Strong electron-phonon scattering results in a smearing of the peak structure in the electronic density of states in high-$T_c$ $A15\mathrm{}$ materials. This smearing may impose limits on the highest $T_c$ achievable for these and similar materials. Numerical estimates are made using band structure and electrical resistivity data.

The influence of cylindrical voids on the thermal magnetoresistance of a model metal is calculated. In the absence of lattice thermal conduction a linear thermal magnetoresistivity results from the presence of the voids in a manner similar to the electrical magnetoresistivity. However, when the lattice conductivity is present, marked deviations from linearity occur.

A marked splitting of the $5p_{\frac{3}{2}}$ peak in the uv photoemission spectrum of physisorbed Xe is observed for the first time. The splitting depends on the concentration in the adlayer, becoming apparent just before maximum coverage is reached. The lateral interactions responsible for this effect also produce a strong dispersion of the $5p$ levels.

We present an accurate determination of the energy dispersion ($E$ vs $k$) and the first direct determination of the energy-dependent lifetime $\Gamma \mathrm{}\left(E\right)\mathrm{}$ of well-defined excited Bloch states in a crystal. Using angle-resolved photoemission for Cu(100), we find that the lifetime broadening increases from $\Gamma =1.2\mathrm{}$ eV (6 × ${10}^{-16\mathrm{}}$ sec) to 1.8 eV (4 × ${10}^{-16\mathrm{}}$ sec) for ${\Delta }_1$ conduction-band states ranging 10.5 to 13.5 eV above the Fermi level. The measured dispersion (∼2% accuracy) shows a reduced effective mass ($\frac{m^{*}}{m_0}=0.90-0.94\mathrm{}$) which is related to self-energy effects.

This paper presents a field theory for the statistics of branched polymers and for the gelation transition. The gelation transition with ${\Lambda }_p{\Lambda }_L=m$, where ${\Lambda }_p$ and ${\Lambda }_L$ are the fugacities for polymer number and loop number, is shown to be in the same universality class as the $m$-state Potts model. A new fixed point governing the statistics of branched polymers in the dilute limit (${\Lambda }_p=0\mathrm{}$) in $6-\epsilon$ dimensions with $\nu =\frac{1}{2}+0.092\mathrm{}\epsilon$ and $\eta =-0.073\mathrm{}\epsilon$ is located. An old result of Zimm and Stockmayer for the radius of gyration of a Gaussion branched polymer is rederived.

The charge ratio of cosmic-ray muons with energies up to 1 TeV in the zenith-angle range 68°-82° has been measured. The data clearly show an enhancement of the charge ratio with increasing energy thus indicating a "normal" mass composition of galactic cosmic rays.

We report the observation of 46 ${\mu }^{-}{\mu }^{-}$ events in high-energy neutrino-nucleon collisions at Fermilab. Measurement of the production rate of the ${\mu }^{-}{\mu }^{-}$ events relative to that of ${\mu }^{-}{\mu }^{+}$ events in targets of different hadronic absorption lengths give $\frac{N^{\mathrm{prompt}}\left({\mu }^{-}{\mu }^{-}\right)}{N^{\mathrm{prompt}}\left({\mu }^{-}{\mu }^{+}\right)}=0.06\mathrm{}\pm 0.05$ for $p_{\mu }>5\mathrm{}$ GeV/c, and 0.12±0.05 for $p_{\mu }>10\mathrm{}$ GeV/c. The properties and possible origins of these events are discussed.

I compare gauge-theory-model predictions for exclusive pion production by the weak neutral current, incorporating corrections for scattering off nuclear targets where appropriate, with all the available data. I find that, based on these data, no model should be completely ruled out.

It has been argued recently that the inclusive, semi-inclusive, and elastic neutrinohadron data require the neutral-current parameters to lie in one of two allowed regions in coupling-parameter space (called regions $A$ and $B$). We remark in this paper that new measurements of $\nu \left(\overline{\nu }\right)p\to \nu \left(\overline{\nu }\right)p$ strongly favor region $A$ [which corresponds to the standard $\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_L\otimes \mathrm{U}\mathrm{}\left(1\right)\mathrm{}$ and $\mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_L\otimes \mathrm{SU}{\mathrm{}\left(2\right)\mathrm{}}_R\otimes \mathrm{U}\mathrm{}\left(1\right)\mathrm{}$ models] over region $B$ [which corresponds to an SU(2) ⊗ U(1) model with a ${(u, b)}_R$ doublet and $d_R$ singlet]. Neutral-current couplings of $u$ and $d$ quarks determined by this analysis are given.

We consider, within the framework of current algebra, the possibility that the up-quark mass vanishes (as an alternative to the axion). We argue that the contrary current-algebra value, $\frac{m_u}{m_d}=\frac{1}{1.8}$, is unreliable. A critical analysis leads to the conclusion that $m_u=0\mathrm{}$ is not unreasonable and furthermore leads to a surprisingly good prediction for the $\delta$-meson mass.

