Interference effects in the decay of resonance states in three-body Coulomb systems

The lowest 1Se resonance state in a family of symmetric three-body Coulomb systems is systematically studied as a function of the mass-ratio M for the constituting particles. The Siegert pseudostate method for calculating resonances is described and accurate results obtained by this method for the resonance position E(M) and width Γ(M) in the interval 0<~M<~30 are reported. The principal finding of these calculations is that the function Γ(M) oscillates, almost vanishing for certain values of M, which indicates the existence of an interference mechanism in the resonance decay dynamics. To clarify this mechanism, a simplified model obtained from the three-body Coulomb problem in the limit M→∞ is analyzed. This analysis extends the range of M up to M=300 and confirms that Γ(M) continues to oscillate with an increasing period and decreasing envelope as M grows. Simultaneously it points to semiclassical theory as an appropriate framework for explaining the oscillations. On the basis of Demkov’s construction, the oscillations are interpreted as a result of interference between two paths of the resonance decay on the Riemann surface of adiabatic potential energy, i.e., as a manifestation of the Stueckelberg phase. It is shown that the implications of this interpretation for the period and envelope of the oscillations of Γ(M) agree excellently with the calculated results

Three-Body Coulomb Resonances in Hydrogenic Plasmas

Abstract Results of a systematic study of the lowest r,S&quot; Feshbach resonance in symmetric three-bod

Ionization of highly charged relativistic ions by neutral atoms and ions

Ionization of highly charged relativistic ions by neutral atoms and ions is considered. Numerical results of recently developed computer codes based on the relativistic Born and the equivalent-photon approximations are presented. The ionization of the outer shells dominate. For the outer projectile electron shells, which give the main contribution to the process, the non-relativistic Schr\"odinger wave functions can be used. The formulae for the non-relativistic reduction of the Dirac matrix-elements are obtained for ionization of electrons with arbitrary quantum numbers $n$ and $\ell$.Comment: 7 pages, 3 figure

The target-density effect in electron-capture processes

The influence of the target density on the electron-capture (EC) processes in collisions of fast ions with atoms and molecules is considered. The partial EC cross sections σn on the principal quantum number n of the scattered projectile, as well as the total σtot = Σnσn values, are calculated for highly charged ions interacting with gaseous and solid targets in the energy range of E = 100 keV u-1 to 10 MeV u-1. It is shown that with the target density increasing, the populations of the excited states of the scattered projectiles, formed via the EC channel, are drastically suppressed due to projectile ionization by the target particles and, as a result, the total EC cross sections decrease by orders of magnitude at low energies, while the reduction is less prominent at high energies