Transfer cross sections have been measured for ${}_{}{}^{58}{}_{}{}^{}$Ni${+\mathrm{}}^{58}$,64Ni in the energy range $E_{\mathrm{c}.\mathrm{m}.\mathrm{}=100\mathrm{}–}$107 MeV with use of time of flight in a magnetic spectrograph. The direct reactions are dominated by one-neutron transfer, with other transfer cross sections being smaller by a factor of 3–4 or more. The average kinetic energy loss is ∼2 MeV. Over the measured energy range the total transfer cross section for ${}_{}{}^{58}{}_{}{}^{}$Ni${+\mathrm{}}^{58}$Ni is smaller than that observed for ${}_{}{}^{58}{}_{}{}^{}$Ni${+\mathrm{}}^{64}$Ni by a factor of 4.

Radiative lifetimes have been measured for five triplet states of atomic oxygen. The oxygen atoms were generated by photodissociation of ${\mathrm{NO}}_2$ and the investigated states were populated through a two-step process involving a two-photon excitation to the lowest excited triplet state of even parity, 2${\mathrm{p}}^3$3p ${\mathrm{}}^3$P, followed by a one-photon excitation to the investigated state. A similar scheme is applicable to the study of excited states in many light atoms.

Measurements of static and dynamic electric birefringence of nonionic micellar solutions near the critical consolution point show a diverging Kerr coefficient B and a diverging rise time of the birefringence signal. The static data are consistent with the droplet model which predicts that B grow as the correlation length ξ. The transient behavior, observed for the first time in a critical system, shows a strong asymmetry between rise and decay of birefringence. The rise is nonexponential and follows, sufficiently close to the critical point, a universal function of scaled time. The time-scaling factor approximately behaves as ${\xi }^{\mathrm{-}2}$.

Certain polymer-coated solid surfaces prepared to produce an isotropic (random) planar liquid-crystal boundary condition can be rendered strongly anisotropic by exposure to orientationally ordered liquid-crystal phases. This effect reveals a plastic coupling of liquid crystal molecular orientation to hydrophobic surfaces which is absent for hydrophyilic surfaces.

Measurements of the scaling of 1/f noise magnitude versus resistance were made in metal films as the metal was removed by sandblasting. This procedure gives an approximate experimental realization of a Swiss-cheese continuum-percolation model, for which theory indicates some scaling properties very different from lattice percolation. The ratio of the resistance and noise exponents was in strong disagreement with lattice-percolation predictions and agreed approximately with simple continuum predictions.

Strong two-photon photoemission is observed from Ag(111) and Cu(111) surfaces with image-potential states as intermediates. Three processes are found: (a) resonant excitation, (b) relaxation into the intermediate state, and (c) energy pooling via collisions between excited electrons. For Ag(111) we find two image-potential states with binding energies of 0.77±0.03 and 0.23±0.03 eV, close to the hydrogenic values, and an unidentified state 2.57±0.05 eV below the vacuum level. The work function is 4.49±0.02 eV.

Randomly interacting p-state Potts spins may freeze into a Potts-glass phase in which the Potts symmetry is unbroken, on the average. The mean-field theory of this phase transition is presented. Unlike the spin-glass case, there exist two distinct Potts-glass phases that differ in the nature of the correlations among the many degenerate ground states of the system. For p>4, the transition from the disordered phase is unusual: The freezing occurs discontinuously but without latent heat. Similar results hold for mean-field quadrupolar-glass models.

We present a theory of the first-order transition to the metallic state in polyacetylene in terms of a crossover from a lattice of charged solitons to a regular array of polaronlike distortions. The polaronic metal is shown to have a strong indirect attractive interaction, ${\mathrm{U}}^{\mathrm{*}}$≃-2Δ/3, between electrons in the half-filled, narrow, polaron subband within the Peierls energy gap (${\mathrm{E}}_{\mathrm{g}}$=2Δ).

Determination of the magnetic properties of nearly stoichiometric ${\mathrm{EuRh}}_3$B2 on macroscopic and microscopic levels reveals that its ferromagnetism originates from the ordering of the spins of divalent Eu perpendicular to the hexagonal c aixs. This finding contradicts previous reports of Rh 4d-band itinerant-electron ferromagnetism and a nonmagnetic trivalent Eu state. The value of the ${}_{}{}^{151}{}_{}{}^{}\mathrm{Eu}$ Mössbauer quadrupole splitting, ${\mathrm{e}}^2$qQ=48±1 mm/s, is by far the largest ever reported for any Eu system and results from the extremely short Eu-Eu separation.

From structural, magnetic, ${}_{}{}^{151}{}_{}{}^{}\mathrm{Eu}$ Mössbauer and ${\mathrm{L}}_{\mathrm{III}}$ absorption-edge studies, it is observed that the valence state of Eu and the magnetism in ${\mathrm{Eu}}_{\mathrm{x}}$${\mathrm{Rh}}_3$${\mathrm{B}}_2$ (0.65≤x≤1) show unusual behavior. The Eu ions change from a predominantly divalent state for x=1.0 to a combination of divalent and mixed valent states for x<1.0. Curie temperatures and saturation moments decrease with decreasing x. The quadrupole interaction ${\mathrm{e}}^2$qQ of 770±10 MHz at the ${\mathrm{Eu}}^{2+}$ site is the largest observed to date in any Eu compound and can be understood from the unusual atomic arrangement in this structure.

