Inelastic electron scattering with 90-MeV electrons shows previously observed giant resonances at excitation energies of $63A^{-\frac{1}{3}}$ ($E2\mathrm{}$), $81A^{-\frac{1}{3}}$ ($E1\mathrm{}$), $105A^{-\frac{1}{3}}$ ($E3\mathrm{}$), and $130A^{-\frac{1}{3}}$ MeV ($E2\mathrm{}$). Distorted-wave-Born-approximation analysis of additional structure at $53A^{-\frac{1}{3}}$ and $195A^{-\frac{1}{3}}$ MeV suggests a monopole assignment. Transverse contributions to the $E1\mathrm{}$ matrix element are compatible with an electric spin-flip. Differing widths of the respective resonances in the two nuclei are explained through dynamic deformation of Au. The reduced electric transition strengths $B\left(\mathrm{EL}\right)\mathrm{}$ are given.

The distorted spectral function of the protons in the reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}(e, e^{\prime }p)$ is measured. For the $2s-1d$ region the distorted-wave impulse-approximation calculation using the Elton-Swift wave functions explains the data within 20%. The $1p$ occupation number is 1.7 times that of the shell-model prediction. After correcting for the radiative effects and for the multiple-collision background the $1s$ state is clearly observed at $E_S\simeq 58$ MeV with a reasonable occupation number.

Differential cross sections of the ($p, n$) reaction to the ground-state analogs of the stable Mo isotopes have been measured for proton energies between 16 and 26 MeV. The integrated cross sections deviate strongly from the linear dependence on $N-Z$ predicted by the $\overrightarrow{\mathrm{t}}·\overrightarrow{\mathrm{T}}$ form of the isovector interaction commonly used to describe quasielastic scattering.

The delayed-neutron spectra following decay of 2.05-sec ${}_{}{}^{85}{}_{}{}^{}\mathrm{As}$ and 1.7-sec ${}_{}{}^{135}{}_{}{}^{}\mathrm{Sb}$ are found to consist of a small number of discrete lines and the fluctuations in the experimental spectra differ significantly from those calculated with a statistical model. The data indicate that the $\beta$-strength function for these decays contains narrow resonances in the energy range 5-8 MeV.

We examine the energy dependence of ${\pi }^{+}$ and ${\pi }^{-}$ production in $\mathrm{pp}$ collisions for incident laboratory momenta between 6 and 400 GeV/c. The cross section for pion emission into the backward hemisphere in the laboratory frame falls substantially with incident momentum. This departure from the hypothesis of limiting fragmentation for momenta in excess of 20 GeV/c is consistent with an energy dependence of the form expected on the basis of Mueller-Regge ideas.

We report measurements of inclusive ${\pi }^0$ and $\eta$ production from 21-GeV bremsstrahlung on protons, at $p_T$ between 1 and 2 GeV/c. The ${\pi }^0$ cross section is reasonably well described by a single term of the constituent-interchange model, involving the irreducible subprocess $\overline{q}p\to \mathrm{qq}\pi$. The $\frac{{\pi }^0}{{\pi }^{+}}$ ratio is approximately 0.8 throughout our kinematic region. The $\frac{\eta }{{\pi }^0}$ ratio averages 0.53±0.17.

We have measured inelastic Compton scattering of 21-GeV bremsstrahlung photons on protons, for $p_T$ above 1 GeV/c. The yield of photons after subtracting ${\pi }^0$ and $\eta$ decay contributions appears to be nonhadronic and is greater than parton-model predictions for integer-charged partons. The constituent-interchange model provides a possible explanation.

The strong projectile—charge-state dependence of $K$ x-ray production in gases establishes a charge-state scale for ions penetrating solids. Si $K$ x-ray cross sections in gaseous Si${\mathrm{H}}_4$ were compared to those in solid Si for 40-MeV O (6+ to 8+) and 86-MeV Ar (6+ to 16+) projectiles. For Ar an effective charge of 11 ± 1 is found compared to an emergent charge of 14.8 ± 0.5. The result is discussed in terms of alternate models for steady-state excitation in solids.

