57Zn β-delayed proton emission establishes the 56Ni rp-process waiting point bypass
Type-1 X-ray bursts, Waiting-point, β-decay measurement of proton rich isotope
We measured the Zn57 β-delayed proton (βp) and γ emission at the National Superconducting Cyclotron Laboratory. We find a Zn57 half-life of 43.6±0.2 ms, βp branching ratio of (84.7±1.4)%, and identify four transitions corresponding to the exotic β-γ-p decay mode, the second such identification in the fp-shell. The p/γ ratio was used to correct for isospin mixing while determining the Zn57 mass via the isobaric multiplet mass equation. Previously, it was uncertain as to whether the rp-process flow could bypass the textbook waiting point Ni56 for astrophysical conditions relevant to Type-I X-ray bursts. Our results definitively establish the existence of the Ni56 bypass, with 14-17% of the rp-process flow taking this route.
Saxena, M.; J Ong, W.; Meisel, Z.; Hoff, D. E.M.; Smirnova, N.; Bender, P. C.; Burcher, S. P.; Carpenter, M. P.; Carroll, J. J.; Chester, A.; Chiara, C. J.; Conaway, R.; Copp, P. A.; Crider, B. P.; Derkin, J.; Estradé, A.; Hamad, G.; Harke, J. T.; Jain, R.; Jayatissa, H.; Liddick, S. N.; Longfellow, B.; Mogannam, M.; Montes, F.; Nepal, N.; Ogunbeku, T. H.; Richard, A. L.; Schatz, H.; Soltesz, D.; and Subedi, S. K., "57Zn β-delayed proton emission establishes the 56Ni rp-process waiting point bypass" (2022). Physics & Astronomy Open Access Publications. 168.