29 research outputs found
Parity nonconservation effect in the resonance elastic electron scattering on heavy He-like ions
We investigate the parity nonconservation effect in the elastic scattering of
polarized electrons on heavy He-like ions, being initially in the ground state.
The enhancement of the parity violation is achieved by tuning the energy of the
incident electron in resonance with quasidegenerate doubly-excited states of
the corresponding Li-like ion. We consider two possible scenarios. In the first
one we assume that the polarization of the scattered electron is measured,
while in the second one it is not detected.Comment: 13 pages, 3 figures, 2 table
Relativistic calculations of charge transfer probabilities in U92+ - U91+(1s) collisions using the basis set of cubic Hermite splines
A new approach for solving the time-dependent two-center Dirac equation is
presented. The method is based on using the finite basis set of cubic Hermite
splines on a two-dimensional lattice. The Dirac equation is treated in rotating
reference frame. The collision of U92+ (as a projectile) and U91+ (as a target)
is considered at energy E_lab=6 MeV/u. The charge transfer probabilities are
calculated for different values of the impact parameter. The obtained results
are compared with the previous calculations [I. I. Tupitsyn et al., Phys. Rev.
A 82, 042701 (2010)], where a method based on atomic-like Dirac-Sturm orbitals
was employed. This work can provide a new tool for investigation of quantum
electrodynamics effects in heavy-ion collisions near the supercritical regime
Parity nonconservation effect in the dielectronic recombination of polarized electrons with heavy He-like ions
We investigate the parity nonconservation (PNC) effect in the dielectronic
recombination (DR) of a polarized electron with a heavy He-like ion into
doubly-excited and states of Li-like ion. We determine the
nuclear charge number for which these opposite-parity levels are near to
cross and, therefore, the PNC effect will be significantly enhanced.
Calculations are performed for quantum numbers and .Comment: 12 pages, 1 figur
Ionization in a laser assisted ion-ion collision
The ionization of a hydrogen-like heavy ion by impact of a charged projectile
under simultaneous irradiation by a short laser pulse is investigated within
the non-perturbative approach, based on numerical solutions of the
time-dependent Dirac equation. Special emphasis is placed on the question of
whether the laser- and impact-ionization channels interfere with each other,
and how this intereference affects the ionization probability. To answer this
question we performed detailed calculations for the laser-assisted collisions
between hydrogen-like and alpha particles. The results of the
calculations clearly indicate that for the experimentally relevant set of
(collision and laser) parameters, the interference contribution can reach 10%
and can be easily controlled by varying the laser frequency.Comment: 9 pages, 10 figure
Relativistic calculations of the U91+(1s)-U92+ collision using the finite basis set of cubic Hermite splines on a lattice in coordinate space
A new method for solving the time-dependent two-center Dirac equation is
developed. The approach is based on the using of the finite basis of cubic
Hermite splines on a three-dimensional lattice in the coordinate space. The
relativistic calculations of the excitation and charge-transfer probabilities
in the U91+(1s)-U92+ collisions in two and three dimensional approaches are
performed. The obtained results are compared with our previous calculations
employing the Dirac-Sturm basis sets [I.I. Tupitsyn et al., Phys. Rev. A 82,
042701 (2010)]. The role of the negative-energy Dirac spectrum is investigated
within the monopole approximation
Quantum electrodynamics in one- and two-electron high-Z ions
International audienceOne- and two-electron ions traditionally serve as an important testing ground for fundamental atomic structure theories and for investigation of QED, relativistic and correlation effects. In the domain of high nuclear charges, new opportunities open up for precise testing and consolidating of the present understanding of the atomic structure, in the regime of extreme electromagnetic fields. In this article, the current progress in experimental investigations of the heaviest H- and He-like systems at GSI Darmstadt is presented. In addition, the planned future experimental studies and developments devoted in particular to high-resolution spectroscopy of excited states in heavy He-like ions as welt as of the is state in hydrogen-like systems, are reviewed
State selective x ray studies of radiative recombination into bare and H like uranium at threshold energies
A state selective investigation of radiative recombination RR at threshold energies has been performed by x ray detection at the electron cooler of the ESR storage ring at GSI for decelerated bare and hydrogen like uranium ions. The application of the deceleration mode enabled us to observe state selective RR into the K and L shell of bare and H like uranium. The observed relative RR intensities into these low laying bound states exhibit a good agreement with rigorous relativistic predictions, whereas the nonrelativistic approach fails to reproduce the data. Furthermore, the scaled relativistic one electron treatment seems to be insufficient for the state selective description of RR into H like species at extremely low energies, suggesting the importance of electron electron interactions for the RR process at the threshold