Development of a recoil ion source providing slow Th ions including 229(m) Th in a broad charge state distribution

Ions of the isomer 229m Th are a topic of high interest for the construction of a “nuclear clock” and in the field of fundamental physics for testing symmetries of nature. They can be efficiently captured in Paul traps which are ideal for performing high precision quantum logic spectroscopy. Trapping and identification of long-lived 232 Th + ions from a laser ablation source was already demonstrated by the TACTICa collaboration on Trapping And Cooling of Thorium Ions with Calcium. The 229m Th is most easily accessible as α -decay daughter of the decay of 233 U. We report on the development of a source for slow Th ions, including 229m Th for the TACTICa experiment. The 229m Th source is currently under construction and comprises a 233 U monolayer, from which 229m Th ions recoil. These are decelerated in an electric field. Conservation of the full initial charge state distribution of the 229m Th recoil ions is one of the unique features of this source. We present ion-flight simulations for our adopted layout and give a final source design. This source will provide Th ions in their original charge state at energies suitable for capture in a linear Paul trap for spectroscopy investigations.