Extended R-matrix description of two-proton radioactivity

Abstract

Two-proton ($2p$) radioactivity provides fundamental knowledge on the three-body decay mechanism and the residual nuclear interaction. In this work, we propose decay width formulae in the extended R-matrix framework for different decay mechanisms, including sequential $2p$ decay, diproton decay, tri-body decay, and sequential two-diproton decay. The diproton and tri-body formulae, combined with information on the two-nucleon transfer amplitude and Wigner single-particle reduced width, can reproduce well experimental $2p$ radioactivity half-lives. For the case of ${}^{67}$Kr, theoretical predictions for direct $2p$ decay give much larger half-lives than the recent measurement from RIKEN. A combination of direct and sequential $2p$ emission is analyzed by considering a small negative one-proton separation energy and a possible enhanced contribution from the $p$-wave component. The present method predicts that ${}^{71}$Sr and ${}^{74}$Zr may be the most promising candidates for future study on $2p$ radioactivity. Our model gives an upper limit of 55(4) keV for the decay width of $4p$ emission in recently found four-proton resonant nuclide, ${}^{18}$Mg, which agrees with the observed width of 115(100) keV.

version accepted for publication in Physics Letters B

References in corpus (5)

• Shell-model study of boron, carbon, nitrogen and oxygen isotopes based on monopole-based-universal interaction
• Proton spectroscopy of 48Ni, 46Fe, and 44Cr
• Proton-proton correlations observed in two-proton decay of ${}^{19}$Mg and ${}^{16}$Ne
• Recent Progress in Two-proton Radioactivity
• Shell-model study on properties of proton dripline nuclides with Z, N = 30-50 including uncertainty analysis

Cited by in corpus (1)

• Exploring the possible two-proton radioactivity of ${}^{38,39}$Ti