Evidence has been obtained for collision-free momentum transfer between the ions of interstreaming plasmas in a laser-produced-plasma experiment. Diagnostics employed included fast photography, shadowgraphy, and electric potential probes. Spectroscopy provided direct evidence of momentum transfer from Doppler shifts of ion lines.

Plasma computer simulation in two dimensions shows that there are three different regions for plasma diffusion across a magnetic field. These regions may be called collisional or classical, intermediate, and Bohm diffusions. In the intermediate region, which lies between the collisional and Bohm regions, the diffusion coefficient is essentially independent of the magnetic field. We believe that diffusion in the intermediate and the Bohm regions is caused by thermally excited convective motions.

Values of the total correlation length have been calculated in the hydrodynamical region by equating the critical part of measured values of the thermal diffusivity to the Kawasaki expression for the diffusivity. These new values of the correlation length are found to agree rather closely in the range $0.1<~\Delta T<~10°$ C with values calculated from (a) angular anisotropy data and (b) static compressibility data, the latter interpreted according to Ornstein-Zernike theory, with a constant direct correlation length $R_0=4.2\mathrm{}$ Å.

In turbulent heating experiments the electrical resistivity is anomalously large, once turbulence has developed. But before turbulent levels build up in a dense, collisionless plasma, the high conductivity can cause a skin effect that impedes current penetration. We find that this skin effect has an influence on the onset of current-driven instabilities and on the ultimate heating. Low levels of residual turbulence before heating are found to play a role in the rate of current penetration.

An experimental study is reported of steps induced in the flux-flow $I-V$ characteristics of superconducting aluminum films by a superimposed rf current, whose frequency is a harmonic or subharmonic of the ratio of the vortex velocity and the lattice parameter.

The electrical conductivity of niobium tetrachloride increases sharply by a factor of ${10}^4$-${10}^5$ on heating to 533°K, but the temperature dependence remains remains typical for a semiconductor.

Splitting observed in the x-ray photoelectron spectra of rare-earth ions with more than half-filled $4f$ shells is shown to arise from the exchange-energy difference between final $4f$ states.

Precise de Haas-van Alphen phase measurements for the lens orbit in Cd with the magnetic field in the basal plane show that the Onsager phase factor $\gamma$ for this orbit is $\frac{1}{2}$ and not $\frac{3}{4}$ as predicted recently by Hosack and Taylor. A spin-splitting zero is observed in the (10¯10) plane, giving a value for $g\approx 1.6$.

Linear dichrosim of the optical transitions of rare-earth ions in the garnets can be used to determine growth-related site preferences. Site selectivity is detected for ${\mathrm{Pr}}^{3+}$ and ${\mathrm{Nd}}^{3+}$ in yttrium aluminum garnet but not for ${\mathrm{Eu}}^{3+}$, ${\mathrm{Tb}}^{3+}$, or ${\mathrm{Ho}}^{3+}$.

The magnetic susceptibility of SmS indicates a discontinuous and hysteretic magnetic transition at 6 kbar. The ground state of the $4f$ shell in the metallic high-pressure "collapsed" phase is nonmagnetic, contrary to Hund's rules. Nonmagnetic behavior of the $4f$ shell is correlated with an intermediate valence in SmS, Sm${\mathrm{B}}_6$, and $\alpha -\mathrm{Ce}$. It is suggested that in such intermediate-valence phases at $T=0\mathrm{}$ the $4f$ shell is demagnetized in the sense of the Friedel-Anderson model as modified by Hirst.

$\mathrm{La}{\mathrm{Ce}}^{137m}$ alloys prepared by proton bombardment of La metal have been studied by orientation of the ${\mathrm{Ce}}^{137m}$ nuclei. From the variation of the anisotropy of the emitted $\gamma$ rays with applied field, the Kondo temperature is estimated to be 0.1 K. AuCe and AgCe have also been studied using the same technique. The results for the three systems are compared with those obtained by other methods.

We consider two subsets of the set of spectrally equivalent two-particle interactions. The interactions in one subset have identical bound-state eigenfunctions and those in the other have bound-state eigenfunctions that differ in any preassigned manner for small distances of separation. These results enable one to investigate the off-shell properties of on-shell equivalent two-particle potentials that have identical bound-state properties consistent with all information available about such states.

