A Curie-Weiss anomaly in the elasto-optic (Pockels') coefficient ${p_{66}}^{E=0\mathrm{}}$ measured under the "shorted" condition has been observed by spontaneous Brillouin light scattering above the ferroelectric transition at 122°K. The observed relation ${p_{66}}^{E=0\mathrm{}}=-0.0345-\frac{2.132}{\mathrm{}(T-117.45\mathrm{})\mathrm{}}$ is shown to be a direct consequence of the anomaly in the "clamped" dielectric constant ${{\epsilon }_{33}}^{X=0\mathrm{}}$.

A comparison between the $\gamma$-ray spectra following the capture of $l=0\mathrm{}$ and $l=1\mathrm{}$ neutrons in niobium shows characteristic differences which are not expected with a purely statistical model of compound nucleus decay. The data suggest that the strong $E1\mathrm{}$ $\gamma$ rays are due to particle-hole annihilations across the $Z=50\mathrm{}$ proton shell, and demonstrate the influence of two-particle, one-hole "doorway" states in the neutron capture process.

Theoretical zero-range and finite-range ($d, p$) angular distribution shapes are nearly identical; however, the cross sections differ in magnitude by a factor proportional to the square of the normalization of the deuteron internal wave function but independent of the corresponding potential. If a Hamada-Johnston wave function is used, then this zero-range multiplying factor is 2.38.

Multiple Coulomb-excitation measurements of absolute transition-matrix elements from $\beta$-band states in ${\mathrm{Sm}}^{152}$ indicate that the previously reported discrepancies with band mixing arise from a source different from that previously suggested; the matrix elements for the $2_{\beta }\to 2$, $0_{\beta }\to 2$, and $2_{\beta }\to 0$ transitions are consistent with a band-mixing parameter $Z_0\simeq 0.08$, although an inconsistency remains for the $2_{\beta }\to 4$ transition. Angular correlation studies show that $\delta (2_{\beta }\to 2)=-{67}_{-\infty }^{+54\mathrm{}}$ and $\delta (4_{\beta }\to 4)=-{2.94}_{-1.86\mathrm{}}^{+0.85\mathrm{}}$.

Measurements of transition-matrix elements between states with spin up to ${10}^{+}$ in the ground-state bands of ${\mathrm{Sm}}^{152}$ and ${\mathrm{Sm}}^{154}$ indicate large deviations from the adiabatic rotational-model predictions in ${\mathrm{Sm}}^{152}$ but not in ${\mathrm{Sm}}^{154}$. The nonrotational effects are compared with band mixing deduced from $\beta$-band de-excitation matrix elements and with measurements of changes in the mean-square radius with increasing spin.

We measured the differential production cross section for producing pions in 12.2-GeV/c $p-p$ collisions on lines of fixed $P_1$ and $P_{\perp }$ in the c.m. system. We found that $\frac{d^2\sigma }{d\Omega \mathrm{dp}}$ is maximum at $P_1=0\mathrm{}$, in disagreement with our earlier result, which supported the two-center model. We have evidence that the earlier result is wrong. It also appears that in the c.m. system, $\frac{d^2\sigma }{d\Omega \mathrm{dp}}$ is factorable into functions of $P_1$ and $P_{\perp }$. In the $P_{\perp }$ dependence we found a very sharp forward peak of the form $e^{-15\mathrm{}{P_{\perp }}^2}$.

A high-statistics (100 000 events) measurement of photoproduction of charged pion pairs on protons is reported in two parts. First, the measured cross sections are presented in a three-dimensional data matrix where all the dynamical features are explicitly shown. Second, fitting the data in the energy region 2.6-6.8 GeV with various assumptions on $\rho$ production indicates that ${\frac{d\sigma }{\mathrm{dt}}|}_{t=0\mathrm{}}$ for the photoproduction of $\rho$ decreases with increasing energy similar to $\pi N$ scattering.

Proton-proton interactions with four or more charged particles in the final state are studied over a range of incident momenta between 13 and 28.5 GeV/c. Topology cross sections are presented. The center-of-mass momentum distributions of ${\pi }^{+}$ and ${\pi }^{-}$ are determined and are successfully parametrized. The ${\pi }^{+}$ and ${\pi }^{-}$ momentum spectra are found to have approximately the same shape. Multiple fireball production is not required by our data.

