The ratio of neutral-current to charged-current cross sections is determined from a sample of events obtained in an exposure of the Fermilab 15-ft hydrogen bubble chamber to a high-energy, horn-focused neutrino beam. For events with three or more prongs and with visible hadron momentum above 10 GeV/c, the ratio is 0.40 ± 0.14. A Monte Carlo calculation assuming the Weinberg-Salam model is used to correct for excluded events, yielding $R_{\frac{\mathrm{NC}}{\mathrm{CC}}}=0.48\mathrm{}\pm 0.17$.

It is shown, on very general grounds, that the Goldberger-Treiman (GT) value for the induced pseudoscalar form factor, $h_A$, in muon-capture reactions represents an upper bound for any realistic $h_A$ that takes into account corrections to (i) nuclear GT relations and (ii) the hypothesis of partial conservation of axial-vector current. The proof is independent of the particular model one might choose for these corrections. An application of this bound to muon capture on ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ makes it difficult to understand the sign of the experimentally reported induced pseudotensor form factor in ${}_{}{}^{12}{}_{}{}^{}\mathrm{B}$ $\beta$ decay.

Isospin effects in nucleon inelastic scattering have been studied by comparing quadrupole deformation parameters deduced from measured ($n, n^{\prime }$) cross sections with values for ($p, p^{\prime }$) and values for electromagnetic excitation found in the literature. Proton-vibrational nuclei with $N=50\mathrm{}$ and neutron-vibrational nuclei with $Z=50\mathrm{}$ were studied. Predicted effects of core polarization are observed. Difficulties in interpreting detailed numerical relationships are discussed.

The static quadrupole moment of the first $2^{+}$ state in ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ has been determined using the reorientation effect in the Coulomb excitation of ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ projectiles. For constructive interference from the coupling through the second $2^{+}$ state, the values obtained are $Q_{2^{+}}=-(0.073\mathrm{}\pm 0.027)e·\mathrm{b}$ and $B(E2,0^{+}\to {2_1}^{+})=(0.004\mathrm{}53\pm 0.0025)e^2·{\mathrm{b}}^2$. Our result for $Q_{2^{+}}$ strongly disagrees with a recent measurement [$Q_{2^{+}}=-(0.19\mathrm{}\pm 0.02)e·\mathrm{b})$] but is consistent with theoretical calculations [$Q_2=(0.03-0.06)e·\mathrm{b}$].

We have measured the elastic scattering from ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ of 135.1-MeV ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ and 186-MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions. The shapes of the angular distributions and the resultant optical-model analyses indicate that ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ scattering is quite similar to that of light ions, while ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions behave like heavier ions. Thus there appears to be a pronounced and quite rapid transition of scattering characteristics with projectile mass.

The evolution of a single tearing mode is investigated. The "collisionless" and "collisional" tearing modes nonlinearly evolve into the "semicollisional" regime where the dynamics of the "singular layer" are dominated by electron diffusion along the perturbed magnetic surfaces. The "semicollisional" mode grows algebraically in the nonlinear phase as in the "collisional" calculation of Rutherford.

We propose a kinetic theory for electron-drift-velocity maxima in polyatomic gases. The case of methane is considered in detail, and good agreement with experiment is obtained with use of model cross sections. The Boltzmann equation is solved directly by applying an iterative numerical technique, which converges well when inelastic scattering effects are important.

It is shown that the collisional detrapping of magnetically trapped electrons in tokamaks can excite drift tearing modes with high azimuthal mode numbers. For normal temperature gradients ($\frac{d\ln T_e}{d\ln n}>0\mathrm{}$), the modes are unstable in the collisional regime (${\nu }_{\mathrm{eff}}>{\omega }_{{}_{}{}^{*}{}_{}{}^{}e}$), but stable in the collisionless regime (${\nu }_{\mathrm{eff}}<{\omega }_{{}_{}{}^{*}{}_{}{}^{}e}$).

A theoretically based proposal of a concrete physical realization of a Lifshitz point is given for the first time. This point should occur on the $\mathcal{H}-T$ diagram of a chiral liquid crystal exhibiting a second-order transition between the smectic phases $A$ and helicoidal $C$ ($\mathcal{H}$ is a magnetic field parallel to the smectic layers). The phase diagram near this point is shown to be similar to the one obtained in the case of uniaxial magnetization.

The thermal conductivity of the two-dimensional magnetic systems ${\left({\mathrm{C}}_n{\mathrm{H}}_{2n+1}\mathrm{N}{\mathrm{H}}_3\right)}_2\mathrm{Cu}{\mathrm{Cl}}_4$ (with $n=1,2\mathrm{}$) has been measured from $0.12T_c$ to $2.5T_c$ in fields up to 6.5 T. We found a considerable heat transport by the magnetic system, both below and above $T_c$. Above $T_c$ this heat transport can be attributed to magnonlike states which can exist well into the paramagnetic region in low-dimensionality systems.

