Deceleration and velocity bunching of Na atoms in an atomic beam have been observed. The deceleration, caused by absorption of counterpropagating resonant laser light, amounts to 40% of the initial thermal velocity, corresponding to about 15 000 absorptions. Atoms were kept in resonance with the laser by using a spatially varying magnetic field to provide a changing Zeeman shift to compensate for the changing Doppler shift as the atoms decelerated.

We report the first observation of radiation-pressure cooling on a system of resonant absorbers which are elastically bound to a laboratory fixed apparatus. Mg ii ions confined in a Penning electromagnetic trap are cooled to <40 K by irradiating them with the 8-μW output of a frequency doubled, single- mode dye laser tuned to the low- frequency side of the Doppler profile on the ${}_{}{}^2{}_{}{}^{}S_{\frac{1}{2}}^{}{}_{}{}^{}\leftrightarrow {}_{}{}^2{}_{}{}^{}P_{\frac{3}{2}}^{}{}_{}{}^{}$ ($M_J=+\frac{1}{2}\leftrightarrow M_J=+\frac{3}{2}$ or $M_J=-\frac{1}{2}\leftrightarrow M_J=-\frac{3}{2}$) transitions. Cooling to approximately ${10}^{-3\mathrm{}}$ K should be possible.

We have demonstrated the feasibility of Doppler-free two-photon spectroscopy with a train of picosecond standing-wave light pulses from a synchronously pumped mode-locked cw dye laser. The actively controlled mode spectrum provides a means for accurate measurements of large frequency intervals. From a multipulse spectrum of the sodium $3s-4d$ transition we have determined a new value of the $4d$ fine-structure splitting, 1028±0.4 MHz.

Doped polyacetylene forms a new class of conducting polymers in which the electrical conductivity can be systematically and continuously varied over a range of eleven orders of magnitude. Transport studies and far-infrared transmission measurements imply a metal-to-insulator transition at dopant concentrations near 1%.

A free-electron laser oscillator has been operated above threshold at a wavelength of 3.4 μm.

Gain has been observed for optical radiation at 10.6 μm due to stimulated radiation by a relativistic electron beam in a constant spatially periodic transverse magnetic field. A gain of 7% per pass was obtained at an electron current of 70 mA. The experiments indicate the possibility of a new class of tunable high-power free-electron lasers.

It is shown that a wide class of non-Abelian gauge theories have, up to calculable logarithmic corrections, free-field-theory asymptotic behavior. It is suggested that Bjorken scaling may be obtained from strong-interaction dynamics based on non-Abelian gauge symmetry.

An explicit calculation shows perturbation theory to be arbitrarily good for the deep Euclidean Green's functions of any Yang-Mills theory and of many Yang-Mills theories with fermions. Under the hypothesis that spontaneous symmetry breakdown is of dynamical origin, these symmetric Green's functions are the asymptotic forms of the physically significant spontaneously broken solution, whose coupling could be strong.

It is demonstrated that recent NMR results in ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ indicate that at 2.65 mK, the liquid makes a second-order transition to a phase in which the "spin-orbit" symmetry is spontaneously broken. The hypothesis that this phase is a BCS-type phase in which pairs form with $l$ odd, $S=1\mathrm{}$, $S_z=\pm 1$ leads to reasonable agreement with both NMR and thermodynamic data, but involves some difficulties as to stability.

Large anisotropy is observed for gravitational-radiation-detector intensity as a function of sidereal time, with peaks in the direction of the galactic center and in the opposite direction consistent with 12-h antenna symmetry. The 12-h sidereal-time histograms exhibit anisotropy exceeding 6 standard deviations from the mean.

Cross sections for inelastic scattering of electrons from hydrogen were measured for incident energies from 7 to 17 GeV at scattering angles of 6° to 10° covering a range of squared four-momentum transfers up to 7.4 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. For low center-of-mass energies of the final hadronic system the cross section shows prominent resonances at low momentum transfer and diminishes markedly at higher momentum transfer. For high excitations the cross section shows only a weak momentum-transfer dependence.

Results of electron-proton inelastic scattering at 6° and 10° are discussed, and values of the structure function $W_2$ are estimated. If the interaction is dominated by transverse virtual photons, $\nu W_2$ can be expressed as a function of $\omega =\frac{2M\nu }{q^2}$ within experimental errors for $q^2>1\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and $\omega >4\mathrm{}$, where $\nu$ is the invariant energy transfer and $q^2$ is the invariant momentum transfer of the electron. Various theoretical models and sum rules are briefly discussed.

Coincidences have been observed on gravitational-radiation detectors over a base line of about 1000 km at Argonne National Laboratory and at the University of Maryland. The probability that all of these coincidences were accidental is incredibly small. Experiments imply that electromagnetic and seismic effects can be ruled out with a high level of confidence. These data are consistent with the conclusion that the detectors are being excited by gravitational radiation.

A search was made for solar neutrinos with a detector based upon the reaction ${\mathrm{Cl}}^{37}(\nu , e^{-}){\mathrm{Ar}}^{37}$. The upper limit of the product of the neutrino flux and the cross sections for all sources of neutrinos was 3×${10}^{-36\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ per ${\mathrm{Cl}}^{37}$ atom. It was concluded specifically that the flux of neutrinos from ${\mathrm{B}}^8$ decay in the sun was equal to or less than 2×${10}^6$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ at the earth, and that less than 9% of the sun's energy is produced by the carbon-nitrogen cycle.