A phenomenological description of spin-polarized hydrogen is proposed in terms of two Bose fields which correspond in the low-density limit to the two lowest atomic hyperfine states. Experiments should initially populate both states and the equilibration time of the relative population will be long. When Bose condensation occurs in both states, a spontaneous coherent magnetization perpendicular to the stabilizing field will appear that may be observable in a magnetic resonance experiment.

The first direct measurement of local disorder in the relative positions of electrons on the surface of liquid helium is reported. The disorder is measured using the change in the transition frequency between one-electron bound states caused by the dipole electric field of nearby surface electrons. The measured value is in agreement with published theoretical predictions.

Holographic interference electron microscopy is presented for investigating the structure of domain walls in plate-shaped cobalt particles. Circular magnetic lines of force are directly observed as contour fringes which overlap individual particle micrographs. These fringes show at a glance how the spin rotates across domain walls. It is also suggested from holographic electron diffraction that the spin stands up in the center of the particle.

The results are given of accurate computations of the polarization of the cosmic micro-wave background radiation in homogenous anisotropic universes with flat spacelike hyper-surfaces. The degree of polarization never exceeds twice the maximum temperature quadrupole anisotropy, and its value is found to be very sensitive both to the mass fraction in the form of hydrogen and to its ionization history. There is no spectral distortion to first order.

The method of Newton for the solution of the inverse-scattering problem is modified with the assumption that the potential is known for radial distances $\mathcal{r}>{\mathcal{r}}_0$. The modified method is improved by applying a least-squares method.

The existence of finite-energy dyon solutions satisfying the Julia-Zee Ansatz and the generalization of $\mathrm{SU}\mathrm{}\left(N\right)\mathrm{}$ gauge groups is rigorously established. It is also proved that the solutions are real analytic on (0, $\infty$) and infinitely differentiable at 0. The proof is based on an abstract theorem that allows one to study constrained variational problems without introducing Lagrange multipliers.

Quasistationary states of ultracold neutrons have been observed in a double-hump potential barrier. This potential barrier was created by sandwiching a thin film of aluminum between two thin copper films. Measurements of reflection from and transmission through such composite films displayed clear resonances. The resonance positions and widths are in agreement with calculations.

Photoproduction of the ${D^{*}}^{+}$ have been observed where the ${D^{*}}^{+}$ decays via ${D^{*}}^{+}\to {\pi }^{+}{D}^0$ and the $D^0$ decays via $K^{-}{\pi }^{+}$ and $K_s{\pi }^{+}{\pi }^{-}$. The ${D^{*}}^{+}$, $D^0$ mass difference and the $D^0$ mass observed here are in excellent agreement with previous measurements of charmed mesons produced in $e^{+}{e}^{-}$ annihilations. The photoproduced ${D^{*}}^{+}$ and ${D^{*}}^{-}$ signals are produced nearly equally at the level of about 100 nb/nucleon.

In an experiment to measure multimuon final states in interactions of 225-GeV/c ${\pi }^{-}$ with nuclear targets we have observed 65 900 $\frac{J}{\psi }\to {\mu }^{+}{\mu }^{-}$ decays, of which 487 are accompanied by a third muon. We have used this sample to search for production of bottommeson pairs, followed by the decays $B\to \frac{J}{\psi }+X$, $\overline{B}\to \mu +X$. We find, supposing linear $A$ dependence, that $\sigma \left(B\overline{B}\right)<\mathrm{}8\mathrm{}$ nb/nucleon with 90% confidence. This limit is in contradiction with a recent report that $\sigma \left(B\overline{B}\right)\approx 200$ nb/nucleon.

Interpretation of the U(1) generator of the left-right-symmetric electroweak model in terms of $B-L$ enables us to study the spontaneous breaking of local $B-L$ symmetry. The same Higgs mechanism at the "partial unification" level of $\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_L\otimes \mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_R\otimes \mathrm{SU}\left(4^{\prime }\right)$ that produces ${\Delta }_L=2\mathrm{}$ processes (e.g., Majorana neutrinos) also yields $\Delta B=2\mathrm{}$ processes (e.g., "neutron oscillations"). The observation of "neutrinoless" double $\beta$ decay and $\Delta B=2\mathrm{}$ nucleon transitions without proton decay would favor this model and an intermediate mass scale.

