Ablative acceleration of thin-foil targets at low laser irradiance (${10}^{12}$-${10}^{13}$ W/${\mathrm{cm}}^2$) is studied experimentally and theoretically. Ablative acceleration of foils up to ∼${10}^7$ cm/sec with good hydrodynamic efficiency (20%) has been achieved. These and other results are in good agreement with a simple rocket model.

The paradox of the infinite-conductivity $\alpha$-effect dynamo is resolved by properly treating the boundary layer. If the turbulence is not too intermittent the expansion of the mean electromotive force in powers of the wave number of the mean magnetic field $\overrightarrow{\mathrm{B}}$ is found to converge, and the usual truncation gives little error. The $\alpha$ effect is demonstrated in the strong-field limit where the turbulence consists of Alfvén waves propagating along $\overrightarrow{\mathrm{B}}$.

We present preliminary results on the self-diffusion coefficient $D_{\mathrm{self}}$ of polystyrene chains (molecular weight $M_n=245\mathrm{}000 \mathrm{and} 123000$) in benzene, obtained by forced Rayleigh scattering. In the semidilute regime where the chains overlap, $D_{\mathrm{self}}$ decreases with the polymer concentration $c$ as $c^{-1.7\mathrm{}\pm 0.1}$. This behavior is compatible with scaling-law predictions and is the first experimental evidence for the existence of reptation in this regime.

Ultrasonic attenuation and phase velocity measurements as a function of temperature and frequency are reported in the $\beta$ phase of AgI. Below about 50 MHz the dominant effect is the piezoelectric coupling between the mobile ions and the ultrasonic waves; an analysis similar to that of Hutson and White for piezoelectric semiconductors gives good agreement. Above 50 MHz this interaction becomes screened. An additional attenuation mechanism is observed at 540 MHz.

A nonlinear theory of the capillary waves accounts for the macroscopic lattice formation on the electron-charged surface of liquid helium observed in a recent experiment. The lattice allows both shear and compressional lattice waves to propagate.

The electric-field-gradient asymmetry parameter has been measured in several vitreous chalcogenides at arsenic sites which undergo a strong quadrupolar coupling. Results in vitreous ${\mathrm{As}}_2$${\mathrm{S}}_3$ and ${\mathrm{As}}_2$${\mathrm{Se}}_3$ reveal a cylindrical local symmetry which contrasts with the distortion associated with the lamellar structure crystalline ${\mathrm{As}}_2$${\mathrm{S}}_3$. However, in amorphous ${\mathrm{As}}_{25}$${\mathrm{Te}}_{75}$ and ${\mathrm{As}}_{45}$${\mathrm{Te}}_{55}$ the local environment of arsenic displays a sizable distortion.

A careful measurement of the lattice parameters of pure Pb and a Pb+(0.0918 at.% Au) sample after a quench and equilibrium annealing cycle shows that Au in both monomer and "tetramer" defect states produces lattice contraction with the "tetramer" somewhat remarkably having the larger effect per atom. The observed monomer contraction suggests that the majority site occupancy for Au is substitutional and that the rapid Au diffusion must therefore involve a substitutional-interstitial mechanism.

We present a theoretical study of soliton formation in long-chain polyenes, including the energy of formation, length, mass, and activation energy for motion. The results provide an explanation of the mobile neutral defect observed in undoped ${\left(\mathrm{CH}\right)}_x$. Since the soliton formation energy is less than that needed to create band excitation, solitons play a fundamental role in the charge-transfer doping mechanism.

We have studied, in a two-stage nuclear demagnetization cryostat, the NMR properties of copper nuclei in magnetic fields from 0 to 15 mT and at polarizations up to 0.9. In zero field the spin entropy decreases less rapidly with temperature than expected for an interacting paramagnet with a constant local field; at 50 nK the entropy is still 45% of $R\ln 4$. The temperature dependence of magnetic susceptibility points to nuclear antiferromagnetism in copper.

We have found that the spin polarization of the photoyield from single crystal Ni(111) at 16.8- and 21.2-eV photon energy is (8.0±3.5)% and (8.1±2)%, respectively, which is significantly larger than the bulk electron-spin polarization. The results of a theoretical model calculation are in good agreement with the experiment. We interpret this as direct evidence for spin-dependent electron-electron scattering in an itinerant strong ferromagnet.

