Abstract
We report laser cooling and trapping of 224Ra+ ions. This was realized via two-step photoionization loading of radium into an ion trap. A robust source for Ra224 atoms, which have a 3.6-day half-life, was realized with an effusive oven containing Th228, which has a 1.9-yr half-life, which continuously generates Ra224 via its α-decay. We characterized the efficacy of this source and found that after depleting built-up radium the thorium decay provides a continuous source of radium atoms suitable for ion trapping. The vacuum system has been sealed for more than 6 months and continues to trap ions on demand. We also report a measurement of the Ra224 7s21S0→7s7p1P1 transition frequency: 621043830±60 MHz, which is helpful for efficient photoionization. With this measurement and previous isotope shift measurements we find that the frequency of the same transition in Ra226 is 621037830±60 MHz, which disagrees with the most precise measurement, 621038489±15 MHz, which is used for the recommended value in the National Institute of Standards and Technology Atomic Spectra Database.
| Original language | English |
|---|---|
| Article number | 043201 |
| Journal | Physical Review Research |
| Volume | 5 |
| Issue number | 4 |
| DOIs | |
| State | Published - Oct 2023 |
Funding
We thank Chris Palmstrøm, Dave DeMille, Bodhaditya Santra, and Lorenz Willmann for helpful discussions, Craig Bichrt for help with the MBE oven configuration, and Dave Patterson for lending a 461-nm laser. We thank Chris Greene and Miguel A. Alarcón for guiding calculations. M.F. and H.L. were supported by DOE Award No. DE-SC0022034. S.K. was supported by ONR Grant No. N00014-21-1-2597. R.A.R., R.K., C.A.H., M.S.L., and A.M.J. were supported by NSF Award No. PHY-2146555, NIST Award No. 60NANB21D185, the Heising-Simons Foundation, the W.M. Keck Foundation, and the Eddleman Center. A.N.G. acknowledges the support of startup funds and Michigan State University. The isotope used in this research was supplied by the U.S. Department of Energy Isotope Program, managed by the Office of Isotope R&D and Production.