A generalization of the Kittel-Van Vleck relationship between the gyromagnetic factor $g^{\prime }$ and the spectroscopic splitting factor $g$ is given for a large class of spin Hamiltonians with any number of levels.

Luminescent transitions at divalent copper impurities in ZnO give rise to a close-spaced, no-phonon doublet at ∼2.8590 eV, as well as a broad multiphonon side band. The transition is found to be an optical charge transfer between a highly shielded localized level of the copper impurity and a level which is strongly perturbed by the valence-band states of the crystal. The analysis provides information about the role of deep acceptor states in electronic processes in covalent solids.

The $g$ values, line shapes, and linewidths of the ESR signals from within the bulk of amorphous silicon, germanium, and silicon carbide are found to be similar to those of the electron states observed in the surface regions of the corresponding crystalline forms. Discussion is given in terms of a microcrystalline model.

The mobility of an electron in an infinite system of randomly located identical hard-core scatterers is calculated to all orders in the density of scatterers. For fixed temperature a large drop in mobility is found at a characteristic density. The possible relevance of this result to the switching effect observed in amorphous semiconductors and the metal-insulator transition in a noncrystalline system is discussed.

Measurements of acoustic attenuation in SrTi${\mathrm{O}}_3$ reveal critical scattering behavior near the structural phase transition at $T_a\cong 105$ K. Power laws for the frequency and temperature dependences have been found. By these measurements the behavior of the soft mode frequencies could be studied in a temperature range one order of magnitude closer to $T_a$ than by other methods so far.

Results of a systematic study of atomic-mass differences in the region $82<~N<~126$ are presented as plots of double-neutron separation energy and neutron-pairing energy. These plots provide information concerning the extent of the nuclear deformation which begins in the region of 90 neutrons, its dependence upon $Z$, and its gradual dissappearance in the region $106\lesssim N\lesssim 116$.

We have measured a mean life of 392 ± 12 psec for the 4.49-MeV ($5^{-}$) state of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$, corresponding to an $E2\mathrm{}$ transition strength of 1.04 ± 0.03 Weisskopf units which is considerably stronger than that predicted by a one-particle, one-hole description of the states. However, this $E2\mathrm{}$ decay rate and those of eight other $E2\mathrm{}$ transitions between odd-parity states can be understood when the states are described as admixtures of deformed and spherical wave functions.

We calculate the flux of x rays produced by low-energy cosmic-ray nuclei in HI regions. We consider electron capture to excited states by cosmic-ray nuclei of heavy elements, followed by cascades down to the ground state. It is found that the electron-capture processes may yield appreciable line intensities in the range 1-10 keV in the galactic plane.

Differential cross sections for the elastic scattering of negative pions from hydrogen have been measured over a limited range of squared four-momentum transfer ($t$) in the vicinity of $t\simeq -3\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ for incident pion momenta of 2.51, 2.76, and 3.01 GeV/c. These measurements confirm the existence of a minimum in the differential cross section in this region of incident momentum and scattering angle. The minimum occurs at a smaller value of $t$ [$t\simeq -2.6\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$] than has been observed at higher momenta.

Differential cross sections for the reactions $\overline{p}p\to {\pi }^{+}{\pi }^{-}$ and $\overline{p}p\to K^{+}{K}^{-}$ have been measured in the angular region $0.65\lesssim \left|{cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right|<\mathrm{}1.0\mathrm{}$ at 13 momenta between 0.7 and 2.4 GeV/c. These cross sections have been combined with those of Fong et al. for $\left|{cos\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\right|\lesssim 0.70$ to give complete folded angular distributions. The data are consistent with resonances in the $J=3\mathrm{}$ and $J=5\mathrm{}$ states.

In a recent series of experiments, ${\pi }^{\pm }p$ and $K^{\pm }p$ backward scattering and $\overline{p}p$ annihilations into ${\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$ in the forward-backward direction have been measured. These data are compared assuming the dominance of a baryon-exchange amplitude and the validity of the crossing-symmetry relations.

Evidence is presented for the existence of a boson resonance ($\delta$) with $M=970\mathrm{}\pm 15$ MeV and $\Gamma <~50$ MeV produced in the reaction $K^{-}p\to {\Sigma }^{+}\mathrm{}\left(1385\right)\mathrm{}{\delta }^{-}$, ${\delta }^{-}\to {\pi }^{-}\eta$. By studying the ${\delta }^{-}$ produced in association with ${\Sigma }^{+}\mathrm{}\left(1385\right)\mathrm{}$, we are able to rule out possible kinematic effects as a source of the enhancement in our data. We give upper limits to other decay modes such as $2\pi$, $3\pi$, and $K\overline{K}$.

