The Coulomb-fission cross sections for ${}_{}{}^{132}{}_{}{}^{}\mathrm{Xe}$ and ${}_{}{}^{148}{}_{}{}^{}\mathrm{Nd}$ incident on ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ are calculated in a dynamical classical model. In particular the influence of nuclear forces on the cross sections is studied. Since they are counteracting the Coulomb force, they diminish the cross sections for Coulomb fission significantly and shift the Coulomb barrier towards lower energies.

If the photon has a finite rest mass $m$, a filament of magnetic flux sustained by a partially ionized gas decays exponentially at a rate proportional to $m^2$. Arguing from assumptions regarding the galactic magnetic field that are plausible though not yet rigorously established, we find an upper limit $m<~3\times {10}^{-56\mathrm{}}$ gm, corresponding to a Compton wavelength of 6 lt yr.

We examine all of the black-hole geometries which can be analytically developed in terms of a parameter from the Schwarzschild geometry. It is shown that this analytic family is completely spanned by the Kerr-Newman space-times with $e^2+a^2<m^2$, where $e$, $a$, and $m$ denote charge, specific angular momentum, and mass. If general (nonspherical) gravitational collapse produces black holes and if analytic variation of the initial conditions of gravitational collapse causes analytic variation of the final space-time geometry of the black holes produced by the collapse, this result implies that the generic final state of gravitational collapse is a Kerr-Newman black hole, fully specified by its mass, angular momentum, and charge.

It is shown that for every spacelike three-geometry there exists a symmetric tensor that is (1) defined locally using only the three-metric and its derivatives, (2) conformally invariant, (3) traceless, and (4) covariantly divergence free ("transverse"). As a result, the arbitrarily specifiable (unconstrained) initial-value data in the Einstein initial-value problem for gravity can be completely characterized by a pair of symmetric, transverse, traceless tensors.

A measurement of the angular distribution for the reaction $n+p\to \gamma +d$ has been made at the Lawrence Radiation Laboratory 184-in. cyclotron for neutron kinetic energies in range 300 to 720 MeV. A total of 30 000 $n+p\to \gamma +d$ events were collected in twenty energy-angle bins. A comparison with the angular distribution for the inverse process indicates that the data are consistent with time-reversal invariance in this reaction. If the results are interpreted in the framework of a model by Barshay, the measured $T$-invariance violating phase angle is $\varphi ={(4\mathrm{}\pm 10)}^{\circ }$, where $\varphi ={90}^{\circ }$ for a maximal $T$-invariance violation.

Observations of the mass distribution of the $A_2$ meson produced in the reaction $\pi p\to A_{2}p$ are reported. The $A_2$'s were observed using a missing-mass technique. Measurements were made with 5- and 7-GeV ${\pi }^{-}$ as well as 5-GeV ${\pi }^{+}$ beams. For each beam setting more than 17000 $A_2$'s above background were observed with $0.20<~\mathrm{}\left|t\right|\mathrm{}<~0.29$ Ge${\mathrm{V}}^2$. The $A_2$ peaks are well described by a Breit-Wigner shape, whereas the dipole mass formula does not fit the data.

We have performed a search at the Bevatron for the decays ${K_L}^0\to {\mu }^{+}{\mu }^{-},e^{+}{e}^{-}, \mathrm{and} {\mu }^{\pm }{e}^{\mp }$ with a double magnetic spectrometer using wire spark chambers. Over ${10}^6$ observed ${K_L}^0\to {\pi }^{+}{\pi }^{-}$ decays determine the normalization for the di-lepton decay modes. No $e^{+}{e}^{-}$ or ${\mu }^{\pm }{e}^{\mp }$ events were observed. For each of these decays the upper limit on the branching ratio relative to all modes is 1.57 × ${10}^{-9\mathrm{}}$ (90% confidence level). For the decay ${K_L}^0\to {\mu }^{+}{\mu }^{-}$, the limit is 1.82 × ${10}^{-9\mathrm{}}$ (90% confidence level).

The differential cross sections at 180° for the reactions $\gamma +p\to {\pi }^{+}+n$ and $\gamma +n\to {\pi }^{-}+p$ were measured using a magnetic spectrometer to detect ${\pi }^{\pm }$ mesons. In order to reduce the spread of energy resolution due to the nucleon motion inside the deuteron, a photon difference method was employed with a 50-MeV step for the reaction $\gamma +n\to {\pi }^{-}+p$. The data show structures at the second- and the third-resonance regions for both reactions. A simple phenomenological analysis was made for fitting the data, and the results are compared with those of previous analyses.

Evidence is found for the coherent production of high-mass meson states in the 1.6- and 1.9-GeV mass regions. These states are observed, respectively, in the $3\pi$ and $5\pi$ systems produced in the reactions ${\pi }^{+}d\to d{\pi }^{+}{\pi }^{+}{\pi }^{-}$ and ${\pi }^{+}d\to d{\pi }^{+}{\pi }^{+}{\pi }^{+}{\pi }^{-}{\pi }^{-}$ at 13 $\frac{\mathrm{GeV}}{c}$. The spin and parity of the $3\pi$ state, identified as the $A_3$ meson, is determined to be in the series $2^{-},3^{+},\cdots$ with a dominant $f\pi$ decay.

