Total charge-transfer cross sections of fast sodium ions on sodium atoms are calculated by an impact-parameter method using an analytical Hartree-Fock wave function. The results show oscillations in the cross section as a function of the velocity of ions, and they are compared with the experimental result observed by Daley and Perel.

We present a theoretical interpretation of an effect recently observed in two- and three-photon ionization of Cs. We show that the total cross sections for two- and three-photon ionization of a one-electron atom depend on the polarization of the incident light. Expressions are derived for the ratio of the cross section for circularly polarized light to that for linearly polarized, and their maximum values are obtained.

We present the energy-conservation relation in the presence of an ion acoustic wave. An energy-transfer collision frequency is given in terms of the energy spectrum of the ion acoustic wave. It will be shown that this satisfies the relation ${\nu }_E\simeq \left(\frac{v_0{c}_s}{{v_e}^2}\right){\nu }_{\mathrm{eff}}$, and that electron heating is realized when $v_i\ll c_s\ll v_0\ll v_e$.

We formulate a new theory of plasma turbulence which begins by viewing particle diffusion in phase space as a Weiner process. We construct the turbulent particle propagator from physical arguments and find a general expression for the turbulent diffusion coefficient and dielectric function. Earlier results of Dupree and others are extended and clarified. The method readily applies to turbulent problems with boundary conditions on the particle distribution.

We have observed a two-dimensional, gridlike deformation of a cholesteric liquid crystal in a magnetic field, proving that this periodic structure does not require space charge or fluid flow. The frequency response of the threshold voltage in an electric field shows that there is a continuous transformation from the pure dielectric to the electrohydrodynamic regime. Investigations near Grandjean-Cano disclinations show the considerable effect of torsional strain on the threshold values.

Previously unexplained asymmetries observed in neutron guides are described by modifying the neutron index-of-refraction formalism through the inclusion of the spin-orbit interaction. The latter is due to the magnetic moment of the neutron in the electrostatic dipole field at the surface of the neutron mirror. For a single reflection, this effect may be of about 1% per volt of surface dipole, and it provides us with a direct method of measuring the surface dipole barrier.

We interpret the recently observed anomalies in the phonon spectra of some transition-metal compounds as resonances in the electronic polarization. These effects are described by a specific extension of the shell model. The possible connections of these anomalies to lattice instabilities and superconductivity are discussed.

We have studied the conditions under which a carrier in a deformable lattice, characterized by a short-ranged electron-lattice interaction, can be "self-trapped" or remain untrapped. The establishment of both situations is found to be explicitly dependent on the vibrational state of the lattice. The temperature-dependent appearance or disappearance of states from the energy spectrum manifests itself in an abrupt change in the electrical properties of the material.

The temperature dependence of the elastic constant $\frac{1}{2}(c_{11}-c_{12})$ shows that the $B_{1g}$ acoustic phonon branch is the soft mode at the cooperative Jahn-Teller phase transition in DyV${\mathrm{O}}_4$. For $T>\mathrm{}2\mathrm{}{T}_{ D}$ ($T_{ D}$ is the transition temperature) the data can be described by mean field theory and show that the dominant driving mechanism for the transition is the coupling of the Jahn-Teller ions to the static elastic strain. However, for $T_D<T<\mathrm{}2\mathrm{}{T}_D$ we find significant deviations from mean field theory due to critical fluctuations.

Photoelectrons from cesiated Co films with different work functions exhibit a positive spin polarization with magnetic moments preferentially parallel to the magnetization at photon energies from 2.8 to 5.5 eV. The photoelectron polarization spectra show that the existing band-structure calculations with either a direct or nondirect transition interpretation of the photoemission process are inadequate.

A form for the relaxation shape function for a Heisenberg paramagnet is proposed which has the merit of satisfying certain sum rules and limits. It is shown by comparison with exact infinite-temperature calculations by Carboni and Richards, and inelastic neutron scattering measurements by Hutchings et al. on ${\left(\mathrm{C}{\mathrm{D}}_3\right)}_4$NMn${\mathrm{Cl}}_3$, to provide a very good description of an antiferromagnetic linear chain at all temperatures.

