Pion production on a C${\mathrm{D}}_2$ target has been measured using the high-resolution magnetic spectrometer SPES I. Differential cross sections for the reaction $\mathrm{D}(p, {\pi }^{+})\mathrm{T}$ have been determed at $T_p=410, 605, \mathrm{and} 809$ MeV. The present data, together with previous results establish a complete angular distribution of the reaction $\mathrm{D}(p, {\pi }^{+})\mathrm{T}$ at ∼ 600 MeV and the energy dependence of the differential cross section for this reaction at several constant momentum transfers.

We have produced the van der Waals molecule NaNe in a supersonic expansion, and have studied the $A{}_{}{}^2{}_{}{}^{}\Pi \to X{}_{}{}^2{}_{}{}^{}\Sigma$ transition using a single-mode cw dye laser. Using analysis based on isotope shifts and the long-range $R^{-6\mathrm{}}$ behavior of the excited-state $A{}_{}{}^2{}_{}{}^{}\Pi$ potential, we find its well depth and location to be $D_{\mathrm{eA}}=140\mathrm{}\pm 3$ ${\mathrm{cm}}^{-1\mathrm{}}$ at ${\mathcal{r}}_{\mathrm{eA}}=(5.1\mathrm{}\pm 0.1)a_0$ and for the $X{}_{}{}^2{}_{}{}^{}\Sigma$ ground state, $D_{\mathrm{eX}}=8.1\mathrm{}\pm 0.9$ ${\mathrm{cm}}^{-1\mathrm{}}$ at ${\mathcal{r}}_{\mathrm{eX}}=(10.0\mathrm{}\pm 0.2)a_0$. These results are compared with pseudopotential calculations and several recent line-broadening and collisions experiments.

Nonlinear shift of the ion gyrofrequency by the electrostatic ion cyclotron wave is shown to detune the resonance between the ion cyclotron wave and the ion drift wave, thereby stabilizing the drift-cyclotron instability. Solution to the resulting wave equation exhibits nonlinear oscillations.

The radial localization of the destabilizing trapped-electron term that is caused by the differences in the pitch of the magnetic field and the mode structure is shown to result in a completely new form of the dispersion relation for the trapped-electron instability.

The smectic-$A$ phase of a liquid crystal is characterized by a one-dimensional mass density wave in a three-dimensional liquid. High-resolution x ray measurements in the smectic-$A$ phase of octyloxycyanobenzylidene (8OCB) show that the order-parameter scattering does not exhibit normal Bragg line profiles but rather corresponds to a power-law singularity of the form ${(q_{\parallel }-q_0)}^{-2\mathrm{}}$, with $q_{\parallel }$ being the longitudinal wave-vector component. Also, the transverse line profile is anomalous.

Metastable microalloys of 25 metallic elements with beryllium have been prepared by ion implantation. The injected atoms have been found to occupy one of three sites available in the solvent lattice. A modified Landau-Ginsburg expansion using bulk alloy variables proposed by Miedema is completely successful in predicting the observed metastable-site preferences and indicates a broader applicability of these variables than was heretofore anticipated.

In Nb${\mathrm{Se}}_3$ one-dimensional diffuse scattering was observed above 140 K and the satellite spots at a lower temperature. They correspond to the Kohn anomaly and the superlattice coupled with charge-density wave, respectively. The superlattice was found to be incommensurate, with the period $a^{\prime }=a$, $b^{\prime }\simeq 4.1b$, and $c^{\prime }=c$.

A nuclear double-resonance interferometric technique is developed and applied to a spin-$\frac{3}{2}$ system. The $90°\left({\nu }_1\right)-360\mathrm{}°\left({\nu }_2\right)$ pulse scheme which is applied to ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ in $\beta$-alumina allows the indirect detection of the first-order quadrupolar-shifted spectrum (the $\frac{3}{2}\to \frac{1}{2}$ and $-\frac{1}{2}\to -\frac{3}{2}$ transitions) through observation of the phase of the ½ → -½ central line. The broad satellites of the ${}_{}{}^{23}{}_{}{}^{}\mathrm{Na}$ spectrum in single-crystal $\beta$-alumina thus mapped out have not been reported in numerous previous NMR studies of this material.

We report the results of the first band-structure calculation for AlAs-GaAs superlattice structures consisting of several atomic monolayers of AlAs and GaAs per repeated slab. The tight-binding method is used to investigate the band gaps and the character of the electronic states as a function of the number of monolayers per slab. For any fixed concentration of Al, the material becomes direct as the number of monolayers per slab is increased. The states at the band edges are predominantly in the GaAs layers and die away into the AlAs.

