Fast protons (1-2.4 times the beam velocity) have been studied. The spectral shapes in both singles and coincidence are similar. The most energetic protons are associated with intermediate-velocity products rather than beam-velocity ones. The observed high energies and the forward-peaked angular distributions could be explained by evaporation calculations which included thermal fluctuations in the division of the excitation energy between the two fragments of the intermediate complex.

Use was made of a special feature in the detection of unbound ejectiles, to extend previous measurements of the ($\alpha$,${\alpha }^{*}$) reaction on ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ and ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ to very forward angles. The characteristic differential cross sections obtained for mutual as well as for single excitation are well reproduced in a full coupled-channels calculation in which the strong couplings to the first excited $2^{+}$ states of the target nuclei are taken into account.

The first realistic calculations of the energy and angular distributions of electrons ejected in ion-atom collisions, where the ion carries along its own electrons, are presented. The calculations, within the Born-approximation framework, have been performed for ${\mathrm{He}}^{+}$ + He collisions, and measurements have also been made. Rather good quantitative agreement between our measurements and calculations has been obtained over a broad range of energies and angles. Some difficulties persist, however, near the forward direction.

Strong heating of a laboratory plasma is experimentally observed in the presence of a standing wave when the wave amplitude exceeds a certain threshold. This threshold amplitude is absolutely measured from observations of the ponderomotive force effects and compared to the theoretically expected value for the onset of large-scale stochasticity.

$d$-${}_{}{}^3{}_{}{}^{}\mathrm{He}$ reactions have been observed in the Princeton Large Torus by detecting the unconfined 14.7-MeV proton. Reaction rates as high as 2×${10}^{13}$ ${\sec }^{-1\mathrm{}}$ resulting in 60 W of fusion power were obtained by 500-kW heating of a ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ minority in the ion-cyclotron range of frequencies to energies above 80 keV. The fusion-power multiplication of about ${10}^{-4\mathrm{}}$ is equal to the highest obtained in any controlled-fusion experiment.

A magnetically self-confined ring of 430-keV protons with a field reversal on axis of 3% is formed in an 8-kG solenoid, as evidenced by propagation more than 1 m in 15-400 mTorr air or hydrogen without dispersion. Up to 83% of the proton kinetic energy is in rotation and inductive coupling of axial ring energy to azimuthal plasma current induced in air (but not hydrogen) gives reflection of >50% of the ring from a 23% mirror.

A simple relation between three-point correlation functions is derived for two-component materials. This relation enables one to find concise expressions for the Beran, Molyneux, and McCoy bounds on transport and elastic coefficients in terms of the volume fraction, $f_1$, and two fundamental geometric parameters, ${\zeta }_1$ and ${\eta }_1$. The parameter ${\zeta }_1$ also determines bounds on the complex electrical permittivity. No simple interpretation of ${\zeta }_1$ and ${\eta }_1$ has been found.

On the basis of the specific surface energy ratio ${\gamma }^{*}$ and atomic-size ratio ${\sigma }^{*}$ of the two solid-solution constituents, it is shown that dilute substitutional alloys map into regions of the ${\gamma }^{*}-{\sigma }^{*}$ plane with common surface-segregation behavior, the mapping being different for the various surface-segregation theories. A comparison of theory with experiment is made for 45 bimetallic alloys, and general conclusions concerning the validity of the different theories and future directions are made.

The incommensurate adsorbed solid is found to become unstable to dislocations when the lattice period approaches that of a sufficiently low-order commensurate phase such as a 2×1 rectangular overlayer or the $(\sqrt{3}\times \sqrt{3})R30°$ hexagonal structure which occurs for krypton on graphite. In these cases, a fluid phase is expected between the commensurate and incommensurate solids.

Experiments are presented which show that surface imperfections can give rise to a larger linear magnetoresistance than previously supposed; in fact, large enough to explain many hitherto-unexplained published results. A theoretical model, which takes into account both the finite width of the sample and the Hall fields within it, is shown to describe the experimental results quantitatively, without the use of adjustable parameters.

Tunneling measurements of the electronic density of states of amorphous ${\mathrm{Ge}}_{1-x}{\mathrm{Au}}_x$ near the metal-insulator transition at $x=0.12\mathrm{}$ are reported. In the metallic phase there is a giant zero-bias anomaly with a minimum in the density of states at the Fermi energy. In the insulating phase a pseudogap opens, centered about the Fermi energy, with zero density of states at the Fermi energy.

Photoluminescence has been used to elucidate the electronic structure of the ferromagnetic semiconductor Cd${\mathrm{Cr}}_2$${\mathrm{Se}}_4$. Luminescence spectra and decay have been measured and analyzed as a function of temperature and the quantum efficiency has been determined at 77 K. The data indicate that the observed emission results from conduction-band to valence-band transitions and place the fundamental gap at 1.8 eV.

