The possibility that dimuons observed in $\nu \left(\overline{\nu }\right)-N$ scattering are due to the production of a neutral heavy lepton is considered. Various distributions are presented.

A $T^2$ behavior for the conductivity across the layers is observed in $4Hb$-Ta${\mathrm{S}}_2$ crystals below 35 K. This indicates that tunneling occurs between metallic layers separated by an insulating layer. Evidence for thermally activated hopping is observed at higher temperatures.

We have searched for production of $\varphi$ mesons at high transverse momenta. Upper limits with a 95% confidence level on the ratio $\frac{\varphi }{{\pi }^{-}}$ ranging from 0.055 at $p_t=2.48\mathrm{}$ GeV/c to 0.103 at $p_t=3.33\mathrm{}$ GeV/c are given, ruling out the $\varphi$ meson as a significant source of the high-$p_t$ leptons observed to be produced directly in hadron collisions.

A pulsed HCl chemical laser is used to excite HCl molecules vibrationally in the presence of Br atoms in a discharge-flow reactor. The rate of the reaction $\mathrm{Br}+\mathrm{HCl}\mathrm{}\left(v\right)\mathrm{}\to \mathrm{HBR}+\mathrm{Cl}$ increases by a factor of ${10}^{11}$ at room temperature if $\mathrm{HCl}\mathrm{}(v=0\mathrm{})\mathrm{}$ is excited into $v=2\mathrm{}$. Excitation occurs predominantly for ${\mathrm{H}}^{35}$Cl. Cl atoms generated by the laser-stimulated reaction react with ${\mathrm{Br}}_2$ to form BrCl, which is detected by time-resolved mass spectrometry and shows an enrichment of ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$ (90% ${}_{}{}^{35}{}_{}{}^{}\mathrm{Cl}$).

Mass-spectrometric observations have been made of H${\mathrm{D}}^{-}$, ${\mathrm{D}}_2^{-}$, ${\mathrm{H}}_3^{-}$, ${\mathrm{H}}_2$${\mathrm{D}}^{-}$, H${\mathrm{D}}_2^{-}$, and ${\mathrm{D}}_3^{-}$, using a hollow-cathode duoplasmatron negative-ion source operating between 0.1 and 2 Torr. Both the diatomic and triatomic hydrogen negative ions appear stable, with half-lives greater than ${10}^{-5\mathrm{}}$ sec. Attenuation-cross-section measurements of ${\mathrm{D}}_2^{-}$ and ${\mathrm{D}}_3^{-}$ with helium between 3 and 5 keV yield average values of (5.5 and 7.0) × ${10}^{-15\mathrm{}}$ ${\mathrm{cm}}^2$, respectively.

The photodissociation cross section for $\mathrm{C}{{\mathrm{O}}_3}^{-}+h\nu \to \mathrm{C}{\mathrm{O}}_2+{\mathrm{O}}^{-}$ has been measured from 6400 to 5650 Å using a drift-tube mass spectrometer and a continuously tunable dye laser. The cross section has very detailed structure, which is interpreted as reflecting the vibrational levels of a bound, predissociating state of C${\mathrm{O}}_3^{-}$.

rf power near the ion cyclotron-resonance frequency has been used to produce a hundredfold increase (from ≲ 1 to ∼ 100 eV) in the ion temperature in a toroidal octupole device. The heating produces no noticeable instabilities or other deleterious effects except for a high reflux of neutrals from the walls. The heating rate is consistent with theory and the limiting ion temperature is determined by charge-exchange losses.

Nonlinear damping of a broad-band spectrum of plasma waves has been observed. Frequencies lower than the spectrum are growing from background noise. A shift of the entire spectrum towards lower frequencies results. The evolution of the spectrum is in good agreement with the predictions of weak-turbulence theory. Measurements of the electron velocity distribution are presented.

The nature of a particle orbit in an electrostatic plasma wave is modified by a magnetostatic field, because there exists a set of resonant parallel velocities $\frac{(\omega +l\Omega )}{k_z}$. If the wave amplitude ${\Phi }_0$ is sufficiently large, neighboring resonant regions overlap, and the particle motion becomes stochastic; the threshold condition is ${k_z}^2\left(\frac{e}{m}\right){\Phi }_0\left|J_l\right(k_{\perp }\rho \left)\right|\approx \frac{{\Omega }^2}{16}$. As an application, a weakly damped intermediate-frequency ion-acoustic wave may be used to heat the tail of an ion distribution.

We present an analytic solution for Raman backscatter in a cold homogeneous plasma, valid until saturation by breaking of the longitudinal waves, or by self-consistent depletion of the pump. We give quantitative values for the pump strength necessary for the former to occur first, and the transmission at saturation. Nonlinear particle bunching causes growth of electromagnetic sidebands. In quarter-critical plasma, a sideband at $\omega =\frac{3}{2}{\omega }_0$ reaches 8% of the pump intensity at wave breaking.

