[en] Important facts about the GSI UNILAC accelerator are reviewed under the special aspects of target and stripper foil applications including general range considerations as seen after the upgrading of the machine to an energy of 20 MeV/u for all ions up to uranium. It is also reported about current works and recent developments in target preparations at GSI divided into four main groups of preparation procedures with sufficient overlap: cold rollings, carbon sublimation-condensations, focussed heavy-ion sputter deposition, and the wide field of high-vacuum evaporation-condensations. Among others, a Ca reduction-distillation procedure is described, a new assembly is shown for sublimation-condensations of uniform C layers of 0.1 to 0.76 mg/cm² area densities. A selection of only a few applications of targets at the UNILAC can be given. Improved actinide targets are discussed, in-beam measurements of properties of targets on rotating wheels are explained, and a large-area target wheel with a circumference of nearly one meter is shown. SEM micrographs of damaged targets are given and explained. (orig.)

[en] Targets of 0.7-1.0 mg/cm² lead (sup(nat)Pb,²⁰⁶Pb,²⁰⁷Pb,²⁰⁸Pb) of large size (44 mm x 15 mm) have been prepared and covered on both sides with C foils of 0.02-0.03 mg/cm². Due to the higher total hemispherical emissivity of C in relation to Pb the radiation cooling of these targets in an intense heavy ion beam is increased and the target temperature decreased. The targets were mounted on a wheel that rotates in synchronization with the pulsed beam of the accelerator UNILAC at GSI and were irradiated by 10¹³s^-1cm^-2 Ar ions of 5 MeV/u specific energy without being destroyed by melting. These targets on the wheel sustained an about 15 times higher beam current density than stationary targets. Different modes of rotation are discussed. (orig.)

[en] Important facts about the GSI UNILAC accelerator are reviewed under the special aspects of target and stripper foil applications including general range considerations as seen after the upgrading of the machine to an energy of 20 MeV/u for all ions up to uranium. Current work and recent developments in target preparations at GSI are also reported, divided into four main groups of preparation procedures with sufficient overlap: cold rollings, carbon sublimation-condensations, focused heavy-ion sputter deposition, and the wide field of high-vacuum evaporation-condensations. Among others, a Ca reduction-distillation procedure is described, a new assembly is shown for sublimation-condensations of uniform C layers of 0.1 to 0.76 mg/cm² area densities. A selection of only a few applications of targets at the UNILAC can be given. Improved actinide targets are discussed, in-beam measurements of properties of targets on rotating wheels are explained, and a large-area target wheel with a circumference of nearly one meter is shown. SEM micrographs of damaged targets are given and explained

No abstract available

[en] Uranium layers of ≅ 0.4 mg/cm² are evaporated by means of a 6 kW electron-beam gun onto 0.04 mg/cm² thick carbon films in a high-vacuum process; a protecting layer of ≅ 0.01 mg/cm² of carbon is added in the same vacuum cycle. The evaporation- and deposition yields are discussed and measurements of target characteristics are described. C/U/C sandwich targets in the shape of a sector of an annulus are prepared for use on rotating target wheels of 155 mm radius to be bombarded with a pulsed beam of heavy ions. One type of circular targets of 20 mm in diameter is mounted to a target wobbler. Both, wheel and wobbler, distribute the intensity of the heavy-ion beam to a larger area to reduce radiation damages. Examples of target applications will be mentioned. (orig.)

[en] Tungsten layers of 1-6 mg/cm² with diameters of 10 mm are needed as heavy-ion targets and as flat or domed windows for in-beam ion sources. They are prepared by a high-vacuum evaporation-deposition process carried out in a computer-controlled apparatus. The tungsten, placed in the water-cooled crucible of an electron-beam gun, is gradually heated and evaporates at about its melting point (T_m=3643 K). The tungsten is deposited onto 9 mg/cm² copper backings which are preheated by the thermal radiation from the evaporant. The deposition rate is controlled by a quartz crystal monitor. After the high-vacuum deposition process, the copper backings are removed by selective etching and the self-supported tungsten foils are characterized by their areal mass. The features of the commercially available evaporation unit used are discussed by way of this deposition process. (orig.)

[en] At GSI accelerator beams are now available from 0.045 to 2000 MeV/u; therefore heavy-ion targets of a wide variety have to be prepared in thicknesses from ≅ 2x10^-3 to ≅ 5x10⁴ mg/cm². Range values of ²³⁸U beams in various targets for energies up to 1 GeV/u are illustrated as well as ranges of 1-GeV/u projectiles in some targets, and practicable target thicknesses for relativistic ions are discussed. The new water-cooled target system with target screws and the ion-optical fragment energy degrader system consisting of plane plates, wedged plates and wedged discs to be used in the fragment separator are described in detail. (orig.)

[en] The developments of ²⁰⁷Pb, ²⁰⁸Pb and ²⁰⁹Bi target wheels and their applications in heavy-ion fusion reactions are reviewed. In both, fabrication and use, the centers of the evaporator or accelerator beams are focussed at wheel radii of 155 mm to specially shaped frames which generate very homogeneous target layers and very constant reaction and counting rates in the experiment. Target areas of up to ∼98% of a wheel's circumference of 974 mm can be provided. The preparation procedures for necessary C backings and protecting layers of C are described, and details are given for the developments of high-vacuum evaporations of ²⁰⁷Pb, ²⁰⁸Pb and ²⁰⁹Bi with deposition yields of 35-55% from tantalum crucibles. The applications of the target wheels in heavy-ion fusion reactions with beams of ⁵⁴Cr and ⁵⁸Fe at energies near the Coulomb barrier and intensities of ∼10¹² particles/s are mentioned. The target parameters for the production runs of the new chemical elements ₁₀₇Ns, ₁₀₈Hs and ₁₀₉Mt are included. (orig.)

No abstract available

[en] A target wheel rotating synchronously with the pulsed heavy ion beam of the GSI UNILAC is described. Isotopically enriched Pb targets of 4.5 X 1.5 cm² and of thicknesses of 0.5 to 1.2 mg/cm², covered with thin C layers on both sides, were mounted on the wheel and irradiated by up to 2 X 10¹²s^-1 Ar ions of 5 MeV/u on a beam spot of 0.25 cm² without being destroyed. The total particle dose on the targets was 4 X 10¹⁶ ions. (Auth.)