New test of modulated electron capture decay of hydrogen-like $^{142}mathrm{Pm}^{60_s16}$ ions: Precision measurement of purely exponential decay

Abstract

_s15An experiment addressing electron capture (EC) decay of hydrogen-like 142Pm60_s16 ions has been conducted at the experimental storage ring (ESR) at GSI. The decay appears to be purely exponential and no modulations were observed. Decay times for about 9000 individual EC decays have been measured by applying the single-ion decay spectroscopy method. Both visually and automatically analysed data can be described by a single exponential decay with decay constants of 0.0126(7)sâˆâ_s08™1 for automatic analysis and 0.0141(7)sâˆâ_s08™1 for manual analysis. If a modulation superimposed on the exponential decay curve is assumed, the best fit gives a modulation amplitude of merely 0.019(15), which is compatible with zero and by 4.9 standard deviations smaller than in the original observation which had an amplitude of 0.23(4)._s15