The short-wavelength collective excitations in liquid rubidium at 320 K have been studied by coherent neutron scattering. For values of $\kappa =\frac{2\pi }{\lambda }$ up to 1.0 ${\mathrm{\AA }}^{-1\mathrm{}}$, clear evidence of propagating modes was found from the shape of the scattering function $S(\kappa , \omega )$ at constant values of $\kappa$. This result shows that the existence of such modes does not depend upon either quantum effects or low thermal population of the modes.

Liquid rubidium has been simulated on a computer. Density fluctuations in the computer liquid are essentially identical with those in the real liquid as measured by neutron in-elastic-scattering experiments. Hence the interaction potential used for the simulation should be considered reliable for the study of liquid rubidium. Density waves are found to propagate even at wavelengths as small as the nearest neighbor distance in the liquid, a property not found in liquid argon.

A calorimetric investigation of the magnetic-nonmagnetic transition of an impurity (Ce) in a superconducting binary-alloy matrix (La, Th) is reported for the first time. The continuous demagnetization of the Ce ions with increasing Th composition is documented in terms of the specific heat jump at the superconducting transition temperature $T_c$ as a function of $T_c$. A recent calculation by Müller-Hartmann and Zittartz for superconducting Kondo systems describes these data remarkably well out to ∼ 70 at.% Th, but fails at higher Th compositions.

The infrared absorption in NaF at the two C${\mathrm{O}}_2$ laser wavelengths 10.6 and 9.3 μm was measured between 4 and 400 K. The results complement the previously measured absorption for higher temperatures, and allow for a detailed comparison with theoretical predictions. The experimental temperature dependence at 10.6 μm can be excellently fitted by a curve expected for three-phonon processes in the whole temperature range; the absorption at 9.3 μm fits a mixture of three- and four-phonon processes.

We have observed the nuclear resonances of five shells of Cu atoms which are near neighbors to single Fe atoms in dilute alloys of $\mathrm{Cu}\mathrm{Fe}$, following four shells from 300 K to well below the Kondo temperature, 29 K. The spin density has the same temperature dependence as the magnetic susceptibility, showing that contrary to some speculation there is no drastic change in the spatial polarization associated with the "Kondo condensation."

Thermally stimulated ionic conductivity measurements have been made of sodium motion through Si${\mathrm{O}}_2$ grown thermally on silicon, and through thermal Si${\mathrm{O}}_2$ after bombardment by ${\mathrm{Ar}}^{+}$, ${\mathrm{B}}^{+}$, and ${\mathrm{P}}^{+}$ ions of 5 keV energy. Ion implantation of Si${\mathrm{O}}_2$ by glass-forming ions such as ${\mathrm{B}}^{+}$ or ${\mathrm{P}}^{+}$ creates traps at the Si${\mathrm{O}}_2$-Al interface that can markedly reduce ${\mathrm{Na}}^{+}$ motion in Si${\mathrm{O}}_2$.

The ($\alpha , 3n\gamma$) reaction has been used to study the level structure of ${}_{}{}^{151}{}_{}{}^{}\mathrm{Gd}$. Energy spacings and other information indicate a small deformation for the observed $i_{\frac{13}{2}}$ decoupled band; whereas, a large prolate deformation is indicated by the normal rotational band associated with the $h_{\frac{11}{2}}$ hole excitation. A simple explanation for these two shapes in ${}_{}{}^{151}{}_{}{}^{}\mathrm{Gd}$ is given, based on the Nilsson diagram, and the behavior is shown to be related to the well-known shape change occurring between 88 and 90 neutrons.

A distorted-wave Born-approximation (DWBA) calculation has been done for the reaction ${}_{}{}^{62}{}_{}{}^{}\mathrm{Ni}$(${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$)${}_{}{}^{64}{}_{}{}^{}\mathrm{Ni}$, in which full account is taken of finite-range and recoil effects. It is found that finite-range no-recoil calculations for this reaction overestimate the DWBA cross-section by about a factor of 5. The no-recoil result concerning the strong dependence of the cross section on the single-particle states involved is confirmed by this fullrecoil calculation.

We have shown that backbending can occur in rotational bands of odd-$A$ nuclei. The $\mathcal{I}$ versus ${\omega }^2$ plots for the lowest $h_{\frac{11}{2}}$ band in ${}_{}{}^{157,159,161}{}_{}{}^{}\mathrm{Ho}$ are rather similar to the ones for the adjacent even-even nuclei. This is interpreted to mean that the $h_{\frac{11}{2}}$ proton is not strongly involved in the mechanism producing the backbending in this region.

An experiment was done using an accelerated polarized proton beam and a polarized proton target. The elastic cross section for proton-proton scattering at 6.0 GeV/c and ${P_{\perp }}^2=0.5-1.6\mathrm{}$ ${(\mathrm{G}\mathrm{e}\mathrm{V}/\mathit{c})}^2$ was measured in the spin states ↑ ↑, ↓ ↓, and ↑ ↓ perpendicular to the scattering plane. The cross sections were found to be unequal by up to a factor of 2.

