A conservative upper limit of 4 times the prediction of $V-A$ theory has been determined for the process ${\overline{\nu }}_e+e^{-}\to {\overline{\nu }}_e+e^{-}$. The target detector used in a fission ${\overline{\nu }}_e$ flux of 2.8×${10}^{13}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ was a 7.84-kg plastic scintillator arrangement enclosed by 330 kg of NaI and a 2200-liter liquid detector, the latter two operated in anticoincidence with the plastic.

Total cross sections for collisions between high-energy hadrons and nuclei are calculated using both Woods-Saxon and Gaussian density distributions for the nuclei. Comparisons with measurements are made. Errors incurred by truncating multiple-scattering series are investigated.

At infinite energy, we predict: (1) ${\sigma }_{\mathrm{tot}}$ approaches infinity; (2) the ratio of the real part to the imaginary part of the forward elastic amplitude approaches zero; (3) $\frac{{\sigma }_{\mathrm{el}}}{{\sigma }_{\mathrm{tot}}}$ approaches ½; (4) the width of diffraction peak approaches zero; its product with ${\sigma }_{\mathrm{tot}}$ is a constant. We give theoretical evidence based on massive quantum electrodynamics as well as experimental evidence in support of these predictions, and a physical picture for high-energy scattering.

The consequences of the assumption that the imaginary parts of the direct-channel helicity amplitudes vanish in the forward (backward) scattering if the crossed $t$ channel ($u$ channel) is exotic are examined in the case of meson-decuplet scattering. Confining ourselves to a limited energy region above the threshold, we show that the solutions of the set of equations provided by different external helicities predict the existence of certain patterns of octet and decuplet baryons degenerate in mass and having spin and parity assignments ${\frac{5}{2}}^{\pm }$, ${\frac{3}{2}}^{\pm }$, ${\mathrm{½}}^{\pm }$.

Assuming constant but unequal asymptotic total cross sections ${\sigma }_{\pm }\left(\infty \right)$ leads to a ${\left(\ln s\right)}^2$ shrinkage of the forward elastic peak. Moreover, under rather general assumptions, $\frac{d{\sigma }^{\mathrm{el}}}{\mathrm{dt}}$ exhibits and infinitude of oscillations in $t$ as $s\to \infty$, a result derived earlier by Finkelstein within the Regge-cut model.

Seven distinct positive-ion mobilities have been found in liquid helium I at 4.2°K. These mobilities correspond to the plateau regions of a mobility discontinuity curve similar to those discovered earlier in liquids helium II, argon, and nitrogen. A semiempirical equation is given which relates the mobilities corresponding to the plateau regions to a set of integers.

Plasma-electron-echo experiments are described in which the relation between the echo wavelength and frequency is given by $\frac{{\omega }_3}{k_3}=v^{\prime }$, where $v^{\prime }$ is a constant independent of the primary frequencies used to generate the echo. The velocity $v^{\prime }$ is approximately equal to the velocity at which the electron distribution has maximum slope. It is concluded that the relation between echo frequency and wavelength is determined by the ballistic properties of the electrons.

Measurements are presented which show that the thermal conductivity $\kappa$ in a ${\mathrm{He}}^3$-${\mathrm{He}}^4$ mixture is finite but singular at the superfluid transition temperature $T_{\lambda }$. From this it can be concluded that dynamic scaling predicts a divergent mass-diffusion coefficient for the normal phase. Through a semiempirical approach, $\kappa$ for the mixture is shown to be consistent with the divergent $\kappa$ for pure ${\mathrm{He}}^4$.

Analysis of the simplest classical model for resistive diffusion in an axially symmetric Tokomak geometry shows that present experiments are in a transitional regime which requires analysis of the interaction between several distinct, nonlinearly coupled, tranient processes. A few consequences of this theory are examined, and a limiting steady state with much simpler scaling is described.

A simple model is discussed which illustrates the general features of plasma stabilization by an external feedback system. This indicates that different phase relations in the feedback loop are needed to stabilize differing classes of electrostatic instability.

Relations among critical exponents are derived. They are based upon a consideration of two correlation lengths, not necessarily equal, that arise in our analysis.

