Impact of experimental mass of ${}^{70}$Kr on the ${}^{68}$Se waiting-point in $rp$-process

Abstract

The recent mass measurement of ${}^{70}$Kr using the $B\ddot{I}$-defined isochronous mass spectrometry yields a mass excess of $-41320(140)$ keV, indicating a 220-keV increase in binding energy compared to the AME2020 prediction. We utilize this experimental mass -- the last piece of information needed -- to model the potential waiting point ${}^{68}$Se in $rp$-process and quantitatively constrain the sequential $p$-capture reaction flow bypassing this waiting point. Our investigation shows that the more tightly bound nature of ${}^{70}$Kr enhances this reaction flow up to a factor of four. This enhancement reduces the effective half-life of ${}^{68}$Se. {A} one-zone X-ray burst model calculations reveal that the higher flow of ${}^{70}$Kr has distinct effects on the tail structure of light curve and the final SnSbTe abundances in the ashes due to a stronger $rp$-process heating.

6 pages, 5 figures, accepted by Phys. Rev. C