We have studied $\rho -\omega$ interference in di-pion photoproduction in the energy range 5-7 GeV with a total of 630 000 pion pairs from hydrogen, carbon, and lead. The mass spectra show clear interference in the vicinity of the $\omega$ mass. A branching ratio $\frac{{\Gamma }_{\omega \to 2\pi }}{{\Gamma }_{\omega \to \mathrm{all}}}=(1.22\mathrm{}\pm 0.30)\%$ and a relative phase to the $\rho \to \pi \pi$ amplitude of 96°±15° is found, where the errors include model-dependent uncertainties and are twice the size of the statistical errors alone.

A theoretical model for the hadrons as extended objects is discussed. The size and shape of hadrons are taken into account by means of an algebraic harmonic-oscillator formalism. This model can explain, with essentially the same parameters, (a) the magnetic form factor of the proton, (b) deep-inelastic electroproduction, and (c) ${\mu }^{+}{\mu }^{-}$ pair production at high energy. The model is also consistent with the known experimental data on the spacelike and timelike pion form factor.

Combining the Chou-Yang idea with the scaling property of inelastic electron scattering experiments, we derive a scaling law for the form factors of the hadronic transitions $N\to N*$ in diffractive scattering. The agreement with experiment is very good.

The probability for producing $K$ vacancies in violent ion-atom collisions has been found to depend not only on the impact parameter, but also on the impact velocity and the number of vacancies in the atomic $2p$ subshells of the particles prior to the collision. This indicates that the $K$-electron promotion mechanism is different from the $L_{2,3}$-promotion mechanism determined for $Z_1-\mathrm{Ar}$ collisions. The $K$ vacancies are almost exclusively produced in the lower-$Z$ collision partner.

The absorption spectrum of Si${\mathrm{H}}_4$ gas has been measured in the silicon $L$ region. Three spin-orbit-split Rydberg series with sharp structure have been observed converging on the $L_{\mathrm{III},\mathrm{II}}$ edges of Si${\mathrm{H}}_4$ at 107.2 and 107.8 eV. The three series correspond in a unitedatom picture (the united atom for Si${\mathrm{H}}_4$ is argon) to transitions from a $2p$ core state to $4s$ and higher $s$ states and to $3d$ and higher $d$ states $d$ states are split into two components by the molecular field). A molecular-orbital calculation of some peak positions gives reasonable agreement with experiment.

The $K$ x-ray spectrum arising from doubly $K$-ionized gallium atoms has been studied by means of a coincidence experiment with two solid-state detectors. A new energy range in $K$ x-ray spectra (hypersatellite range) is observed. Hypersatellite lines are shifted about 15 times more than the usual satellite lines. The $K$-satellite spectrum following $\mathrm{KL}$-ionized states has also been studied.

A previous covariant evaluation of the Lamb shift for small atomic numbers $Z$ is extended to be valid for large $Z$ and agrees with independent numerical evaluations for $Z$ near 80. The results improve the precision tests of quantum electrodynamics and could be used for one-electron atoms with any $Z$, x rays at large $Z$, and superheavy elements with $Z\alpha >1\mathrm{}$. A substantially new value (due to deuteron size) is found for the deuterium Lamb shift: 1059.27 ± 0.03 MHz.

A method is suggested by which the local magnetic field direction can be determined in Tokamaks. A numerical application is made to the Princeton ST Tokamak.

The imposition of a hollow longitudinal beam of 2-kV electrons about a $Q$-machine potassium plasma column serves to deepen the radial potential well across that column. Transverse plasma flux is consequently decreased, while the peak ion density and end-plate collector current rise an order of magnitude. A calculation is made of the transverse flux of ions in the plasma column with energy sufficient to surmount the potential well.

Rheological studies on a 23/77 wt% cholesteryl chloride-cholesteryl oleyl carbonate liquid-crystal system show isothermal shear-induced texture changes. The shear-induced textures show non-Newtonian behavior at shear rates below ∼ 5 ${\sec }^{-1\mathrm{}}$ and Newtonian behavior above this value. These textures have been optically characterized as the Grandjean and focal conic. At shear rates in excess of ∼ 1000 ${\sec }^{-1\mathrm{}}$, non-Newtonian behavior is observed and identified with the homeotropic texture. The first normal-force measurements on a liquid-crystal system are reported.

From a perturbation analysis of the fluid equations for a homogeneous, unmagnetized plasma it is shown that long-wavelength ion waves are unstable when $T_e\gtrsim T_i$. The additional destabilizing effect of a current is also investigated.

The thermal resistances between seven samples of sintered copper powder and a nearly saturated dilute ${\mathrm{He}}^3$-${\mathrm{He}}^4$ solution were measured between 14 and 200 mK. All samples showed the anomalously high thermal resistances seen in metal foils, and the values are in semiquantitative agreement with recent calculations of Seiden. Reproducibility of samples was found to be excellent and oxide layers formed at room temperature had no detectable effect.

We have measured the temperature dependence of photoelectron energy distributions from nickel for $T=100\mathrm{}-400°$ C. An anomalous critical behavior in the $d$-band peak energy versus temperature was observed in the vicinity of the Curie temperature ($T_C=358\mathrm{}°$ C). A comparison of the temperature variation of $d$-band photoelectrons from nickel and palladium indicates at least partial agreement with band-structure calculations. A lower limit of the exchange splitting $\delta E_{\mathrm{ex}}\approx 0.2-0.3$ eV is estimated from the experimental data.

For a duration of several times ${10}^{-12\mathrm{}}$ sec, TO modes are excited to an occupation number exceeding the equilibrium value (at 300°K) by more than thirteen orders of magnitude. The relaxation times of these phonos are measured directly and found to agree with the known anharmonic decay at low power level. Phonon breakdown is not significant in our experiments.

The resistivity of AlMn alloys of concentrations up to 5% is found to decrease linearly in temperature above 50 K, while at lower temperatures it follows the same $T^2$ behavior observed at lower concentrations. The linear behavior of $\rho \mathrm{}\left(T\right)\mathrm{}$ rules out the possibility that AlMn is a Kondo system with $T_{\mathrm{K}}\simeq 500$ K. Possible explanations in terms of localized spin fluctuations are suggested.

Electric-field-induced scattering by normally Raman-inactive LO phonons is observed in the IV-VI-compound (NaCl structure) semiconductors PbTe and SnTe with Pb films on $p$-type samples to induce energy-band bending. The observed Raman peaks correspond to unscreened $q\approx 0$ LO phonons. A discussion of the mechanisms contributing to the surface field-induced Raman scattering in these materials is presented.

In fitting electronic band structures of solids by means of scattering phase shifts, the level of the "muffin-tin" potential can be chosen at will relative to the Fermi level. Different choices correspond to distinct ways of expressing the total valence-electron density as a sum of atomic contributions.

We have observed $\Gamma _3^{}{}_{}{}^{+}$ excitations by Raman scattering in KNi${\mathrm{F}}_3$ at 1270 ${\mathrm{cm}}^{-1\mathrm{}}$ ($17.9J$), and in NiO at 2800 ${\mathrm{cm}}^{-1\mathrm{}}$ ($18.9J$). These excitations are identified as four-magnon excitations by agreement of the peak frequencies with calculated values, and in the case of NiO by the temperature shift. Scattering by four magnons is the highest-order nonresonant Raman scattering yet observed. The excitation of four magnons is interpreted in terms of excited-state propagation effects.

The transverse relaxation rate of ${\mathrm{Eu}}^{153}$ in EuO, caused by the indirect Suhl-Nakamura interaction, has been calculated and measured. The results confirm the validity of a theoretical model that was developed recently to treat inhomogeneously broadened NMR lines. The local variation of the ${\mathrm{Eu}}^{153}$ hyperfine field is determined and interpreted in terms of a local strain.

The angular correlation of the first-emitted $\alpha$ and an $\alpha$ from the sequential decay of the ${}_{}{}^8{}_{}{}^{}\mathrm{Be}_{2.9}^{}{}_{}{}^{}$ state in the reaction ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}(d,\alpha ){}_{}{}^8{}_{}{}^{}\mathrm{Be}_{2.9}^{}{}_{}{}^{}\left(\alpha \right){}_{}{}^4{}_{}{}^{}\mathrm{He}$ strongly suggests that this reaction proceeds by compound-nucleus formation at $E_d=0.4\mathrm{}$ MeV and by a deuteron-pickup direct interaction at $E_d=1.0\mathrm{} \mathrm{and} 1.5$ MeV. The observed symmetry axis for the ${}_{}{}^8{}_{}{}^{}\mathrm{Be}_{2.9}^{}{}_{}{}^{}$ breakup distribution in its own center of mass is compared to the momentum-transfer and recoil directions associated with various possible mechanisms and appears to provide the necessary information to select the mechanism.