Superfluid-vortex thresholds in a rotating annulus were detected with second sound in the temperature range $0.01 \mathrm{K}<T_{\lambda }-T<\mathrm{}0.2\mathrm{} \mathrm{K}$. A rapid decrease of the threshold angular velocity ${\omega }_{c1\mathrm{}}$ was observed as $T\to T_{\lambda }$. The data can only be fitted to the theory of Fetter if a rapidly diverging vortex-core parameter is assumed.

Evidence is presented for the existence of a critical mixing point of a protein and saltwater binary mixture. The asymptotic behavior of the osmotic isothermal compressibility and the long-range correlation length near the critical mixing point is consistent with the scaling laws predicted by the mean-field theory. The dynamic behavior of concentration fluctuations is not described by the mode-coupling theory.

We show that the critical dynamics of dense pseudospin systems interacting via retarded long-range forces (e.g., acoustic phonons) gives rise to the appearance of a $Z$ branch in the central-peak dispersion which should be observable by light-scattering techniques. The evolution of an initially nonconserved quantity towards a hydrodynamic regime leads to liquidlike behavior of the solid for a range of wave vectors.

Introducing magnetic ions (e.g., ${\mathrm{Mn}}^{2+}$) into a superionic conductor produces large temperature-dependent effects on the NMR linewidths. This makes possible the determination of the mobile species, hopping times of ${10}^{-3\mathrm{}}$-${10}^{-12\mathrm{}}$ seconds, and the range of ionic motion In magnetically "tagged" Pb${\mathrm{F}}_2$, comparison is made between experiment and theory for the various regions of temperature in which the hopping rate of the ${\mathrm{F}}^{-}$ ions is slow, comparable to, or fast, compared with the ${\mathrm{F}}^{19}$ transferred hyperfine interaction with the ${\mathrm{Mn}}^{2+}$ electronic spin.

Vacancies in thermal equilibrium were investigated by measuring the Doppler broadening of the $2\gamma$ positron-annihilation line of Ta from 35 K to the melting temperature. Experimental evidence for detrapping of positrons from vacancies at high temperatures was found. The consequences of the values obtained for monovacancy-formation and -migration enthalpies, ${H_{\mathrm{IV}}}^F\approx 2.2$ eV, ${H_{\mathrm{IV}}}^M\approx 1.9$ eV, for the interpretation of radiation damage and cold-work experiments are discussed.

The optical transmission of powdered single crystals of magnetite was measured in the spectral range from 200 to 4000 ${\mathrm{cm}}^{-1\mathrm{}}$ at temperatures between 77 and 300 K. The measurements are compared with those on Ti-substituted magnetite. The spectrum of pure magnetite shows drastic changes at the Verwey transition. In the low-temperature phase, a small splitting up of the two high-temperature phonon bands is observed.

We report the first ultralow-temperature resistivity measurements on Bi with a precision better than 0.01% using a superconducting quantum interference device null detector. The results are inconsistent with simple carrier-carrier scattering. A Bloch-Grüneisen formula for electron-phonon scattering gives an approximate fit to the lowest-temperature data with an effective reduced Debye temperature of the order of 2 K.

We report results of electrical conductivity and thermoelectric power measurements on ${\mathrm{Ni}}_{1-x}{\mathrm{Co}}_x{\mathrm{S}}_2$ ($0<~x<~0.12$) in the temperature range $77 \mathrm{K}<T<\mathrm{}600\mathrm{} \mathrm{K}$. When analyzed on the basis of conventional one-electron theories, these results are difficult to explain. However, the measurements can be quantitatively interpreted in terms of a model involving polaron transport in highly correlated, narrow energy bands associated primarily with the transition-metal cations.

Dynamical caluclations which include initial- and final-state scattering effects are presented for $c(2\mathrm{}\times 2)$ O- and S-Ni(001). The dependence of emission intensity on polar angle of emission, plane of emission, photon emission, photon incidence, and polarization are reported. Evidence is presented for separating contributions from $a_1$ and $e$ symmetry orbitals in S-derived levels with use of polarized light. Results of intensity dependence on azimuthal angle for $c(2\mathrm{}\times 2)$ S-Ni(001) are shown.

Superhyperfine structure for the ferrous ion in KMg${\mathrm{F}}_3$ has been observed. A Jahn-Teller energy of 108 ${\mathrm{cm}}^{-1\mathrm{}}$ is determined from the magnitude of the $g$ factor as an upper limit, ignoring covalent contributions. The temperature dependence of the width of the normal electronic Zeeman transitions indicates an excited level at 94 ${\mathrm{cm}}^{-1\mathrm{}}$ above the ground state. This energy-level separation agrees with the calculated position of the lowest spin-orbit-split excited state reduced by the dynamic Jahn-Teller effect.