Correlations between resonances in a statistical scattering model

The distortion of the regular motion in a quantum system by its coupling to the continuum of decay channels is investigated. The regular motion is described by means of a Poissonian ensemble. We focus on the case of only few channels K<10. The coupling to the continuum induces two main effects, due to which the distorted system differs from a chaotic system (described by a Gaussian ensemble): 1. The width distribution for large coupling becomes broader than the corresponding $\chi^2_K$ distribution in the GOE case. 2. Due to the coupling to the continuum, correlations are induced not only between the positions of the resonances but also between positions and widths. These correlations remain even in the strong coupling limit. In order to explain these results, an asymptotic expression for the width distribution is derived for the one channel case. It relates the width of a trapped resonance state to the distance between its two neighboring levels.Comment: 23 pages, 7 Postscript figures. Submitted to Phys. Rev. E, Jan. 9

Bethe-Salpeter Amplitudes and Static Properties of the Deuteron

Extended calculations of the deuteron's static properties, based on the numerical solution of the Bethe-Salpeter equation, are presented. A formalism is developed, which provides a comparative analysis of the covariant amplitudes in various representations and nonrelativistic wave functions. The magnetic and quadrupole moments of the deuteron are calculated in the Bethe-Salpeter formalism and the role of relativistic corrections is discussed.Comment: 33 pages ([aps]{revtex} style), 9 Postscript figures; (55 pages if [preprint,aps]{revtex} style is used

Resonance phenomena near thresholds

The trapping effect is investigated close to the elastic threshold. The nucleus is described as an open quantum mechanical many-body system embedded in the continuum of decay channels. An ensemble of compound nucleus states with both discrete and resonance states is investigated in an energy-dependent formalism. It is shown that the discrete states can trap the resonance ones and also that the discrete states can directly influence the scattering cross section. (orig.)26 refs.Available from TIB Hannover: RR 1847(95-119) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Freie Elektronen Laser an der Strahlungsquelle ELBE: Theoretische Vorhersagen und eindimensionale Modellrechnungen

Available from TIB Hannover: RR 1847(276) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

General axial shapes of sodium clusters

The shell correction method is applied to Na clusters to calculate their shapes and binding energies. The equilibrium shapes are calculated minimizing simultaneously five deformation parameters. Strong deviations from spheroidal shape including reflection asymmetric shapes are found. The influence of cluster deformation on the splitting of the dipole resonance and the separation energies is studied and compared with the available experimental data. (orig.)SIGLEAvailable from TIB Hannover: RR 1847(94-37) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Tilted cranking

SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Kernstruktur bei hohen Drehimpulsen. Messung hochenergetischer Myonen aus kosmischen Schauern (KASKADE). n&quot;+-Kontaktierung bei HP-Ge-Detektoren Wissenschaftlicher Schlussbericht

Available from TIB Hannover: F96B660+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Tilted rotation of triaxial nuclei

The Tilted Axis Cranking theory is applied to the model of two particles coupled to a triaxial rotor. Comparing with the exact quantal solutions, the interpretation and quality of the mean field approximation is studied. Conditions are discussed when the axis of rotation lies inside or outside of the principal planes of the triaxial density distribution. The planar solutions represent #DELTA#I=1 bands, whereas the aplanar solutions represent pairs of identical #DELTA#I=1 bands with the same parity. The two bands differ by the chirality of the principal axes with respect to the angular momentum vector. The transition from planar to chiral solutions is evident in both the quantal and the mean field calculations. Its physical origin is discussed. (orig.)SIGLEAvailable from TIB Hannover: RR 1847(96-156) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Radial pattern of nuclear decay processes

At high level density of nuclear states, a separation of different time scales is observed (trapping effect). We calculate the radial profile of partial widths in the framework of the continuum shell model for some 1&quot;- resonances with 2p-2h nuclear structure in &quot;1&quot;6O as a function of the coupling strength to the continuum. A correlation between the lifetime of a nuclear state and the radial profile of the corresponding decay process is observed. We conclude from our numerical results that the trapping effect creates structures in space and time characterized by a small radial extension and a short lifetime. (orig.)Available from TIB Hannover: RR 1847(94-39) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Pre- and post-scission light charged particle multiplicities in incomplete fusion reactions

In this article we present results concerning the extraction of light charged particle multiplicities in incomplete fusion-fission reactions with a moving source fitting procedure. To demonstrate the feasibility and reliability of the procedure we have used simulated events of known multiplicity to construct kinetic energy distributions at different angles that are fitted assuming several pre- and post-scission sources. In particular, we show that it is necessary to include at least two pre-equilibrium sources in order to extract correctly the known pre-equilibrium proton multiplicity. These two sources are characterized by high emission temperatures, low emission barriers and high velocities, having #propor to#70% and #propor to#25% of the beam velocity along the beam axis, respectively. The former source is naturally dominant at forward angles due to the strong focusing effect of its high velocity. Contrary to normal expectations, however, the slower pre-equilibrium source is present with considerable yield at the most backward angles #theta##propor to#145 where it is normally assumed only evaporative components are present. The extracted proton multiplicities are well reproduced by the moving source procedure, as well as fitting parameters with physical relevance. (orig.)SIGLEAvailable from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman