We present a simple form for the vector and axial-vector charges, transformed so that their matrix elements between (constituent) quark-model states correspond to measurable transitions between physical states. A comparison with experiment of predictions for pionic transitions is made.

It is shown that multiphoton ionization of unpolarized atoms with circularly polarized light can lead to the production of highly polarized electrons. The connection of this effect with the Fano effect in single-photon ionization is discussed.

The lifetime of the $5{}_{}{}^1{}_{}{}^{}D_2^{}{}_{}{}^{}$ state of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ was measured by the beam-foil, zero-field, level-crossing techniques. The result is compared with measurements based on conventional beam-foil and level-crossing methods. A multiparameter least-squares reduction of the data was used to determine the alignment in addition to the lifetime, thus eliminating the need for separate measurements to determine the alignment.

Substantial nuclear orientation of excited ${\mathrm{F}}^{19}$ has been preserved in flight through vacuum at velocities where only a few electrons remain bound. Identification of the fraction of atoms with one electron has been made by applying a weak field and observing the effect of the atomic precession in flight on the $\gamma$-ray angular correlation.

The narrow spectral bandwith (0.4 Å) of a Nd-glass laser was tuned over a range of 40 Å to populate selectively the $6f$ level of cesium atoms. The resulting variation of the multiphoton ionization probability was investigated as a function of the laser wavelength.

We have observed the second-sound contribution to the Brillouin spectrum of liquid ${\mathrm{He}}^4$ near the $\lambda$ transition at saturated vapor pressure and at 25.1 atm. Its spectral shape is compared with theoretical predictions. We have determined the intensity ratio of second- and first-sound scattering between ${10}^{-5\mathrm{}}{}_{}{}^{\circ }{}_{}{}^{}\mathrm{K}<T_{\lambda }-T<\mathrm{}{10}^{-1\mathrm{}}{}_{}{}^{\circ }{}_{}{}^{}\mathrm{K}$, and we present data on the dispersion and damping of high-frequency first and second sound.

A new type of diffusion is observed. The observed dependences and magnitude of the diffusion coefficient are consistent with the theory of "classical" diffusion due to thermal equilibrium fluctuations for closed line configurations. The experimental results with the toroidal field are essentially the same as those without the toroidal field. The shear may be ineffective in modifying the diffusion rate because of the short perpendicular diffusion damping time compared with the parallel phase mixing time.

We have proved the strong subadditivity of quantum-mechanical entropy and the Wigner-Yanase-Dyson conjecture.

The magnetic resonance of dilute La${\mathrm{Ru}}_2$:Gd has been observed in both the superconducting and normal states. A reduction in the $g$ shift and an increase in the thermal broadening were observed, upon going from the normal to the superconducting regime. The spin-orbit scattering rate, $\frac{1}{{\tau }_{\mathrm{s}.\mathrm{o}.\mathrm{}}}$, is estimated from both EPR and the re-entrant behavior of the upper critical field in La${\mathrm{Ru}}_2$:Gd.

The interband optical conductivity of potassium has been calculated in the range 1-10 eV by a first-principles technique. Energy levels, wave functions, and matrix elements were obtained at 2470 inequivalent points in the Brillouin zone from a self-consistent calculation using the method of linear combinations of atomic orbitals. Good agreement with experiment was obtained. An explanation is given for the increased absorption observed in the 5-10-eV range.

A study of the thermal depolarization spectra for crystals of calcium fluoride containing trivalent gadolinium has been made before and after oxygen contamination. In the oxygen-contaminated crystals, a new ionic thermocurrent peak, with an activation energy of 0.49 eV and a reciprocal frequency factor of 5 × ${10}^{-14\mathrm{}}$ sec, is attributed to the relaxation of ${\mathrm{Gd}}^{3+}$-${\mathrm{F}}^{-}$ dipoles in the $T_1$ complex (${\mathrm{Gd}}^{3+}$$\mathrm{O}_4^{}{}_{}{}^{2-}$${\mathrm{F}}^{-}$).

