We started with radium 226 and found interesting systematics associated with its decay to the relatively long-lived radon 222, which caused collisional shifts. At some point we even figured out we could load strontium ions with the background ionizing radiation.
In 2019 we started a collaboration with Marianna Safronova and Sergey Porsev to measure and calculate the metastable D state lifetimes of the radium ion.
Spectroscopy of the Ra-224 ion's important transitions. With this and our photoionization paper, Ra-224 (3.6 d half-life) is straightforward to use. arxiv.org/abs/2409.09873
Yesterday in the lab the radium team realized Rabi flopping of the electron spin in the hyperfine ground state of a radium-225 ion. A microwave drove the electron's orientation between up and down. This is a plot from the lab notebook.
Radium-224 has a 3.6 day half-life. We've been laser cooling Ra-224 ions in a sealed system since February. Persistence and careful work to see the first ions got us through a bottleneck, opening many opportunities, starting with this paper posted today: arxiv.org/abs/2308.00241
Our perspective piece on the latest measurement (and best limit) of the electron's permanent electric dipole moment came out yesterday: science.org/doi/10.1126/sc…