Beam-based approach to verify nuclear hyperfine mixing effect

Abstract

Electromagnetic coupling between a nucleus and its bound electron(s) can induce mixing of nuclear levels—a phenomenon known as nuclear hyperfine mixing (NHM). This effect can greatly enhance light-nucleus interactions and is expected to play a key role in laser-based nuclear control. Although predicted in 1966, NHM has not yet been experimentally confirmed. Here we propose a beam-based scheme to test the NHM effect via collisions between hydrogenlike ²²⁹Th ions (²²⁹Th⁸⁹⁺) and a thin-layer target. This approach avoids the need for resonance tuning and enables detection of prompt ultraviolet photons as a clear experimental signature of NHM. To evaluate the excitation probability of the nuclear isomeric state, we develop, for the first time, nuclear excitation theories that incorporate NHM in both electron- and nucleus-induced processes.