The coherent reaction $p+A\to p{\pi }^{+}{\pi }^{-}+A$ was measured at 22.5 and 15.3 GeV in order to study diffraction dissociation free from normal Regge exchange background. Glauber-model analysis yields a $\mathrm{pN}\to N^{*}N$ signal in good agreement with $\mathrm{pp}$ scattering. Through the model it is found that ${\sigma }_T\left(N^{*}N\right)$ decreases rapidly from 36±3 mb for $M\left(N^{*}\right)=1.4\mathrm{}$ GeV to 18±4 mb for $M>~1.7$ GeV and that $\alpha \left(N^{*}N\right)\sim -0.5\mathrm{}$ for $M<\mathrm{}1.7\mathrm{}$ GeV.

I present a method to extract hadron-neutron scattering amplitudes from hadron-proton and hadron-deuteron measurements within the framework of the Glauber approximation. This method, which involves the solution of a linear integral equation, is applied to $\mathrm{pn}$ collisions between 15 and 275 GeV/c, and effects arising from inelastic intermediate states are estimated.

In a search for charmed particles the reactions ${\pi }^{-}+p\to p_r+\mu +X$ and $p+p\to p_r+\mu +X$ have been studied at beam energies of 200 and 240 GeV, respectively. Measurements of the beam particle and the slow recoil proton, $p_r$, were used to reconstruct the mass ($M$) of the $\mu +X$ system. Model-dependent upper limits, sensitive to threshold behavior, are presented for the forward production cross section times the muon branching ratio for high-mass states ($6<\mathrm{}{M}^2<54\mathrm{}$ Ge${\mathrm{V}}^2$).

In the quark bag model, the same gluon-exchange forces which make the proton lighter than the $\Delta \mathrm{}\left(1236\right)\mathrm{}$ bind six quarks to form a stable, flavor-singlet (with strangeness of - 2) $J^P=0^{+}$ dihyperon ($H$) at 2150 MeV. Another isosinglet dihyperon ($H^{*}$) with $J^P=1^{+}$ at 2335 MeV should appear as a bump in $\Lambda \Lambda$ invariant-mass plots. Production and decay systematics of the $H$ are discussed.

$\eta \gamma$ decays of ${\rho }^0$, $\omega$, and $\varphi$ are studied. We find $\Gamma (\varphi \to \eta \gamma )=55\mathrm{}\pm 12$ keV. Our data admit two solutions for $({\rho }^0, \omega )\to \eta \gamma$: Either $\Gamma ({\rho }^0\to \eta \gamma )=50\mathrm{}\pm 13$ keV, $\Gamma (\omega \to \eta \gamma )={3.0}_{-1.8\mathrm{}}^{+2.5\mathrm{}}$ keV, and the $(\omega , \rho )\to \eta \gamma$ relative decay phase is near zero; or $\Gamma ({\rho }^0\to \eta \gamma )=76\mathrm{}\pm 15$ keV, $\Gamma (\omega \to \eta \gamma )=29\mathrm{}\pm 7$ keV, and the decay phase is near 180°.

We have studied the neutral-current reactions ${\nu }_{\mu }N\to {\nu }_{\mu }{N}^{\prime }{\pi }^0$ and ${\overline{\nu }}_{\mu }N\to {\overline{\nu }}_{\mu }{N}^{\prime }{\pi }^0$ and compared them to the charged-current reactions ${\nu }_{\mu }N\to {\mu }^{-}{N}^{\prime \prime }{\pi }^0$ and ${\overline{\nu }}_{\mu }N\to {\mu }^{+}{N}^{\prime \prime }{\pi }^0$. We have measured the ratios ${R_0}^{\prime }=\frac{\sigma ({\nu }_{\mu }N\to {\nu }_{\mu }{N}^{\prime }{\pi }^0)}{2\sigma ({\nu }_{\mu }N\to {\mu }^{-}{N}^{\prime \prime }{\pi }^0)}$ and ${{\overline{R}}_0}^{\prime }=\frac{\sigma ({\overline{\nu }}_{\mu }N\to {\overline{\nu }}_{\mu }{N}^{\prime }{\pi }^0)}{2\sigma ({\overline{\nu }}_{\mu }N\to {\mu }^{+}{N}^{\prime \prime }{\pi }^0)}$ to be 0.17±0.04 and 0.39±0.18, respectively. We also present the ${\pi }^{0}p$ invariant-mass distribution of the neutrino-induced reactions.

Synchrotron radiation was used to excite x-ray spectra from monazite inclusions taken from the same piece of mica as those recently reported to show evidence of primordial superheavy elements. No evidence was found for the existence of superheavy elements in the range of $Z$ from 105 to 129, and, in particular, no evidence was found for $Z=126\mathrm{}$ at concentrations of ∼5×${10}^9$ atoms per inclusion or ∼1-2 ppm by weight.

The splitting of the magnetic dipole states in ${}_{}{}^{208}{}_{}{}^{}\mathrm{Pb}$ due to the admixture of two-particle, two-hole configurations is calculated. The qualitative structure of a one-particle, onehole calculation remains but about 30% of the $M1\mathrm{}$ strength is distributed over many levels above 8 MeV. The influence of the spin-dependent part of the interaction on the results is critically discussed.

