[en] Most targets of isotopes with very low vapor pressure can only be fabricated by vacuum deposition using an electron gun system or a heavy ion sputtering system. Heavy ion sputtering is a very new technique with many unsolved problems. Therefore it seems to be easier to work with an electron gun. Different commercially available electron guns, which are all designed for the high evaporation rates used in industry, are examined for their qualification in processing small amounts of material as used in fabrication of isotope targets. Electron backscattering and the associated efficiency of the electron beam power is strongly dependent on the atomic number Z of the evaporant and the incident angle of the electron beam on the surface of the evaporant. This dependence leads also to the undesired effects to the target layers from electrons and ions. Some precautions are necessary against the effects of the electrons and ions, which are formed in the plasma directly over the beam impact point. Beam power and beam density have to be chosen to get a constant evaporation rate and a low enough condensation rate in order not to overheat the target substrates. To evaporate some metals it may be helpful to pulse the electron beam

[en] With carbon as an example, the possible accuracy of the thickness measurement of light transparent foils is demonstrated. With a quartz prism-spectrophotometer, the transmission characteristics of carbon foils in the energy range of 200 to 2500 nm was investigated. The transmittance as a function of carbon foil thickness was measured at different wavelengths. With these data the absorption coefficients and the reflectivities of carbon foils were calculated. Knowing these optical constants for one wavelength, it is easy to calculate the absolute thickness of a carbon foil by measuring only its transmittance for this monochromatic light. With this method carbon foils were investigated grown on different parting agents to see if there might be an epitaxial effect giving different crystalline clusters in the almost amorphous carbon foils

[en] The vacuum facility for the evaporation by means of a laser beam and the development of stripper foils are described. (HSI)

[en] For the fabrication of ultra cold neutron detectors a new deposition plant was purchased and assembled in 2006. It was recently decided to equip the system with a more versatile deposition setup and complement the already existing 7-hearth electron gun with 4 sputter guns and an ion gun. In addition, the entire vacuum system has been automated to facilitate its operation end exclude handling errors. Additionally it is planned to automate the deposition process to render the fabrication of extremely multilayered (several hundred layers) systems possible. (author)

[en] The work performed in the named laboratory is described. It concerns advances in the laser-beam evaporation, better focusing in the electron beam evaporation, and the preparation of ¹²⁹I targets. (HSI)

[en] Rolled target foils withstand due to their crystalline structure longer a heavy ion beam than evaporated targets. This fact is important for experiments with very heavy ions available now at the SUPER HILAC at Berkeley or at the UNILAC at Darmstadt, Germany. Because the crystalline disorientation of the targets by the heavy ion beam requires a frequent target exchange to prevent a deterioration of the energy resolution, a method was developed to produce large quantities of rolled targets with thicknesses below 1 mg/cm²

No abstract available

[en] Carbon occupies a special place compared to all other elements. Without carbon, the basis for life would be impossible. Organic chemistry or carbon chemistry is an independent part of chemistry. Just so the element carbon occupies an exceptional position in target preparation for nuclear measurements due to its melting point, the highest of all elements, the very low vapor pressure and the chemical stability which is comparable to that of the noble metals. Carbon has only two stable isotopes and one radioactive isotope the half-life of which is long enough to prepare targets. The natural abundance of carbon-12 is nearly 99% which means a natural carbon target can be used in most cases as isotopic ¹² C-target. But this is only one part of the story, the other one is given by the excellent properties of the selfsupporting foils. The good tensile strength of an amorphous carbon layer can be estimated by the minimum thickness of a selfsupporting foil. Carbon foils can be prepared even below 1 μg/cm₂ (approx. = 60 ₀A), they are one order of magnitude thinner than foils of any other element

[en] Laser ablation techniques are used for the preparation of accelerator targets at our laboratory since 1978. For refractory materials, where the evaporation out of a collimating crucible is not possible, laser ablation is the most efficient method, because all other procedures cannot cover such a large solid angle for the substrates. Evaporation of isotopic refractory materials at a controlled partial pressure of an oxidizing or reducing gas can be performed only with laser ablation techniques. Procedures for target preparation are described using different Nd:YAG laser systems, optically coupled to a vacuum chamber with a base vacuum of 10^-5 Pa. Differences in the results depending mainly on the time structure of the laser beam are discussed for lasers with up to 100 W cw power and pulsed lasers with a peak pulse power of 0.1 MW for 120 ns and 30 MW for 10 ns pulses. (orig.)

[en] Thin and uniform targets are needed for high-resolution spectroscopy, especially with heavy ions. Typical target thicknesses are of the order 5-50 μg/cm² which precludes the use of self-supporting foils. Therefore thin backings have to be used, mainly carbon backings. The preparation techniques are unproblematic if the isotopes can be evaporated at moderate temperatures from a boat or heated crucible. Damage to the carbon backing can be avoided by a thermic shield and by limiting the evaporation rate. Metals with very low vapor pressures can only be evaporated by electron bombardment from a cooled crucible. Because of the large primary beam energy special precautions have to be followed in order to prevent damage to the backing material. We have studied the influence of energy dissipation in the vapor source on the preparation procedure, especially heat conduction, convection and radiation. (author)