When going far from beta stability, the available energy for radioactive decay increases (Qbeta value), and for proton-rich isotopes, the proton separation energy SP decreases.
The decay (+ or electron capture EC) can then populate excited states above SP in the daughter nucleus that can emit a subsequent proton. With increasing excitation energy of populated states, the delayed proton emission (after decay) first concurrences, then replaces, the electromagnetic ( emission) de-excitation. For even more exotic isotopes, the delayed 2- or 3-proton emission becomes possible (-2p. -3p).
The isotopes are produced using fragmentation reactions and implantation in a silicon detectors setup, or using ISOL technique and collecting the nuclei inside the detection setup.
The measurement of protons and gamma-rays emitted during the decay process allows to build the decay scheme of those nuclei.
This kind of spectroscopic studies allows to investigate a wide range of topics concerning nuclear physics, such as :
beta transition strengh distribution ;
ground states mass differences and analog states masse using IMME;
isospin mixing of proton emitting states;
search for direct 2-proton emission components (without involving any intermediate state)