13 research outputs found
The ground state of relativistic ions in the limit of high magnetic fields
We consider the pseudorelativistic no-pair Brown-Ravenhall operator for the
description of relativistic one-electron ions in a homogeneous magnetic field
B. It is shown for central charge not exceeding Z=87 that their ground state
energy decreases according to the square root of B as B tends to infinity, in
contrast to the nonrelativistic behaviour.Comment: 15 page
Complete Break Up of Ortho Positronium (Ps)- Hydrogenic ion System
The dynamics of the complete breakup process in an Ortho Ps - He+ system
including electron loss to the continuum (ELC) is studied where both the
projectile and the target get ionized. The process is essentially a four body
problem and the present model takes account of the two centre effect on the
electron ejected from the Ps atom which is crucial for a proper description of
the ELC phenomena. The calculations are performed in the framework of Coulomb
Distorted Eikonal Approximation. The exchange effect between the target and the
projectile electron is taken into account in a consistent manner. The proper
asymptotic 3-body boundary condition for this ionization process is also
satisfied in the present model. A distinct broad ELC peak is noted in the fully
differential cross sections (5DCS) for the Ps electron corroborating
qualitatively the experiment for the Ps - He system. Both the dynamics of the
ELC from the Ps and the ejected electron from the target He+ in the FDCS are
studied using coplanar geometry. Interesting features are noted in the FDCS for
both the electrons belonging to the target and the projectile.Comment: 14 pages,7 figure
Scattering of e
The differential, total, momentum transfer and viscosity cross sections for the elastic scattering of electrons and positrons by ytterbium atoms have been calculated. We have also calculated the total inelastic and ionization cross sections. In addition, the Sherman function S(θ) and the inelastic mean free paths have been determined for the scattering of both projectiles. The critical minima in the elastic differential cross sections (DCS) were determined from the analysis of the DCS and S(θ). These investigations have been carried out within the framework of two different theoretical approaches at the impact energies 1 eV–0.5 GeV for both projectiles. In the atomic domain the solution involves a complex projectile-atom optical potential while in the nuclear domain only the nuclear potential has been employed. Both approaches employ the Dirac partial wave analysis. Our results are in reasonable agreement with available experimental data and other theoretical findings. To the best of our knowledge, for positron scattering, there are no experimental data available in the literature
Validity of sum rules for the polarization transfer in electron bremsstrahlung
The polarization correlations, which describe the spin transfer from a high-energy spin-polarized electron to the photon in the elementary process of bremsstrahlung induced by strong potentials, obey a strict sum rule in the case of coplanar emission. The proof is carried out within the relativistic partial-wave approach. Further sum estimates are obtained by means of a variational principle under the sole condition that the transition amplitude is linear in the electron wavefunctions and in the photon field. Numerical sum rule results are given for light and heavy bare target atoms in the energy range 1–10 MeV