Recent progress in two-proton radioactivity

Abstract

During the last few decades, rare isotope beam facilities have provided unique data for studying the properties of nuclides located far from the beta-stability line. Such nuclei are often accompanied by exotic structures and radioactive modes, which represent the forefront of nuclear research. Among them, two-proton (2p) radioactivity is a rare decay mode found in a few highly proton-rich isotopes. The 2p decay lifetimes and properties of emitted protons hold invaluable information regarding the nuclear structures in the presence of a low-lying proton continuum; as such, they have attracted considerable research attention. In this review, we present some of the recent experimental and theoretical progress regarding the 2p decay, including technical innovations for measuring nucleonnucleon correlations and developments in the models that connect their structural aspects with their decay properties. This impressive progress should play a significant role in elucidating the mechanism of these exotic decays, probing the corresponding components inside nuclei, and providing deep insights into the open quantum nature of dripline systems.

Laser-assisted two-proton radioactivity

“…This result can be interpreted as the fact that current theoretical methods almost all regard the 2p radioactivity as the only diproton emission case [40][41][42][43][44][45]. For the not true 2p radioactivity whose Q 2p > 0 and Q p > 0 and the true 2p radioactivity whose two protons are emitted with large opening angles in the direction of emission, the cases of cascade emission and three-body emission should also be further considered [39,70]. Nevertheless, it remains appropriate for the systematic investigations of the 2p radioactivity utilizing the diproton emission model at present, particularly for the true 2p radioactivity.…”

“…Therefore, cascade emission can be viewed as a double sequential emission. Owing to the involvement of nucleon wave function configurations and nucleon-nucleon interaction in the two correlated protons, the first two mechanisms attract the interest of researchers [39]. For the estimation of the 2p decay rate, one of the viable theoretical methods of calculating the 2p radioactive half-lives is the semiclassical Wentzel-Kramers-Brillouin (WKB) approximation.…”

Extended R-matrix description of two-proton radioactivity

“…A review of recent progress can be found in Ref. [3]. The 2p radioactivity occurs in even-Z nuclei where one proton emission is energetically forbidden while 2p emission is allowed.…”