A calculation is presented to explain the anomalous experimental behavior of the Si 2p core-exciton binding energy and linewidth in ${\mathrm{Si}}_{\mathrm{x}}$${\mathrm{Ge}}_{1\mathrm{-}\mathrm{x}}$ alloys. The observed minimum in the line width near x≃0.15 can be explained as being the result of a competition between intrinsic broadening due to screening and extrinsic alloy broadening. For pure Si, the binding energy is estimated to be 0.15±0.05 eV and the width is shown to be smaller that that observed at x≃0.15.

We report a model system for studying resonant tunneling in thin a-Si tunnel barriers. The system explores the interesting crossover regime between quantum mechanical tunneling and classical transport via localized states. Some surprising features of this process are revealed.

Photoluminescence spectroscopy and resonant Raman scattering were applied to investigate electronic properties of HgTe-CdTe superlattices. It is established that the spin-orbit split-off valence states in the CdTe layers are quantized and that the small band offset affects the lifetime of the holes. Radiative recombinations from electron subbands in the HgTe square wells can be measured when the subband energies are close to the conduction-band edge of CdTe. The spectra suggest that relaxation processes in the HgTe subbands involve the emission of optical phonons.

We have measured the spectrum of the cosmic background radiation in five frequency bands extending from 2.3 to 11.0 ${\mathrm{cm}}^{\mathrm{-}1}$ with a balloon-borne liquid-helium cooled pho- tometer. The photometer compares the flux from the sky to the flux from an internal blackbody at 3.2 K. All five measurements are consistent with temperatures in the range 2.78±0.11 K, which is in good agreement with temperatures measured at lower frequencies. We find no significant deviation from a thermal spectrum.

Effects that could distinguish the Lorentz ether theory from Einstein’s special relativity, and their measurability, are analyzed.

A general approximation scheme for solving the quantum Liouville equation has been developed and is presented here specifically within the Hartree approximation. This method uses the connection between the density matrix and the Wigner phase-space representations. By use of the Wigner representation the off-diagonal elements of the density matrix are expanded in powers of deviations from the mean momentum value. The time evolution of these deviations is governed by a closed self-consistent set of equations.

Measurements of the branching ratios of ten Cabibbo-suppressed hadronic weak decays of the $D^{+}$ and $D^0$ are presented from data collected with the Mark III detector SPEAR. In addition to the previously observed channels $D^0$→$K^{\mathrm{-}}$$K^{+}$ and ${\pi }^{\mathrm{-}}$${\pi }^{+}$, we report new measurements of $D^0$→${\pi }^{\mathrm{-}}$${\pi }^{+}$${\pi }^0$ and ${\pi }^{\mathrm{-}}$${\pi }^{+}$${\pi }^{\mathrm{-}}$${\pi }^{+}$, and $D^{+}$→K${¯}^0$$K^{+}$, ${\pi }^0$${\pi }^{+}$, K${¯}^{\mathrm{*}0}$(892)$K^{+}$, φ${\pi }^{+}$, $K^{\mathrm{-}}$$K^{+}$${\pi }^{+}$, and ${\pi }^{\mathrm{-}}$${\pi }^{+}$${\pi }^{+}$.

We present the results of an experiment to search for associated charm production near threshold in 13-GeV/c ${\pi }^{\mathrm{-}}$p interactions. A large aperture PWC spectrometer was sensitive to the decay fragments of the forward-produced $D^{\mathrm{*}\mathrm{-}}$’s expected from the two-body reactions ${\pi }^{\mathrm{-}}$+p→$D^{\mathrm{*}\mathrm{-}}$+${\Lambda }_c^{+}$,${\Sigma }_c$ ${}_{}{}^{+}{}_{}{}^{}$,. . . . The missing baryon mass was determined from the vector momenta of the incident pion and the candidate $D^{\mathrm{*}\mathrm{-}}$. No evidence for these reactions was found, which resulted in a 7-nb upper limit (95% confidence level) for each of the cross sections σ(${\pi }^{\mathrm{-}}$p→$D^{\mathrm{*}\mathrm{-}}$${\Lambda }_c^{+}$) and σ(${\pi }^{\mathrm{-}}$p→$D^{\mathrm{*}\mathrm{-}}$${\Sigma }_c^{+}$).

Fluctuations of the order parameter of chiral transition in a hot and dense quark gas are examined in the random-phase approximation with the use of a QCD-motivated effective Lagrangian. We show that there arise soft modes having a large strength and a narrow width above the critical temperature, which are analogous to the fluctuations of the order parameter in a superconductor above the critical point. It is argued that the modes contribute to the cooling of the quark-gluon plasma.

We survey the CP-odd asymmetries which can signal CP nonconservation in hyperon decay. The optimal measurement involves the β parameter in the decay distribution, i.e., (β+β¯)/(β-β¯), which can be quite large in some models. Explicit calculations are provided for all the observables for several theories of CP nonconservation.