Effects of interaction between two superconducting weak links (SWL) at $V=0\mathrm{}$ have been calculated using the Ginzburg-Landau theory. Variations of the critical current of one SWL affected by a dc current in a neighboring SWL are found in good qualitative agreement with a recent experiment. The current-phase relation of the combined system is computed for various separations between the two SWL's; it is shown explicitly that the system behaves as a single SWL when the spacing between links is comparable to the coherence length.

A thermochemical scheme containing two adjustable variables per element has been developed by Miedema and co-workers which correctly predicts the signs of the heats of formation of 500 binary metallic alloys. Here we propose a simple but $l$-dependent orbital quantum model based on the valence energies of hydrogenic ions which contains no adjustable elemental variables and which fits the Miedema variables for 25 simple metals with an rms accuracy of 3%.

A new quantity, the maximum of the directed momentum, is proposed which measures jetlikeness in $e^{+}{e}^{-}$ annihilation. This quantity is computed in the quark-gluon model by using renormalization-group improved perturbation theory.

Two models of $\frac{J}{\psi }$ and ${\psi }^{\prime }$ production in hadronic collisions are considered: (I) Drell-Yan quark annihilation and (II) cascade production $\mathrm{AB}\to {\chi }_{c}X$, ${\chi }_c\to \gamma \psi$. The present experimental data are shown to rule out (I) as the dominant mechanism. The angular distribution of photons from ${\chi }_c$ decay and lepton pairs from $\frac{J}{\psi }$ decays in the cascade $\frac{J}{\psi }$ production in quantum chromodynamics are predicted and may be used as a test for the models.

We interpret the broad dimuon resonance at 9.5 GeV as two or three unresolved narrow states of a $b$ quark and antiquark. We calculate the energy spectrum of $b\overline{b}$ states using a linear plus one-gluon-exchange potential.

Measurements of flux-normalized neutrino and antineutrino total charged-current cross sections ($\sigma$) in the energy range $45<E<\mathrm{}205\mathrm{}$ GeV are presented. We see no evidence for the anomalous sharp rise in $\frac{{\sigma }_{\overline{\nu }}}{{\sigma }_{\nu }}$ reported by earlier authors. The neutrino cross section rises linearly with energy and with $\frac{\sigma }{E}$ about 18% smaller than other measurements below 10 GeV. The average antineutrino slope at 55 GeV is consistent with measurements at low energy; however, a (20 ± 10)% increase is indicated over our energy range.

Cross sections for the inclusive production of charm-anticharm pairs in the hadron showers of neutrino scattering are calculated within framework of quantum chromodynamics. A branching ratio of less than ${10}^{-3\mathrm{}}$, insufficient to account for the like-sign dimuons observed by Barish et al., Benvenuti et al., and Holder et al. and trimuons observed by Barish et al. and Benvenuti et al., is obtained for ${\alpha }_s=0.4\mathrm{}$ at values of $x$ between 0.05 and 0.3, and $\nu \sim 50-75$ GeV.

The spectrum and yield of protons produced by 60-, 100-, and 200-MeV ${\pi }^{+}$ and ${\pi }^{-}$ beams on targets of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, ${}_{}{}^{62}{}_{}{}^{}\mathrm{Ni}$, and ${}_{}{}^{181}{}_{}{}^{}\mathrm{Ta}$ have been measured at 45° and 90°. A distinct high-energy component is seen in the protons from ${}_{}{}^4{}_{}{}^{}\mathrm{He}$, which is consistent with a two-body absorption mechanism. Its cross section at 220 MeV is somewhat larger than calculated from the ${\pi }^{+}$ + D process. Possible evidence is also seen for multinucleon absorption modes. The data on heavier nuclei are consistent with earlier experiments.

The ($p, n$) cross sections for fourteen nuclei from $A=89\mathrm{}$ to $A=130\mathrm{}$ were measured from about 2.5 to 5.8 MeV in order to obtain total reaction cross sections. These cross sections disagree with optical-model predictions in that the predicted $3p$ resonance is missing near $A=105\mathrm{}$ and the peak near $A=90\mathrm{}$ is replaced by a valley. The data can be described by introducing an anomalous $A$ dependence into the depth of the absorptive potential.

${\pi }^{+}$ and ${\pi }^{-}$ data were obtained for scattering off ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ca}$ and ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ at 130 MeV. The ${}_{}{}^{48}{}_{}{}^{}\mathrm{Ca}$ angular distributions showed important ${\pi }^{+}-{\pi }^{-}$ cross-section differences as well as significant position shifts of the cross-section minima, thereby indicating the sensitivity of pions for investigating neutron radii of nuclei.

A simple differential analysis of the Lamb-dip structure using a stationary helicoidal wave is described. This technique enables us to separate the anisotropic contribution from the isotropic one and shows that the observed Lamb dip on the 3.39-μm line of ${\mathrm{Ne}}^{20}$ is partially anisotropic.