Calculations of $4f-6s$ electron exchange integrals have been made in order to determine the sign of the exchange integral and the dependence of the integral upon interatomic distance. The exchange integral is found to be positive in sign, and insensitive to changes of interatomic distance. By contrast, the magnetic interactions in rare-earth metals are quite sensitive to changes of interatomic distances in the crystal; it is concluded that this sensitivity is not attributable to variations of the exchange integral.

Observations of magnetic breakdown of cyclotron-resonance orbits in gallium are reported and interpreted as an additional scattering mechanism. Possible implications for other experiments in gallium are discussed.

New measurements of the solar oblateness have given a value for the fractional difference of equatorial and polar radii of (5.0±0.7)×${10}^{-5\mathrm{}}$. A corresponding discrepancy of 8% of the Einstein value for the perihelion motion of Mercury is implied.

Assuming that all $I=2\mathrm{}$ meson Regge trajectories have $\alpha \mathrm{}\left(0\right)<0\mathrm{}$, we derive a new set of sum rules for Compton scattering on $I>~1$ hadrons. We compare our results with experiment and with other theoretical ideas.

The total muon-capture rate in ${\mathrm{He}}^3$ is calculated using the elementary-particle treatment of $\mu$ capture in complex nuclei and the current commutation relations introduced by Gell-Mann. Our calculation gives ${\Gamma }_{\mathrm{theor}}\left({\mathrm{He}}^3\right)=2020\mathrm{}$ ${\sec }^{-1\mathrm{}}$ to be compared with ${\Gamma }_{\mathrm{exptl}}\left({\mathrm{He}}^3\right)={2170}_{-430\mathrm{}}^{+170\mathrm{}}$ ${\sec }^{-1\mathrm{}}$.

A simple description of spin-resonance transmission in a paramagnetic metal is presented and applied to the recent observation of the effect in gadolinium. The resonance condition is shown to be $\gamma B_z={\omega }_0$. As a consequence, resonance transmission occurs at a lower value of applied field than does resonance absorption. In conduction-electron spin-resonance transmission the same condition is shown to hold, and it is suggested that a measurement of the relative separation of the transmission and absorption resonances permits a determination of the conduction-electron spin susceptibility ${\chi }_s$.

Using the Fermi-liquid theory, we have calculated the wave-number-dependent rf spin susceptibility of an interacting electron gas. For large $\omega \tau$ the kernel exhibits a branch of singularities, spin waves, which show up as sidebands on the electron spin-resonance line in thin slabs of metals. The character of these spin waves and their influence on electron spin resonance is discussed in detail.

We report the first observation of spin waves in sodium and potassium at low temperatures. Utilizing the theory of Platzman and Wolff, we are able to deduce the first two Legendre coefficients of the Landau correlation function for a Fermi liquid.

Using the ac Josephson effect, we have determined that $\frac{2e}{h}=483.5912\mathrm{}\pm 0.0030$ MHz/μV. The implications of this measurement for quantum electrodynamics are discussed as well as its effect on our knowledge of the fundamental physical constants.

The wave functions and energy levels of low-lying positive-parity states of ${}_{}{}^{41}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{47}{}_{}{}^{}\mathrm{Ca}$ are calculated by assuming a configuration consisting of one hole in the $2s-1d$ shell and the valence nucleons in the $1f-2p$ shell.

Six independent combinations of cross-section data involving meson-nucleon charge-exchange amplitudes at the forward direction are analyzed in terms of $\rho$ ($J^P=1^{-}$, $I^G=1^{+}$) and $A$ ($J^P=2^{+}$, $I^G=1^{-}$) Regge-exchange model. SU(3) tests for the ratios of the Regge-pole residues give $\frac{{\gamma }_{\rho \overline{K}K}}{{\gamma }_{\rho \pi \pi }}=1.12\mathrm{}\pm 0.12$ and $\frac{{\gamma }_{A\overline{K}K}}{{\gamma }_{A\pi \eta }}=1.07\mathrm{}\pm 0.15$, consistent with exact symmetry values of 1.

The Cook-Lee model for the "second" pion-nucleon resonance (1512, ${\frac{3}{2}}^{-}$) has been generalized to arbitrary initial and final baryons. It is shown that the virtual production of $S$-wave $\rho$ mesons included in $\pi +S^{+}\to \rho +S^{+}$, where $S^{+}$ is the set of all positive-parity resonances originating in the nucleon and the 3-3 resonance, generates the pair of trajectories $S^{-}$ comprised of a series with $(T, J^P)=(\frac{1}{2}, {\frac{3}{2}}^{-}), (\frac{1}{2}, {\frac{7}{2}}^{-}), \cdots \mathrm{and} (\frac{1}{2}, {\frac{5}{2}}^{-}), (\frac{1}{2}, {\frac{9}{2}}^{-}), \cdots$. In addition, subsidiary trajectories $(\frac{1}{2}, {\frac{1}{2}}^{-}), (\frac{1}{2}, {\frac{5}{2}}^{-}), \cdots$ and $(\frac{3}{2}, {\frac{1}{2}}^{-}), (\frac{3}{2}, {\frac{5}{2}}^{-}), \cdots$ are obtained.

Monte Carlo techniques are used to evaluate particle confinement in mirror systems, including ones in which several mirrors are used in series. Predictions are compared with an experiment, and possible advantages of multiple-mirror systems with respect to plasma stability are described.

This Letter reports the observation of a Davydov splitting in the optical absorption spectrum of ${\mathrm{Cr}}_2$${\mathrm{O}}_3$. In zero external field, a transition to only one level of the Davydov pair is observed. With $H$ parallel to the $c$ axis, an additional line having a field-dependent absorption appears. The extrapolated zero-field splitting is 3.75(±0.25) ${\mathrm{cm}}^{-1\mathrm{}}$.