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. (orig.)Available from TIB Hannover: RO 801(96-34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Full scale relativistic ab initio time dependent caculations for the the L-K vacancy transfer in 208 MeV Ni"2"3"+ on Ge solid target

We present full scale ab initio relativistic calculations for the L-K vacancy transfer in collisions of 208 MeV Ni"2"3"+ on Ge-solid target. Our time dependent Dirac-Fock-Slater method allows to achieve a very accurate quantitative explanation for the experimental impact parameter-dependent Ni-K and Ge-K vacancy probabilities recently measured at GSI. Darmstadt in terms of dynamic creation and annihilation of Ni n=2 shell vacancies in the collision. Our calculations reveal that both the radial and rotational coupling between the molecular levels contribute to the L-K vacancy transfer. (orig.)17 refs.Available from TIB Hannover: RO 801(95-82) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

X-ray emission from very-heavy H- and He-like ions in collisions with gaseous and solid targets

Projectile X-ray emission and charge-exchange processes are studied for bare and one-electron Bi, Pb, and U ions in collisions with gaseous and solid targets at relativistic energies. The experimental data for both, the total and sub-shell differential cross sections, are discussed and compared with theoretical predictions. Moreover, the experiments were extended to atomic structure studies. The result on the groundstate Lamb-shift for hydrogenic uranium is presented which compares very well with theoretical prediction. (orig.)Available from TIB Hannover: RO 801(93-59) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Groundstate Lamb-shift for hydrogen-like uranium measured at the ESR storage ring

The Lyman #alpha# transitions of hydrogen-like uranium associated with electron capture were measured in collisions of stored bare U"9"2"+ ions with gaseous targets at the storage ring ESR. By applying X-ray/particle coincidence techniques the groundstate transition energies in the rest frame could be determined with a precision of about 600 ppm. The experimental result is excellent agreement with the theoretical prediction for the groundstate Lamb-shift in hydrogen-like uranium and is already sensitive to the 2s Lamb-shift. (orig.)SIGLEAvailable from TIB Hannover: RO 801(93-70) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

L-subshell resolved photon angular distribution of radiative electron capture into He-like uranium

The photon angular distributions for radiative electron capture (REC) into the j=1/2 and j=3/2 L-subshell levels were measured and calculated for U"9"0"+#->#C collisions at 89 MeV/u. The experiment provides the first study of the photon angular distribution of REC into a projectile p-state (j=3/2) which was found to exhibit a slight backward peaking in the laboratory frame. For radiative capture to the j=1/2 states the measured angular distribution deviates considerably from symmetry around 90 . The results demonstrate that the usual sin"2#theta#_l_a_b distribution is not valid in the high-Z regime. (orig.)SIGLEAvailable from TIB Hannover: RO 801(94-49) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman