The extraction of 229Th3+ from a buffer-gas stopping cell

In the whole landscape of atomic nuclei, ²²⁹Th is currently the only known nucleus which could allow for the development of a nuclear-based frequency standard, as it possesses an isomeric state of just 7.6 eV energy above the ground state. The 3+ charge state is of special importance in this context, as Th³⁺ allows for a simple laser-cooling scheme. Here we emphasize the direct extraction of triply-charged ²²⁹Th from a buffer-gas stopping cell. This finding will not only simplify any future approach of ²²⁹Th ion cooling, but is also used for thorium-beam purification and in this way provides a powerful tool for the direct identification of the ²²⁹Th isomer to ground state nuclear transition.