67 Kr two-proton radioactivity: Results and theoretical interpretations

The two-proton radioactivity is a unique tool to study the nuclear structure beyond the proton drip-line. Since its discovery in 2002, the known emitters have been 19Mg, 45Fe, 48Ni, 54Zn and 67Kr. 67Kr was observed for the first time at the RIKEN Nishina Center in 2015. Its decay energy was measured at 1690(17) keV with a branching ratio of 37(14)%. The half-life, 7.4(30) ms, was found in contradiction with theoretical calculations, pointing out effects of decay dynamics and nuclear deformation.