Direct detection of elusive thorium-229 isomer Among "Physics World Top Ten Breakthroughs of the Year 2016"

The direct detection of the exotic isomeric state in thorium-229 at the LMU Munich, achieved in collaboration with the Institute of Nuclear Chemistry belongs to the IOP's "Physics World Top Ten Breakthroughs of the Year 2016" as identified according to their fundamental importance of research, significant advance in knowledge, strong connection between theory and experiment, and general interest to all physicists. The work lays a basis for next steps on the way to a potential future "nuclear clock" built upon the ground state transition of this isomeric state. Such a clock's precision might significantly surpass that of the best current timekeepers, the atomic clocks.

Graphical representation of a nuclear clock based on a transition in the atomic nucleus of thorium-229 (left). For the first time, electrons emitted in the deexcitation of the isomer into the ground state (top right) could be directly detected. The corresponding cut-out from the chart of nuclei, which tabulates all known atomic nuclei, is visible in the background. The thorium-229 ground state is listed with ist half-life of 7932 years, while the now directly detected isomer with >60 s half-life.
Credit: Christoph Düllmann, JGU Mainz

The work, led by PD Dr. Peter Thirolf and Dr. Lars von der Wense from LMU, is published in the May 05 issue of Nature (see also accompanying "News & Views" feature by M. Safronova). Further information is available from the LMU Munich group and the NuClock consortium.