Direct detection of the (229)Th nuclear clock transition

Area of Science:

• Nuclear Physics
• Metrology
• Atomic and Molecular Physics

Background:

• Optical atomic clocks represent the current state-of-the-art in time and frequency measurements.
• Nuclear clocks, utilizing nuclear transitions, offer the potential for superior precision.
• The isomeric first excited state of Thorium-229 ((229m)Th) is the only known candidate for a nuclear clock with current technology.

Purpose of the Study:

• To directly detect the isomeric first excited state of Thorium-229 ((229m)Th).
• To confirm the existence of the (229m)Th isomer.
• To lay the groundwork for precise measurements of its decay parameters for nuclear clock development.

Main Methods:

• Direct detection of the (229m)Th nuclear state.
• Characterization of the isomer's energy and half-life.

Main Results:

• Successful direct detection of the (229m)Th nuclear state.
• Confirmation of the existence of the (229m)Th isomer.
• Constrained isomeric energy range of 6.3–18.3 eV and a half-life exceeding 60 seconds for (229m)Th(2+).

Conclusions:

• The direct detection provides crucial evidence for the (229m)Th isomer.
• The results pave the way for precise studies of decay parameters.
• This research is a significant step towards developing a nuclear frequency standard.