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

Abstract

Two-proton (2$p$) radioactivity represents a rare decay mode that has been experimentally observed only in a selected few nuclei. The exploration of 2$p$ emission is crucial for elucidating the structure, mass, and nucleon-nucleon interactions within exotic proton-rich nuclei. $^{39}$Ti has long been postulated as a potential candidate for 2$p$ emission; however, experimental investigations have yet to confirm its 2$p$ decay. To provide more accurate information for further studies, we utilize the Gamow shell model (GSM) and the Gamow coupled channel (GCC) method to analyze the prospective 2$p$ radioactivity of isotopes $^{38,39}$Ti. Our calculations suggest that $^{39}$Ti is indeed a viable candidate for 2$p$ emission. Notably, the estimated partial 2$p$ decay width for $^{39}$Ti, predicted from the three-body GCC method, suggests that its 2$p$ decay could rival its $\beta$ decay in likelihood, although this is highly dependent on the specific 2$p$ decay energy. Additionally, our analysis indicates a propensity for pairing between the valence protons in $^{39}$Ti. A similar investigative approach reveals that $^{38}$Ti exhibits a higher 2$p$ decay energy and a broader decay width than $^{39}$Ti, positioning it as a more promising candidate for 2$p$ decay.