Two new alpha activities with half-lives of 25 and 9 min have been observed in reaction of heavy ions with a variety of heavy targets. The 25-min activity was found by combined radiochemical methods and mass separations to be an isomer in ${}_{}{}^{212}{}_{}{}^{}\mathrm{Bi}$; the 9-min activity is also likely to be an isomer in ${}_{}{}^{212}{}_{}{}^{}\mathrm{Bi}$.

A new isomer has been established in ${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$ which decays by $\alpha$ as well as $\gamma$-ray emission and probably has spin and parity $8^{+}$. It may consist of a superposition of the ${[{\left(\pi {h_{\frac{9}{2}}}^2\right)}_{0^{+}}\times {\left(\nu {g_{\frac{9}{2}}}^2\right)}_{8^{+}}]}_{8^{+}}$ and ${\left[{\left(\pi {h_{\frac{9}{2}}}^2\right)}_{8^{+}}{\left(\nu {g_{\frac{9}{2}}}^2\right)}_{0^{+}}\right]}_{8^{+}}$ configurations. From this result conclusions have been drawn about the configuration of the previously known high-spin isomer in ${}_{}{}^{212}{}_{}{}^{}\mathrm{Po}$ of spin and parity ${16}^{+}$ or ${18}^{+}$.

Time-resolved spectroscopy is applied to the problem of collisionless intramolecular relaxation within the ground electronic state of polyatomic molecules. The redistribution of vibrational energy within a molecule may be monitored by the different anharmonic shifts which occur when the energy is localized in the different modes. Picosecond infrared-laser-absorption saturation-recovery measurements on S${\mathrm{F}}_6$ show that the relaxation time, for statistical behavior to set in, falls within the limits $1 \mathrm{psec}<T_1<30\mathrm{} \mathrm{psec}$.

Inelastic and superelastic scattering of 30- and 100-eV electrons by laser-excited $6s6p{}_{}{}^1{}_{}{}^{}P$ and subsequent cascade-populated $6s6p{}_{}{}^3{}_{}{}^{}P$, $6s5d{}_{}{}^1{}_{}{}^{}D$, and $6s5d{}_{}{}^3{}_{}{}^{}D$ Ba atoms have been observed for the first time. Absolute differential cross sections for the singlet and relative scattering intensities for the triplet species have been determined in the 5°-20° angular region. Under the present conditions excitations dominate over de-excitations.

We investigate electron transport for a thermal plasma using a magnetostatic plasma model. Three cases are investigated; (1) fixed ions, only magnetic fluctuations; (2) fixed ions, magnetic and electrostatic fluctuations; (3) mobile ions, magnetic, and electrostatic fluctuations. For (1), magnetic islands as well as many unclosed field lines occurred; for (2) and (3) electrostatic convective cells occurred along with magnetic islands giving a much more turbulent situation. Generally the transport due to electrostatic convective cells dominated.

A spectrum line in the Princeton Large Torus (PLT) tokamak discharges, with wave-length measured as 2665.1 ± 0.3 Å, has been identified as the $2s^{2}2p^3{}_{}{}^2{}_{}{}^{}D_{\frac{5}{2}}^{}{}_{}{}^{}\to {}_{}{}^2{}_{}{}^{}D_{\frac{3}{2}}^{}{}_{}{}^{}$ magnetic dipole transition in Fe xx ground configuration. A variety of localized spectroscopic diagnostics, e.g., ion temperature and density distribution measurements in the high-temperature interior of the plasma, are feasible by means of forbidden lines of this type. The 2665-Å line has been used to measure near-central ion temperature in a discharge with auxiliary neutral-beam heating.

Neutron diffraction has shown evidence for a two-dimensional first-order melting transition in the first layer of NO adsorbed on graphite (0001). Two different incommensurate solid phases $\beta$ and $\gamma$ have been observed. The data suggest that ${\mathrm{N}}_2$${\mathrm{O}}_2$ dimers are standing up on the graphite surface in the $\beta$ phase and lying down in the $\gamma$ phase.

We calculate the charge distribution $\rho \mathrm{}\left(z\right)\mathrm{}$ and Fermi-level distribution among the different graphite layers in a lamellar graphite acceptor compound. The charge distribution is highly nonhomogeneous and, because of the semimetallic nature of graphite, nonlinear effects are important. The calculations for $\rho \mathrm{}\left(z\right)\mathrm{}$ are performed in terms of a generalized Thomas-Fermi model and show that there is a transition at short distances from the intercalate from a $z^{-4\mathrm{}}$ power law to an exponential asymptotic decay.

The magnetization-reversal process within a [100] [010] [001] picture-frame FeSi (3.5 wt% Si) crystal has been investigated by means of the time-dependent neutron-depolarization technique, applying a periodic block-shaped magnetic field. Various distinct states are observed in the magnetization-reversal process: firstly, nucleation of regions of reversed magnetization; subsequently, the merging of these regions into two wavy domain walls according to a sandwich structure and the motion of these straightening walls towards the center.

With an average $\sigma \approx 0.65$ amu we have measured the isotopic composition of Cr, Mn, Fe, and Ni in the galactic cosmic radiation for energies ∼300 to ∼600 MeV/amu at the detector. Large deviations from solar-system source composition reported by other workers are not observed.