Small depressions of supercurrent and critical temperature that indicate intrinsic thermodynamic fluctuations have been revealed in thin superconducting tin whisker crystals.

The first direct measurements of neutron-proton and neutron-deuteron total cross sections in the momentum range 14 to 27 GeV/c are presented. The $\mathrm{np}$ total cross section apparently becomes less than the $\mathrm{pp}$ total cross section in this momentum region. Our results show no evidence for a rapid vanishing of the Glauber screening correction as predicted by Abers et al. on the basis of Regge theory.

We find the final states ${\Sigma }^{+}{K}^{+}$ and ${\Sigma }^{+}{K}^{*+}$ to be produced peripherally with evidence, in both cases, for a small backward peak. The forward differential cross sections for both reactions are compared with the predictions of a Regge-pole model. For ${\Sigma }^{+}{K}^{*+}$ we find that the angular correlations in the resonance decay are predicted quite well by an absorptive peripheral model although the model is unable to account for the production angular distribution.

A mass-shell current-algebra calculation of $\pi -\pi$ scattering is given. The Weinberg scattering lengths and effective ranges are shown to be valid within a few percent. At the $K$ meson mass, we find the essentially model-independent result ${\delta }^0-{\delta }^2\simeq 35°$. The existing data at higher energies (up to 1 GeV) can be fitted by adjusting a model-dependent parameter.

The velocity dependence of the total elastic cross section for the scattering of a fast Na atomic beam by a thermal-energy Cs beam has been investigated in the energy range 14-2300 eV. Detailed information on the interatomic potential for both the singlet and triplet state of NaCs has been obtained from an analysis of the experimental data.

The modulated cross-beam technique has been used to measure the excitation function and the polarization of the Balmer-$\alpha$ line of atomic hydrogen excited by electron impact. Normalization of the ${\mathrm{H}}_{\alpha }$ excitation function to the Born approximation above 300 eV provides cross sections in the energy range from the threshold up to 350 eV. The polarization of the ${\mathrm{H}}_{\alpha }$ line shows an abrupt decrease, which is contrary to the "normal" behavior of increasing polarization up to the threshold observed for the alkali atom resonance line.

Quantitative measurements of nonradiative decay rates in the $C{}_{}{}^2{}_{}{}^{}\Sigma _{}^{+}{}_{}{}^{}$ state of CH and CD molecules are presented via absolute phase shift versus frequency data and are interpreted as direct measures of predissociation probabilities. The $C$-state decay rates measured in CH are approximately three times larger than those in CD and comparison with absorption oscillator strength measurements shows that the predissociation probabilities of the rotational levels observed in CH range from approximately 3×${10}^7$ to 1.6×${10}^8$ ${\sec }^{-1\mathrm{}}$, i.e., approximately 3 to 18 times the radiative transition probability.

The transient and steady-state behavior of stimulated Brillouin scattering in amplifiers was investigated theoretically and experimentally. There is good agreement between calculations and measurements with high time resolution. Direct methods for measuring phonon lifetimes are presented.

The charge-exchange cross section for cesium ions moving in their own vapor has been analyzed and found sufficiently large to influence particle loss measurements made on $Q$-machine plasmas.

The electron-phonon coupling strength in Pb, as measured by the "gap ratio" $\frac{2{\Delta }_0}{k{T}_c}$, decreases with increasing pressure.

We have directly observed quantum phase fluctuations at the onset of long-range quantum phase coherence in single-crystal bulk tin as it becomes superconducting.

A temperature-dependent dip has been observed in the infrared reflectivity of chromium, which is attributed to excitation of an electron across the antiferromagnetic energy gap. At 80°K, the absorption maximum occurs at photon energy $5.1k{T}_{\mathrm{N}}$, which is larger than the value predicted by the simplest BCS-type model, $3.5k{T}_{\mathrm{N}}$. Both the position and shape of the adsorption can be explained if the effects of electron-phonon scattering are incorporated in the model.

It is found experimentally that the thermodynamic behavior of superconductors in multiple pair-breaking regimes can be described by a particularly simple formalism due to Abrikosov and Gor'kov, and Fulde and Maki.

Stress-induced nuclear quadrupolar splittings are reported for ${\mathrm{Mn}}^{2+}$ and ${\mathrm{Eu}}^{2+}$ in MgO and Ca${\mathrm{F}}_2$, respectively, using ENDOR techniques. The magnitude of all observed splittings are shown to be in agreement with point-charge estimates, in the absence of any correction for the difference between local and bulk compressibilities. An overlap contribution to the pressure-induced electric field gradient at the nucleus is calculated, and shown to be a factor of 2 smaller than the point-charge contribution. A pressure-induced dipolar contribution, appropriate to Ca${\mathrm{F}}_2$ stressed along a [111] direction, though calculated to be large (twice the point-charge value), is shown to be absent experimentally.

In addition to the two ion species previously observed in the solar wind, ${}_{}{}^1{}_{}{}^{}\mathrm{H}_{}^{+}{}_{}{}^{}$ and ${}_{}{}^4{}_{}{}^{}\mathrm{He}_{}^{++}{}_{}{}^{}$, Vela satellite measurements reveal the presence of ions of ${}_{}{}^3{}_{}{}^{}\mathrm{He}_{}^{++}{}_{}{}^{}$, ${}_{}{}^4{}_{}{}^{}\mathrm{He}_{}^{+}{}_{}{}^{}$, various ion species of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, and other unidentified heavy ions. From the number ratios of the ${\mathrm{O}}^{+7\mathrm{}}$, ${\mathrm{O}}^{+6\mathrm{}}$, and ${\mathrm{O}}^{+5\mathrm{}}$ ion species measured near earth, it may be inferred that the ionization state ratios are established deep within the solar corona at million-degree temperatures.

The consequences of the following two assumptions are discussed: (1) There exist strange leptons; (2) strangeness is conserved in all semileptonic interactions. These hypotheses could explain the absence of neutral currents in semileptonic processes and the $\Delta S=\Delta Q$ rule without assuming that the weak current transforms like a SU(3) octet. We propose experiments, well within the reach of present possibilities, to test these assumptions.