Study of $^{\mathrm{57}}$Zn $\beta $-delayed proton emission and its impact on the $^{\mathrm{56}}$Ni rp-process waiting point

A strong bypass circumventing $^{56}$Ni waiting point and diverting the rp-process flow through the path $^{55}$Ni(p,$\gamma$)$^{56}$Cu(p,$\gamma$)$^{57}$Zn($\beta^{+})$$^{57}$Cu(p,$\gamma$)$^{58}$Zn has been proposed \footnote{W.-J. Ong, et. al, Phy. Rev C {\bf 95} 055806 (2017).}. The $^{56}$Ni(p,$\gamma$) and $^{56}$Cu(p,$\gamma$) reaction rates calculated with the recently measured mass of $^{56}$Cu \footnote {A.A.Valverde, et. al, Phy. Rev Lett. {\bf 120} 032701 (2018).} show that the rp-process flow can redirect around the $^{56}$Ni waiting point. However, the dominant source of uncertainty regarding the strength of this bypass is the $\beta^{+}$-delayed proton emission decay branch of $^{57}$Zn, having a present estimate of 78$\pm$17\% \footnote {B. Blank et. al, Eur. Phys. J. A {\bf 31} 262-272 (2007).}. We measured $\beta$-delayed proton emission of $^{\mathrm{57}}$Zn at the National Superconducting Cyclotron Laboratory using implantation in a DSSD surrounded by a clover array for p-$\gamma$-coincidences. We substantianlly improved the precision for the proton-emission branching ratio and identified new $\gamma$-ray transitions that each correspond to the exotic $\beta$-$\gamma$-p decay mode. These results, along with the impact on the rp-process flow will be discussed