The thermal conductivity of a plasma of density 6 × ${10}^{16}$ ${\mathrm{cm}}^{-3\mathrm{}}$ is measured when it is heated by a 300-MW, 3-ns C${\mathrm{O}}_2$ laser pulse. The data are best represented using a heat flux which is limited to ∼ 4% of the free-streaming limit. Low-frequency turbulence is observed of sufficient intensity to cause this flux limit.

The kinetic treatment of the ponderomotive force concept is found from nonresonant quasilinear theory for waves with spatially dependent amplitude. In general, the ponderomotive effect appears as a velocity-space diffusion term, not just as a force. For an unmagnetized plasma, the qualilinear equations are solved directly, and the correct density modification exhibited explicitly. Examples are considered for both a homogeneous and an inhomogeneous magnetic field, and aspects of rf end plugging are discussed.

Computer simulations of the kinetic warm-beam instability with finite-mass ions are reported. It is shown that strong turbulence, including Langmuir collapse, stabilized the beam-plasma instability before quasilinear plateau formation. This process decreases significantly the beam-plasma coupling and increases the propagation distance in accordance with laboratory and space observations.

We report the observation of an instability pattern in a homeotropically oriented nematic slab subject to elliptically polarized shear flow, a phenomenon which we explain as resulting from nonzero time-averaged Leslie-Ericksen viscous stresses.

We have measured the static nuclear magnetization of solid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ as a function of temperature and molar volume through its nuclear ordering temperature. Below 5 mK the magnetization increases with decreasing temperature more rapidly than the Curie-Weiss behavior displayed at higher temperatures. At $T_S$ it decreases rapidly to 40% of its maximum value and becomes temperature independent at the lowest temperature we measure. $T_S$ decreases with decreasing molar volumes.

We have observed resonant Brillouin scattering by TA phonons near the $A$ exciton of CdS in a usually forbidden backscattering configuration. This effect, attributed to electron-phonon piezoelectric coupling, is equivalent to the Fröhlich-interaction-induced forbidden LO scattering. A numerical estimate of the scattering strength of the forbidden TA scattering accounts for the intensity of the observed lines.

The stability condition is derived for uniform bulk superflow along a uniform texture in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$--$A$. The weak-coupling free-energy parameters in the dipole-locked Ginzburg-Landau regime give stable flow, but a 10% departure from these values can give instability. When present, the instability can reflect the absence of any activation-energy barrier against decay of the superflow through the appearance of vortex textures near the surface. We relate these conclusions to the hydrodynamic instability reported by Hook and Hall.

The microwave spectrum of amorphous sputtered films of ${\mathrm{Gd}}_{0.37}$${\mathrm{Al}}_{0.63}$ exhibits a resonance which moves rapidly to lower fields as temperature is decreased below the paramagnetic Curie temperature at 30 K and which exhibits no anomaly at the spin-glass ordering temperature of 16 K. The shift of the resonance field is interpreted as an effective anisotropy field arising from local demagnetizing fields of the inhomogeneous magnetic system. The theory is also compared to earlier resonance results on CuMn.

We calculate the two-dimensional energy bands of a 35-layer (100) Ni film. Surface states exist above the majority-spin $d$ bands throughout the two-dimensional Brillouin zone. Transitions from these surface states into an evanescent LEED (low-energy electron-diffraction) state account for the reversal of photoelectron spin polarization observed 0.1 eV above threshold.

We have measured the single-particle inclusive cross sections for $p+p\to {\pi }^{\pm }+X$, $K^{\pm }+X$, $p+X$, $\overline{p}+X$ in the low-$p_{\perp }$ region (≲ 1.5 GeV/c) as a function of the radial scaling variable $X_R$ in $p-p$ collisions at 100, 200, and 400 GeV at Fermilab. The measured $\frac{{\pi }^{+}}{{\pi }^{-}}$ and $\frac{K^{+}}{K^{-}}$ ratios are shown to be remarkably similar to the same ratios which have recently been measured at large $p_{\perp }$ at 90° in the center-of-mass system.

We have measured the electromagnetic form factor of the charged pion by direct scattering of 100-GeV/c ${\pi }^{-}$ from stationary electrons in a liquid-hydrogen target at Fermilab. The deviations from the pointlike pion-scattering cross section may be characterized by a root-mean-square charge radius for the pion of ${〈{{\mathcal{r}}_{\pi }}^2〉}^{\frac{1}{2}}=0.56\mathrm{}\pm 0.04$ F.

