Large contributions to the excitation of $4^{+}$ rotational states from $E4\mathrm{}$ transitions have been observed in precision Coulomb-excitation experiments with ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ projectiles for even-even targets in the mass range $230<~A<~252$. The values of $B(E4,0\mathrm{}\to 4)$ deduced from an analysis of the Coulomb-excitation probabilities for ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$ are $(1.10\mathrm{}\pm 0.44)e^2{\mathrm{b}}^4$ and $(1.26\mathrm{}\pm 0.52)e^2{\mathrm{b}}^4$, respectively. The deformation parameters ${\beta }_{40}$ are 0.110±0.027 and 0.100±0.028 for ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$ and ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$, respectively.

Single-particle spectra from multiparticle production in $\mathrm{pp}$ collisions at $28.5 \frac{\mathrm{GeV}}{c}$ from bubble-chamber data are compared with cosmic-ray emulsion data above ${10}^4$ GeV. The spectrum at high energies does not develop a plateau as expected from multiperipheral models, and the target-fragmentation cross section decreases, approximately as $\frac{1}{\ln s}$.

We give new experimental results on $\frac{\rho }{\omega }$ interference and two-body cross sections in $\overline{p}p$ annihilation at $2.3\frac{\mathrm{GeV}}{c}$. These are used, together with $\frac{\rho }{\omega }$ interference results from lower energies, to argue that the annihilation process is not mediated by discrete $s$-channel mesonic resonances in the mass range 2.1-2.6 GeV.

Coherent $K^{{*}^{-}}\mathrm{}\left(890\right)\mathrm{}$ production by $K^{-}$ of $10.0 \mathrm{}\left(12.7\right)\mathrm{}\frac{\mathrm{GeV}}{c}$ on $A\approx 20$ nuclei is observed with ${\sigma }_A=150\mathrm{}\pm 50 (131\mathrm{}\pm 35)$ μ b/nucleus. The $K^{*}$ alignment, $t^{\prime }$ distribution and cross section are consistent with production via isoscalar, natural-parity exchange.

High-energy total cross sections for the ${\pi }^{\pm }p$, $K^{\pm }p$, $\overline{p}p$, and $\mathrm{pp}$ reactions are analyzed using a Regge-pole model combined with an odd-signature cut. It is found that the asymptotic cross sections, when plotted versus $\omega =\frac{s}{2M_1{M}_2}$, satisfy a scaling law within specified normalization constants.

We present a dual-resonance model for $N$ pions which satisfies the Adler self-consistency condition and provides a generalization of the Lovelace-Shapiro formula for four pions. Our model has difficulty with SU(3) since there is no candidate for the $\omega$ degenerate with the $\rho$. We also discuss briefly the problem of extending the model to include fermions.

In energetic heavy-ion-atom collisions there is an extremely high probability for producing electron holes in inner shells of the collision partners. The resulting high x-ray yield opens the possibility of detecting superheavy elements by their collision-induced characteristic x rays. A $Z$ determination of fast recoils with lifetimes longer than ${10}^{-6\mathrm{}}$ sec seems to be possible. The applicability of the method is discussed.

We have measured the Lamb shift in the $n=2\mathrm{}$ state of hydrogenic carbon-12. The result is 780.1 ± 8.0 GHz as compared with the quantum-electrodynamic calculation of 783.7 ± 0.24 GHz. The ratio of the electron-pickup cross section to the $2S_{\frac{1}{2}}$ metastable state to the total electron-pickup cross section has also been determined as 0.022 ± 0.010 in argon at 25 MeV.

Photodetachment of electrons from an ${\mathrm{H}}^{-}$ beam by means of a $Q$-switched Nd laser can produce a pulsed ${\mathrm{H}}^0$ beam. We have been able to produce 20-40-nsec ${\mathrm{H}}^0$ pulses with near 100% efficiency. The technique is proposed for selection of single micropulses (¼ nsec) at the Los Alamos Meson Physics Facility for use in a high-resolution time-of-flight system, and is of potential usefulness for other negative-ion accelerators.

X-ray spectra are presented for Ar-C collisions in gas and solid (graphite) targets, for collision energies of 80 and 90 keV. In gas targets, with either carbon or argon as the target, inner-shell vacancies are produced essentially only in the argon $L$ shell. For ${\mathrm{Ar}}^{+}$ ions incident on graphite, however, there is a high probability of producing vacancies in the $K$ shell of carbon. These observations are plausibly explained within a diabatic molecular-orbitals framework, and lend strong support to such a description.

