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The Hamiltonian of Quantum Chromodynamics is approximated by restricting the spatial dependencies of the quark-antiquark and gluon fields to a small number of modes (few-mode approximation). As a working hypothesis, we assume that the ground states of the dynamical sectors of the theory are automatically gauge invariant so that Gauss's law need not be strictly satisfied by a trial state. We derive and apply a method for explicit calculation of expectation values for wavefunctions in colour space depending on the twoSU (3) invariants acting as dynamical variables. An interacting ground state is constructed by a dynamical dressing transformation of the bare fermionic vacuum which may be regarded as a few-mode approximation to a quark-gluon (or mesonic) condensate. Based on this vacuum a nucleon state is formulated quite similar to the solition bag construction. Some of its effective properties are calculated by a variational calculation and comparison is made with experimental data as well as with other theoretical models of bag-type.

Energy distributions of electrons were measured under an observation angle of 42.3° by bombarding thin carbon foils with protons of 0.5 to 2.5 MeV and with Neon of 10 MeV energies. Comparison of the experimental results with binary-encounter-approximation calculations, taking into account the electron energy loss in the solid, show that the spectra from proton bombardment can be described by this model.

Energy spectra of electrons ejected from collisions between a carbon foil and Ne projectiles with energies between 1.4 and 20 MeV have been measured. Continuous and discrete electron energy distributions are observed. Auger transitions of foil-excited Ne have been studied. Using relativistic Dirac-Fock multiconfiguration calculations, most of the measured Auger transitions have been identified.

Augerelectron emission from foil-excited Ne-ions (6 to 10 MeV beam energy) has been measured. The beam-foil time-of-flight technique has been applied to study electronic transitions of metastable states (delayed spectra) and to determine their lifetimes. To achieve a line identification for the complex structure observed in the prompt spectrum, the spectrum is separated into its isoelectronic parts by an Augerelectron-ion coincidence correlating the emitted electrons and the emitting projectiles of well defined final charge statesqf. Well resolved spectra were obtained and the lines could be identified using intermediate coupling Dirac-Fock multiconfiguration calculations.

K-shell ionization cross sections in collisions of S and Cl ions with target atoms with atomic numberZ2=11–22 have been measured in the energy range from 3.9 to 48 MeV. The data are interpreted in terms of the statistical model of electron diffusion to the continuum. The distribution ofK-vacancies between the projectile and the target atoms are discussed in the framework of the vacancy sharing process.

In order to obtain data on the photon absorption process between the giant resonance and the meson threshold the cross sections of the reactions12C(γ,n)11C,12C(γ, 2n)10C,39K(γ,n)38Kg, and40Ca(γ,np)38Kg have been determined by the analysis of yield curves at the 140 MeV electron synchrotron of the PTB.

Es wird eine Technik zum Unterfahren von städtischen Versorgungseinrichtungen mit Hilfe der Schlitzwandbauweise im Zuge der Erstellung von U‐Bahntunneln in offener Bauweise vorgestellt.

The impact parameter (b) dependence of K-shell vacancy production probability for 1,5 MeV/u Nb on Mo collisions has been measured. Consistent with previous experiments on other high Z collision systems, the shape of the b-dependence shows significant deviations from the two-state 2p«-2ps rotational coupling model.