We report a strong dependence of the Al $K$ x-ray cross section in solid Al targets, for thicknesses ranging from 0.5 to 25 μg/${\mathrm{cm}}^2$, on the charge state of the incident oxygen projectiles, in the energy range 12-68 MeV. The results are analyzed in terms of the dynamic screening of the projectile charge by the electrons in the dense target, yielding a dynamic screening rate $\lambda =5.5\mathrm{}\times {10}^{14}$ ${\sec }^{-1\mathrm{}}$ which is consistent with this approach.

A convergent cross-field diffusion coefficient due to flute-type thermal fluctuations (vortices) is derived, taking into account the nonlinear, orbit-diffusion effect on the dynamic screening of the interaction and the fluctuation spectrum. Because of the finite-gyroradius reduction of the correlation, there is a region where the diffusion coefficient depends on $B$ only logarithmically.

A microscopic calculation of the scattering cross sections between ${\mathrm{He}}^3$ quasiparticles and rotons in very dilute ${\mathrm{He}}^3$-${\mathrm{He}}^4$ solutions leads to theoretical results on the diffusion constant at high temperatures (∼1.5 K). These results are in good agreement with experiment and demonstrate that the cross sections between elementary excitations in liquid helium are at least in the present case strongly energy dependent.

We give a Herring-Kittel type of discussion of the nuclear-magnetic-resonance phenomena in the presumed anisotropic superfluid phase of liquid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. The results agree with Leggett's derivation for high fields in an Anderson-Morel phase but differ fundamentally in other regimes. We observe that all observations so far published suggest that the "$A$" phase is of Anderson-Morel type (probably $L=1\mathrm{}$), and the "$B$" phase of Balian-Werthamer type.

It is shown that Auger spectroscopy can be used to determine the density of valence states in compound semiconductors. We determined the density of valence states by this method in ${\mathrm{Mg}}_2$Sn and find it in basic agreement with those which we obtained by x-ray-and uv-induced photoelectron spectroscopy. A comparison is made with the calculated ${\mathrm{Mg}}_2$Sn valence band. The ${\mathrm{Mg}}_2$Sn valence band obtained by Auger spectroscopy (involving the $\mathrm{KL}$ transition in Mg) is contrasted with the analogous spectrum for Mg metal.

We present results of model calculations based on two different approximations which were both intended to be improvements over the coherent potential approximation. We show that both approximations yield nonphysical solutions; specifically, they predict average Green's functions which contain singularities on both the upper and lower halves of the complex energy plane. We conjecture that nonanalytic behavior will occur generally in high-order approximations to the average Green's function.

In this paper we evaluate the effect of the cubic crystalline field on the magnetic susceptibility of the Kondo system La: Ce. We show the coexistence of the crystal-field splitting and the Kondo effect whenever the crystal field does not remove the degeneracy of the localized states completely. The theoretical curve is in good agreement with the experimental data for a choice of the Kondo temperature $T_{\mathrm{K}}=0.1\mathrm{}$ K.

The Hall coefficient ($R$) for homogeneous potassium single crystals was measured at 4.2°K in magnetic fields ($H$) up to 85 kG. Above 15 kG, $R$ approached $H$-independent values in excellent agreement with free-electron calculations. Thus, the Fermi surface must be simply connected. Below 15 kG, $R$ exhibited weak $H$ dependence stemming almost unambiguously from scattering anisotropy (due predominantly to phonons). At low $H$, $R$ is compared with pseudopotential calculations. Correlations between $R$ and magnetoresistance are identified for either scattering or inhomogeneity phenomena.

It is shown that the depolarization field in a ferroelectric thin film changes the order of the phase transition as well as the magnitude of the polarization and transition temperature.

