Transverse acoustic phonons were generated electromagnetically at 9 GHz in the temperature range of 4-60 K using thin tin films on silicon substrates. The conversion efficiency of electromagnetic into acoustic energy decreases with temperatures. This temperature dependence is accounted for theoretically as due to the decrease of the electronic mean free path upon raising the temperature.

We report a pressure-induced phase transition in paratellurite which occurs at 9.0 kbar at room temperature. The transition appears to be second order and is driven by the soft acoustic mode $\rho V^2=\frac{1}{2}(C_{11}-C_{12})$ propagating along <110>. This is the only known phonondriven transition that can be induced with pressure, but not with temperature, for which the details of the transition mechanism have been definitely established. The phase transition was investigated using Brillouin-scattering, ultrasonic-velocity, and dielectricconstant measurements.

Photoemission energy distributions for $20<~h\nu <~50$eV for semiconducting Fe${\mathrm{S}}_2$ (fool's gold) show a narrow, ∼1 eV wide, localized uppermost valence level, whereas the corresponding levels of semiconducting Ni${\mathrm{S}}_2$ are broad (∼3.5 eV) and bandlike. Self-consistent-field $X\alpha$ cluster calculations indicate that this level in Fe${\mathrm{S}}_2$ is the $3d$-like $t_{2g}$ state, while in Ni${\mathrm{S}}_2$ the uppermost level is the more bandlike $e_g$ state, with $t_{2g}$ states about 2 eV lower that overlap the broad S $3p$-derived valence bands.

The leading corrections to the large-momentum behavior of the correlation function with nonzero magnetization are computed. It is shown that for Ising-like systems only the coefficient of the singular term in $T-T_c$ is modified. However for an $n$-component system, a new power related to the crossover exponent is present.

The Magnetization of several bulk amorphous ferromagnetic CoP alloys is shown to obey a corresponding-states law which differs significantly from comparable crystalline ferromagnets such as Co or Ni. This difference originates in an anomalously large $T^{\frac{3}{2}}$ low-temperature demagnetization extending beyond $0.2T_C$. The temperature and field dependence of this term provide evidence for the presence of spin-wave excitations characterized by a high density of states at low energies.

We have detected and identified prompt $\gamma$ rays from residual formed in 220-MeV ${\pi }^{-}$ reactions with C, F, O, Mg, Al, Si, S, Ca, and V. Cross sections for $2n+2p$ removal from the even-$A$, even-$Z=N$ targets are found to be camparable to inelastic cross sections; multiple-($2n+2p$)-removal cross sections are also large. For the odd-$A$ target, ($n+2p$)-and ($2n+2p$)-removal cross sections are of the same order as inelastic cross sections. The results are campared with previously reported hadron-induced $\alpha$-particle-removal cross sections.

We have measured the cross section, the distribution of scattering angles, and the distribution of noncoplanarity angles for electron-positron elastic scattering at 5 GeV c. m. energy. An analysis based on 230 events with scattering angles between 50 and 130° yields a ratio of the experimental to theoretical quantum-electrodynamic cross section of 1.03 ± 0.09. The scattering-angle and noncoplanarity-angle distributions are also found to be in excellent agreement with the quantum-electrodynamic predictions.

We have measured muon-proton deep inelastic scattering in the range $0.4<\mathrm{}{q}^2<3.6\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. The data are consistent with muon-electron universality, and if the ratio $\rho =\frac{\nu W_2(\mu -p)}{\nu W_2\mathrm{}(e-p)\mathrm{}}$ is fitted with the form $\rho =N{(1+\frac{q^2}{{\Lambda }^2})}^{-2\mathrm{}}$, we obtain $N=0.997\mathrm{}\pm 0.043$ and ${\Lambda }^{-2\mathrm{}}=+0.006\mathrm{}\pm 0.016$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. This result establishes that $\left|\Lambda \right|>~5.1$ GeV/c with 95% confidence.

We have measured muon-proton elastic scattering in the range $0.6<\mathrm{}{q}^2<3.2\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. We compared these data with the corresponding elastic electron-proton cross sections by forming the ratio $r\left(q^2\right)=\frac{G^2(\mu -p)}{G^2\mathrm{}(e-p)\mathrm{}}$, where $G\left(q^2\right)=\frac{G_M\left(q^2\right)}{\mu }$ is the form factor of the proton. By fitting $r\left(q^2\right)=N{(1+\frac{q^2}{{\Lambda }^2})}^{-2\mathrm{}}$ we find $N=1.043\mathrm{}\pm 0.080$ and ${\Lambda }^{-2\mathrm{}}=+0.064\mathrm{}\pm 0.038$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{-2\mathrm{}}$. Combining our data with those of two previous $\mu -p$ elastic scattering experiments yields ${\Lambda }^{-2\mathrm{}}=+0.051\mathrm{}\pm 0.024$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^{-2\mathrm{}}$ which is a much weaker limit on muon-electron universality than that obtained from $\mu -p$ inelastic scattering.

