We report on the first measurement of the \beta^+- and orbital electron capture decay rates of ^{140}Pr nuclei with the most simple electron configurations: bare nuclei, hydrogen-like and helium-like ions. The measured electron capture decay constant of hydrogen-like ^{140}Pr^{58+} ions is about 50% larger than that of helium-like ^{140}Pr^{57+} ions.... Show more