We have obtained inelastic electron-scattering $2_1^{+}$ and $2_2^{+}$ form factors in ${}_{}{}^{106}{}_{}{}^{}\mathrm{Pd}$ and ${}_{}{}^{114}{}_{}{}^{}\mathrm{Cd}$ in the momentum-transfer range between 0.6 and 1.8 ${\mathrm{fm}}^{-1\mathrm{}}$. The transition charge densities of the $2_1^{+}$ and $2_2^{+}$ levels were extracted from the experimental form factors by assuming a phonon model in which the one- and two-phonon states are mixed. The wave functions (transition charge densities) obtained have been found to describe reasonably the measured $2_1^{+}$ quadrupole moments and the radiative transition rates of the crossover and cascade $\gamma$ rays.

The multipole mixing in the $3^{+}$(5.22 MeV) → $2^{+}$(1.369 MeV) transition in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ has been determined by a method based on observing the asymmetry in the radiation emitted from a state which is oriented by a reaction initiated with a vector polarized beam. The particular reaction employed was ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}(p, p^{\prime }){}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}\left(3^{+}\right)$.

A model is proposed which leads to intermediate structure in isospin-forbidden reactions. It is shown that the effects predicted by the model occur in the recent data of Jolivette for ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}(d, {\alpha }_1){}_{}{}^{14}{}_{}{}^{}\mathrm{N}\mathrm{}\left(2.31\right)\mathrm{}$.

An examination of the Sato-Tomimatsu solution shows it to represent a spinning naked singularity with causality violation and a singular ergosphere. It does not contain an event horizon.

We present the results of an analysis of 8141 $K_{e4\mathrm{}}$ decays. These include (i) the form factors of the weak hadronic current and their dependences on the invariant di-lepton and di-pion masses, and (ii) the magnitude and dependence on invariant di-pion mass of the $\pi -\pi$ scattering phase shift ${\delta }_s-{\delta }_p$.

The differential cross section for ${\pi }^{-}-p$ elastic scattering has been measured at 13.8 and 22.6 GeV/c up to $-t=5\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$. The dips in the angular distribution at $-t\approx 0.8 \mathrm{and} 2.8$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ previously observed at lower momenta become less prominent at higher momentum. The $-t=2.8\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ dip is still observed at 13.8 GeV/c, but at 22.6 GeV/c it has become a sharp kink in the angular distribution. At large momentum transfers, $\frac{d\sigma }{\mathrm{dt}}$ at fixed $t$ is still decreasing with increasing $s$, but at a slower rate in the 14- to 23-GeV/c region than at lower momenta.

A modified form of the Goldberger-Miyazawa-Oehme sum rule is given in terms of experimental quantities at finite energy. It can be used either to test dispersion relations or to determine accurately and unambiguously the pion-nucleon coupling constant in terms of the $\pi N$ scattering lengths.

Assuming that the multiplicity moments $f_k\mathrm{}\left(s\right)\mathrm{}$ formed from the topological cross section ${\sigma }_n\mathrm{}\left(s\right)\mathrm{}$ or from integrated inclusive correlation functions behave for large $s$ as $f_k\mathrm{}\left(s\right)\mathrm{}\sim c_k\ln s$, we discuss a general relation between the $c_k$ and the leading asymptotic behavior of ${\sigma }_n\mathrm{}\left(s\right)\mathrm{}$. The relation has been given by Harari, but our arguments demonstrate that it is not connected with any hypothesis concerning the dependence of hadronic parameters on some underlying coupling constants.

An expression is given for the asymmetry parameter $\beta$ in terms of matrix elements of relativistic wave functions. It is predicted that $\beta$ will vary rapidly near the minimum of the photoionization continua of the alkali metals.

We have found that room-temperature HF gas at millitorr pressures, optically pumped to produce a total inversion at a rotational transition in the $v=1\mathrm{}$ vibrational state, emits a superradiant pulse with ringing after a considerable delay (∼ microseconds). A semiclassical analysis shows that for a high-gain system the pulse evolution is determined by a single parameter ${\tau }_R$, and that inhomogeneous broadening is unimportant. Close agreement between theory and experiment is obtained.

Collective excitations of the phonon gas in liquid helium-4 are considered. It is proposed that below 0.5°K there are other propagating collective excitations in addition to second sound.