GoKawiilPhysicists directly measure thorium-229 nuclear transition with tunable VUV laser
Researchers built a vacuum ultraviolet spectroscopy setup, using frequency-doubled laser light guided by dichroic mirrors into a chamber holding a thorium-229-doped crystal, to probe the nucleus's unusually low-energy isomeric transition. The system combined a stabilized frequency comb, referenced either to an atomic maser clock or an Yb+ ion clock, with precise beam alignment and a photomultiplier detector to record absorption signals from the crystal as the laser was scanned across the transition frequency.