The depressions of the superconducting transition temperature $T_c$ as a function of Pr concentration and the specific-heat jump $\Delta C$ at $T_c$ as a function of $T_c$ have been measured for the singlet-ground-state system $\left(La\mathrm{Pr}\right){\mathrm{Sn}}_3$. The results are well represented by numerical calculations based on the Pr energy-level scheme determined from separate measurement of the Schottky heat-capacity anomaly and the Van Vleck paramagnetic susceptibility contributed by the Pr ions.

We report new evidence that intrinsic surface states play a predominant role in determining Schottky-barrier energies for III-V semiconductors. Namely, empty surfacestate levels have been measured (using photoelectron yield spectroscopy) for (110) GaSb, GaAs, GaP, InSb, and InAs whose one-electron energies correlate with Schottky-barrier energies reported by Mead and Spitzer. Also, these sharp molecularlike surface states are shown to be insensitive to metal overlayers and to be cation derived.

Results from capacitance measurements on $n$-type silicon versus donor concentration show the onset of a possible divergence (polarization catastrophe) in the static dielectric constant at a critical concentration $N_c$, which is donor dependent, as $N_c$ is approached from the insulating side. A substantial deviation from Clausius-Mosotti behavior occurs as $N\to N_c$.

It is shown that a correct interpretation of the spectroscopic data for most chemisorbed systems implies the existence of considerable screening and polarization effects. A specific view of chemisorption on transition metals is suggested, incorporating the importance of the metallic nature of the substrate as well as the effect of the local environment of the adsorbate.

The orientation of the scaling axes at nonsymmetric critical and multicritical points is discussed. Although nonuniversal, the orientations at a spin-flop bicritical point may be found to leading order in the magnetic anisotropy and in $\epsilon =4-d$ (where $d$ is the dimensionality). The resulting geometry of the antiferromagnetic phase boundaries accords well with new experimental data.

I have determined the phase boundaries, magnetization discontinuity across the spin-flop transition, and divergence of the susceptibility close to the bicritical point in antiferromagnetic GdAl${\mathrm{O}}_3$. The experiments yield the first confirmation of the predictions of renormalization-group studies of the anisotropy crossover exponent, orientation of scaling axes, and some exponent relations.

It is shown that the forward-angle cross section in heavy-ion reactions can be strongly enhanced by indirect processes in the projectile or outgoing nucleus. This is demonstrated specifically for the reaction ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$(${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$)${}_{}{}^{120}{}_{}{}^{}\mathrm{Sn}$ at 100 MeV, where data for the relevant transitions exist. At the lower energy of 60 MeV, which is just above the barrier, the effect on the forward cross section vanishes but at large angles beyond the peak the cross section is reduced in agreement with experiment.

The breaking of the Zweig-Iizuka rule in vector-meson decays is explained by mixing the $\omega$, $\varphi$, and $\psi$ mesons with a new SU(4)-singlet meson $O$ (a Pomeron daughter), expected to lie between 1.4 and 1.8 GeV/${\mathit{c}}^2$. We predict rates for many $\psi$-decay modes. The $O$ meson itself is predicted to decay copiously into $\rho \pi$, but its branching ratios into the $K\overline{K}$, $e^{-}{e}^{+}$, and ${\mu }^{-}{\mu }^{+}$ modes are severely suppressed.

The $2{}_{}{}^3{}_{}{}^{}S_1^{}{}_{}{}^{}-2\mathrm{}{}_{}{}^3{}_{}{}^{}P_2^{}{}_{}{}^{}$ energy splitting of positronium has been observed by inducing rf transitions in a weak magnetic field (≃ 50 G) in the absence of a buffer gas and observing a resonant increase in the Lyman-$\alpha$ emission. We obtain 8628.4±2.8 MHz, which is within 2 standard deviations of the theoretical value computed to order $\alpha {}_{}{}^3{}_{}{}^{}R$ by Fulton and Martin.

Measurements are reported of $T_1\left(\omega \right)$ for ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ impurity in solid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ at molar volume 21 ${\mathrm{cm}}^3$ and temperature 0.6 K. Data for fractional impurity concentrations $x_3$ of 1.0×${10}^{-3\mathrm{}}$, 0.5×${10}^{-3\mathrm{}}$, and 0.25×${10}^{-3\mathrm{}}$ show striking anomalies at about 1.3 and 2.6 MHz, superimposed on a background obeying $x_3{T}_1=1.3\mathrm{}\times {10}^{-2\mathrm{}} \exp (\frac{\omega }{7.4}\times {10}^6)$ sec. A theory is proposed which fits this background and yields a value for the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$-${}_{}{}^4{}_{}{}^{}\mathrm{He}$ tunneling frequency of about 1 MHz. The anomalies are not fully explained.