The thickness of a superfluid helium film in steady radial horizontal flow to a central sink has been determined at two radii. The thickness difference is found to be consistent with the prediction of Kontorovich, despite conditions which would favor recondensation from the vapor onto the flowing film.

The spontaneous generation of reversed fields in toroidal plasmas is shown to be a consequence of relaxation under constraints. With perfect conductivity a topological constraint exists for each field line and the final state is not unique. With small departures from perfect conductivity, topological constraints are relaxed and the final state becomes unique. The onset of the reversed field and other features of this model agree well with observations on ZETA.

Long mean free paths for ions in the tail of the distribution may allow escape, quenching the burn of marginal ($\rho R<\mathrm{}{10}^{-2\mathrm{}}$ g/${\mathrm{cm}}^2$) deuterium-tritium microspheres, possibly explaining the lack of success in experiments to date.

We study the transport property of symmetry-induced zero-gap semiconductors, such as gray tin, under uniaxial tensile stress and at absolute zero temperature. It is shown that there is a negative-differential-resistance region in the current-voltage characteristics for $p$-type samples with small hole concentrations. This calculation confirms an earlier speculation by Liu.

The linear combination of muffin-tin orbitals technique has been used to calculate the effect of overlayers of O and Na on Ni(001) electronic-energy levels. We find that both Na and O induce surface states in the $s-d$ gap with the density and energies depending on the overlayer separation $d$. The peak observed experimentally at -0.4 Ry and O on Ni is due to nonbonding oxygen states as originally interpreted by Hagstrum and Becker.

The Gor'kov model for the $A15\mathrm{}$ compounds predicts the appearance of a gap in the $d$-electron spectrum between the superconducting transition temperature, $T_c$, and the martensitic-phase-transition temperature, $T_m$. A mean-field calculation of the gap parameter is carried out for ${\mathrm{Nb}}_3$Sn and ${\mathrm{V}}_3$Si, using the measurements of the soft mode in the cubic phase. It is suggested that the theory be verified by optical or tunneling measurements.

Heat pulses transmitted into $n$-type InSb were detected by using superconducting diodes. By change of InSb doping, and by magnetic tuning of the superconducting gap, a singularity in phonon attenuation was observed at twice the Fermi radius. The long waves, whose absorption is screened by the conduction electrons, are resolved by time-of-flight spectroscopy.

The thermal conductivity of a borosilicate glass has been measured in the temperature range 0.05-50 K. The samples contained well-defined holes to provide a source of phonon scattering. The results are consistent with the predictions of the Debye model using experimentally measured sound velocities. The results also indicate that thermal transport at temperatures below ≈ 30 K is provided by low-frequency phonons having a characteristic temperature ≲ 3 K.

We have determined the radius and spatial distribution of electron-hole droplets in Ge at 2 K excited by a 100-mW focused beam of 5145-Å light. The droplet distribution can be approximated by a uniform hemispherical cloud of radius ≈ 1 mm containing droplets with radii of 2.0±0.5 μm. These results disagree with solutions of simple diffusion equations and with recent reports of the observations of single large droplets with radii ≈ 1 mm.

The density-functional formalism has been used to treat self-consistently the nonlinear screening of a proton in an electron gas. The results have been used to calculate activation energies for diffusion of hydrogen in Al and Mg. The theory is in good agreement with experimental results which are only available for Al. Hydrogen-vacancy trapping has also been investigated and was found to be a distinct possibility in the case of Al.

The cross section for the reaction ${}_{}{}^4{}_{}{}^{}\mathrm{He}(\gamma , pnd)$ is calculated via the quasideuteron mechanism, assuming a ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ Gaussian ground state fitted to the form factor. From the ($\gamma , \mathrm{pnd}$) amplitude the contribution to the reactions ${}_{}{}^4{}_{}{}^{}\mathrm{He}(\gamma , p){}_{}{}^3{}_{}{}^{}\mathrm{H}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}(\gamma , n){}_{}{}^3{}_{}{}^{}\mathrm{He}$ due to $\mathrm{nd}$ ($\mathrm{pd}$) rescattering to form ${}_{}{}^3{}_{}{}^{}\mathrm{H}$ (${}_{}{}^3{}_{}{}^{}\mathrm{He}$) are calculated. This contribution dominates the high-energy photonucleon cross section. An asymmetry coefficient $\beta =1.51\mathrm{}$ at $E_{\gamma }=120\mathrm{}$ MeV is obtained, close to the observed values.

