Lifetime measurements of nuclei in few-electron ions

TL;DR

This review summarizes lifetime measurements of highly ionized ions with up to two electrons, focusing on weak interaction decays, novel observations of bound-state beta-decay, and intriguing decay rate modulations.

Contribution

It compiles and discusses experimental results on decay processes of few-electron ions, highlighting new phenomena like bound-state beta-decay and decay rate oscillations.

Findings

Observation of beta-decay into bound atomic states

Comparison of hydrogen- and helium-like ion decays

Detection of sinusoidal decay rate modulations

Abstract

In this review lifetime measurements of ions with at most two electrons are summarized. Such highly ionized systems have been studied - until now - only in the Experimental Storage Ring of the GSI in Darmstadt. Emphasis is put on decays via the weak interaction. The first observations of beta-decay into bound atomic states are described as well as its time mirrored counterpart, the electron-capture decay. In the latter case the decays of hydrogen- and helium-like ions are compared with a surprising result. Further on, the observation of sinusoidal modulations of the decay rate in two-body decays is summarized. As a possible cause an interference due to the emission of neutrinos with different rest mass is discussed.