An improved lower limit of >2 × ${10}^{30}$ yr against baryon-conservation-violating nucleon decay has been obtained for modes which produce $\mu \to e$ decays. The detector, employing a 20-ton large-area (180 ${\mathrm{m}}^2$) liquid scintillator, was operated deep underground (3.2 km) to eliminate stopping muons from cosmic rays, leaving only the background from muons produced by atmospheric neutrinos. A run length of 2.7 yr was required to achieve the sensitivity quoted.

We derive the anomalous moment of the electron from the quantum-electrodynamic equations of motion for the electron spin precession.

We propose a new class of apparently renormalizable heavy-vector-boson theories. These models are spontaneously broken gauge theories, modifed by the addition of arbitrary mass terms for vectors associated with invariant Abelian subgroups. The vacuum is not invariant under these subgroups. Such theories are probably renormalizable since their multiparticle $S$-matrix elements are unitarily bounded in the tree approximation. As illustrations, the Higgs [U(1)] and Weinberg gauge theories are modified in this way.

Carbon monoxide bound to myoglobin can be photodissociated with high quantum yield. The subsequent rebinding can be followed optically. In the temperature range between 40 and 200 K, rebinding can be described by a function of the form $t_0$, where $n$ and $H\left(t\right)={(1+\frac{t}{t_0})}^{-n}$ are temperature-dependent parameters. This behavior can be explained by assuming the existence of an activation-energy spectrum; the form of this spectrum is determined. The energy spectrum may be due to the existence of myoglobin conformers.

Electron plasma waves driven unstable by the electron beam-plasma instability are observed to decay into convectively and absolutely growing ion waves and electron waves propagating in opposite directions. Ion waves excited to large amplitudes further couple with the high-frequency unstable waves to produce nonresonant short-wavelength electron modes. The nonresonant modes are found effective in accelerating electrons and thermalizing the beam.

The spatial and temporal evolution of the plasma density distribution and its relation to the magnetic-piston-field structure during a theta-pinch implosion have been experimentally investigated. With a deuterium fill density of 0.7 × ${10}^{15}$ atoms ${\mathrm{cm}}^{-3\mathrm{}}$, evidence of particle reflections from the imploding piston field is indicated.

The dispersion due to $M$ centers is determined through an ellipsometric technique which utilizes their polarization properties. While this contribution is small compared to the overall refractive index, it could lead to substantial phase variations and high diffraction efficiencies in holographic storage.

Energy-loss spectra of low-energy electrons reflected from the nickel (100) plane were measured as a function of coverage by oxygen. A characteristic energy loss at 5.8 eV was observed in the $p(2\mathrm{}\times 2)$ arrangement. This loss peak splits into 5.4 and 6.4 eV in $c(2\mathrm{}\times 2)$. These peaks are caused by excitation of electrons in chemisorption bonds of nickel-oxygen. The split shows the change in bond nature in the different coverages of oxygen on Ni(100).

The nonlinear optical properties of a high-purity germanium wafer have been measured at 1.06 μm using picosecond pulses from a mode-locked neodymium:glass laster. By using such pulses we are also able to probe the hot electron distribution in order to obtain information on the ultrafast carrier relaxation times.

Photoemission measurements have been made on clean silicon surfaces having (111) 7 × 7, (111) 2 × 1, and (100) 2 × 1 low-energy electron diffraction patterns. An approximate separation of the data into surface and bulk components yields a bulk distribution which is in better agreement with the theoretical density of states than previous results. The surface distribution for the (111) 7 × 7 surface contains five distinct features.

An upper limit ${\Gamma }_{X^0}<0.8\mathrm{}$ MeV${/\mathit{c}}^2$ (95% confidence level) is deduced from the missing-mass spectrum near 958 MeV${/\mathit{c}}^2$ in the reaction ${\pi }^{-}+p\to \mathrm{MM}+n$ close to threshold. Measurement of those missing masses which decay to $2\gamma$ shows a single peak with a central mass of 957.4 ± 0.5 MeV${/\mathit{c}}^2$ close to the value of 957.46 ± 0.33 MeV${/\mathit{c}}^2$ deduced from the total missing-mass spectrum.