Differential cross sections for the reaction ${\pi }^{-}p\to {\pi }^{0}n$ near 180° at 4, 6, 8, and 11 GeV/c have been measured. Data analysis and results are presented.

It is shown that the $K_N\mathrm{}\left(1420\right)\mathrm{}$ and the $K^{*}\mathrm{}\left(890\right)\mathrm{}$ in our 12-GeV/c $K^{+}p$ experiment fit poorly to the double-pole structure reported for the $A_2$ meson. The probability that our data agree with the double-pole hypothesis is less than 1% for the $K_N\mathrm{}\left(1420\right)\mathrm{}$ and completely negligible for the $K^{*}\mathrm{}\left(890\right)\mathrm{}$, although both resonances are fitted well by a Breit-Wigner shape. Our mass resolution is ±7 MeV at the $K_N\mathrm{}\left(1420\right)\mathrm{}$ and ±5 MeV at the $K^{*}\mathrm{}\left(890\right)\mathrm{}$.

The problem of distinguishing between kinematic enhancements and true resonance production is discussed. It is shown that a systematic study of production on nuclei should provide a way of making this distinction.

The determination of the $\rho$-photon coupling constant by photoproduction from complex nuclei can be brought into agreement with other determinations by invoking a real part of the $\rho$-nucleon scattering amplitude, thus determining the magnitude of the real part. A similar analysis with $\varphi$ mesons is possible with available data.

$S$-wave ${\pi }^{-}$-nucleus scattering lengths for nuclei of mass number 3 to 24 are extracted from all available $2P-1S$ transition-energy data in ${\pi }^{-}$-mesonic atoms.

We investigate chiral-symmetry breaking within the $K\pi$ system when a Veneziano model is assumed for various off-mass-shell extrapolations. We derive expressions for the matrix elements of $\sigma$ terms and the divergence of the strangeness-changing current and discuss the implications to chiral-symmetry-breaking interactions. Application of our results to the $K_{l3\mathrm{}}$ form factors gives $\frac{f_K}{f_{\pi }{f}_{+}\mathrm{}\left(0\right)\mathrm{}}=1.35\mathrm{}$ and the relation ${\left(\frac{f_K}{f_{\pi }}\right)}^2=cos\left[{{\alpha }_{K^{*}}}^{\prime }\mathrm{}\right(0\left)\right({{\mu }_K}^2-{{\mu }_{\pi }}^2\left)\right]$.

Molecular Raman spectra taken at high resolution with high sensitivity reveal spectral features that have not previously been observed and which can be employed to obtain quantitative information on rotational and other kinetic behavior of the molecules. Data are given for N${\mathrm{O}}_2^{-}$ and C${\mathrm{N}}^{-}$ molecular impurities in alkali halides to illustrate potential applications.

Stark-tuned level crossing resonances in an excited vibration-rotation state of methane were detected through nonlinear optical absorption. The signal accurately follows a Lorentzian line shape with a 200-kHz minimum width. Pressure broadening studies yield the rotational relaxation in the excited vibrational state.

This paper presents an analysis of gas breakdown by laser action, assuming that the final state of the laser-beam-gas interaction is described by a plasma in local thermodynamic equilibrium. A simple formula is obtained which correlates the threshold electric field with the initial gas pressure and the temperature, in agreement with experiments.

The investigation of trapped particles in a negative electrostatic well by small perturbing pulses (separation $\tau$) reveals long trapping time and anharmonic orbits. New echoes occurring at fractions of $\tau$ are observed whose frequencies are harmonics of the main echo frequency. These temporal trapped-ion echoes are very sensitive to local turbulence.

We investigate the magnetohydrodynamic equilibrium of a resistive, low-density plasma in a model stellarator field. The effect of inertia on plasma motion is treated exactly, and its influence on plasma loss determined. It is shown that the losses due to inertia are limited by the conditions for the existence of an equilibrium.

An experimental and theoretical investigation has been made of the absolute instability that occurs near $\frac{1}{2}{\omega }_c$ when two opposing drifting electron beams interpenetrate in a static magnetic field. The theory allows determination of the beam temperature by measurement of cutoff magnetic field or cutoff beam velocity. The result of the measurement is that the beam temperature is equal to the cathode temperature and we conclude that no irreversible change takes place.