Ultrasonic absorption measurements made in the nematic liquid crystals $p$-azoxyanisole and $p$-azoxyphenetole, which were oriented by an external magnetic field, are used to calculate anisotropic viscosity coefficients. Values of $\frac{\alpha }{f^2}$ and the anisotropy of $\frac{\alpha }{f^2}$ are found to be frequency independent for frequencies of 5-18 MHz in $p$-azoxyanisole and 3-15 MHz in $p$-azoxyphenetole. The relative angular orientation dependence of the two materials is similar.

Stability of a magnetized plasma with skin current, characterized by nonuniformity of the current and the electron temperature, is analyzed for perturbations with frequency and growth rate higher than the ion gyrofrequency. New instabilities due to the electron temperature gradient are found in both ion and electron acoustic branches, important for experiments with turbulent heating. The ion-acoustic instability observed in experiments leads to a Bohm-like turbulent thermal conductivity. The theoretical results, both linear and nonlinear, agree well with experiment.

An ESR study of $v_{\mathrm{F}}$ centers in single crystals of MgO enriched in ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ is reported. The ${}_{}{}^{17}{}_{}{}^{}\mathrm{O}$ hyperfine tensor components are found to be $\left|{t_{\parallel }}^{17}\right|=104.5\mathrm{}\pm 0.5$ G and $\left|{t_{\perp }}^{17}\right|=14.5\mathrm{}\pm 0.5$ G. From these results and those for $g_{\parallel }$ and $g_{\perp }$, two parameters of the ${\mathrm{O}}^{-}$ ion in MgO are determined: The hyperfine interaction parameter ${\alpha }^{17}$ is found to be 22.8 G and the average of $r^{-3\mathrm{}}$ over the $2p$ orbital is ${<r^{-3\mathrm{}}>}_s=2.75\mathrm{}\times {10}^{25}$ ${\mathrm{cm}}^{-3\mathrm{}}$.

The reflectance and luminescence of high-purity epitaxial layers of GaAs have been studied at low temperatures. Strong polariton and spatial dispersion effects are seen for the $n=1\mathrm{}$ free exciton. The longitudinal-exciton energy is found to be 1.5151±0.0001 eV (at 2 K) and the transverse-exciton energy is quite near 1.5149 eV. Two luminescence structures at 1.5154 and 1.5148 eV are identified with radiative decay from the upper and lower polariton branches, respectively.

We report observations which can be interpreted as super-radiant laser emission in the indirect—band-gap semiconductor GaP. Optical gain, as high as ${10}^4$ ${\mathrm{cm}}^{-1\mathrm{}}$ at 2°K, has been measured over a range of temperatures from 2 to 300°K. The gain arises from a new process not important at low excitation intensities. It is demonstrated that isoelectronic traps are an important part of this new process.

The parametric excitation of density waves in semiconducting plasmas is considered. A new nonlinear mechanism for the direct conversion of photons into plasmons is presented, resulting from the nonparabolic momentum-energy relations for the single electron. Applications to InSb yield threshold intensities typically in the range ${10}^4$-${10}^6$ ${\mathrm{W}/\mathrm{c}\mathrm{m}}^2$.

The reaction ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}(\gamma ,n)$ has been studied near threshold. Intermediate structure observed in a strong $p$-wave resonance structure excited by $M1\mathrm{}$ transitions is interpreted in terms of a doorway state resulting from a particle-hole excitation of ${}_{}{}^{57}{}_{}{}^{}\mathrm{Fe}$.

A tentative explanation of the broad plateau observed in the spectra of directly scattered helium ions producing highly excited nuclear states is advanced. In the case of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ projectiles, we propose that, in addition to the suggested formation of short-lived ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ (${}_{}{}^5{}_{}{}^{}\mathrm{Li}$), the excitation of single-particle states in the continuum with and without subsequent nucleon emission can account for the data. Calculations are presented which corroborate this conjecture.

The Treiman-Yang criterion to test the dominance of the pole graph has been applied to the reaction $\mathrm{H}\mathrm{}(d,2p)n$ in the quasifree condition and at a deuteron energy of 20 MeV. The distribution obtained is not constant, thus indicating the need for further graphs.

We present the results of distorted-wave Born-approximation calculations for the reaction ${}_{}{}^{92}{}_{}{}^{}\mathrm{Mo}\mathrm{}(d,n)\mathrm{}{}_{}{}^{93}{}_{}{}^{}\mathrm{Tc}$ to unbound $d_{\frac{5}{2}}$, $s_{\frac{1}{2}}$, and $d_{\frac{3}{2}}$ analog states. Unlike the results of previous authors, our calculated angular distributions agree with experiment (to within 20%) at forward angles. We conclude that the distorted-wave Born approximation with single-particle form factors describes the reaction with as much accuracy as for bound final states.