Bound-state beta decay and nuclear lifetime measurements at the storage-cooler ring ESR

Abstract

Strong effects on nuclear half-lives have been observed due to stripping the nucleus of all its atomic electrons: For the 52Fe nucleus the electron-capture branch was switched off completely, and the eight-hours half-life increased by about 50%. For bare 163Dy and 187Re ions the empty K shells enabled β − decay into these atomic orbits (bound-state β decay) with half-lives of 48 ± 3 d or 32.9 ± 2.0 yr, respectively, while in the corresponding neutral atoms the nuclei are stable ( 163Dy) or live 10 9 times longer ( 187Re). This half-life reduction for the latter nucleus may have implications on the 187 Re 187 Os galactic-chronometer. Different methods are presented that use a storage ring to measure nuclear half-lives in the range from seconds to years. These techniques are based either on counting the daughter nuclei after magnetic separation from the stored mother nuclei or on measuring revolution frequencies and beam intensities of cooled beams by Schottky-noise analysis.