A time-dependent Hartree-Fock method using Skyrme's interaction is presented which allows evaluation of adiabatic mass parameters by solving decoupled inhomogeneous differential equations without discretizing the continuum. The collective Schrödinger equation is constructed including corrections due to zero-point motions. Under the assumption that the collective path is given by constrained Hartree-Fock, the formalism is applied to monopole vibrations of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ and yields remarkable differences with other collective approaches and with the random-phase approximation.

Pionic $3d-2p$ atomic transitions in F, Na, and Mg have been studied using a bent crystal spectrometer. The pionic atoms were formed in the production target placed in the external proton beam of the Space Radiation Effects Laboratory synchrocyclotron. The observed energies and widths of the transitions are $E=41\mathrm{}679\left(3\right)\mathrm{}$ eV and $\Gamma =21\mathrm{}\left(8\right)\mathrm{}$ eV, $E=62\mathrm{}434\left(18\right)\mathrm{}$ eV and $\Gamma =22\mathrm{}\left(80\right)\mathrm{}$ eV, $E=74\mathrm{}389\left(9\right)\mathrm{}$ eV and $\Gamma =67\mathrm{}\left(35\right)\mathrm{}$ eV, in F, Na, and Mg, respectively. The results are compared with calculations based on a pion-nucleus optical potential.

A rotation of the perturbed angular correlation of de-excitation $\gamma$ rays from ${}_{}{}^{18}{}_{}{}^{}\mathrm{O}$ nuclei recoiling into vacuum at high velocity has been observed in a tilted-foil geometry. This rotation is due to the polarization of electronic configurations which interact strongly with the nuclear state via the hyperfine interaction. This experiment provides the first experimental evidence for polarization by surface interactions of deeply bound electrons in highly stripped oxygen ions.

A spin-rotation-type modification of a $\gamma$-ray angular-distribution pattern has been observed in $\gamma$ rays emitted from ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ nuclei recoiling from a target tilted to the direction of recoil (which is also the beam direction and the symmetry axis). The spin rotation is ascribed to the effect of hyperfine interactions with ionic states that are polarized when the ions emerge from the tilted foil.

We construct a simple model to explain the qualitative features of level clusters in the asymptotic regions or limbs of centrifugally split $J$ levels in S${\mathrm{F}}_6$, as observed in diode spectroscopy and computer experiments. Parametric formulas for cluster splittings are derived by use of methods which may be useful for analysis of other molecular and solid-state resonance effects.

We have used a colliding-beam method to find two resonances in the photodetachment of electrons from ${\mathrm{H}}^{-}$. A nitrogen laser beam is directed at variable angle across the 800-meV ${\mathrm{H}}^{-}$ beam at the Clinton P. Anderson Meson Physics Facility (LAMPF), resulting in a center-of-mass photon beam wavelength which is continuously tunable from the visible to the vacuum ultraviolet. Our preliminary measurements of the two resonances observed near 11 eV agree well with theoretical predictions within our experimental resolution of 10 meV.

Experimental data are presented which show that during lower-hybrid, radio-frequency heating of the Princeton University adiabatic toroidal compressor tokamak, parametric instabilities are excited, and the ion heating correlates with the presence of the parametric spectra. A theoretical interpretation of the parametric instabilities is presented.

Optimized current profiles are shown to be capable of providing simultaneous stability against all resistive kink modes in the tokamak.

The potential, charge density, and interface states have been calculated for the ideal interface between intrinsic GaAs, terminated on a (100) Ga plane, and intrinsic Ge. The conduction band is continuous across the interface and negligible interface dipole moment is found. Fractional occupancy of the interface bonds arises via a single partially occupied band of interface states. We find that a long-range potential disturbance must occur unless interface bonds are longer than bulk bonds by about 4%.

The momentum profiles from positron annihilation with core electrons in Al have been observed with a recently developed two-detector Doppler-broadening technique. Independent-particle-model (IPM) calculations are in good agreement with the experimental results beyond twice the Fermi momentum and suggest the absence of strong positron-electron correlation effects in this region. Comparisons of calculations with properly normalized momentum profiles indicate that high-momentum core contributions may provide information on the nature of vacancy-type defects and self-trapping effects.

Coupled plasmon modes have been observed at interfaces of thin (3-100-Å) Al films with CdSe and CdS by low-energy electron energy-loss spectroscopy. The spectral features and their dependence on film thickness demonstrate that chemically reacted layers form at the metal-semiconductor junctions with frequency-dependent dielectric constants which are significantly different from their semiconductor counterparts.

Theoretical energy distributions are presented for ultraviolet photoemission from the valence states of an ordered (1 × 1) oxygen monolayer adsorbed on a (001) Ni surface. The spectra show the expected oxygen $2p$ resonances which are split and broadened as a result of the hybridization with the Ni conduction bands. Their intensity and shape depend strongly on the detector angles and the polarization of the incident light.