We present a microscopic approach to the monopole and quadrupole isoscalar giant resonances based on appropriate sum rules. The energies of both modes contain the same model-independent contribution ($\sqrt{2}\hslash \omega$) and a contribution involving antisymmetrization effects and the nuclear potential. Several potentials are considered and the results of many other approaches are derived in a simple and compact way.

High-resolution x-ray spectral measurements are used to determine the relative intensity of He-like fluorine x-ray transitions, $2{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}\to 1{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$ and $2{}_{}{}^1{}_{}{}^{}P_1^{}{}_{}{}^{}\to 1{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$, produced in 30-MeV ${\mathrm{F}}^{5+}$ collisions with Ne, Ar, and Kr gas targets at various pressures. The relative intensities are observed to be strong functions of both gas pressure and target $Z$. The data permit extraction for the first time of the total quenching cross sections (${\sigma }_Q$) for fast fluorine ions in the $1s2p{}_{}{}^3{}_{}{}^{}P_1^{}{}_{}{}^{}$ state. The measured ${\sigma }_Q$ are found to be approximately geometrical in size.

Light scattered from strontium vapor near its 460.73-nm (${}_{}{}^1{}_{}{}^{}{P}_1_{}^{\circ }{}_{}{}^{}-{}_{}{}^1{}_{}{}^{}S_0^{}{}_{}{}^{}$) resonance transition was resolved into its three spectral components: Rayleigh scattering, collision-induced fluorescence, and three-photon scattering. The saturation behavior of the central (Rayleigh) component and the intensity and ac Stark shift of the three-photon component were studied as a function of detuning and laser intensity. Good agreement is obtained with theoretical predictions.

Molecular absorption lines from a common lower level are intensity modulated by chopped-laser saturation of another line from that level. Populations of some other levels are also modulated by subsequent fluorescence. Both types of modulated lines are free of Doppler broadening. Also, collisional depopulation modulates absorption from rotational levels near the laser-depleted level. In ${\mathrm{Na}}_2$, we have identified 113 lines. Analysis of the $A$ state by Kusch and Hessel is confirmed and extended.

The saturated state of the current-driven ion-acoustic instability in a He positive-column plasma is studied using C${\mathrm{O}}_2$-laser scattering and heterodyne detection. It is found that small concentrations of hydrogen present in the positive-column plasma play a crucial role in saturating the instability. The measured angular extent and level of saturation of the turbulence are found to be consistent with "resonance-broadening"-enhanced ion Landau damping by 1 to 4% ${\mathrm{H}}^{+}$ impurity ions.

The number and energy distribution of suprathermal electrons produced in a laser-heated plasma can be quantitatively obtained directly from the experimental x-ray spectrum with only the assumption that the fast electrons lose energy by bremsstrahlung and electron-electron collisions. The result is independent of the spatial and temporal distribution of electron density and temperature.

Surface exciton polaritons are observed in a semiconductor for the first time. The modes are excited in ZnO crystals by the method of attenuated total reflection. Changing the angle of incidence of the ultraviolet radiation gives an experimental dispersion relation for surface exciton polaritons.

The probability $S$ of energy transfer from excited host lattice to activator ions can be calculated from experimental concentration-dependence data. It is 0.66 for ${\mathrm{Y}}_2$${\mathrm{O}}_2$S: Eu, $S$ is the quantum efficiency for host-excited luminescence and can be used to calculate cathodoluminescence efficiency.

An analysis of six years of lunar-laser-ranging data gives a zero amplitude for the Nordtvedt term in the Earth-Moon distance yielding the Nordtvedt parameter $\eta =0.00\mathrm{}\pm 0.03$ Thus, Earth's gravitational self-energy contributes equally, ±3%, to its inertial mass and passive gravitational mass. At the 70% confidence level this result is only consistent with the Brans-Dicke theory for $\omega >29\mathrm{}$. We obtain $|\beta -1|\lesssim 0.02 \mathrm{to} 0.05$ for five-parameter parametrized post-Newtonian theories of gravitation with energy-momentum conservation, or $|\beta -1|\lesssim 0.01$ if only $\beta$ and $\gamma$ are considered.

Analysis of 1389 measurements, accumulated between 1970 and 1974, of echo delays of laser signals transmitted from Earth and reflected from cube corners on the Moon shows gravitational binding energy to contribute equally to Earth's inertial and passive gravitational masses to within the estimated uncertainty of 1.5%. The corresponding restriction on the Eddington-Robertson parameters is $4\beta -\gamma -3=-0.001\mathrm{}\pm 0.015$. Combination with other results, as if independent, yields $\beta =1.003\mathrm{}\pm 0.005$ and $\gamma =1.008\mathrm{}\pm 0.008$, in accord with general relativity.

