Studies of the monotonic magnetostriction of cadmium at 4.2°K in applied magnetic fields to 70 kG have shown that the angular variation of an extremal point $H_m$ is proportional to $sec\theta$. The magnitude of $H_m$ is in close agreement with the onset of a breakdown orbit ${\gamma }_{\frac{1}{3}}$ observed for the applied field within 35° of the $c$ axis. The range of observation of $H_m$ coincides with the range of the orbit $\gamma$.

The $g$ value for electron spin resonance of Gd impurities in Sc is found to be anistropic. The anisotropy is shown to result from spin-orbit coupling in the impurity cell.

Detailed calculations of the temperature dependence of the heat capacity and magnetic spin susceptibility of small metal particles are presented. The results depend sensitively upon the symmetries or near symmetries of the dynamics, and exhibit the usual thermodynamic behavior only as the particle size becomes sufficiently large.

The multiple-scattering approach with strong inelastic damping has been used to formulate low-energy electron-diffraction intensity curves without the use of adjustable parameters. The results have been applied to the interpretation of spectra for the clean (001) face of aluminum with good agreement. Inclusion of energy-dependent higher order phase shifts obtained from a realistic potential, of energy-dependent strong inelastic damping, and of temperature effects contributes significantly to the agreement of the calculation with experiment.

A simple theory for the magnetism of the rare-earth metals is presented. It is based on assuming strongly correlated, well-defined $f$-electron states of an atomiclike character which are weakly hybridized with conduction-band states. This hybridization plays the role of an indirect exchange interaction. A model calculation is presented: It yields for various values of the two relevant parameters ferromagnetic, antiferromagnetic, and helical arrangements. These arrangements are strongly dependent on the features of the conduction-electron band structure (Fermi surface). Order of magnitude estimates give reasonable agreement for physical parameters as determined from unrelated experiments.

Quasielastic magnetic neutron scattering from the linear-chain antiferromagnet ${\left(\mathrm{C}{\mathrm{D}}_3\right)}_4$NMn${\mathrm{Cl}}_3$ is reported. The system is found to exhibit planes of critical scattering perpendicular to the Mn${\mathrm{Cl}}_3$ chains from >40°K down to 1.1°K. Both the spatial and thermal variation of the scattering can be quantitatively accounted for at all temperatures using Fisher's theory for the classical Heisenberg linear chain.

A high-frequency test of Coulomb's law is described. The sensitivity of the experiment is given in terms of a finite photon rest mass using the Proca equations. The null result of our measurement expressed in the form of the photon rest mass squared is ${\mu }^2=(1.04\mathrm{}\pm 1.2)\times {10}^{-19\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$. Expressed as a deviation from Coulomb's law of the form $\frac{1}{r^{2+q}}$, our experiment gives $q=(2.7\mathrm{}\pm 3.1)\times {10}^{-16\mathrm{}}$. This result extends the validity of Coulomb's law by two orders of magnitude.

We show that a sufficient condition for stability for the spherical modes of a stellar system is that the distribution function $F\left(\epsilon \right)$ decrease with the energy $\epsilon$. For this demonstration we approximate the function $F\left(\epsilon \right)$ by a succession of steps corresponding to a multiple "water-bag" model. The total energy is shown to be an absolute minimum: The second variation $\delta W$ of the energy is always strictly positive and there is no marginal mode.

A cosmic-ray experiment at Echo Lake, Colorado, employing a liquid hydrogen target, spark chambers, and an ionization calorimeter has been performed to study the interactions of protons with protons above 90 GeV. We report here the results on the angular distribution of the charged secondaries.

Polarization phenomena in inclusive reactions are shown to exhibit remarkably simple features from the point of view of $J$-plane physics with factorizable singularities. In particular, straightforward tests of factorization are proposed in single- and multiple-particle inclusive experiments initiated with polarized photon beams— real and virtual — or polarized proton targets.

Modulation of the intensity of light emitted by ${\mathrm{Sr}}^{+}\left({}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}\right)$ ions at the resonance frequency of metastable helium atoms has been observed, demonstrating that coherence has been transferred in the Penning collision. The coherent excitation of the Penning ions suggests that the techniques of "coherence spectroscopy" such as level-crossing and Hanle experiments can be extended to excited states of Penning ions which are currently inaccessible by means of optical excitation.

