A search has been made for resonant structures with a width greater than 10 MeV/${\mathit{c}}^2$ in $\overline{p}p$ total cross section between 335 and 960 MeV/c. The measurement has been performed by a transmission method supplemented with proportional chambers and a beammonitoring spectrometer. No resonant structure has been found, and 90% confidence-level upper limits for the resonant cross sections are presented.

The prompt photon decay $\psi \mathrm{}\left(3095\right)\mathrm{}\to \gamma {\pi }^{+}{\pi }^{-}{\pi }^{+}{\pi }^{-}$ has been studied with the Mark II detector at SPEAR. This channel is found to contain a $\gamma {\rho }^0{\rho }^0$ component with ${\rho }^0{\rho }^0$ masses concentrated between 1.4 and 2.0 GeV/${\mathit{c}}^2$. The branching fraction for the $\psi \to \gamma {\rho }^0{\rho }^0$ decay with masses less than 2.0 GeV/${\mathit{c}}^2$ is measured to be (1.25±0.35±0.40)×${10}^{-3\mathrm{}}$.

A new value for the nuclear magnetic moment of ${}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}$ has been obtained: ${\mu }_{\mathrm{nucl}}\left({}_{}{}^{141}{}_{}{}^{}\mathrm{Pr}\right)=4.2754\mathrm{}\left(5\right)\mathrm{}{\mu }_N$. This is two orders of magnitude more precise than the best previous (atomic beam) measurement. Major limitations of previous measurements were circumvented by a direct measurement of the moment in an electronically excited state (${}_{}{}^1{}_{}{}^{}D_2^{}{}_{}{}^{}$ of the ${\mathrm{Pr}}^{3+}$ ion in Ca${\mathrm{F}}_2$), where electronic contributions to the nuclear moment are only 3 parts in ${10}^4$.

A kinematic analysis of broad peaks seen in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}({}_{}{}^{16}{}_{}{}^{}\mathrm{O}, \alpha )$ is performed which demonstrates that contrary to previous speculations most of these structures are not states in ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$. Much weaker structures with $E_x\left({}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}\right)\cong 25 \mathrm{and} 28$ MeV are identified as clusters of several narrow ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$ states.

The reaction rate constants for charge transfer from atomic hydrogen to ${\mathrm{O}}^{+2\mathrm{}}$ and ${\mathrm{O}}^{+3\mathrm{}}$ ions have been measured at temperatures near 1.5×${10}^4$ K by using a stored, multicharged ion gas interacting with a hydrogen atomic beam. The results are $k({\mathrm{O}}^{+2\mathrm{}}, \mathrm{H})=1.4\mathrm{}\left(0.6\right)\mathrm{}\times {10}^{-9\mathrm{}}$ ${\mathrm{cm}}^3$/sec and $k({\mathrm{O}}^{+3\mathrm{}}, \mathrm{H})=10.2\mathrm{}\left(6\right)\mathrm{}\times {10}^{-9\mathrm{}}$ ${\mathrm{cm}}^3$/sec in agreement with recent theory.

Experimentally determined intensity correlation functions of a single-mode dye laser are compared with theoretically predicted forms given in a recent paper by Graham, Höhnerbach, and Schenzle. Although good agreement is obtained in some cases for which the parameters are chosen for best fit, large discrepancies appear for other working points of the laser. These results suggest that the dynamical theory of the dye laser needs to be modified.

The structure of wall plasmas near neutralizer plates or limiters is calculated with a kinetic transport model which includes binary collision processes between the various ion, atomic, and molecular species, and the self-consistent electrostatic field. A family of solutions is found which may be used in calculating removal of heat and impurities.

The stability of multihelical tearing modes in tokamaks with shaped cross sections is determined numerically. The method allows inclusion of a large number of singular surfaces resolved with high accuracy. Poloidal and radial couplings are discussed and the convergence is well understood. Modes of high poloidal $m$ number are found to be unstable for typical equilibria. Completely stable current distributions have been constructed for $D$-shaped plasmas.

Experimental measurements of magnetic fluctuations arising from resistive magnetohydrodynamic tearing modes reveal unexpected behavior in Alcator $C$. After the plasma current has risen to its steady-state level, no significant magnetohydrodynamic activity is observed unless the electron density is above a threshold value, ${\overline{n}}_c$. For a given toroidal field, ${\overline{n}}_c$ is remarkably repeatable. We find ${\overline{n}}_c$ to be proportional to $B^2$ and independent of $I_p$.