The nonexponential ${\pi }^{+}{\pi }^{-}$ decay of neutral $K\text{'}\mathrm{s}$, due to the interference of $K_S$ and $K_L$ in this common channel, has been quantitiatively studied using a beam which is preponderantly $K^0$ at $t=0\mathrm{}$. The value (40±5)° is obtained for $\arg {\eta }_{+-}$ (${\eta }_{+-}=\frac{〈{\pi }^{+}{\pi }^{-}\mathrm{}\left|T\right|\mathrm{}{K}_L〉}{〈{\pi }^{+}{\pi }^{-}|T\times |K_S〉}$), using $\frac{\Delta m}{h}=\frac{(M_L-M_S)}{h}=0.538\mathrm{}\times {10}^{10}$ ${\sec }^{-1\mathrm{}}$; allowing for the current uncertainty in $\Delta m$, the error in $\arg {\eta }_{+-}$ becomes ± 12.5°. This result agrees with the predictions of that class of theories which give $\arg {\eta }_{+-}\simeq invtan\left(\frac{2\Delta m}{h{\Gamma }_S}\right)$, in particular the "superweak" theory, for which this prediction is exact.

We write minimal Veneziano representations, normalized to the $t$-channel $\rho$ poles, for the ${\pi }^{-}{\rho }^{+}\to {\pi }^{-}{\rho }^{+}$ and ${\pi }^{-}{A_1}^{+}\to {\pi }^{-}{A_1}^{+}$ invariant amplitudes relevant to the Adler-Weisberger theorem. Using these amplitudes and the results of other authors for ${\pi }^{-}{\pi }^{+}$ and ${\pi }^{-}{K}^{+}$, we find that the Adler-Weisberger theorem is satisfied for ${\pi }^{-}{\pi }^{+}$, ${\pi }^{-}{K}^{+}$, ${\pi }^{-}{\rho }^{+}$, and ${\pi }^{-}{A_1}^{+}$ elastic scattering if the $\rho \pi \pi$, $\rho \mathrm{KK}$, $\rho \rho \rho$, and $\rho \mathrm{AA}$ charge couplings all have the same (universal) value.

There are several experiments involving photon interactions with nucleons or nuclei which are in apparent disagreement with the usual predictions of the vector-meson-dominance model. We present a tentative analysis of these experiments in terms of additional mass dependences arising from the vector-meson amplitudes.

There are several experiments involving photon interactions with nucleons or nuclei which are in apparent disagreement with the usual predictions of the vector-meson-dominance model. We present a tentative analysis of these experiments in terms of additional mass dependences arising from the vector-meson amplitudes.

A particle spectrum is obtained from duality.

Measured energy spectra of electrons ejected in collisions of ${\mathrm{Ar}}^{+}$ ions with Ar at laboratory kinetic energies from 0.2 to 3 keV consist of a low-energy part, from 0 to ∼9 eV, showing weak oscillatory structure, and a high-energy part, from ∼9 to ∼16 eV, showing pronounced peaks. These peaks can be explained by autoionization processes of superexcited Ar in the states $\cdots 3s3p^6\mathrm{ns}$, $\mathrm{np}$ and $\cdots 3s^{2}3p^{4}4sns$, $\mathrm{np}$.

The ground-state hyperfine interval $\Delta \nu$ of muonium has been redetermined in argon by measuring the (1, 1) ↔ (1, 0) Zeeman frequency ${\nu }_1$ at that external-field value where $\frac{\partial {\nu }_1}{\partial B}=0\mathrm{}$. The measurements were performed with good statistics at much lower argon pressures than heretofore, greatly reducing uncertainties in extrapolating $\Delta \nu \mathrm{}\left(p\right)\mathrm{}$ to zero pressure. Our result, $\Delta \nu \mathrm{}\left(0\right)=4463.317\mathrm{}\pm 0.21$ MHz, disagrees with the value found by Thompson et al. in Ar, but is consistent with their result in Kr.

From measurements of ${\left(\frac{\partial p}{\partial T}\right)}_V$, values of $\frac{{\ominus }_D}{{\gamma }^{\frac{1}{3}}}$ have been obtained for bcc ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ and hcp ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. Below $\frac{T}{{\ominus }_{\mathrm{Dmax}}}\approx 0.02$ a decrease in ${\ominus }_{\mathrm{D}}$ occurs for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ but not for ${}_{}{}^4{}_{}{}^{}\mathrm{He}$.