One of the experimental facilities at the German laboratory GSI Helmholtz Centre for Heavy Ion Research in Darmstadt is an Experimental Storage Ring (ESR) with electron cooling in which large numbers of highly charged radioactive ions can be stored for extended periods of time. This facility provides the means to make precise measurements of their decay modes. The absence of most or all of the electrons in the ions simplifies theoretical treatments of their influence on the decay. Also, such a high degree of ionization is typical in stellar environments where such decays play an important role in nucleosynthesis.