Observation by fluorescence detection of direct two-photon absorption within the $4f$ configuration of the ${\mathrm{Gd}}^{3+}$ ion following excitation with a continuous-wave laser is reported. Quantitative intensity measurements test assumptions behind the Judd-Ofelt theory of lanthanide transition intensities in a new way, and significant discrepancies are found. The discrepancies indicate that the radial integrals $〈4f\left|\mathcal{r}\right|5d〉$ vary markedly for different $J$ multiplets, and that ligands significantly influence two-photon intensities.

Resistance measurements have been made on low-resistivity thin Cu films (50-500 Å) between 1 and 20 K. A logarithmic temperature dependence of the resistance is observed. For a resistance per square of $R<\mathrm{}20\mathrm{}$ Ω/□, good agreement is obtained with the localization theory. The amplitude of the resistance variation and its large magnetic-field dependence exclude possible Coulomb-interaction effects predicted by Altshuler et al. as the main source of the observed behavior.

A tendency toward a cusp at zero temperature in the electrical conductivity of Si crystals doped with P is observed. It is found that, within the metallic state, decreasing P concentration enhances the cusp and then rapidly changes its sign as a pseudogap opens. Such a cusp has been predicted for a disordered metal in which Coulomb interactions dominate the scattering.

If $\psi$ is a determinantal eigenfunction for the $N$-fermion Hamiltonian, $H$, with one- and two-body terms, then $e_0<~〈\psi ,H\psi 〉=E\left(K\right)\mathrm{}$, where $e_0$ is the ground-state energy, $K$ is the one-body reduced density matrix of $\psi$, and $E\left(K\right)\mathrm{}$ is the well-known expression in terms of direct and exchange energies. If an arbitrary one-body $K$ is given, which does not come from a determinantal $\psi$, then $E>~e_0$ does not necessarily hold. This Letter proves, however, that if the two-body part of $H$ is positive, then in fact $e_0<~e_{\mathrm{HF}}<~E\left(K\right)\mathrm{}$, where $e_{\mathrm{HF}}$ is the Hartree-Fock ground-state energy.

It is shown that evidence on cosmic-ray showers of energy 3×${10}^{16}$ to ${10}^{20}$ eV indicates that scaling in the fragmentation region is valid up to the highest energies if (and only if) hadron-air inelastic cross sections continue to rise in the manner observed at lower energies. It is also shown, with use of additional air-shower evidence, that $〈\ln A〉$, the logarithmic mean primary mass number, changes from (4±2) at 1.6×${10}^{15}$ eV to ($0_{-0\mathrm{}}^{+0.6\mathrm{}}$) at and above 3×${10}^{16}$ eV.

The pionic two-body decay amplitude of the proton in the SU(5) grand unified gauge theory is computed by using the soft-pion method in the reference frame of the pion at rest. The normalization condition of the relativistic three-body Bethe-Salpeter wave function of the proton is used in the computation. It is shown that the partial decay rate of the process, proton →$e^{+}{\pi }^0$, is (${0.86\times {10}^{30}\mathrm{y}\mathrm{r})}^{-1\mathrm{}}$ and (${1.4\times {10}^{31}\mathrm{y}\mathrm{r})}^{-1\mathrm{}}$ for $m_X=4.0\mathrm{}\times {10}^{14} \mathrm{GeV}\mathrm{and} 8.0\times {10}^{14} \mathrm{GeV}$, respectively. These values are on the boundary of the present experimental limit.

Data from four reactor experiments is analyzed without using any calculated ${\overline{\nu }}_e$ spectrum. $N_{e1\mathrm{}}$ and $N_{e2\mathrm{}}$, for $e^{+}$ observed with $2.2<\mathrm{}{E}_{e1\mathrm{}}<6.7\mathrm{}$ MeV and $4.4<\mathrm{}{E}_{e2\mathrm{}}<6.7\mathrm{}$ MeV, are extracted and $\frac{N_{e1\mathrm{}}}{N_{e2\mathrm{}}}$ is found to be 2.7±0.5, 5.6±0.6, and 8.20±0.35 for the 6.5-, 8.7-, and 11.2-m experiments, respectively. In pairs, these numbers differ by 3-8 standard deviations. No distance-independent ${\overline{\nu }}_e$ spectrum accounts for all the data with a confidence level (C.L.) >0.0028. Oscillations with three (two) $\nu$'s yield fits to all data with C.L.=0.061 (0.033) and to the high-statistics experiments with C.L.≳0.31 (0.18).

Pauli correlations are shown to be important in interpreting the momentum distribution of nuclear fragments formed in high-energy heavy-ion collisions.