First-principles calculations of the vibrational lifetime of atomic and molecular hydrogen adsorbed on metal surfaces due to excitation of electron-hole pairs in the substrate are reported. The calculated electronic contribution to the vibrational linewidth compares favorably with experimental observations. A correlation is demonstrated between enhanced damping rate and the passage of an adsorbate-induced resonance through the Fermi level.

The linear infrared absorption spectra of C${\mathrm{H}}_3$F gas, multilayer film, and C${\mathrm{H}}_3$F adsorbate on NaCl crystal surfaces have been found to be distinctly different and significantly coverage dependent. On resonant infrared-laser excitation of the ${\nu }_3$ internal vibration of the adsorbate C${\mathrm{H}}_3$F on NaCl, molecular desorption of C${\mathrm{H}}_3$F occurs. Measurement of the resonance, rate coefficient, and quantum yield has revealed high spectral selectivity and efficiency of the desorption due to multiphoton ($n>\mathrm{}2\mathrm{}$) adsorbate vibrational excitation.

Complementary studies of the Cu(110) surface have been carried out by means of low-energy electron diffraction and high-energy ion scattering. The results obtained from the use of the two techniques are in acceptable agreement and indicate that the interlayer spacings in the Cu(110) surface exhibit a damped, oscillatory deviation from the bulk value, in qualitative agreement with the predictions of Landman, Hill, and Mostoller.

The vibrational frequencies of selected normal modes can be obtained entirely from first principles with use of frozen phonon calculations which involve the precise evaluation of crystal total energy as a function of lattice displacement. The calculations allow a detailed analysis of the microscopic mechanisms causing phonon anomalies and softmode phase transitions. Successful calculations for Zr, Nb, and Mo have been made with use of both tight-binding and pseudopotential methods.

A system of diatomic molecules with atoms interacting via Lennard-Jones potential and with the centers of mass of molecules fixed on a square lattice is studied by molecular dynamics technique. Temperature dependences of internal energy and orientational order parameter are calculated. The development of an ordered state from a disordered state is also studied. It is found that the system undergoes a continuous orientational order-disorder transition.

Quantum fluctuations in a microscopic model of a Josephson junction including dissipative effects, parametrized by $\eta =\frac{\hslash }{2\pi e^{2}R}$ with $R$ the resistance, are discussed. It is shown that the parameter space divides sharply into two regions: One in which scaling trajectories lead to a vanishing mean tunneling rate at $T=0\mathrm{}$ and the other in which they do not.

It is argued on the basis of a new interface model that the lower critical dimension of random-field Ising systems is two, in agreement with simple domain estimates.

The temperature-dependent thermal conductivity and the charge relaxation time of a strong-coupling superconductor are determined from solutions to the Eliashberg equations and a kinetic equation for the distribution function. The results yield a pronounced maximum at low temperatures in the thermal conductivity of pure Pb and a gradual disappearance of the maximum with increasing amounts of impurity scattering.

A periodically kicked quantum rotator is related to the Anderson problem of conduction in a one-dimensional disordered lattice. Classically the second model is always chaotic, while the first is chaotic for some values of the parameters. With use of the Anderson-model result that all states are localized, it is concluded that the local quasienergy spectrum of the rotator problem is discrete and that its wave function is almost periodic in time. This allows one to understand on physical grounds some numerical results recently obtained in the context of the rotator problem.

Given the assumption that ${G_{\mathrm{ind}}}^{-1\mathrm{}}$ given by the Adler-Zee formula is positive, an explicit and rigorous upper bound is derived for it. For pure $\mathrm{SU}\mathrm{}\left(N\right)\mathrm{}$ gauge theory, ${\left(16\mathrm{}\pi G\right)}^{-1\mathrm{}}<~\left(\frac{25}{12{\pi }^2}\right)(N^2-1){{\Lambda }_N}^2$ is obtained where ${\Lambda }_N$ is the mass scale. In general the bound ${\left(16\mathrm{}\pi G\right)}^{-1\mathrm{}}<~25\left(\frac{{\pi }^2}{144}\right)C_{\psi }{\Lambda }^2$ is obtained, where $C_{\psi }$ is the coefficient of the most singular anomaly contribution in $x$ space, a constant easily determined by low-order perturbation theory for any gauge group.

A search for charged, pointlike, spin-0 particles with large couplings to the $\tau$ lepton has been done at the PEP $e^{+}{e}^{-}$ storage ring (Stanford Linear Accelerator Center). No evidence for such particles is seen, and limits are placed on the branching fraction to $\tau {\nu }_{\tau }$ as a function of mass.