Broad peaks observed in the photoabsorption spectra of rare earths ∼10-20 eV above the $4d$ edge are attributed to transitions $4d^{10}4f^N\to 4d^{9}4f^{N+1\mathrm{}}$. Exchange interaction splits the $4d^{9}4f^{N+1\mathrm{}}$ configuration and raises some multiplets by ∼20 eV. Autoionization to $4d^9-4f^N\epsilon f$ broadens the high levels. The interpretation extends to $p\to d$ processes observed in the absorption of synchrotron light by transition elements.

The Ericksen-Leslie theory for nematic liquid crystals is simplified and improved. The most general linear hydrodynamic equations are obtained following the conservation laws, thermodynamics laws, and symmetry properties. The rigorous low-frequency, long-wavelength equations are then deduced by taking such a limit. It is a simple alternative way to derive the theory of Forster, Lubensky, Martin, Swift, and Pershan. It would be of interest to study the more general equations experimentally.

Ion heating and relatively large radial, rf electric fields have been observed in an experiment in which an electron beam modulated near the ion plasma frequency excites the resonances of a partially filled plasma cavity. Predictions based on a theoretical self-consistent model for a finite-length beam-plasma system are in good agreement with the experimental observations.

Recent experimental data on He II have been analyzed in order to test various analytic properties of the phonon dispersion curve. In particular ${\left[\frac{\epsilon \mathrm{}\left(p\right)\mathrm{}}{p}\right]}^2$, where $\epsilon \mathrm{}\left(p\right)\mathrm{}$ is the energy of an elementary excitation, seems to be well represented by a power expansion in $p$ up to $p=2.6\mathrm{}$ ${\mathrm{\AA }}^{-1\mathrm{}}$.

New vapor-pressure measurements of ${\mathrm{He}}^3$ - ${\mathrm{He}}^4$ solutions in the region between 0.5 and 1.2°K have been made and are used to calculate changes in the chemical potential. Special emphasis is directed towards the region of the tricritical point. The variation of the chemical potential and its derivative along certain paths leading to the critical point yields critical indices which satisfy the scaling relation proposed by Griffiths.

A free-energy expression for a pure superconductor is derived microscopically which includes effects of a nonlocal order parameter. In the presence of strong field the simple transformation $\overrightarrow{\mathrm{q}}\to \overrightarrow{\mathrm{q}}+\frac{2e\overrightarrow{\mathrm{A}}}{c}$ is no longer valid. Using this free energy, fluctuation-induced diamagnetism of a superconductor above $T_c$ is calculated. The resulting universal behavior for pure superconductors is in good agreement with the experiment of Gollub, Beasley, and Tinkham.

Rigorous bounds for the density of electronic states are given for an idealized model of a group-IV semiconductor based on the tight-binding method. These include inner bounds which define a minimum gap in the density of states. The importance of this development lies in its independence of periodicity. It applies not only to crystalline structures made up of tetrahedral bonds but also the random tetrahedral network which recent studies have suggested for amorphous Si and Ge.

The nature of the surface and pseudosurface modes in ionic-crystal slabs is clarified, and some apparent discrepancies among the previous studies are resolved. The first shell-model calculations of surface-mode spectra are reported; the results for NaCl are significantly different from those obtained with the rigid-ion model. A new type of long-wavelength optical surface mode has been found in the shell-model results for RbF.

The equilibrium Kondo problem is solved using a spin-boson representation of the partition function. For antiferromagnetic coupling, a canonical transformation removes infrared singularities in the energy and magnetization series. At $T=0\mathrm{}$ the moment vanishes, the energy is nonanalytic in $J_{\perp }$, the magnetization saturates at a field $H_S$ of order ${\left(\frac{{J_{\perp }}^2}{J_{\parallel }}\right)}^{\frac{1}{2J_{\parallel }}}$, and the susceptibility $\chi$ is proportional to ${H_S}^{-1\mathrm{}}$. $J_{\parallel }$ and $J_{\perp }$ are longitudinal and transverse exchange constants.) For ferromagnetic coupling the free moment is only slightly renormalized.

It has long been postulated that, in those metals where the Fermi surface does not touch the Brillouin zone boundary, the electron-phonon umklapp scattering contribution to the electrical resistivity should rapidly disappear at sufficiently low temperatures. New experimental and theoretical evidence for such an effect is reported in the low-temperature electrical resistivity of potassium; the contribution from umklapp processes prevails over that of normal processes above ∼2.5°K, but decreases rapidly for temperatures below this.

Observations of the Azbel'-Kaner cyclotron resonance spectra in thick slabs of high-purity potassium metal have revealed additional oscillations on the high-field side of the fundamental resonance. These anomalies in the surface impedance correspond to turning points of the cyclotron-wave dispersion curve at wavelengths which are short compared to orbit radii. The behavior of the signals agrees quite well with free-electron theory and confirms the extremely oscillatory character of the extraordinary mode. The absence of deviations due to Fermi-liquid effects in our experiments is investigated, and in particular we show under what circumstances the Fermi-liquid parameter $A_1$ can be determined from these signals.