We have used ${}_{}{}^{92,94,96,98,100}{}_{}{}^{}\mathrm{Mo}\mathrm{}(p,t)\mathrm{}$ reactions to investigate the $0^{+}$ states in even Mo isotopes. The appearance of low-lying excited $0^{+}$ states in ${}_{}{}^{98,100,102}{}_{}{}^{}\mathrm{Mo}$ with large two-neutron transfer strengths, together with the systematics of the lowest $2^{+}$ states, suggests the existence of a new transitional region. The large cross section for the excited $0^{+}$ state in the reaction ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}\mathrm{}(p,t)\mathrm{}{}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ may be able to explain the anomaly in the $l=0\mathrm{}$ spectroscopic factors in ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}\mathrm{}(d,p)\mathrm{}$ and ${}_{}{}^{100}{}_{}{}^{}\mathrm{Mo}\mathrm{}(d,t)\mathrm{}$ reactions.

With the time-differential angular-distribution method the $g$ factor of the lowest ($\nu f_{\frac{7}{2}}^{}{}_{}{}^2$) $6^{+}$ state in ${}_{}{}^{42}{}_{}{}^{}\mathrm{Ca}$ has been determined to be ${-0.50\mathrm{}}_{-0.03\mathrm{}}^{+0.02\mathrm{}}$, which is closer to the Schmidt value for the $0f_{\frac{7}{2}}$ neutron than is that of the ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ ground state. Strong violation of the additivity of the effective magnetic moment for these states is interpreted by a larger mixing of the core-excited deformed states into the ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ ground state.

Inelastic scattering of polarized protons from ${}_{}{}^{140}{}_{}{}^{}\mathrm{Ce}$ to the $2_1^{+}$ ($E_x=1.596\mathrm{}$ MeV) state near isobaric analog resonances shows the importance of direct, off-resonant inelastic scattering, and provides enough information to determine parentage coefficients for six $p$ and $f$ states in ${}_{}{}^{141}{}_{}{}^{}\mathrm{Ce}$ up to an excitation energy of 1.88 MeV.

Weak electromagnetic perturbations (test fields) in the exterior of a Kerr-metric black hole are studied. It is shown that (i) the only physically acceptable, time-independent perturbation is an axisymmetric field which corresponds to adding charge to the source and (ii) all axisymmetric normal modes are stable which, assuming completeness, guarantees stability for arbitrary axisymmetric perturbations. The proof of the nonexistence of time-independent, nonaxisymmetric test fields actually holds for perturbations associated with any physical (e.g., gravitational) field.

We report properties of single-wire proportional chambers and multiple-wire ionization chambers filled with liquid xenon. Proportional multiplication is seen for anode fields > ${10}^6$ V/cm (anode-cathode voltage >1 kV for a 3.5-μm-diam anode wire). The efficiency for detecting ionizing radiation is ≅100%. The time resolution of the chambers is ±${10}^{-7\mathrm{}}$ sec. We attained a spatial resolution of ±15 μm with a multiwire ionization chamber, considerably better than that of any other real-time particle detector.

We have studied the electroproduction of single charged pions from deuterium in a coincidence experiment at the Cambridge Electron Accelerator. Data are presented for a virtual-photon mass squared near -0.4 ${\mathrm{GeV}}^2$ and virtual photoproduction center-of-mass energy and angle near 2.15 GeV and 0°, respectively. The data are used to study the isoscalar-isovector interference and the nuclear-physics corrections arising from the use of a deuterium target.

The forward cross sections for the reactions ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ and $K^{-}p\to {\pi }^{+}{\Sigma }^{-}$ have been determined for incident particle momenta in the range of 2.75 to 3.50 GeV/c, and an upper limit was established at 5.00 GeV/c. These measurements show that the double-charge-exchange process ${\pi }^{-}p\to K^{+}{\Sigma }^{-}$ is suppressed by a factor of 1500 at 3 GeV/c relative to the single-exchange reaction ${\pi }^{+}p\to K^{+}{\Sigma }^{+}$.

It is argued that the strangeness-conserving weak currents can contribute to the single-pion-exchange parity-nonconserving potential between nucleons bound in nuclei. Although this contribution is reduced by $\frac{V_{\mathrm{nuclear}}}{M}\sim 0.04$, it may be comparable in strength with that usually calculated. Estimates of the strength of an off-mass-shell $\mathrm{NN}\pi$ vertex are carried out; neutral pion emission can occur. It is shown that the $\Delta \mathrm{}\left(1236\right)N\pi$ weak vertex can be neglected.