English

$^{57}$Zn $\beta$-delayed proton emission establishes the $^{56}$Ni $rp$-process waiting point bypass

Nuclear Experiment 2022-04-20 v1 High Energy Astrophysical Phenomena Solar and Stellar Astrophysics

Abstract

We measured the 57^{57}Zn β\beta-delayed proton (β\betap) and γ\gamma emission at the National Superconducting Cyclotron Laboratory. We find a 57^{57}Zn half-life of 43.6 ±\pm 0.2 ms, β\betap branching ratio of (84.7 ±\pm 1.4)%, and identify four transitions corresponding to the exotic β\beta-γ\gamma-pp decay mode, the second such identification in the fpf p-shell. The p/γp/\gamma ratio was used to correct for isospin mixing while determining the 57^{57}Zn mass via the isobaric multiplet mass equation. Previously, it was uncertain as to whether the rp-process flow could bypass the textbook waiting point 56^{56}Ni for astrophysical conditions relevant to Type-I X-ray bursts. Our results definitively establish the existence of the 56^{56}Ni bypass, with 14-17% of the rprp-process flow taking this route.

Keywords

Cite

@article{arxiv.2204.01621,
  title  = {$^{57}$Zn $\beta$-delayed proton emission establishes the $^{56}$Ni $rp$-process waiting point bypass},
  author = {M. Saxena and W. -J Ong and Z. Meisel and D. E. M. Hoff and N. Smirnova and P. C. Bender and S. P. Burcher and M. P. Carpenter and J. J. Carroll and A. Chester and C. J. Chiara and R. Conaway and P. A. Copp and B. P. Crider and J. Derkin and A. Estrade and G. Hamad and J. T. Harke and R. Jain and H. Jayatissa and S. N. Liddick and B. Longfellow and M. Mogannam and F. Montes and N. Nepal and T. H. Ogunbeku and A. L. Richard and H. Schatz and D. Soltesz and S. K. Subedi and I. Sultana and A. S. Tamashiro and V. Tripathi and Y. Xiaog and R. Zink},
  journal= {arXiv preprint arXiv:2204.01621},
  year   = {2022}
}