Research Information System
PHYSICAL REVIEW LETTERS, vol.133, no.2, pp.1-7, 2024 (SCI-Expanded)
The nuclear two-photon or double-gamma (2γ) decay is a second-order electromagnetic process whereby a nucleus in an excited state emits two gamma rays simultaneously. To be able to directly measure the 2γ decay rate in the low-energy regime below the electron-positron pair-creation threshold, we combined the isochronous mode of a storage ring with Schottky resonant cavities. The newly developed technique can be applied to isomers with excitation energies down to ∼100 keV and half-lives as short as ∼10 ms. The half-life for the 2γ decay of the first-excited 0þ state in bare 72Ge ions was determined to be 23.9(6) ms, which strongly deviates from expectations.