Tailor-made thin radionuclide layers for targets and recoil ion sources in nuclear applications
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The present work deals with the production and characterization of thin inorganic layers consisting of natural isotopes and exotic radionuclides by different methods. These layers are usually deposited on thin substrates and are used, e.g., as targets in accelerator experiments and other nuclear applications for nuclear reaction studies and the synthesis of superheavy elements. With steadily increasing beam intensities of new accelerator facilities, the targets have to withstand increasing power inputs. They also have to contain more material, since the cross sections for the synthesis of the heaviest known elements are extremely small. For off-line studies of the chemical reactions of targets with low energetic electron and ion beams, a pilot experiment for “Off-line Deposit Irradiations” (ODIn) of thin layers was constructed, characterized and commissioned with lead targets. This experiment will help to develop a method to condition targets suitable for future accelerator experiments. Furthermore, the fabrication methods in this work were used for the production of thin radioactive samples, so-called recoil ion sources, which are used for the generation of particle beams of their emitted recoil ions and thus have different requirements in contrast to targets. The goal was the production of ideal recoil ions sources consisting of single atomic layers (monolayers) of alpha-decaying radionuclides. They will be used for quantum logic spectroscopy in the “Trapping And Cooling of Thorium Ions with Calcium” (TACTICa) collaboration. The aim of the TACTICa experiment is to study the isomer 229mTh trapped inside a coulomb crystal of 40Ca+ ions in a Paul trap. The 229Th is a nuclide of high interest due to its low lying isomeric state at (8.28 ± 0.17) eV. The precisely known energy and half-life of the isomeric state, which is currently studied by the nuClock collaboration, will make it usable for applications like a “nuclear clock” or quantum computing. The studies of the TACTICa collaboration are in the field of quantum logic spectroscopy and fundamental physics beyond the standard model. In addition to the production of monolayer recoil ion sources for TACTICa, a setup was developed for the electrostatic deceleration of daughter nuclei including 229mTh coming from alpha-decaying sources like 233U while maintaining their initial charge distribution and thus making them available for loading into a Paul trap.