A relativistic wave equation is derived for gauge-invariant $J=0\mathrm{}$ gluonium amplitudes, and show that its reduced eigenvalue equation is identical with that for a quark-antiquark system in ${}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ states. Analyzing relations between potentials in the two respective systems, I obtain an upper limit of 2 GeV to the ground-state mass if I take light quarkonium as a reference system, whereas I estimate the ground state to lie between 2.5 and 3 GeV if I use charmonium potential parameters. The scalar and the pseudoscalar gluonium states are degenerate in the present approach.

This Letter reports on the existence of periodic spontaneous collapse and revival of coherence in the dynamics of a simple quantum model. Also given are the first accurate expressions for the intermediate-time and long-time dynamical behavior of the model.

Electron-irradiated high-purity $\alpha$-iron doped with various amounts of interstitial carbon impurities has been studied by positron-lifetime measurements. It is shown that during vacancy migration at 220 K an asymmetric vacancy-carbon pair is formed, where the carbon atom is located off the center of the vacancy.

The amorphous-to-crystalline surface transition of ${\mathrm{Al}}_x{\mathrm{O}}_y$ on the Al(111) surface is observed between 650 and 800 K with different ${\mathrm{O}}_2$ exposures by measuring the positronium (Ps) fraction produced by $e^{+}$ impinging on the surface. The data are interpreted in terms of vacancy-type defects in the film or at the metal-metal-oxide interface which as trapping sites for $e^{+}$ or Ps. As the ordering process proceeds to completion the trapping centers anneal out and the Ps fraction increases, showing an irreversible transition. This technique provides a new experimental method to study interfaces.

Muon spin precession in iron has been observed from 300 K down to 3 K. The relaxation rate $\lambda$ shows a pronounced temperature dependence with minima at 15 and 90 K. A fit with an Arrhenius function yields $E_a=0.3\mathrm{}$ meV below 10 K, 14 meV between 35 and 90 K, and 86 meV between 150 and 300 K. The data indicate that coherent tunneling becomes important below 35 K. The temperature region between 35 and 90 K is dominated by incoherent tunneling while above 150 K the over-barrier hopping process sets in.

The attenuation of first sound in normal and superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in a cylindrical resonator has been measured from 40 kHz to 300 kHz at 8 and 28 bars. In the $B$ phase a decreasing viscosity down to the lowest temperature ($0.5T_c$) is observed. In the normal phase the viscosity agrees with previously reported values. The data analysis is based on a recent theory of sound propagation in superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in a resonator.

Two recent theories are compared quantitatively in order to describe the intervalley mixing effect on donor impurity levels and excitons in many-valley semiconductors. Deep levels are predicted for a screened point-charge potential, regardless of the position at which the potential is centered. Altarelli-Hsu predict that the same potential has a deep level only if centered at an interstitial site. It is shown that this basic discrepancy is a direct consequence of a key Altarelli-Hsu approximation.

Fluorescence originating from various excited vibrational levels of the $\tilde{B}$ electronic state of several halobenzene cations in solid Ne matrix has been observed and analyzed. The spectra show clearly the Jahn-Teller splitting in the ground electronic state and give for the first time information about the magnitude of the quadratic coupling terms. Excitation spectra of the unrelaxed emission give insight into the dynamics of relaxation and suggest it is a highly nonstatistical process.

The electrical resistance of Bi and Bi-6 at.% Sb whiskers has been measured. Sample diameters were as low as 140 nm, lengths as large as 1.5 mm, and residual resistances as high as 165 kΩ. Down to temperatures of 0.4 K, metallic behavior persists; the resistance $R$ decreases with decreasing temperature $T$ in contrast to other systems in which electron localization is invoked to explain negative $\frac{\mathrm{dR}}{\mathrm{dT}}\text{'}\mathrm{s}$.

Inelastic-electron-scattering experiments indicate that electronic excitations in polyacetylene, ${\left(\mathrm{CH}\right)}_x$, are similar to those of a semiconductor with wide energy bands and an excitonic or indirect absorption edge. However, the measured bulk-plasmon energy increases linearly with momentum unlike that of known inorganic solids. Heavy doping with As${\mathrm{F}}_5$ or iodine is found to result in an inhomogeneous mixture of metallic and insulating regions.