Beta decay along the N=Z line and its relevance in rp-process and X-Ray bursts

¹ Instituto de Física Corpuscular, CSIC Univ. de Valencia, E-46980 Paterna, Valencia, Spain
² Fac. de CC Físicas, Universidad Complutense de Madrid CEI Moncloa, 28040 Madrid, Spain
³ Comisión Chilena de Energía Nuclear, P.O. Box 188-D, Santiago, Chile.
⁴ Dep. of Physics, University of Surrey, Guildford, GU2 7XH, United Kingdom
⁵ Instituto de Estructura de la Materia, CSIC, E-28006 Madrid, Spain
⁶ Dep. of Physics, Istanbul University, Istanbul, 34134, Turkey
⁷ Horia Hulubei Nat. Inst. for Physics and Nuclear Engineering, Bucharest 077125, Romania
⁸ Dep. of Physics & Astronomy, Univ. of the Western Cape, P/B X17 Bellville 7535, South Africa

^* Corresponding author: enrique.nacher@csic.es

Published online: 22 March 2023

Abstract

Nucleosynthesis in Type I X-ray bursts (XRB) proceeds eventually through the rp-process near the proton drip-line. Several N=Z nuclei act as waiting points in the reaction network chain. Astrophysical calculations of XRB light curves depend upon the theoretical modelling of the beta decays of interest, with the N=Z waiting points ⁶⁴Ge, ⁶⁸Se, ⁷²Kr, ⁷⁶Sr, and their second-neighbours N=Z+2 being key nuclei in this context. We have carried out different experimental campaigns at ISOLDE (CERN) to determine the B(GT) distributions, in the decay of several N=Z, N=Z+2 and their daughters, of particular relevance in rp-process calculations. To this aim the Total Absorption Spectroscopy technique is applied. Here we present results on the beta decay of ⁶⁴Ga and the status of the analysis of ⁶⁴Ge. Our results provide benchmarks for testing and constraining models under terrestrial conditions that can be used later for predictions in stellar environments.