Dielectronic Recombination of Very Heavy Lithiumlike Ions

Hyperfine Interactions - An overview of measurements of dielectronic recombination (DR) with the heaviest lithiumlike ions is presented. The experiments have been carried out at the heavy ion...     

Effect of the addition of pore former

Journal of Thermal Analysis and Calorimetry - Tetragonal zirconia (3YSZ) and cermet nickel–tetragonal zirconia (Ni/3YSZ) were obtained by citric method. The porosity of samples was increased...     

Two-photon decay in strong central fields observed for the case of He-like gold

The photon energy differential shape of the second order matrix element for the two-photon (2E1) decay of the 1s2s¹S₀ level in He-like gold has been measured. The results are in agreement with a recent fully relativistic calculation. The corresponding 2E1 matrix element deviates from those in lighter He-like systems due to the strong central field in a heavy two-electron ion.     

1s lamb shift in hydrogenlike uranium measured on cooled, decelerated ion beams

The Lyman- alpha transitions of hydrogenlike uranium associated with electron capture were measured in collisions of stored bare U (92+) ions with gaseous targets at the storage ring ESR. By applying the deceleration technique, the experiment was performed at slow collision energies in order to reduce the uncertainties associated with Doppler corrections. From the measured centroid energies, a ground state Lamb shift of 468 eV+/-13 eV is deduced which gives the most precise test of quantum electrodynamics for a single electron system in the strong field regime. In particular, the technique applied paves the way towards the 1 eV precision regime.     

Manageability of Multiplicative Unitaries Associated with Double Lie Groups

We prove that unitary multiplicative operators associated with double Lie groups are manageable.     

Study of electron bremsstrahlung in strong Coulomb fields at the ESR storage ring

Electron bremsstrahlung has been investigated for collisions of 223.2 MeV/amu He-like uranium ions with N₂ and Ar gaseous targets. The doubly differential cross-sections for bremsstrahlung are compared to the predictions of relativistic first order Born calculations (Bethe-Heitler formula with Elwert correction factor) and to the calculations based on the exact wavefunctions for electrons moving in the external point-Coulomb potential of the projectile. Whereas the “exact” IPA calculations give an improved agreement with experimental data, as compared to the Bethe-Heitler theory, in particular at the end-point region of the bremsstrahlung spectra, discrepancies still remain at lower photon energies. This revised version was published online in July 2006 with corrections to the Cover Date.     

Recombination of U89+ ions with free electrons at the ESR

After an extended upgrading period at the Experimental Storage Ring (ESR) of the GSI in Darmstadt, an experiment on recombination of lithium-like uranium has been carried out. A 107.1 MeV/u U⁸⁹⁺ beam with up to 500 μA effective current was stored and cooled. In addition to measurements of radiative recombination (RR) and dielectronic recombination (DR) with high energy resolution in the range of 0–90 eV, the diagnostic properties of DR have been utilized to characterize the new cooler setup. Preliminary experimental results for the 1s²2p_3/25ℓj(j=3/2,5/2) resonance manifolds are presented and compared with theoretical predictions. This revised version was published online in July 2006 with corrections to the Cover Date.     

Structure and Dynamics of High-Z Ions Studied at the ESR Storage Ring

Hyperfine Interactions - The magnetic order and crystallization of the amorphous Fe75Si15B10 alloy prepared by mechanical alloying was studied in situ by 57Fe Mössbauer spectroscopy. These...     

First experiment with decelerated bare uranium ions conducted at the ESR storage ring

The deceleration capabilities of the ESR have been used for the first time in a dedicated ground state QED experiment conducted at the gasjet target of the ring. By decelerating bare uranium ions from 358 MeV/u down to energies of as low as 49 MeV/u, X-ray spectra have been obtained which provide an abundant yield of characteristic X-ray transitions. The experiment demonstrates that, by choosing the appropriate beam energy and gasjet target, almost all excited projectile states can be selectively populated. Moreover, the experiment provides the first data for beam lifetimes of stored decelerated high-Z ions. Such data are essential for the design of future experiments dealing with decelerated ion beams far below 50 MeV/u. This revised version was published online in August 2006 with corrections to the Cover Date.     

Higher-order effects studied for K-shell excitation of high-Z projectiles

The study of projectile excitation of high-Z ions in collisions with light target atoms is a powerful tool for the investigation of magnetic and higher-order effects occurring in relativistic collisions. Very first investigations performed for bismuth ions were recently extended at the ESR storage ring by using He-like uranium ions in collisions with gaseous targets. At the ESR jet target, the absence of solid-state effects (e.g., multiple collisions) allows one to study higher order processes, such as excitation and ionization or excitation and capture, occurring in single collisions. This revised version was published online in July 2006 with corrections to the Cover Date.