New turbomolecular pump with central opening for free axial access

Standard turbomolecular pumps show typically one annular active intake area on the high vacuum flange side (single-flow pumps). The central circular part of the inlet of the compressor turbine is blind for pumping. The new design proposes a central opening of a turbomolecular pump all along the axis. This central bore can be used e.g. for mounting of feed throughs, manipulators, windows or for coupling to further vacuum devices, in particular also for enclosing tube-like vacuum systems. This design allows a multi-use of a pumping port at a vacuum vessel without reducing there the pumping speed. Moreover, the new design is ideal for axial or radial differential pumping arrangements as e.g. needed for all gas jet like set-ups or other pressure reduction stages. (orig.)To be published in ''Vacuum in Forschung und Praxis''Available from TIB Hannover: RO801(04-01) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

GSI-contributions to HCI-94

SIGLEAvailable from TIB Hannover: RO 801(94-80) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

The physics of highly-charged heavy ions revealed by storage/cooler rings

We first explain the challenging physics of highly-charged heavy ions before we give an introduction to and a survey on storage rings with their cooling properties. Then, the new results on the important charge-changing processes -recombination and capture reactions - are reviewed, before the basic results on the atomic structure are discussed. Here, the ground state transitions give direct insight into Lamb shift contributions. Also the information from doubly-excited states, from Rydberg states and from the ground state hyperfine splitting elucidates the QED structure contributions. The radioactive decay gives another view into the interplay between atomic shell and nucleus. Finally, an outlook on future developments on the physics of highly-charged ions at storage/cooler rings is given. (orig./WL)Available from TIB Hannover: RO 801(96-36) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

EUV spectroscopy of heavy highly-charged ions: a summary of the research at the UNILAC with the GSI 5m grazing incidence spectrometer

The research performed with the high-resolution GSI 5-m grazing incidence spectrometer in the Extreme Ultra-Violet wavelength range of photons (typically 5 - 200 nm) is briefly reviewed. Over the last decade main emphasis was given to precision spectroscopy of heavy few-electron ions, in particular to Li-like ions in the medium heavy Z region. Here, using a beam foil spectroscopy arrangement, the 2s - 2p_1_/_2 transition energies for Li-like Ni"2"5"+, Zn"2"7"+, Ag"4"4"+, Sn"4"7"+ and Xe"5"1"+ ions were determined on an accuracy level of 50 ppm giving true access to two-photon QED terms. (orig.)Available from TIB Hannover: RA 3692(2002-04) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The 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"9"2"+ 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 region. In particular, the technique applied paves the way towards the 1 eV precision. (orig.)Available from TIB Hannover: RO 801(2000-32) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Photoelectric effect in the relativistic domain revealed by the time-reversed process for highly charged uranium ions

The photoelectric effect in the near relativistic energy regime of 80 to 350 keV is studied by the time-reversed process in ion-atom collisions, i.e. by the radiative capture of a quasi-free target electron. We review shell and subshell differential photon-angular distribution studies of radiative capture into highly-charged uranium ions. The experimental data are compared with exact relativistic calculations and give detailed insight into both the atomic structure of high-Z few-electron ions and into the fundamental electron-photon interaction process involved. In particular it is shown that the angular-differential measurements provide a unique method to study the magnetic interaction in relativistic electron-photon encoun- (orig.)Available from TIB Hannover: RO 801(96-50) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Doppler-shift assisted fast ion spectroscopy: a case study for X-ray emission from 277 MeV/u Pb"8"1"+ ions

Utilizing the different information from spatially separated segments of high-granular photon detectors the measured (LAB) energy of photons emitted by fast moving ions can be corrected individually for the Doppler effect according to the particular observation angles of each detector segment. By a redundant fitting procedure the center of mass photon energy can be determined with high precision. This new Doppler-shift assisted spectroscopy is explained for the case study of 277.4 MeV/u Pb"8"2"+ ions colliding with a N_2-gas target at the heavy ion storage ring ESR. Spectroscopic information for hydrogenic Pb"8"1"+ ions is given for the ground-state transitions, for the Balmer transitions, as well as for the total K-binding energy. (orig.)Available from TIB Hannover: RO 801(94-57) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Charge state and energy loss of relativistic heavy ions in matter

Relativistic heavy-ion collisions of few-electron projectiles ranging from argon up to uranium have been investigated in solid and gaseous media. Electron-loss and electron-capture cross sections, charge-state distributions, as well as energy loss and energy deposition have been measured and are compared with theoretical predictions. Especially fully-ionized heavy projectiles represent a unique possibility to test atomic-collision theories. (orig.)Part of the Ph.D. thesis of C. ScheidenbergerAvailable from TIB Hannover: RO 801(93-77) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

The electron-electron interaction studied in strong central fields by resonant transfer and excitation with H-like U ions. - Angular distribution of hypersatellite and satellite radiation emitted after resonant and excitation into U"9"1"+ ions

Electron-electron interaction is studied in the strongest possible atomic fields (Z.#alpha# => 1) in the presence of only two electrons. A quasi-free electron from a hydrogen gas target is resonantly captured into a L_j subshell of a fast H-like U"9"1"+ ion by simultaneous excitation of the strongly bound K electron also into a L_j_' subshell of the projectile, with j and j' the total angular momenta of 1/2 or 3/2 for the electron of concern. This resonant capture and excitation process, KL_jL_j_'-RTE, is mediated by electron-electron interaction. It is equivalent to dielectronic recombination (DR) in ion-electron collisions and leads to a doubly excited He-like U"9"0"+"*"* ion, which stabilizes - almost exclusively - via the emission of two successive K X-rays, first a K hypersatellite (K#alpha#i-H) and then a K satellite (K#alpha#i'-S) transition. The K X-ray emission characteristics associated with one-electron capture in collisions of U"9"1"+ ions with a hydrogen target is studied for the three resonance groups of the KL_jL_j_'-RTE and one off-resonance energy, i.e. in the energy range between 100 and 135 MeV/u. The total cross section for the first resonance group KL_1_/_2L_1_/_2 confirms the importance of the Breit contribution to the interaction. The angular distribution for the K#alpha#2-H transition (j=1/2) is isotropic in the projectile system whereas the K#alpha#1-H transition (j=3/2) indicates a strong alignment for the 3/2 electrons in the doubly excited states for the second resonance group KL_1_/_2L_3_/_2. The experimental results are in agreement with fully relativistic calculations including the generalized Breit interaction. (orig.)SIGLEAvailable from TIB Hannover: RO 801(03-27+28) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Projectile excitation and ionization in relativistic ion-atom collisions

K-shell ionization and excitation is studied for high-Z one- and two-electron ions in relativistic encounters with low-Z targets. For ionization, the data obtained for solid and gaseous targets are compared in detail with the predictions of first order perturbation theory. On the basis of the most recent experimental results, the systematic deviation from first order perturbation theory as observed recently for high-Z ions cannot be confirmed. Moreover, special emphasis is given to a dedicated experiment where projectile excitation has been studied in encounters of heavy one- and two-electron bismuth ions (Z=83) with light solid targets. The measurement of the characteristic groundstate transitions in coincidence with the primary charge state allowed us to study the formation of excited projectile states via direct Coulomb excitation. In particular, due to the large fine structure splitting, the excitation cross-sections for the various L-shell sublevels in H- and He-like bismuth could be determined separately. The results are compared with detailed relativistic calculations showing that for high-Z projectiles the magnetic interaction is of considerable importance at the considered collision energies. (orig.)SIGLEAvailable from TIB Hannover: RO 801(96-49) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman