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HK: Fachverband Hadronen und Kerne

HK 2: Plenary II

HK 2.4: Invited Talk

Monday, March 16, 2009, 12:30–13:00, Audi-Max

Non-exponential electron capture decay of hydrogen-like ions — •Yuri Litvinov — GSI Helmholtzzentrum für Schwerionenforschung, 64291 Darmstadt, Germany

In this contribution we report 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 systematic errors, such as time-modulated detection efficiencies, can be excluded - at the expense of restricted counting statistics, however.

The interpretation of the observed effect is broadly disputed in 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.

Electron capture decay of hydrogen-like 122I52+ has been studied very recently to investigate a possible scaling of the modulation frequency with the mass of the recoiling daughter nucleus. The data analysis is still in progress. The experiment and the preliminary results will be discussed.