new method of high-resolution multiphoton spectroscopy based on competition between ionization and stimulated-emission channels is described. It combines features of multiphoton photoionization with those of optical-optical double resonance. Results obtained for ${\mathrm{I}}_2$ demonstrate the method and identify intermediate states involved in multiphoton photoionization. The method offers the potential for extremely sensitive sub-Doppler spectroscopy of complex molecules.

With long-pulse-duration (4 nsec), moderate-intensity (≃${10}^{13}$ W/${\mathrm{cm}}^2$) Nd-laser irradiation of flat targets, time-integrated images of $\frac{3}{2}{\omega }_0$ and $2{\omega }_0$ emission reveal filaments along the laser axis. Combined with fine-scale structure found in x-ray images, these filaments suggest self-focusing of hot spots in the incident beam.

The interaction distance for relativistic electrons and optical radiation in a mode-locked free-electron laser is often limited by the electron bunch length. For a far-infrared oscillator the round-trip gain and the output coupling efficiency can be increased by the introduction of intracavity filters.

Simulations of the Rayleigh-Taylor instability of ablatively accelerated thin-shell fusion targets show that the nonlinear evolution exhibits spike amplitude saturation due to ablative mass removal; the shell anterior surface evolves to a laminar (nonturbulent) quasistationary distorted state. The perturbed flow causes a significant departure from spherically symmetric behavior, but the laminar shell interior structure makes it appear possible to retain some of the advantages of larger-aspect-ratio fusion targets.

Detailed time- and space-resolved measurements of the electric fields and currents have been made in a laboratory plasma undergoing magnetic-field-line reconnection. The resistivity normalized to the classical value is found to be spatially inhomogeneous ($10<\mathrm{}\frac{\eta }{{\eta }_{\mathrm{cl}}}<250\mathrm{}$), and does not maximize in regions of large currents. Investigation of the energy balance [$\nabla ·\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{H}}=-\overrightarrow{\mathrm{E}}·\overrightarrow{\mathrm{J}}-\left(\frac{\partial }{\partial t}\right)\left(\frac{B^2}{2{\mu }_0}\right)$] shows that electron heating accounts for most of the electromagnetic energy loss.

The dielectronic satellite spectral lines, on the long-wavelength side of the hydrogenic Si XIV Lyman-$\alpha$ line, have been observed in the space-resolved spectra from laser-imploded glass microballoons. In the electron density range 1×${10}^{22}$ to 2×${10}^{23}$ ${\mathrm{cm}}^{-3\mathrm{}}$, the intensities of the Si XIII $2s2p{}_{}{}^3{}_{}{}^{}P-1s2s{}_{}{}^3{}_{}{}^{}S$ and $2p^2{}_{}{}^3{}_{}{}^{}P-1s2p{}_{}{}^3{}_{}{}^{}P$ satellite lines increase with density in agreement with numerical modeling. These satellite lines are a promising density diagnostic for the imploded glass plasma.

A comparison of one- and two-dimensional simulations of the strong turbulence evolution of Langmuir waves such as would be generated by the kinetic beam-plasma instability is reported. It is shown that the initial formation of the localized fields is one dimensional.

The usual power-law description of corrections to dynamic scaling is shown to be inapplicable to the superfluid transition in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. A nonlinear dynamic renormalization-group analysis is presented which treats both large departures from scaling and the possible breakdown of scaling. Recent experimental results on second-sound damping are explained. The temperature dependence for $\frac{(T_{\lambda }-T)}{T_{\lambda }}<{10}^{-4\mathrm{}}$ is predicted to deviate only weakly from the dynamic scaling behavior.

The static structure factor for a finite two-dimensional classical harmonic lattice is evaluated, including finite-size effects from both lattice sums and the lower $k$ cutoff on the phonon spectrum. The numerical results show that the power-law behavior of $S\left(\overrightarrow{\mathrm{q}}\right)$ expected in an infinite two-dimensional crystal should be already quite apparent in crystallites of size $L\sim 1000-5000$ Å.

The thermodynamics of the Kondo model are formulated in terms of coupled integral equations and various properties, in particular the scaling property, are deduced. Then, with definition of the various scales parametrizing various asymptotic regions of the $H-T$ plane, universal numbers are calculated and, in particular, Wilson's result is obtained analytically.

Hall measurements of electron inversion layers at low temperatures and electric fields are reported. For resistances of ≲ 10 kΩ/□ a logarithmic dependence of the Hall coefficient on temperature and Hall voltage is observed. This indicates that the logarithmic dependences observed for the resistance of metal films and metal-oxide-semiconductor field-effect transistors are not evidence for the scaling theory of localization. These results are also difficult to resolve within the theory of interaction effects by Altshuler, Aronov, and Lee.

