A Simple Radionuclide-Driven Single-Ion Source
We describe a source capable of producing single barium ions through nuclear recoils in radioactive decay. The source is fabricated by electroplating ^148Gd onto a silicon α-particle detector and vapor depositing a layer of BaF₂ over it. ^144Sm recoils from the alpha decay of ^148Gd are used to dislodge Ba+ ions from the BaF₂ layer and emit them in the surrounding environment. The simultaneous detection of an α particle in the substrate detector allows for tagging of the nuclear decay and of the Ba+ emission. The source is simple, durable, and can be manipulated and used in different environments. We discuss the fabrication process, which can be easily adapted to emit most other chemical species, and the performance of the source.