We have determined the thermionic parameters—true work function, $A$ constant, and normal energy distribution—for near stoichiometric NiO. The distribution was found to be Maxwellian, with the electron temperature matching the lattice temperature closely. The results show that the Fermi level in NiO is rather insensitive to temperature from room to incandescent temperatures and that the emission probably originates from the itinerant $4s$ band.

The phase velocity and absorption coefficient in a gas of Maxwell molecules (inverse fifth-power repulsion) are determined to high order in the frequency. A nonlinear transformation of the partial sums for the velocity and absorption series is shown to yield sequences which seem to converge rapidly, and the results are in good agreement with experiment over a wide range of frequencies.

The hydrodynamic model for the velocity autocorrelation function is refined by using an expansion of the density distribution and the velocity field in powers of the wave number. This approach, which is applied to rigid-disk systems, extends the validity of the hydrodynamic regime to earlier times. The first correction term indicates the time scale on which the asymptotic form of the velocity autocorrelation function is approached.

By computing the excitation spectrum of the charged Bose gas, we demonstrate explicitly the distinction between Jastrow's theory and Feenberg's method of correlated basis functions. Using a Jastrow correlating factor in the correlated basis functions, we obtain the spectrum exactly to two orders in ${r_s}^{\frac{3}{4}}$. A rearranged expression results when the true ${\psi }_0$ is employed as a correlating factor. We take advantage of the difference between these two procedures to obtain $S\left(k\right)\mathrm{}$ exactly to two orders.

We show that previous calculations of the loss rate of ions from toroidally symmetric line cusps need substantial revision. The symmetry of the toroid produces a conserved generalized momentum which prevents a certain class of particles from penetrating the mirrorlike magnetic fields which exist above the cusp points. The importance of this reduction in loss rate is explained for several geometries including Tormac which can now have a loss rate substantially smaller than a mirror device.

High-resolution (typically 0.15 eV) electron energy distributions are reported for Au at closely spaced intervals of photon energy in the 10- to 40-eV range. The data show much $d$-band structure which continuously varies in energy position and amplitude as the photon energy is varied, thereby indicating conservation of crystal momentum over the entire measured range. An experimental density of states for Au has been determined from the data by averaging over all photon energies using a modified $f$-sum rule for photoemission.

A detailed $3d$ band structure of ferromagnetic Ni is incorporated into a calculation of the electron spin polarization in field emission from the (100) crystal plane. In agreement with a recent experiment of Gleich, Regenfus, and Sizmann, the calculated electron spin polarization is found to -4%, with the preferred spin direction parallel to the magnetization of the crystal.

Electron-magnon interaction processes afford a basis for understanding the large manybody effects in itinerant ferromagnets. Careful observance of the requirements of rotational invariance leads to important corrections to the electron-magnon vertex function. The result is a self-consistent intermediate-coupling theory expected to be applicable to Ni.

An upper limit in the x-ray flux accompanying pulses of gravitational radiation has been determined with relatively simple balloon-borne apparatus. The minimum detectable flux in space, approximately 2×${10}^{-5\mathrm{}}$ erg/${\mathrm{cm}}^2$ event, is about 9 orders of magnitude below the energy flux which produces the gravitational signals observed by Weber. Furthermore, it is lower than that attainable with the much more elaborate and difficult ground-based methods which have been suggested so far.

A considerable flux on the order of 7 particles/${\mathrm{cm}}^2$ sec sr (probably protons) in the energy range above 500 keV is observed in the vicinity of the magnetic equator. The particles show a narrow distribution around 90° pitch angle. The low minimum altitudes of the drift paths of the particles in the $L$ region between 1.0 and 1.15 prevent a full drift around Earth. The particles are probably injected at several hundred kilometers altitude by a yet unknown mechanism.

The photoproduction yields of ${\pi }^0$ mesons from ${\mathrm{D}}_2$, Be, C, Al, Cu, Ag, and Pb targets have been measured at peak bremsstrahlung energies of 4.25, 5.6, 7.8, and 9.6 GeV. The $A$ dependence of ${\pi }^0$ photoproduction is found to be almost independent of energy in this range in contrast to vector-meson dominance predictions.

The puzzle of peaks in $\pi$-exchange processes is resolved in terms of an elementary pion with transverse momentum cutoff. In $\mathrm{np}$ charge exchange, for instance, this implies keeping both $t$- and $u$- channel $\pi$ exchanges. A quantitative fit is obtained for this process maintaining $\rho -A_2$ exchange degeneracy. This quality of the fit is in general comparable with (if not better than) the strong-cut model with less than half the number of parameters.

A complete relativistic analysis for gravitational radiation emitted by a particle in circular orbit around a Schwarzschild black hole is presented in the Regge-Wheeler formalism. For completeness and contrast we also analyze the electromagnetic and scalar radiation emitted by a suitably charged particle. The three radiation spectra are drastically different. We stress some important consequences and astrophysical implications.

The interaction potential between hydrogen and antihydrogen is obtained by a variational calculation. A potential maximum is found, but its peak is below the dissociation limit. A classical calculation shows that the cross section for total annihilation decreases monotonically from $31{a_0}^2$ at 0.01 eV to $4{a_0}^2$ at 20 eV.

We report the respective electronic energies [-5.658 ± 0.024 and -6.369 ± 0.033 keV] and electron emission lifetimes [0.91 ±0.04 and 0.66 ±0.04 nsec] of the longest-lived autoionizing quartet states of lithiumlike ${\mathrm{Cl}}^{14+}$ and ${\mathrm{Ar}}^{15+}$ ions, firmly establishing the energy and lifetime scaling with $Z$. We discuss observable relativistic corrections to non-relativistic variational energy calculations. Production of metastable states belonging to lower charge states is discussed, and it is concluded that many excited heavy ions should exhibit them.

Metastable x-ray-emitting chlorine ions with lifetimes in the nanosecond region have been found to be produced in the beam-foil excitation of fast chlorine beams. Using coincidence techniques we have determined that these metastable states belong to chlorine ions of two, three, and more than three electrons.

The 1s bound state of superheavy atoms and molecules reaches a binding energy of $-2m{c}^2$ at $Z\approx 169$. It is shown that the $K$ shell is still localized in $\mathcal{r}$ space even beyond this critical proton number and that it has a width $\Gamma$ (several keV large) which is a positron escape width for ionized $K$ shells. The suggestion is made that this effect can be observed in the collision of very heavy ions (superheavy molecules) during the collision.

We demonstrate the existence of nuclear spin states associated with the protons of the C${\mathrm{H}}_3$ groups in solid hexamethylbenzene, using a level-crossing experiment to observe conversion of the associated $A$ and $E$ nuclear spin species. The experiment also determines the torsional ground-state splitting of the C${\mathrm{H}}_3$ group to be 11.0±2.5 MHz.

Intense electron beams which are partially current neutralized can be unstable to transverse modes which form small pinch structures. Beams guided by strong $B_z$ fields experience a circular particle drift at frequency $\frac{{{\omega }_{\beta }}^2}{{\omega }_c}$, which proves highly destabilizing for filamentary modes. Growth rates considerably exceed the resistive diffusion rates normal for a resistive instability. The mode may be difficult to distinguish experimentally from interchange, but our computed growth rates are in qualitative agreement with present experiments.

Measurements of charge-carrier mobilities in solid helium have been made which are the first to be sufficiently extensive to allow conclusions to be drawn concerning the fundamental nature of the transport processes involved. Positive and negative charge carriers are quite different physical entities but in each case our data are able to provide quantitative support for a particular model to describe the carrier and its motion.