The center produced by ionizing radiation which has been generally accepted to be the intrinsic $V^{-}$ center in nominally pure MgO is shown to be actually associated with an aluminum impurity. A stable center with identical $g$ values is produced by irradiation with energetic particles and its properties are compatible with the intrinsic $V^{-}$ center.

Angular distributions of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ produced in the reaction ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ + ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ → ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ + ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ have been measured at a center-of-mass energy of 36 MeV. Data were taken for the reactions ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$(${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$)${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$(${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$)${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$ in order to cover the complete angular range (${16}^{\circ }<~{\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}<~{165}^{\circ }$). The angular distributions are symmetric about ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}={90}^{\circ }$ and closely follow a ${\left(sin\theta \right)}^{-1\mathrm{}}$ dependence. This is interpreted as indicating that the reaction proceeds primarily through compound-nucleus formation.

We have observed the influence of the nuclear quadrupole moment on the $\gamma$-ray angular correlation following Coulomb excitation by heavy ions scattered through angles of about 90°. A prolate quadrupole moment precesses the $\gamma$-particle correlation in the opposite direction to that produced by a moment of oblate shape. The method has been applied to the first $2^{+}$ states of ${}_{}{}^{150}{}_{}{}^{}\mathrm{Sm}$ and ${}_{}{}^{194}{}_{}{}^{}\mathrm{Pt}$, which are found to be prolate, $Q=-1.25\mathrm{}\pm 0.2$ b, and oblate, $Q=+0.77\mathrm{}\pm 0.5$ b, respectively.

We investigate the question of quantum-electrodynamic radiative corrections to atomic transition frequencies. It is shown that the Heisenberg equations of motion allow a novel and fruitful exploitation of the concept of radiation reaction.

A scaling relation, $\frac{d\ln \left[{\sigma }_n\mathrm{}\right(s\left)\right]}{d\ln s}\to p\left(\frac{n}{\ln s}\right)$, for high-energy production of $n$ particles is proposed. This relation is supposed to be valid for large $n$ and large $s$. An extension to present energies is suggested and compared with experiment.

The absolute cross section for the $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ reaction was measured in a 12-MeV total c.m. energy range centered at the mass of the $\varphi$ meson. We observe a deviation from the $s^{-1\mathrm{}}$ dependence of the cross section predicted by quantum electrodynamics when hadronic modifications are neglected. A good fit to the data requires that one take into account $\gamma \to \varphi \to \gamma$ virtual transitions. Direct evidence for such a vacuum-polarization effect is thus established with a confidence level higher than 0.99.

In studying the single-pion production amplitudes in the vector-meson mass range ($\rho$ and $K^{*}$) we observed zeros and structures in $\mathrm{Re}{\rho }_{10}^{11}$ and ${\rho }_{1-1}^{11}$ density matrix elements. The zero of $\mathrm{Re}{\rho }_{10}^{11}$ is observed to be approximately independent of beam momentum, charge state, or strangeness of the vector meson and is invariant under $s-t$ crossing at ${\Delta }^2\approx m_v^{}{}_{}{}^2-m_{\mathrm{ps}}^{}{}_{}{}^2$. This gives a strong support to absorptive models. Our analysis shows inconsistencies in the recent amplitude analysis.

Coincidence measurements are reported between the characteristic $K$- shell x rays emerging from a target and the protons of energy 0.3-3 MeV, scattered by 5° from an incident beam, that cause the primary $K$-shell ionization. Absolute impact-parameter-dependent differential $K$-shell ionization cross sections are deduced for Al, Ca, Ni, and Ag. In a reduced plot the data follow a common curve that coincides with the semiclassical prediction of Bang and Hansteen.

We have observed spin conversion of orthopositronium and parapositronium in interaction with photoexcited, metastable, paramagnetic triplet states of phosphorescent molecules in rigid solutions, through changes in the positron lifetime spectra induced by light. The results bear on the statistics of the spin conversion processes, and on the diffusion of positronium in solids.