Systematic trends in beta-delayed particle emitting nuclei: The case of βpαβpα emission from 21Mg

We have observed β+β+-delayed α   and pαpα emission from the proton-rich nucleus 21Mg produced at the ISOLDE facility at CERN. The assignments were cross-checked with a time distribution analysis. This is the third identified case of βpαβpα emission. We discuss the systematic of beta-delayed particle emission decays, show that our observed decays fit naturally into the existing pattern, and argue that the patterns are to a large extent caused by odd–even effects.