At the Experimental Storage Ring ESR at GSI experiments on the investigation of the isolated nuclear two-photon decay were performed [1]. For a better understanding, complementary experiments were planned at the TANDEM accelerator at the University of Cologne, Germany. For these experiments targets from enriched 72 Ge on a thin titanium backing as well as self-supporting targets were needed. As we had only scarce material available, thermal evaporation in a close evaporation geometry was the method of choice. 72 Ge-targets in a thickness range of 350 μg/cm² - 370 μg/cm², self-supporting and with titanium backing, were obtained. We report on the target production and on first results of their application in the experiment.

Scintillating materials are of interest for numerous applications related to ionizing radiation. Exposure to radiation induces damage in these materials, resulting in degradation of their scintillation properties. The knowledge of radiation damage rate as a function of dose is especially important when scintillators are exposed to heavy-ion beams. In this contribution, we report the development of a setup for in-situ characterization of radiation damage of scintillation targets exposed to heavy-ion beams. This setup provides a unique opportunity to study scintillating properties of materials under heavy ion exposure with energies of 300 MeV/u and above. The description of the setup and the sample characterization procedure are discussed on the basis of a study of zinc oxide ceramic scintillators.

Tungsten is applied as target material for experiments in the field of nuclear spectroscopy. Typically, targets of a thickness range of 100 µg/cm² up to 1000 µg/cm² that can safely stand the irradiation by the intense heavy-ion beam over a substantially long period are requested. Natural tungsten is commercially available as thick foils and as sputtering targets. Enriched tungsten is typically available as metal powder. We report on the production of natural and enriched tungsten targets on carbon backing. We compare the different production processes, taking into account the material yield.

Article Corrigendum to: Application of a novel gas phase synthesis approach to carbonyl complexes of accelerator-produced 5d transition metals (Radiochim. Acta 2022; 110 (2): 75–86) was published on January 30, 2023 in the journal Radiochimica Acta (volume 0, issue 0).

We give an overview of the special challenges regarding target development and production for accelerator-based heavy and superheavy-nuclei experiments in the past and perspectives for the future. Production of ever heavier elements, studies of heavy-element production in fusion or transfer reactions, spectroscopic investigations on their nuclear structure and decay and on the fission processes with fragment analyses, laser spectroscopic studies of their atomic structure, high-precision mass measurements as well as chemical studies are lively fields of current science. The ever-increasing beam intensities, feasible with new accelerator development, are crucial for the synthesis of superheavy elements because of the low cross sections for many of the reactions. Therefore, the development of target and backing materials with higher durability and experiment lifetime is increasingly important. Here we concentrate on the techniques necessary for the production of targets that are needed for experiments in this special field of interest. For the future, also development on target monitoring, target cooling, and beam intensity profile shaping techniques will play an important role, but are not in the focus of this article.

For the nuclear chemistry and for the nuclear physics of the heavy elements, bismuth is one of the key target materials, as it is the heaviest stable element. As discussed earlier, compound targets were developed to withstand higher intensive heavy ion beams. In the past, Bi 2 O 3 was evaporated from the tantalum crucible and deposited on carbon backings. As the melting temperature of Bi 2 O 3 is high (817° C), the process is at the limit of the cooling features of the evaporation set-up. Therefore, we decided to test RF magnetron sputtering as an alternative production method. We will present results of the different behavior of the targets produced via alternative processes.

The production of carbon stripper foils that are mounted at different locations of the heavy-ion accelerator is an important task of the target laboratory, and the process for the preparation of carbon foils is constantly improved. Recently, we tested additional heat treatment of the carbon stripping foils following our standard procedure to reduce stress in the foils, since the performance and the durability of these stripping foils is a crucial factor for effective operation. We investigated the properties of foils produced some time ago and of foils freshly produced with the standard procedure, and foils treated thermally after the standard procedure. For the beam diagnostic department at GSI radiation resistant target materials for transverse ion beam profile measurement is an ongoing research topic. In that framework, the feasibility of Optical Transition Radiation (OTR) generation due to ion beam interaction with metal target for beam profile determination has been investigated. Here, carbon stripper foils are applied to enhance the OTR signal. The differently prepared foils were applied in many different experiments of the beam diagnostic department. We describe the performance of the foils during irradiation and compare the features of foils before and after irradiation.

Actinide and lanthanide thin layers with specific requirements regarding thickness, homogeneity, chemical purity, mechanical stability, and backing properties are applied in a multitude of physics and chemistry experiments. A novel target preparation method, the so-called “Drop-on-Demand” (DoD) technique, based on a commercial nanoliter (nL) dispenser is applied since a few years in the Nuclear Chemistry unit at Johannes Gutenberg University Mainz. The wetting behaviour of the nL droplets on the substrate’s surface is a key parameter determining the spatial distribution of the deposited material after evaporation. By switching from aqueous to organic solvents as well as by substrate surface modifications, the wetting behaviour can be influenced. Recent investigations on this influence and applications of the DoD method are presented. The produced actinide deposits were characterized by optical and scanning electron microscopy, by α spectroscopy as well as by radiographic imaging.

One limiting factor in progress in the discovery and study of new superheavy elements (SHE) is the maximum achievable thickness and irradiation stability of current generation actinide targets. The desired thickness of targets, using full excitation function widths, cannot be achieved with current target technology, especially the widely used molecular plating (MP). The aim of this study was to transfer progress in the electrochemistry of lanthanides and actinides to the production of targets. Here, we report on the production of lanthanide targets using anhydrous electrochemical routes. In a first irradiation series, thulium thin films with areal densities up to 1800 mu g/cm(2) were produced using anhydrous triflate compounds and subjected to irradiation tests, using 6.0 MeV/u Ca-48 ions at a fluence of 3.9 x 10(14) ions/cm(2) and 8.6 MeV/u Au-197 ions at fluences in the range of 3.0 x 10(11) to 1.0 x 10(13) ions/cm(2). The thin films were characterised before and after the irradiations using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).