Magnon-pair modes have been studied in the quadratic layer antiferromagnet ${\mathrm{K}}_2$Ni${\mathrm{F}}_4$ at temperatures between 5 and 150°K ($T_{\mathrm{N}}=97.1\mathrm{}°$K) using the technique of second-order Raman scattering. At low temperatures the effect of magnon-magnon interactions is observed to be in excellent agreement with theoretical predictions. The temperature evolution of the pair-mode spectrum demonstrates striking differences between two and three dimensions in the frequency renormalization and damping of short-wavelength magnons.

Ground-state bands of the quadrupole type are found in even-even nuclei ranging from the most deformed to doubly magic. Their analysis indicates how an "internal stress" which tends to keep the nucleus spherical is overcome as the angular momentum increases.

Cross section and polarization in the reaction ${\pi }^{+}p\to K^{+}{\Sigma }^{+}$ have been measured at 3, 4, and 5 GeV/c and for momentum transfers up to 3 ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. Beyond the previously investigated forward peak the cross section shows a secondary maximum and a steep decrease towards large momentum transfers. The ${\Sigma }^{+}$ polarization is large and positive in this region.

A search was made for relativistic quarks of charge $\frac{e}{3}$ in cosmic-ray showers at sea level. A hodoscope of wire proportional counters was used, which was capable of measuring location and specific ionization of several particles arriving simultaneously. An upper limit for the flux of quarks observed singly in the apparatus was established, with 90% confidence, at 1.9 × ${10}^{-9\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$. Corresponding limits were set for quarks with one and two accompanying particles at, respectively, 6.5 × ${10}^{-10\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ and 2.2 × ${10}^{-9\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$.

Data from a high-resolution experiment on the reaction ${\pi }^{+}p\to {\pi }^{+}+p$ at 5 GeV/c show a very deep, sharp dip in $\frac{d\sigma }{\mathrm{dt}}$ at $t=-2.8\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ and a gentle exponential decrease in $\frac{d\sigma }{\mathrm{du}}$ between $u=-1.5\mathrm{} \mathrm{and} -3.5\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$.

The reaction $\gamma p\to \rho \omega$ was studied in a hydrogen bubble chamber using a linearly polarized photon beam. The total cross section was found to be 5.8 ± 0.5 μb at 2.8 GeV and 3.2 ± 0.3 μb at 4.7 GeV. From the decay angular distributions these cross sections have been separated into contributions from natural- and unnatural-parity exchange ${\sigma }^{\mathrm{N}}$, ${\sigma }^{\mathrm{U}}$ in the $t$ channel. For $\mathrm{}\left|t\right|<1\mathrm{}$ Ge${\mathrm{V}}^2$ ${\sigma }^{\mathrm{N}}=2.5\mathrm{}\pm 0.4$ μb, ${\sigma }^{\mathrm{U}}=2.7\mathrm{}\pm 0.4$ μb at 2.8 GeV and ${\sigma }^{\mathrm{N}}=1.8\mathrm{}\pm 0.3$ μb, ${\sigma }^{\mathrm{U}}=1.3\mathrm{}\pm 0.3$ μb at 4.7 GeV. The contributions from unnatural-parity exchange are consistent with the predictions of the one-pion-exchange model.

Muon pairs with invariant pair mass $M_{\mu \mu }$ between 1300 and 2100 MeV have been photoproduced from carbon. No evidence is found for a heavy vector boson decaying into muon pairs in this mass region, and upper limits on its production are given. Limits on a possible breakdown of quantum electrodynamics are also obtained. Assuming a breakdown in the cross section proportional to ${M_{\mu \mu }}^4$, we obtain an upper limit on the breakdown parameter $\lambda$ of $\left|\lambda \right|<\mathrm{}0.035\mathrm{}$ Ge${\mathrm{V}}^{-4\mathrm{}}$, with a confidence level of 95%.

During its occultation by the sun in October 1969, the position of the radio source 3C279 was interferometrically monitored to determine the deviation of its 9.602-GHz radiation in the solar gravitational field. Rapid instrumental calibration and negligible coronal diffraction enabled the measurement of a general relativity deflection of ${1.77}^{\prime \prime }\pm {0.20}^{\prime \prime }$ at the limb of the sun. This is in close agreement with Einstein's prediction.

We have used radio interferometry to measure the deflection of a radio source as it passed the sun. This deflection is a separable combination of refraction in the coronal electron plasma and the general relativistic effect. The observed deflection was ${1.04}_{-0.10\mathrm{}}^{+0.15\mathrm{}}$ times that predicted by Einstein's theory of general relativity. The observation also yielded a reasonable value for the coronal electron density.