New Geiger-Nuttall law for two-proton radioactivity *

Abstract

In the present work, combining with the Geiger-Nuttall law, a two-parameter empirical formula is proposed to study the two-proton (2p) radioactivity. Using this formula, the calculated 2p radioactivity half-lives are in good agreement with the experimental data as well as the calculated ones obtained by Goncalves et al. ([Phys. Lett. B 774, 14 (2017)]) using the effective liquid drop model (ELDM), Sreeja et al. ([Eur. Phys. J. A 55, 33 (2019)]) using a four-parameter empirical formula and Cui et al. ([Phys. Rev. C 101: 014301 (2020)]) using a generalized liquid drop model (GLDM). In addition, this two-parameter empirical formula is extended to predict the half-lives of 22 possible 2p radioactivity candidates, whose the 2p radioactivity released energy Q2p>0, obtained from the latest evaluated atomic mass table AME2016. The predicted results have good consistency with ones using other theoretical models such as the ELDM, GLDM and four-parameter empirical formula.

Systematic study of two-proton radioactivity half-lives within the two-potential approach with Skyrme-Hartree-Fock

“…) i.e. New Geiger-Nuttall law for two-proton radioactivity proposed by Liu et al [38]was plot in Fig. 2.…”

“…Based on the above physical mechanisms, many theoretical models have been proposed to study the 2p radioactivity, such as the direct decay model [23][24][25][26][27][28][29], the simultaneous versus sequential decay model [30], the diproton model [31,32] , three-body model [33][34][35][36] and so on. Moreover, some empirical formulas can also successfully reproduce the half-lives of 2p radioactive nuclei including a four-parameter empirical formula proposed by Sreeja et al [37] and New Geiger-Nuttall law for two-proton radioactivity proposed by Liu et al [38]. The two-potential approach (TPA) [39,40] proposed by Gurvitz was initially used to deal with quasi-stationary problems and has been extended to study α decay, cluster radioactivity and proton radioactivity [41][42][43][44][45][46][47][48][49][50][51][52][53][54][55].…”

Recent progress in two-proton radioactivity

“…However, owing to their short lifetimes and broad intermediate states, the decay mechanisms of these nuclei are not fully understood. The first direct observation of 2p emission from a long-lived ground state was achieved for 45 Fe via projectile fragmentation and in-flight identification [26,27]. So far, researchers have identified only a very small number of nuclei that can decay by emitting two protons from their ground and/or excited states.…”

Semi-microscopic theory of two proton emission

“…Since then, various attempts have been made at describing the two proton emission. The simpler models, using semi-classical tools, have various degrees of success [2][3][4]. They generally depend on multiple parameters, but yield a relatively good predictive power.…”