Relative yields of capture photons have been observed for four nuclei at angles of 55°, 90°, and 125° in bombardments with 14-MeV neutrons. The yields from ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$, ${}_{}{}^{29}{}_{}{}^{}\mathrm{Si}$, and ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ show smaller fore-aft anisotropies than those observed in corresponding proton captures. This suggests that the forward peaking in ($p, \gamma$) reactions is due mainly to direct rather than collective capture amplitudes. Photons from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(n, {\gamma }_0){}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ peak backward, but this peaking cannot be straightforwardly accounted for in terms of the interference between the collective excitations dominant in this energy region.

The transverse polarization transfer coefficient, ${K_y}^{y^{\prime }}$, has been measured for the reaction ${}_{}{}^2{}_{}{}^{}\mathrm{H}(p, n)pp$ at 18° for $E_p=20.4\mathrm{}$ MeV as a function of neutron energy. Although predictions based on a three-body separable-potential model with $S$-wave $N-N$ interactions are in reasonable agreement with the data, the need for a three-body theory with more realistic $N-N$ forces is indicated.

A unitarity relation is derived for the nucleon-nucleus scattering amplitude which displays the reaction mechanisms associated with the absorptive part of the single-scattering optical potential. The reactions implicit in the absorption are nucleon pickup and knockout. The transition amplitudes for these processes are extracted from the unitarity relation and their accuracy is discussed.

Chemiluminescent reactions between ${\mathrm{C}}^{+}$ and ${\mathrm{O}}_2$ were studied in a beam experiment. At $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=3.6\mathrm{}$ eV, $\mathrm{C}{\mathrm{O}}^{+}\left(A {}_{}{}^2{}_{}{}^{}\mathrm{\Pi }\right)$ is formed with abnormally high rotational excitation.

Light-scattering measurements of the time-dependent local radial velocity in a rotating fluid reveal three distinct transitions as the Reynolds number is increased, each of which adds a new frequency to the velocity spectrum. At a higher, sharply defined Reynolds number all discrete spectral peaks suddenly disappear. Our observations disagree with the Landau picture of the onset of turbulence, but are perhaps consistent with proposals of Ruelle and Takens.

The nonlinear distortion of the propagation cones of lower-hybrid waves is shown to be governed by the modified Korteweg-de Vries equation. Since such an equation admits exact solutions of the multiple-soliton form, it is predicted that filamented cones should be formed when large-amplitude lower-hybrid waves are excited in a plasma.

We study the propagation of three-dimensional, localized, transverse, circularly polarized pulses of electromagnetic radiation in ionized matter. Soliton propagation both below and above the plasma frequency can occur. A critical energy for the formation of solitons exists. The solitons can exist with states of internal excitation.

Particle simulations initialized with inhomogeneous, self-consistent Vlasov equilibria that model theta pinches in the implosion and post-implosion phases have revealed a strongly unstable flute mode for $T_i>T_e$. Frequencies and wavelengths are in good agreement with the linear theory of the lower-hybrid-drift instability. Results agree with quasilinear estimates of heating rates and anomalous resistivity during the initial stages of the instability. The nonlinear saturation of the turbulence is consistent with ion trapping.

A study has been made of the response of low-density (∼ ${10}^{13}$ ${\mathrm{cm}}^{-3\mathrm{}}$) plasmas when subjected to the very high electric fields of relativistic-electron-beam-accelerator diodes. An anomalous resistive behavior has not been seen. Instead, sheath formation at the cathode and electron-beam generation across the sheath has been found. This has important applications to the design of diodes for future electron-beam machines.

A relativistic electron stream propagating through a dense plasma induces current and charge densities which determine how the stream can self-focus. Magnetic self-focusing is possible because stream-current neutralization, although extensive, is not complete. Electric self-focusing can occur because the stream charge becomes overneutralized when the net current is smaller than a critical value. Under some circumstances, the latter process can cause the stream to focus into a series of electron bunches.

New methods are introduced for a quantitative evaluation of the dielectric constant describing the interaction of a long-wavelength test wave with electrons in the presence of electron-ion collisions or small-scale turbulence. It is shown that the usual resonance-broadening arguments of strong-turbulence theory do not apply.

A relation between methyl-group tunneling and viscoelastic relaxation has been found in dynamic mechanical studies of the backbone methyl relaxation in polymethyl methacrylate (PMMA). The pronounced curvature found in the plot of $\ln \nu$ versus $\frac{1}{T}$ for the methyl relaxations at low temperatures and the observed large isotope effect for fully deuterated PMMA are in qualitative agreement with tunneling theory.

A comparison of the correlation length for short-range order (30, 40, 70, and 110 Å), the attempt frequency for diffusion (56, 28, 80, and 85 ${\mathrm{cm}}^{-1\mathrm{}}$), and the previously reported values of tracer diffusion coefficient for Na, Ag, K, and Rb, respectively, suggests that ion-ion correlations inhibit diffusion in the $\beta$-aluminas.

We have measured the mobility of positive and negative ions trapped on vortex lines in ${\mathrm{He}}^3$-${\mathrm{He}}^4$ solutions at temperatures from 0.3 to 1.6 K. Abrupt changes in the mobility at certain critical temperatures are interpreted as being associated with the condensation of ${\mathrm{He}}^3$ atoms onto the vortex cores. The dependence of the critical temperature on the bulk ${\mathrm{He}}^3$ concentration is found to be in good agreement with a simple condensation theory.

Measurements of the normal-incidence electroreflectance of clean, strain-free single crystals of Ag and Au with use of a novel drop-electrolyte technique shown an anisotropy on the (110) face of Ag which is not present on Au. It can be explained by field-induced indirect interband transitions which are observed in Ag but not in Au. This work shows that part of the electroreflectance spectrum of Ag arises from electrons which interact with the periodic crystal potential.

We have performed neutron scattering measurements of the antiferromagnetic order parameter in MnO as a function of temperature and applied uniaxial stress. We find evidence for a tricritical point for a stress at about 5 kbar.

We present experimental evidence for the existence of the decay $\psi \mathrm{}\left(3684\right)\mathrm{}\to \gamma \chi$, $\chi \to 4{\pi }^{\pm }, 6{\pi }^{\pm }, {\pi }^{+}{\pi }^{-}{K}^{+}{K}^{-}, {\pi }^{+}{\pi }^{-}, \mathrm{and} K^{+}{K}^{-}$. There is clear evidence for at least two $\chi$ states, one at 3.41 ± 0.01 GeV/${\mathit{c}}^2$ and the other at 3.53±0.02 GeV/${\mathit{c}}^2$. The $\chi \mathrm{}\left(3410\right)\mathrm{}$ decays into $\pi \pi$ and $\mathrm{KK}$ and thus must have even spin and parity.

The $\gamma$-ray spectra from annihilations at rest have been measured with a 10-in.×10-in.-diam NaI(Tl) detector. The resolution of the system was ∼ 15% for $\gamma$-ray energies between 50 and 200 MeV. No clear evidence is found for monoenergetic $\gamma$ rays with intensities greater than 1 per 30 annihilations.

The hypothesis that the physical neutrino is a Goldstone particle associated with spontaneously broken supersymmetry is studied with emphasis on the ensuing low-energy theorems. A picture of low-energy neutrino phenomenology is found which is attractive for neutral-current processes, but is in strong disagreement with experimental end-of-lepton-spectrum behavior in $\beta$ decays.

Restrictions concerning the chiral structural of the $\left|\Delta S\right|=1\mathrm{}$ nonleptonic weak Hamiltonian are derived by studying kaon and hyperon decay amplitudes via current algebra and partial conservation of axial-vector current.