Two-loop self-energy contribution to the Lamb shift in H-like ions

The two-loop self-energy correction is evaluated to all orders in Z\alpha for the ground-state Lamb shift of H-like ions with Z >= 10, where Z is the nuclear charge number and \alpha is the fine structure constant. The results obtained are compared with the analytical values for the Z\alpha-expansion coefficients. An extrapolation of the all-order numerical results to Z=1 is presented and implications of our calculation for the hydrogen Lamb shift are discussed

Relativistic transition wavelenghts and probabilities for spectral lines of Ne II

Transition wavelengths and probabilities for several 2p4 3p - 2p4 3s and 2p4 3d - 2p4 3p lines in fuorine-like neon ion (NeII) have been calculated within the multiconfiguration Dirac-Fock (MCDF) method with quantum electrodynamics (QED) corrections. The results are compared with all existing experimental and theoretical data

Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for 12≤Z≤3012\leq Z\leq30 Elements

Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac-Fock model. The transition energies of competing processes, the K$\alpha$ hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.Comment: accepted versio

QED self-energy contribution to highly-excited atomic states

We present numerical values for the self-energy shifts predicted by QED (Quantum Electrodynamics) for hydrogenlike ions (nuclear charge $60 \le Z \le 110$) with an electron in an $n=3$, 4 or 5 level with high angular momentum ($5/2\le j \le 9/2$). Applications include predictions of precision transition energies and studies of the outer-shell structure of atoms and ions.Comment: 20 pages, 5 figure

Non-perturbative calculation of the two-loop Lamb shift in Li-like ions

A calculation valid to all orders in the nuclear-strength parameter is presented for the two-loop Lamb shift, notably for the two-loop self-energy correction, to the 2p-2s transition energies in heavy Li-like ions. The calculation removes the largest theoretical uncertainty for these transitions and yields the first experimental identification of two-loop QED effects in the region of the strong binding field

K X-Ray Energies and Transition Probabilities for He-, Li- and Be-like Praseodymium ions

Theoretical transition energies and probabilities for He-, Li- and Be-like Praseodymium ions are calculated in the framework of the multi-configuration Dirac-Fock method (MCDF), including QED corrections. These calculated values are compared to recent experimental data obtained in the Livermore SuperEBIT electron beam ion trap facility

Two-photon E1M1 decay of 2 3P0 states in heavy heliumlike ions

Two-photon E1M1 transition rates are evaluated for heliumlike ions with nuclear charges in the range Z = 50-94. The two-photon rates modify previously published lifetimes/transition rates of 2 3P0 states. For isotopes with nuclear spin I not equal 0, where hyperfine quenching dominates the 2 3P0 decay, two-photon contributions are significant; for example, in heliumlike 187 Os the two-photon correction is 3% of the total rate. For isotopes with I= 0, where the 2 3P0 decay is unquenched, the E1M1 corrections are even more important reaching 60% for Z=94. Therefore, to aid in the interpretation of experiments on hyperfine quenching in heliumlike ions and to provide a more complete database for unquenched transitions, a knowledge of E1M1 rates is important.Comment: 6 pages, 3 figures, 3 table

Doppler-tuned Bragg Spectroscopy of Excited Levels in He-Like Uranium: a discussion of the uncertainty contributions

We present the uncertainty discussion of a recent experiment performed at the GSI storage ring ESR for the accurate energy measurement of the He-like uranium 1s2p3P2- 1s2s3S1 intra-shell transition. For this propose we used a Johann-type Bragg spectrometer that enables to obtain a relative energy measurement between the He-like uranium transition, about 4.51 keV, and a calibration x-ray source. As reference, we used the Ka fluorescence lines of zinc and the Li-like uranium 1s22p2P3/2 - 1 s22s 2S1/2 intra-shell transition from fast ions stored in the ESR. A comparison of the two different references, i.e., stationary and moving x-ray source, and a discussion of the experimental uncertainties is presented

Doppler-tuned Bragg Spectroscopy of Excited Levels in He-Like Uranium: a discussion of the uncertainty contributions

We present the uncertainty discussion of a recent experiment performed at the GSI storage ring ESR for the accurate energy measurement of the He-like uranium 1s2p3P2- 1s2s3S1 intra-shell transition. For this propose we used a Johann-type Bragg spectrometer that enables to obtain a relative energy measurement between the He-like uranium transition, about 4.51 keV, and a calibration x-ray source. As reference, we used the Ka fluorescence lines of zinc and the Li-like uranium 1s22p2P3/2 - 1 s22s 2S1/2 intra-shell transition from fast ions stored in the ESR. A comparison of the two different references, i.e., stationary and moving x-ray source, and a discussion of the experimental uncertainties is presented