Several techniques are under development for image-guidance in particle therapy. Positron (β+) emission tomography (PET) is in use since many years, because accelerated ions generate positron-emitting isotopes by nuclear fragmentation in the human body. In heavy ion therapy, a major part of the PET signals is produced by β+-emitters generated via projectile fragmentation. A much higher intensity for the PET signal can be obtained using β+-radioactive beams directly for treatment. This idea has always been hampered by the low intensity of the secondary beams, produced by fragmentation of the primary, stable beams. With the intensity upgrade of the SIS-18 synchrotron and the isotopic separation with the fragment separator FRS in the FAIR-phase-0 in Darmstadt, it is now possible to reach radioactive ion beams with sufficient intensity to treat a tumor in small animals. This was the motivation of the BARB (Biomedical Applications of Radioactive ion Beams) experiment that is ongoing at GSI in Darmstadt. This paper will present the plans and instruments developed by the BARB collaboration for testing the use of radioactive beams in cancer therapy.

Abstract In 2014 the first synthesis of a transactinide carbonyl complex – seaborgium hexacarbonyl – was reported. This was achieved in gas-phase chemical experiments in a beam-free environment behind the recoil separator GARIS. Extending this work to heavier elements requires more efficient techniques to synthesize carbonyl complexes as production rates of transactinide elements drop with increasing atomic number. A novel approach was thus conceived, which retains the benefit of a beam-free environment but avoids the physical preseparation step. The latter reduces the yields for products of asymmetric reactions such as those used for the synthesis of suitable isotopes of Sg, Bh, Hs and Mt. For this a series of experiments with accelerator-produced radioisotopes of the lighter homologues W, Re and Os was carried out at the tandem accelerator of JAEA Tokai, Japan. A newly developed double-chamber system, which allows for a decoupled recoil ion thermalization and chemical complex formation, was used, which avoids the low-efficiency physical preseparation step. Here, we demonstrate the feasibility of this newly developed method using accelerator-produced short-lived radioisotopes of the 5d homologues of the early transactinides.

For characterization of targets and foils prepared at the target laboratory as well as for characterization of e.g. degrader or windows of internal customers, different analytical devices are available. Besides a lot of standard equipment, the target laboratory of GSI holds a 3D-measurement system (MicroProf®) equipped with optical sensors for measuring surface parameters as well as total thickness variations contact-free. In the paper the measuring principle including the possibilities and features of the MicroProf®-system are explained and some different applications are shown.

Uranium targets are very important for accelerator-based research of nuclear properties. Depending on the reaction to be studied and on the conditions during the experiments different restrictions on the target material have to be met; as for example, durability, melting temperature, reactivity or a possible contribution of the additional compounds present to the reaction. Therefore, we are developing processes to produce uranium targets in the elemental form as well as in different compounds. Here we report on the production and application of targets from metallic uranium, UF4 and UO2.

The isotopes 255,256,258Rf were produced in the fusion-evaporation reactions 50Ti + 207,208Pb and 50Ti + 209Bi at GSI Darmstadt, using the velocity filter SHIP. Total kinetic energies of fragments from spontaneous fission for these isotopes were evaluated with a correction to pulse-height defect.

For a special application, carbon-backings with a very flat surface, microscopically as well as macroscopically, were needed as backings for targets of enriched isotopes. However, betaine-sucrose routinely applied at GSI as parting agent for carbon deposition results in a microscopically rough surface which was not perfectly satisfying the experimental requirements. For these targets we investigated the carbon-backing quality in relation to the applied different parting agents and different deposition processes. In this paper we report on the yield, on the structure of the carbon layers and the deposited target layer of (PbS)-Pb-208, (PbS)-Pb-206, and (NdF3)-Nd-142 depending on the parting agent, the thickness and the deposition methods. We report on elastic scattering experiments with a Ti-48-beam demonstrating the influence of the structure of the carbon backing on the experimental results.

The isotope 176 Au has been studied in the complete fusion reaction 40 Ca + 141 Pr → 176 Au + 5 n at the velocity filter SHIP (GSI, Darmstadt). The complex fine-structure α decay of two isomeric states in 176 Au feeding several previously unknown excited states in the daughter nucleus 172 Ir is presented. An α -decay branching ratio of b α = 9.5(11)% was deduced for the high-spin isomer in 172 Ir.

Abstract Online gas-solid adsorption studies with single-atom quantities of Hg, Tl, and Pb, the lighter homologs of the superheavy elements (SHE) copernicium (Cn, Z=112), nihonium (Nh, Z=113), and flerovium (Fl, Z=114), were carried out using short-lived radioisotopes. The interaction with Au and SiO2 surfaces was studied and the overall chemical yield was determined. Suitable radioisotopes were produced in fusion-evaporation reactions, isolated in the gas-filled recoil separator TASCA, and flushed rapidly to an adjacent setup of two gas chromatography detector arrays covered with SiO2 (first array) and Au (second array). While Tl and Pb adsorbed on the SiO2 surface, Hg interacts only weakly and reached the Au-covered array. Our results contribute to elucidating the influence of relativistic effects on chemical properties of the heaviest elements by providing experimental data on these lighter homologs.