Decay curve study in a standard electron capture decay

We have searched for a time-modulated decay in a standard electron capture experiment for ¹⁴⁰Pr_{, in order to confirm a report from GSI, where an oscillatory decay has been observed for hydrogen-like ¹⁴⁰Pr and ¹⁴²Pm ions in the cooler storage ring. ¹⁴⁰Pr has been produced with the ¹⁴⁰Ce(p, n) reaction by a pulsed proton beam accelerated from the Van de Graaff accelerator at Osaka University. Resultant time dependence of the Kα and Kβ} X-ray intensities from the daughter shows no oscillatory behavior.