Measurements of the cross sections for the total loss and the ionization of $X{}_{}{}^1{}_{}{}^{}\Sigma _{\mathrm{g}}^{}{}_{}{}^{+}$ ${\mathrm{H}}_2$ [$1<~E$ (keV/nucleon) ≤ 25] and $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ ${\mathrm{H}}_2$ molecules [$3<~E$ (keV/nucleon) ≤ 20] in collisions with ${\mathrm{H}}_2$ gas are reported. The $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ molecules were formed by electron capture by $\mathrm{H}_2^{}{}_{}{}^{+}$ ions in Mg vapor. The total-loss cross section of the $c{}_{}{}^3{}_{}{}^{}\Pi _{\mathrm{u}}^{}{}_{}{}^{}$ state is about 5 times larger than the total-loss cross section of the $X{}_{}{}^1{}_{}{}^{}\Sigma _{\mathrm{g}}^{}{}_{}{}^{+}$ state.

It is shown that arrays of filamentary channels observed after passage of a laser beam through a cell filled with nitrobenzene are in a one-to-one correspondence to certain intensity spikes of optimal size. These spikes are well hidden in a smooth-looking laser beam.

The Knipp-Teller theory of stopping power for heavy ions is reviewed and revised. The basic idea of using the Thomas-Fermi theory to describe the electron charge around the moving ion is retained. The major alteration which is introduced is in relating the degree of ionization to the velocity of the ion. The zero-order term of the resulting theory comes within 10% or so of predicting observed mean electronic stopping powers for ions with $z>\mathrm{}6\mathrm{}$ and $\frac{\epsilon }{z^{\frac{4}{3}}}>0.002\mathrm{}$, where $z$ is the atomic number of the ion and $\epsilon$ its kinetic energy in million electron volts per atomic mass unit.

A cell model of a Boson quantum system is described. The model has three phases at $T=0\mathrm{}$ K: normal crystal, Bose-condensed liquid, and Bose-condensed crystal. The excitation spectrum for the Bose-condensed crystal has two branches, a gapless vacancy wave mode and a vacancy-interstitial wave mode with a gap. It is proposed that this phase might be detected in ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ near the liquid-solid transition line.

The anomalous skin effect of microwaves is experimentally investigated for a high-density gaseous plasma near the electron cyclotron resonance and is compared with a theoretical prediction.

Toroidal, ideal magnetohydrodynamic equilibrium, with magnetic surfaces enclosing a single magnetic axis, is possibly for arbitrary $\beta$ (plasma pressure/poloidal magnetic pressure). When $\beta$ exceeds about one-half the aspect ratio, the toroidal current reverses on the inner edge of the plasma. The poloidal current balances the pressure gradient.

The liquid structure factor of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ has been determined in the momentum-transfer range 0.2 to 1.0 ${\mathrm{\AA }}^{-1\mathrm{}}$. At temperatures near 0.4 K there is evidence for a gentle change of slope of the structure factor in the region near 0.35 ${\mathrm{\AA }}^{-1\mathrm{}}$ Comparison with the work on helium-4 suggests that the observed behavior is a general feature of the two fluids.

We consider the anomalous diffusion in an axisymmetric toroidal plasma due to low-frequency instabilities. The radial, cross-field diffusion is mainly due to the nonconservation of the azimuthal canonical angular momentum. In particular, the electric field component along the magnetic line of force could contribute significantly to the cross-field diffusion by driving a change of the canonical angular momentum. For trapped particles, this diffusion could be ${\left(\frac{B_T}{B_p}\right)}^2$ larger than the $\overrightarrow{\mathrm{E}}\times \overrightarrow{\mathrm{B}}$ diffusion for comparable $E_{\parallel }$ and $E_{\perp }$, where $B_T$ and $B_p$ are the toroidal and poloidal magnetic fields, repectively.

Nonlinear Landau damping, the nonlinear interaction between two waves in which the beat disturbance is resonant with the particle thermal velocities, has been observed for electron plasma waves. The results confirm the predictions of weak-turbulence theory.