In view of the possible production of heavy leptons or charmed states in $e^{+}{e}^{-}$ collisions, we searched for anomalous muons with momenta $p_{\mu }\gtrsim 1$ GeV/c. The inclusive cross section for $n_{\mathrm{ch}}>~3$ has an upper limit of 96 pb (assuming isotropy). For $n_{\mathrm{ch}}=2\mathrm{}$ and noncoplanarity > 20°, an excess of muonic events is observed, corresponding to ${\left(\frac{d\sigma }{d\Omega }\right)|}_{90°}={23}_{-9\mathrm{}}^{+12\mathrm{}}$ pb/sr; the probability that known processes produce the observed events is 2×${10}^{-4\mathrm{}}$.

We propose a new anomaly-free quark model with weak isotriplets for quarks. The $\Delta I=\frac{1}{2}$ enhancement may be accounted for, the requirement of Golowich and Holstein being satisfied. There arises a mixing of left-handed charmed quarks with left-handed nucleonic ones which essentially gives an overall explanation of neutral-current effects, inclusive $y$ distribution, the ratio $\frac{{\sigma }^T\left(\overline{\nu }d\right)}{{\sigma }^T\left(\overline{\nu }d\right)}$, and copious dilepton events in $\nu$ and $\overline{\nu }$ reactions.

Electron scattering cross sections have been measured at backward angles and momentum transfers where the $M7\mathrm{}$ and $M9\mathrm{}$ form factors are dominant. The measured cross sections are consistent with those predicted by single-particle calculations, and are reasonably reproduced by calculations which take into account the core-polarization effects required to explain the $M1\mathrm{}$ and $M3\mathrm{}$ moments.

Two-dimensional quadrature formulas with a minimal number of points are applied to the computation of the double radial integral in the finite-range distorted-wave Born approximation for nuclear reactions. The resulting code kundry is fast, especially in cluster transfer reactions where the integrated area is largest. The code was used to investigate the reaction ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{15}{}_{}{}^{}\mathrm{N}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and the coherent interference between the proton and alpha-cluster transfer reaction mechanisms.

An accurate numerical calculation of the projectile atomic-number dependence for $K$-shell hole production by Coulomb excitation has been carried out through the two leading terms in the plane-wave Born series. The calculation is restricted to velocities where the projectile is slower than the target $K$-shell electron, but fast enough that Coulomb deflection of the projectile is negligible. Agreement is found with experiments.

We present linear and circular polarization measurements of $3{}_{}{}^1{}_{}{}^{}P-2\mathrm{}{}_{}{}^1{}_{}{}^{}S$ (501.6 nm) photons detected in delayed coincidence with electrons inelastically scattered from the $3{}_{}{}^1{}_{}{}^{}P$ level of helium. Vector polarization and coherence parameters of the coincident radiation provide direct experimental evidence of the coherent nature of the excitation process. Atomic orientation is obtained directly from the circular polarization measurements. Analysis of the data also yields $\lambda$ and $\chi$ parameters for $3{}_{}{}^1{}_{}{}^{}P$ excitations, which are compared with previous data and theory.

Transmission measurements of the total scattering cross section for positrons of welldefined energy colliding with argon atoms in the energy range extending from 0.4 to 18 eV reveal a shallow minimum in the vicinity of 2 eV. The measured total cross section at the minimum is 2.4×${10}^{-16\mathrm{}}$ ${\mathrm{cm}}^2$. These measurements also reveal an abrupt increase in the total cross section above the threshold for positronium formation (9.0 eV).

A polarization-rotation effect is demonstrated which utilizes the dispersion associated with $3S-5S$ two-photon transitions in sodium vapor. A linearly polarized beam at ${\nu }_1$ is rotated by a circularly polarized beam at ${\nu }_2$ when ${\nu }_1+{\nu }_2$ is near the two-photon transition frequency. When combined with a polarizer a rapid optical shutter is obtained.

Magnetic surfaces for a plasma with a helical current perturbation $\sim {\epsilon }^2$ are destroyed by toroidal effects or by a second current perturbation, of incommensurate helicity, and the behavior of magnetic field lines becomes stochastic in layers of relative width ${\epsilon }^{-l}\times \exp (-\frac{\pi }{2\epsilon })$, where $l\sim 2\left|\frac{m_1}{m}\right|+1\mathrm{}$ with $m$ and $m_1$ the azimuthal mode numbers of the original helical field and of the perturbation.

The current associated with the self-generated magnetic field has been measured in air and nitrogen at various pressures in a 4-J, 30-nsec-Nd-laser-produced plasma using a fast probe embedded in the copper target. The results reveal an active participation of the target in the current-flow process with anodic and cathodic regions, the source of the current (magnetic field) being at the plasma-target interface.