Measurements of the neutron-energy-loss spectrum of Ce${\mathrm{Al}}_2$, made using a triple-axis spectrometer, reveal the existence of two inelastic lines in the paramagnetic regime. Only a single line (${\Gamma }_7\to {\Gamma }_8$) is expected from the cubic symmetry of the crystal field. The origin of the two lines is attributed to the removal of the degeneracy of the excited ${\Gamma }_8$ electronic state by the action of the dynamic Jahn-Teller effect.

We report calculations of the electronic structure impurities in Cu by appying the Korringa-Kohn-Rostoker Green's-function method. We use a self-consistent host band structure for the calculation of the Green's function. The additional effort for calculating the impurity problem self-consistently is considerably smaller than for calculating the host band structure. As examples, the local densities of states for Ni, Zn, Ga, and Ge impurities in Cu are presented.

The ortho-to-para conversion time in solid tritium has been measured by NMR techniques. The observed rate is at least ten times faster than the temperature-independent self-conversion in solid ${\mathrm{H}}_2$ and increases exponentially as the temperature decreases, e.g., the $\frac{1}{e}$ times are 490 min at 22.5 K and 64 min at 9.1 K. Because of the analogous situation in solid ${\mathrm{H}}_2$, where atomic H is created when the solid is irradiated, it appears that in ${\mathrm{T}}_2$, the T atoms are the most likely catalysts for the ortho-para conversion.

A new value for the fine-structure constant has been obtained from a new measurement of the gyromagnetic ratio of the proton. The result, ${{\gamma }_p}^{\prime }{\left(\mathrm{low}\right)}_{\mathrm{NBS}}=2.675\mathrm{}13229\left(57\right)\mathrm{}\times {10}^8$ ${\mathrm{s}}^{-1\mathrm{}}$ ${\mathrm{T}}_{\mathrm{NBS}}^{-1\mathrm{}}$ (0.21 ppm), is used to derive ${\alpha }^{-1\mathrm{}}=137.035\mathrm{}963\left(15\right)\mathrm{}$ (0.11 ppm). This value of ${\alpha }^{-1\mathrm{}}$ is (0.33±0.14) ppm less than the value of ${\alpha }^{-1\mathrm{}}$ derived from measurements of the anomalous magnetic moment of the electron, $a_e$, and its current best quantum electrodynamics theoretical estimate.

It is shown that the adoption of the hydrodynamical viewpoint in quantum mechanics provides a way to explain experimental results while giving electromagnetic potentials no more physical significance than they have in classical physics.

We present here a new approach to nonrelativistic perturbation theory. We show that in problems reducible to one dimension, the energy shifts and wave-function corrections, including corrections to the position of the nodes, to any order, can be expressed in quadrature in a hierarchy scheme. The second-order energy shift calculated is explicitly shown to be equivalent to that in the ordinary Rayleigh-Schrödinger theory.

From calculations of the $K_L-K_S$ mass difference and $\mathrm{CP}$ nonconservation based on an effective quark Lagrangian, we limit the ranges of the charged-weak-current mixing angles ${\theta }_2$ and ${\theta }_3$, and phase parameter $\delta$. The relative strength of $b\to u$ and $b\to c$ couplings is determined versus ${\theta }_3$.

Using existing data we determine optimal bounds on the quark mixing angles in the standard six-quark Kobayashi-Maskawa version of the Weinberg-Salam model. The analysis is based on a recent generalized Cabibbo fit and constraints on the predicted values of the $K_L-K_S$ mass difference and $\mathrm{CP}$-nonconservation parameter $\epsilon$. We give resulting bounds on branching ratios and lifetimes of $c$-, $b$-, and $t$-flavored hadrons.

The cross section for the fully constrained reaction $\mathrm{ep}\to \mathrm{epp}\overline{p}$ has been determined as a function of the electroproduction variables $Q^2$ and $s$, in the range $0.7<\mathrm{}{Q}^2<3\mathrm{}$ Ge${\mathrm{V}}^2$ and $8<s<\mathrm{}16\mathrm{}$ Ge${\mathrm{V}}^2$. Evidence is presented and cross-section estimates are made for resonances in the final-state $\overline{p}p$ system.

The charge-plunger technique has been modified to study also short-lived fission isomers in even-even nuclei. Using the reaction ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$($d$,$\mathrm{pn}$) a quadrupole moment of 29 ± 3 b was determined for the 200-ns isomer in ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, corresponding to a deformation of $\frac{c}{a}=1.8\mathrm{}\pm 0.1$ in terms of the axis ratio of a spheroid.