The reaction $\mathrm{pp}\to \mathrm{pp}{\pi }^{+}{\pi }^{-}$ at 205 GeV/c is analyzed in terms of the rapidities of the secondary particles to measure the contribution of the double-Pomeron exchange process. Using a sample of 191 events, we estimate the maximum possible contribution for this process to be 44 μb for the region of $\pi p$ effective mass greater than 2.0 GeV in a total cross section of 680 ± 140 μb.

A method is described for the efficient calculation of temporal correlations in systems whose equation of motion is a Fokker-Planck equation. The speed and accuracy of this approach is illustrated by a calculation of the intensity fluctuation and amplitude-phase correlation functions for a single-mode laser near threshold.

We report heat-capacity, x-ray, electrical-conductivity, and Seebeck-coefficient measurements in the range $200<T<\mathrm{}900\mathrm{}$ K, which indicate that there exist two high-temperature, band-type phases in ${\left({\mathrm{Cr}}_{0.01}{\mathrm{V}}_{0.99}\right)}_2$${\mathrm{O}}_3$. The electrical anomaly encountered in this range is considered to be an extrinsic phenomenon, attributed to the coexistence of these phases over a broad temperature range (∼ 300-500 K). The data are inconsistent with any model invoking a metal-insulator transition in this range of temperature.

The evaporation of electron-hole droplets is studied. Even at the critical temperature $T_c$, the electron-hole density of the fluid is large enough that it is not so badly represented by a plasma model. $T_c$ is obtained using an expansion to the second order in $T$ of the chemical potential $\mu (T, r_s)$ including correlation. The results of this crude method are in good agreement with experiments.

By means of time-differential observation of perturbed angular distributions of $\gamma$ radiation following the nuclear reaction ${}_{}{}^{66}{}_{}{}^{}\mathrm{Zn}(d, p)$,, the electric quadrupole interaction frequency of the isomeric ${\frac{9}{2}}^{+}$ state of ${}_{}{}^{67}{}_{}{}^{}\mathrm{Zn}$ in zinc metal has been measured as a function of temperature. At room temperature the frequency was determined to be $\frac{e^2\mathrm{qQ}}{h}=45.5\mathrm{}\left(4\right)\mathrm{}$ MHz. The temperature dependence is compared with previous results for ${}_{}{}^{111}{}_{}{}^{}\mathrm{Cd}$ in cadmium.

We present data on electroproduction of $K^{+}$ mesons off protons. Measurements were made at data points with nominal ($Q^2$, $W$) values of (0.6, 2.67), (1.2, 2.67), (2.0, 2.67), and (1.2, 2.15) in (Ge${\mathrm{V}}^2$, GeV). The virtual photoproduction cross section for $K^{+}$+MM is studied as a function of missing mass, $x^{\prime }$, ${P_{\perp }}^2$, $Q^2$, and $W$. The data show that the $K^{+}{\Sigma }^0$ cross section falls more rapidly than the $K^{+}{\Lambda }^0$ cross section as $Q^2$ increases.

We have measured $\frac{d^2{\sigma }_{\gamma }}{\mathrm{dkd}\Omega }$ for the reaction $p+p\to \gamma +\mathrm{anything}$ at incident proton energies from 50 to 400 GeV. The experiment was performed in the National Accelerator Laboratory internal target area, using a lead-glass total-absorption counter. The cross sections show a deviation from simple exponential behavior in $p_t$ for incident proton energies above 50 GeV and $p_t$ greater than about 1 GeV/c. We present preliminary results on the energy dependence of this effect.

We present data on electroproduction off protons in which a proton moving in approximately the same direction as the virtual photon is detected. Measurements were made at data points with ($Q^2$, $W$) values of (0.6, 2.67), (1.2, 2.67), (2.0, 2.67), and (1.2, 2.15) in (Ge${\mathrm{V}}^2$, GeV). The virtual photoproduction cross section for $p$+MM is studied as a function of scaling variables $x^{\prime }$ and ${P_{\perp }}^2$, azimuthal angle $\varphi$, $Q^2$, and $W$.

The accelerated-convergence expansion has generated some controversy in applications to single-energy analyses of kaon-nucleon scattering. We have applied this expansion to pion-nucleon scattering at 490 MeV as the first test of the method in a region where strong $s$-channel effects are in evidence. The ${\chi }^2$ values obtained from the accelerated-convergence-expansion analyses are in no case lower than those obtained from the corresponding conventional analyses, and we make several comments to explain this result.

We derive a modified Korteweg-de Vries equation appropriate to small-amplitude, spherically symmetric waves. A numerical solution is obtained which differs qualitatively from the one-dimensional soliton solution.