Quantum field theories of vortices and anyons

We develop the quantization of topological solitons (vortices) in three-dimensional quantum field theory, in terms of the Euclidean region functional integral. We analyze in some detail the vortices of the abelian Higgs model. If a Chern-Simons term is added to the action, the vortices turn out to be anyons, i.e. particles with arbitrary real spin and intermediate () statistics. Localization properties of the interpolating field, scattering theory and spin-statistics connection of anyons are discussed. Such analysis might be relevant in connection with the fractional quantum Hall effect and two-dimensional models of HighT _csuperconductors.     

Precipitation structure in an Al-2·0 at. % Zn-1·0 at. % Mg alloy within and close to the grain boundaries and its effects on mechanical properties

During ageing the Al-2·0 at. %Zn-1·0 at. % Mg alloy at elevated temperatures the width of the precipitation free zone (PFZ) at both sides of the grain boundaries (GB) is identical with that free of quenched-in dislocation loops (DL). After sufficiently long ageing a band of precipitates is growing inside the former PFZ and the DLs in the midgrain regions act as sites for the heterogeneous nucleation of the-phase. Two precipitation processes significantly affect the mechanical properties. TEM correlates grain boundary precipitate density and morphology with grain boundary misorientation.     

Periodic solutions of some infinite-dimensional Hamiltonian systems associated with non-linear partial difference equations. II

This is our second paper devoted to the study of some non-linear Schrödinger equations with random potential. We study the non-linear eigenvalue problems corresponding to these equations. We exhibit a countable family of eigenfunctions corresponding to simple eigenvalues densely embedded in the band tails. Contrary to our results in the first paper, the results established in the present paper hold for an arbitrary strength of the non-linear (cubic) term in the non-linear Schrödinger equation.     

Speeding-up and scaling of domain-wall relaxation nearT c of a uniaxial ferromagnet

The dynamic susceptibility () measured between 10 Hz and 10 MHz on different GdCl₃-ellipsoids (T _c=2.21 K) reveals a completely reversible motion of the domain walls. Taking into account the contribution of the fast adiabatic intradomain magnetization to the nearly Debye-shaped (), we determine for the first time the kinetic Onsager coefficientL _d of the domain wall relaxation of a ferromagnet. Approaching the CurietemperatureL _d speeds up critically, which by a novel simple relaxational model can be related to the increasing width (=correlation length) of linear Bulaevskii-Ginzburg domain-walls and to the shrinking domain period. The reduction ofL _d by an external field can be represented by a universal scaling function, and within the same dynamical model, this effect is ascribed to the increase of the domain period, predicted for a bubble phase. However, the effect of sample size onL _d is much smaller than expected.     

Correlation between intramolecular bond lengths and K-shell σ-shape resonances in gas-phase molecules

Analysis of K-shell excitation spectra of gas-phase molecules containing at least two atoms of either B, C. N. O or F reveals the existence of a striking correlation between the bond length of the atomic pair. the sum of their atomic numbers and the associated α-shape resonance energy. Empirical rules are established which allow the derivation of intramolecular distances with accuracies reliably better than ± 0.05 A from the K-.shell absorption spectrum of one of the atoms in the Molecule.     

Some problems concerning the use of automated radiochemical separation systems in destructive neutron activation analysis

The present state of a long term program is reviewed. It was started to elaborate a remote controlled automated radiochemical processing system for the neutron activation analysis of biological materials. The system is based on wet ashing of the sample, followed by reactive desorption of some volatile components. The distillation residue is passed through a series of columns filled with selective ion screening materials to remove the matrix activity. The solution is thus “stripped” from the interfering radioions, and it is processed to single-elements through group separations using ion-exchange chromatographic techniques. Some special problems concerning this system are treated. (a) General aspects of the construction of a (semi)automated radiochemical processing system are discussed; (b) Comparison is made between various technical realizations of the same basic concept; (c) Some problems concerning the “reconstruction” of an already published processing system are outlined.