Researchers have successfully cooled and trapped radioactive radium monofluoride (RaF) molecules to temperatures just above absolute zero, a breakthrough that could enable sensitive tabletop experiments to search for physics beyond the Standard Model. The work, published in Nature on July 28, 2026, demonstrates a method to stabilize these short-lived molecules long enough for precision measurements.
Radium-225, with a half-life of 15 days, was used to create RaF molecules. The team, led by scientists at the University of California, Berkeley, and Lawrence Berkeley National Laboratory, used laser cooling to bring the molecules to about 10 microkelvin. This is the first time radioactive molecules have been laser-cooled, opening a new avenue for studying fundamental symmetries.
The molecules' high atomic number and octupole deformation make them exceptionally sensitive to violations of time-reversal symmetry, which could indicate new particles or forces. The tabletop setup avoids the need for large particle accelerators, making such searches more accessible.
βThis is a game-changer for precision measurements,β said Dr. Emily Liu, lead author of the study. βWe can now probe physics at energy scales previously only reachable in colliders.β The team plans to use the cooled molecules to measure the electron's electric dipole moment, a key test for beyond-Standard-Model theories.
