Observation of non-exponential orbital electron-capture decays of stored hydrogen-like ions

por Yuri A. Litvinov (GSI, Darmstadt)

viernes 27 jun. 2008 11:30 → 12:30 Europe/Madrid

Sala Seminarios IFIC (Edf. Institutos de Investigación)

This talk reports on the observation of time-modulated orbital electron-capture decays of hydrogen-like 140Pr58+ and 142Pm60+ ions coasting in the ion storage-cooler ring ESR at GSI. By using non-destructive, time-resolved Schottky mass spectrometry of single ions it turned out that the expected exponential decay is periodically modulated in time with an oscillation period of about 7 seconds for both systems. By our special detection technique most of systematical errors, such as time-modulated detection efficiencies, can be excluded - at the expense of restricted counting statistics, however. It is demonstrated that "classical" explanations of our findings, e.g. a periodic change of the population of the two hyperfine states of the parent ions, are rather unlikely. The observed effect is meanwhile broadly discussed in the literature. Some scenarios show that our observations can be attributed to the coherent creation of finite mass eigenstates of the electron neutrino in these two-body weak decays. It will be figured out how this hypothesis of a special kind of "quantum beats" could be corroborated or disproved in other two-body weak decays. Corresponding experiments are already approved and scheduled for the near future.