Cross sections for charged-pi-meson production by 7.28-GeV nitrogen ions on elemental targets were measured at a laboratory angle of 15° at the Princeton Particle Accelerator. At pion energies of ∼ 260 and ∼ 415 MeV, the data show the $A^{\frac{1}{3}}$ dependence predicted by an "effective number of nucleons" model. For ${\pi }^{-}$ energies above ∼ 415 MeV, the measured cross sections exceed those calculated from nucleon-nucleus data, even after the inclusion of Fermi-motion effects.

The description of strongly distorted rotational bands within the cranking model allows an interpretation of the attenuation factors used in the particle-plus-rotor model. It turns out that they are not very much influenced by the residual interaction, but are strongly dependent on the angular momentum. A simple model is proposed to calculate distorted spectra which is in rather good agreement with the experimental data and with the fully self-consistent calculation.

In order to study the gravitational force on an electron Witteborn and Fairbank have measured the acceleration of electrons moving along the axis of a vertical copper tube. I show that in experiments of this type there are large corrections to the motion of the electrons due to thermal fluctuations in the electromagnetic fields in the tube.

We report the observation of fine-structure and Zeeman quantum beats in highly excited sodium $D$ states prepared, for the first time in a quantum-beat experiment, by stepwise excitation using two synchronously pulsed dye lasers. We have used this new technique to measure the previously unknown fine-structure intervals of levels $9D$ and $10D$ of sodium, the values being, respectively, 124.5±1.5 and 91.5±1 MHz.

We show that the ground state of ${\mathrm{Ti}}^{3+}$ in CsAl alum is a quasi-${\Gamma }_8$ state with a very small trigonal splitting. A spin Hamiltonian for this quasi-${\Gamma }_8$ state is derived and used to describe the experimental EPR anisotropy. The near cancelation of the trigonal splitting is due to the presence of a dynamic Jahn-Teller effect.

It is shown that the $2p^{5}4d{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}\to 2p^6{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ line of the ${\mathrm{Al}}^{3+}$ ion at a wavelength of 117.41 Å is superradiant in a dense laser-produced plasma. The measured gain in a two-plasma experiment is 17%. The gain coefficient is of the order of 10 ${\mathrm{cm}}^{-1\mathrm{}}$ with a lower limit of 2.5 ${\mathrm{cm}}^{-1\mathrm{}}$ and an upper limit of 22 ${\mathrm{cm}}^{-1\mathrm{}}$.

We report the first observation of a persistent flow around a closed path consisting entirely of saturated superfluid helium film in a macroscopic geometry in which the saturated vapor was in unconstrained proximity to the film.

Ion-cyclotron drift waves with discrete and continuous spectra are identified by measurements of $\omega$ and $\overrightarrow{\mathrm{k}}$ and explained by a theory which includes parallel electron current. This instability has a spectrum and effects on the plasma similar to those of ion sound, and can exist in plasmas which are ion-sound stable.

We report a single-crystal neutron-diffraction structure study of ${\mathrm{K}}_2$Pt${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_4$${\mathrm{Br}}_{0.3}$·3${\mathrm{H}}_2$O (KCP). Contrary to previous x-ray results we find that KCP is noncentrosymmetric (space group $P4\mathrm{mm}$ rather than $\frac{P4\mathrm{}}{\mathrm{mmm}}$). New water-molecule positions have been derived. The Pt${\mathrm{}\left(\mathrm{CN}\right)\mathrm{}}_4^{-2\mathrm{}}$ groups are not precisely planar, the ${\mathrm{K}}^{+}$ ions occupy ordered sites, and two crystallographically different ${\mathrm{Br}}^{-}$ ion sites are observed. The possible relationship of the ${\mathrm{Br}}^{-}$-ion disorder to the diffuse x-ray scattering previously observed is discussed.