GoKawiil
Tech News
Scientists working on a nuclear clock based on the thorium-229 isotope described how they processed fluorescence signal data to measure the transition's frequency accurately. Their method corrects for leftover excited-state population from prior measurements and for fluctuations in the vacuum-ultraviolet excitation power used to probe the nuclear transition.
Researchers describe a laser interrogation system built around a commercial frequency-quadrupled diode laser that reaches roughly 500 mW at 296.8 nm, used to probe a thorium-229-doped crystal sample. The setup combines offset-frequency phase locking and Pound-Drever-Hall stabilization to a reference cavity, with a photomultiplier tube detecting fluorescence signals inside a vacuum chamber, and the clock laser's frequency also compared against an optical frequency comb.
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.