In a new technique for studying electron collisions, the electrons are confined by electromagnetic fields and exposed to a known low density of atoms or molecules. Collisions rates are measured by electron diffusion in the trap. The use of spin-oriented atoms allows triplet and singlet contributions to be separated. Results of such studies are reported for room-temperature collisions of electrons with potassium atoms and with nitrogen molecules.

Experimental results are presented which verify a nonlinear skin effect of high-power microwaves incident on a collisionless, uniform plasma having a sharp boundary. The skin depth, observed by microwave reflection techniques, increases with the incident microwave power.

We measured several characteristics of the x-ray emission from plasmas produced at the focus of a high-power (∼10 GW) laser. X-ray spectra in the 1-2-keV region show that the plasmas contain highly stripped atoms (10-12 electrons missing from Al, 20-22 from Zn, and 36-38 from Gd). The laser-plasma x-ray source can emit about 0.1 J of x rays above 1 keV in 1 nsec from a volume about 100 μm in diameter. This corresponds to more than ${10}^{13}$ W/${\mathrm{cm}}^3$.

The dependence of energetic x-ray emission from laser-produced plasmas on laser energy, pulse duration, and atomic number of the target ($Z=4\mathrm{} \mathrm{to} 42$) has been studied for irradiations of ${10}^{13}$ to ${10}^{16}$ W/${\mathrm{cm}}^2$. Energetic x-ray emission is more than ${10}^3$ times greater than bremsstrahlung expected for a Maxwellian electron velocity distribution and is more sensitive to energy density in the target than to power density.

Simulations and theory of driven plasmas show the existence of long-lived, extremely intense spikes of high-frequency electric field, accompanied by a self-consistent depression in density. These entities are the limit to which solitons collapse in a driven plasma when the wave-particle interaction is included. Alterations in the density profile due to such entities is especially important for the absorption of radiation in inhomogeneous plasmas.

The ion-ion instability is studied in a cylindrical double-plasma device. Low frequency cylindrical standing waves are found which are one-dimensional in character with frequency proportional to beam velocity. An approximate dispersion relation for the cylindrical standing waves is derived.

We present the first measurements of the power, polarization, and frequency spectrum of the electron cyclotron emission from a tokamak plasma. The radiation is not polarized, does not have the previously predicted spectrum, and under certain circumstances is an order of magnitude above the predicted power level. We interpret the results in terms of a scrambling of polarization on reflection within the torus and in terms of the emission from suprathermal electrons.

The Rayleigh-Taylor instability in laser-driven spherical implosions can be stabilized by convective flow and by the "fire-polishing" effect, but the size of the stabilization effect depends on details of the thermal conductivity near the ablation surface.

We have observed and confirmed significant ion heating by the electrostatic ion-cyclotron instability in a barium plasma. We present spectroscopic evidence showing that this mechanism drastically alters the velocity distribution, demonstrating at least a highly nonlinear process and giving strong evidence for randomization of the particle motion. Experimental corroboration of a theory of Drummond and Rosenbluth is presented.

When nuclear spin relaxation in solids is due to rapid random rotational motion of molecular groups, magnetic relaxation parameters are dynamically coupled to populations of molecular rotational states. Relaxation of magnetization induces population differences between clockwise and anticlockwise rotational states (rotational polarization), resulting in nonexponential magnetic relaxation. At low temperature a nonequilibrium population difference between rotational states may be generated by a temperature change, and subsequent relaxation induces magnetic dipolar polarization.

We report measurements of the scattering and absorption of 3.39-μm light by electron-hole drops in Ge. An unexpected Fabry-Perot effect in our samples allows us to measure not only the drop size but also their absolute concentration and the optical indices of refraction of the electron-hole condensate.

Crystal field parameters of Tb, Dy, and Er in Sc, Y, and Lu are summarized. These parameters are obtained from magnetization measurements on dilute single crystals, and successfully checked by a number of different methods. The crystal field parameters vary unpredictably with the rare-earth solute. $B_{40}$, $B_{60}$, and $B_{66}$ are similar in Y and Lu. Crystal field parameters for the pure metals Tb, Dy, and Er are estimated from the crystal fields in Y and Lu.