We call attention to the fact that an accumulation of recent data concerning ${\mathcal{r}}_n$, the rms radius of neutron density distributions, in neutron-rich nuclei indicate that values of $\Delta \mathcal{r}={\mathcal{r}}_n-{\mathcal{r}}_p$ are considerably smaller than those obtained from simple shell-model prescriptions or predicted by common Hartree-Fock calculations. We show that values of $\Delta \mathcal{r}$ consistent with these data can explain the long-standing Coulomb energy problem (Nolen-Schiffer anomaly).

A study of the inelastic scattering of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ from ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ at 82 MeV, a bombarding energy at which deep-inelastic collisions occur, suggests the population of giant resonances in the target. This result supports the suggestion of Broglia, Dasso, and Winther regarding the mechanism of deep-inelastic collisions.

We report the result of a calculation of the yrast levels for a system of four nucleons in the $i_{\frac{13}{2}}$ shell, interacting via a pairing force, and coupled to a strongly deformed, axially symmetric core. In addition to an initial backbend at $I=12\mathrm{}$, a second smaller backbend occurs at $I=38\mathrm{}$. The structure of the wave functions at the second discontinuity indicates that it arises because of the decoupling of all four nucleons and subsequent alignment with the core angular momentum.

Inelastic $\alpha$-scattering experiments have been performed on ${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ at $E_{\alpha }=96\mathrm{}$ MeV over the angular range $3°<~{\theta }_L<~8°$. It is apparent that the isoscalar giant resonance in these nuclei consists of at least two broad components. The angular distribution for one component (${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ $E_x\sim 12.4$ MeV, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ $E_x\sim 11.0$ MeV) is well described as $E2\mathrm{}$, while that for other component (${}_{}{}^{144}{}_{}{}^{}\mathrm{Sm}$ $E_x\sim 15.1$ MeV, ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ $E_x\sim 13.7$ MeV) is well described by an $E0\mathrm{}$ excitation exhausting approximately 100% of the $E0\mathrm{}$ energy-weighted sum rule.

A new technique is reported for measuring atomic lifetimes in uranium and other refractory metals. Selective excitation of low-lying levels in neutral atoms can be obtained by means of a fast heavy-ion-induced sputtering. By pulsing the ion beam, the lifetimes of the 16 900- and 19 885-${\mathrm{cm}}^{-1\mathrm{}}$ levels in neutral uranium have been determined by the delayed-coincidence technique to be 232±25 and 142±15 ns, respectively. New lifetime determinations in ZrI are also reported.

Extension of Floquet theory to include continuum as well as bound atomic states yields a practical technique for computation of multiphoton ionization rates in the region where rms field strengths approach the strength of the internal atomic fields.

The reflectance of planar targets irradiated by 400-mJ, 30-ps Nd: glass laser pulses was measured as a function of angle of incidence and polarization with an Ulbricht spherical photometer. At normal incidence we find reflectances > 0.6. The reflectance for $p$-polarized light has a minimum at an incidence angle of 20° to 30°; for angles greater than 60° total reflection occurs for both $s$- and $p$-polarized light. The results seem consistent with simulations.

We observe that recent theories of phase transitions in the two-dimensional $\mathrm{XY}$ model predict a universal jump in the superfluid density of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ films as $T_c$ is approached from below. Specifically, we find that ${\lim }_{T\to T_c}-{\rho }_s\frac{\mathrm{}\left(T\right)\mathrm{}}{T}=3.52\mathrm{}\times {10}^{-9\mathrm{}}$ g/${\mathrm{cm}}^2$°K. Analogous results should hold for two-dimensional planar magnets and liquid crystals.

We report thermal conductivity measurements of a ${\mathrm{Pb}}_{0.9}$${\mathrm{Cu}}_{0.1}$ film before (amorphous) and after (crystalline) annealing. Below $T_c$, where electronic effects are negligible, we found that the phonon contribution in the amorphous phase ${k_{\mathrm{am}}}^{\mathrm{ph}}$ was much larger than that in the crystalline phase. We also found that the temperature dependence of ${k_{\mathrm{am}}}^{\mathrm{ph}}$ resembles that of amorphous dielectrics, thus providing evidence that this sort of "glassy" behavior does not require the presence of covalent bonds.