The Curie temperature $T_0$ of CeAg as a function of hydrostatic pressure exhibits a well-defined maximum at $P\simeq 0.7$ GPa, giving clear evidence for Anderson lattice behavior. A rapid broadening of the resistive anomaly at $T_0$ for $P>~2.1$ GPa suggests a change in the character of the magnetic ordering. At these pressures the temperature dependence of the electrical resistivity to 300 K is highly anomalous, resembling closely that of Ce compounds thought to be in or near the mixed-valence regime.

Neutron scattering has been used to investigate the development of magnetic order in the region of the reentrant superconducting transition in Ho${\mathrm{Mo}}_6$${\mathrm{S}}_8$. On cooling, an ordered oscillatory magnetic state develops in the superconducting phase, with a wavelength which increases with the application of a magnetic field. On further cooling the sample reverts to the normal conducting state as ferromagnetism sets in. No oscillatory magnetic phase is observed, however, when the superconducting phase is approached from low temperatures.

The recombination lifetime in phosphorus-doped hydrogenated amorphous silicon is determined from the dispersive photocurrent decay following a short-pulse excitation. The electron drift mobility and dispersion parameter $\alpha$ are obtained as well. It is found that $\alpha$ is temperature dependent as expected for extended-state transport controlled by multiple trapping. A lower limit to the extended-state mobility is determined: ${\mu }_c>~1$ ${\mathrm{cm}}^2$/V.s.

Measurements are reported of a singularity in the dielectric constant of a random metal-insulator composite below the percolation threshold. The composite sample consists of small silver particles randomly dispersed throughout a KCl matrix. The dielectric constant is found to obey a scaling relation with a critical exponent of $s=0.73\mathrm{}\pm 0.07$.

A quantum system which can tunnel, at $T=0\mathrm{}$, out of a metastable state and whose interaction with its environment is adequately described in the classically accessible region by a phenomenological friction coefficient $\eta$, is considered. By only assuming that the environment response is linear, it is found that dissipation multiplies the tunneling probability by the factor $\exp [-\frac{A\eta {\left(\Delta q\right)}^2}{\hslash }]$, where $\Delta q$ is the "distance under the barrier" and $A$ is a numerical factor which is generally of order unity.

This Letter presents a measurement of the branching fraction for the Cabibbo-suppressed decay ${\tau }^{-}\to K^{{*}^{-}}\mathrm{}\left(892\right)\mathrm{}{\nu }_{\tau }$ with use of data obtained with the Mark-II detector at SPEAR. Eleven events containing a $K^{{*}^{\pm }}\mathrm{}\left(892\right)\mathrm{}$ in coincidence with a muon or an electron of opposite charge were found in data which span the center-of-mass energy region $4.2<\mathrm{}{E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}<6.7\mathrm{}$ GeV. It was determined that $B[{\tau }^{-}\to K^{{*}^{-}}\mathrm{}(892\left)\mathrm{}{\nu }_{\tau }\right]=(1.7\mathrm{}\pm 0.7)$%. The absence of events at the $K^{{*}^{\pm }}\mathrm{}\left(1430\right)\mathrm{}$ yields a 2-standard-deviation upper limit $B[{\tau }^{-}\to K^{{*}^{-}}\mathrm{}(1430\left)\mathrm{}{\nu }_{\tau }\right]<\mathrm{}0.9\mathrm{}$%.

First results for the ($d$,$p$) reaction on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$, ${}_{}{}^9{}_{}{}^{}\mathrm{Be}$, and ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ are presented for a scattering energy $T_d=698\mathrm{}$ MeV at momentum transfers $2 {\mathrm{fm}}^{-1\mathrm{}}<~q<~5 {\mathrm{fm}}^{-1\mathrm{}}$. Simple distorted-wave Born-approximation and rescattering calculations stress the need for a more comprehensive analysis by explicitly including both the stripping amplitude and mesonic degrees of freedom.

Candidates for the $4^{+}$, $6^{+}$, and $8^{+}$ members of the $S$ band in ${}_{}{}^{160}{}_{}{}^{}\mathrm{Dy}$ are established by $\nu \left(i_{\frac{13}{2}}\right)$ pickup from the ${\frac{5}{2}}^{+}$ ground state of ${}_{}{}^{161}{}_{}{}^{}\mathrm{Dy}$ with use of the (${}_{}{}^3{}_{}{}^{}\mathrm{He}$,$\alpha$) reaction. The alignments and $K$ values corresponding to this identification are discussed.