Radioactive decays at limits of nuclear stability

TL;DR

This paper reviews the various radioactive decay modes observed near the nuclear stability limits, emphasizing experimental techniques and recent theoretical advances, especially in two-proton radioactivity.

Contribution

It provides a comprehensive overview of decay modes at nuclear stability limits, including new decay processes and detailed discussion of two-proton radioactivity.

Findings

Identification of new decay modes near stability limits

Experimental methods for detecting exotic decay processes

Theoretical models explaining two-proton radioactivity

Abstract

The last decades brought an impressive progress in synthesizing and studying properties of nuclides located very far from the beta stability line. Among the most fundamental properties of such exotic nuclides, usually established first, is the half-life, possible radioactive decay modes, and their relative probabilities. When approaching limits of nuclear stability, new decay modes set in. First, beta decays become accompanied by emission of nucleons from highly excited states of daughter nuclei. Second, when the nucleon separation energy becomes negative, nucleons start to be emitted from the ground state. Here, we present a review of the decay modes occurring close to the limits of stability. The experimental methods used to produce, identify and detect new species and their radiation are discussed. The current theoretical understanding of these decay processes is overviewed. The theoretical description of the most recently discovered and most complex radioactive process - the two-proton radioactivity - is discussed in more detail.