Multifragmentation calculated with relativistic force

A saturating hamiltonian is presented in a relativistically covariant formalism. The interaction is described by scalar and vector mesons, with coupling strengths adjusted to the nuclear matter. No explicit density depe ndence is assumed. The hamiltonian is applied in a QMD calculation to determine the fragment distribution in O + Br collision at different energies (50 -- 200 MeV/u) to test the applicability of the model at low energies. The results are compared with experiment and with previous non-relativistic calculations. PACS: 25.70Mn, 25.75.+rComment: 23 pages, latex, with 10 PS figures, available at http://www.gsi.de/~papp

Instabilities in Nuclei

The evolution of dynamical perturbations is examined in nuclear multifragmentation in the frame of Vlasov equation. Both plane wave and bubble type of perturbations are investigated in the presence of surface (Yukawa) forces. An energy condition is given for the allowed type of instabilities and the time scale of the exponential growth of the instabilities is calculated. The results are compared to the mechanical spinodal region predictions. PACS: 25.70 MnComment: 22 pages, latex, with 5 PS figures, available at http://www.gsi.de/~papp

Spectral Determinant Method for Interacting N-body Systems Including Impurities

A general expression for the Green's function of a system of $N$ particles (bosons/fermions) interacting by contact potentials, including impurities with Dirac-delta type potentials is derived. In one dimension for $N>2$ bosons from our {\it spectral determinant method} the numerically calculated energy levels agree very well with those obtained from the exact Bethe ansatz solutions while they are an order of magnitude more accurate than those found by direct diagonalization. For N=2 bosons the agreement is shown analytically. In the case of N=2 interacting bosons and one impurity, the energy levels are calculated numerically from the spectral determinant of the system. The spectral determinant method is applied to an interacting fermion system including an impurity to calculate the persistent current at the presence of magnetic field.Comment: revtex, 19 pages, 4 figure

AN ELECTION ALGORITHM FOR A MULTIPROCESSOR CONTROLLED DIGITAL EXCHANGE

A multiprocessor controlled distributed digital exchange is studied in case of some failure types. The recovery from a failure is based on temporary suspension of the normal operation and the active processors elect a coordinator controlling the reconfiguration of the system. The algorithm developed for such an election is used at initial (cold) start of the system and in case of reintroducing one or more processors repaired as well. The failure environment is given and the assertions are proved verifying the algorithm described

Au+Au central collisions at 150, 250 and 400 AMeV energies in QMD with relativistic forces

An extensive comparison of the recent experimental data published by the FOPI collaboration at GSI with the results of a relativistically covariant formulation of a QMD code is presented. For most of the quantities we find agreement with the experimental results showing that the derived force has a reasonable momentum dependence.Comment: 33 pages with 18 EPSF figures included. Final version to appear in Nucl. Phys.