Measurements were made to detect $\gamma$ rays preceding isomeric fission in ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$ induced by eV-range neutrons captured in ${}_{}{}^{235}{}_{}{}^{}\mathrm{U}$. A limit of ≤ 6 × ${10}^{-5\mathrm{}}$ was placed on the ratio of the rate of isomeric fission events with prefission $\gamma$ rays to the rate for prompt fission events. This experiment provides direct evidence that the penetration of the outer barrier is much greater than that for the inner barrier for $3^{-}$ and $4^{-}$ states in ${}_{}{}^{236}{}_{}{}^{}\mathrm{U}$.

Nuclear $\gamma$ rays from kaons captured at rest in S and Cl have been observed. The $\gamma$ rays correspond to the first excited state of ${}_{}{}^{32}{}_{}{}^{}\mathrm{P}$, 78.1 keV, and the first two levels of ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$, 110 and 197 keV.

We discuss the conjecture that a determination of the axis of symmetry in a sequential decay provides the necessary information to select the reaction mechanism. Experimental results and a distorted-wave Born approximation analysis are given for the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}\mathrm{}(d,n)\mathrm{}{}_{}{}^{13}{}_{}{}^{}\mathrm{N}_{}^{*}{}_{}{}^{}\mathrm{}\left(p\right)\mathrm{}{}_{}{}^{12}{}_{}{}^{}\mathrm{C}$.

${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$-induced reactions on ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{54}{}_{}{}^{}\mathrm{Fe}$ have been studied at 48 MeV. The one- and two- proton pickup reactions were observed with large cross sections. Systematic and unexpected differences are found in the angular distributions to different final states. The reaction ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$) ${}_{}{}^{44}{}_{}{}^{}\mathrm{Ti}$ yields spectra remarkably similar to those found in the (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$) and (${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$) reactions.

We present data and coupled-channel calculations on charge-exchange reactions in ${}_{}{}^{56}{}_{}{}^{}\mathrm{Fe}$ and ${}_{}{}^{26}{}_{}{}^{}\mathrm{Mg}$ to $0^{+}$ and $2^{+}$ analog states. For the ($p,n$) reaction in the neighborhood of 20 MeV the two-step processes dominate the excited $2^{+}$ analog transitions, thus explaining the large strength of these states in the ($p,n$) spectrum. The two-step mechanism is relatively weaker but still important in the corresponding (${}_{}{}^3{}_{}{}^{}\mathrm{He},t$) reaction.

A measurement of the $\alpha -\alpha$ bremsstrahlung cross section at 9.35 MeV has established the upper limit 5.1 ${\mathrm{\mu }\mathrm{b}/\mathrm{s}\mathrm{r}}^2$ with 90% probability. We give a comparison with predictions, including only single-scattering terms.

If the electromagnetic wave theory of pulsars is correct, then particle acceleration occurs within the nebulous debris of the supernova explosion. Model calculations show that each event produces about ${10}^{49}$ erg in ionic cosmic rays. Particle energies range from ${10}^9$ to ${10}^{16}$ eV (with spectral index ∼ 2 before corrections for losses), and the chemical composition is mostly that of matter processed through several stages of nuclear burning. Both the electronic and the ionic components of the galactic cosmic rays can be maintained by particles accelerated in supernova remnants.

We find that the recent discrepancies observed by Dixit et al. in muonic-atom transition energies can be reproduced by various simple potentials.

We present new single-particle spectra and average charged multiplicity distributions for the inclusive reactions ${\pi }^{+}+p\to X$ + anything at 6 and 22 $\frac{\mathrm{GeV}}{c}$. We observe limiting behavior for exotic reactions ($X={\pi }^{-},{K_S}^0$) and nonlimiting behavior for the nonexotic reaction ($X={\pi }^{+}$).