Details

Autor(en) / Beteiligte

• Kraemer, Sandro
• Moens, Janni
• Athanasakis-Kaklamanakis, Michail
• Bara, Silvia
• Beeks, Kjeld
• Chhetri, Premaditya
• Chrysalidis, Katerina
• Claessens, Arno
• Cocolios, Thomas E.
• Correia, João G. M.
• Witte, Hilde De
• Ferrer, Rafael
• Geldhof, Sarina
• Heinke, Reinhard
• Hosseini, Niyusha
• Huyse, Mark
• Köster, Ulli
• Kudryavtsev, Yuri
• Laatiaoui, Mustapha
• Lica, Razvan
• Magchiels, Goele
• Manea, Vladimir
• Merckling, Clement
• Pereira, Lino M. C.
• Raeder, Sebastian
• Schumm, Thorsten
• Sels, Simon
• Thirolf, Peter G.
• Tunhuma, Shandirai Malven
• Van Den Bergh, Paul
• Van Duppen, Piet
• Vantomme, André
• Verlinde, Matthias
• Villarreal, Renan
• Wahl, Ulrich

Titel

Observation of the radiative decay of the 229Th nuclear clock isomer

Ist Teil von

• Nature (London), 2023-05, Vol.617 (7962), p.706-710

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2023

Beschreibungen/Notizen

• The radionuclide thorium-229 features an isomer with an exceptionally low excitation energy that enables direct laser manipulation of nuclear states. It constitutes one of the leading candidates for use in next-generation optical clocks 1 – 3 . This nuclear clock will be a unique tool for precise tests of fundamental physics 4 – 9 . Whereas indirect experimental evidence for the existence of such an extraordinary nuclear state is substantially older 10 , the proof of existence has been delivered only recently by observing the isomer’s electron conversion decay 11 . The isomer’s excitation energy, nuclear spin and electromagnetic moments, the electron conversion lifetime and a refined energy of the isomer have been measured 12 – 16 . In spite of recent progress, the isomer’s radiative decay, a key ingredient for the development of a nuclear clock, remained unobserved. Here, we report the detection of the radiative decay of this low-energy isomer in thorium-229 ( 229m Th). By performing vacuum-ultraviolet spectroscopy of 229m Th incorporated into large-bandgap CaF 2 and MgF 2 crystals at the ISOLDE facility at CERN, photons of 8.338(24) eV are measured, in agreement with recent measurements 14 – 16 and the uncertainty is decreased by a factor of seven. The half-life of 229m Th embedded in MgF 2 is determined to be 670(102) s. The observation of the radiative decay in a large-bandgap crystal has important consequences for the design of a future nuclear clock and the improved uncertainty of the energy eases the search for direct laser excitation of the atomic nucleus. The authors report on the radiative decay of a low-energy isomer in thorium-229 ( 229m Th), which has consequences for the design of a future nuclear clock and eases the search for direct laser excitation of the atomic nucleus.