Orce, José NicolásNácher E.Parra, Selene2026-09-092026-09-092026Nácher, E., Parra, S., Briz, J.A., Poves, A., Gelletly, W., Rubio, B., Agramunt, J., Algora, A., Aguilera, P., Berry, T. and Borge, M.J.G., 2026. Experimental Gamow–Teller Strength in the rp-Process Waiting-Point Nucleus 64Ge and its Impact on Stellar Weak-Decay Rates. Physics Letters B, p.140800.10.1016/j.physletb.2026.140800https://hdl.handle.net/10566/25385The β decay of the rp -process waiting-point nucleus 64Ge plays a key role in Type-I X-ray bursts. Reliable theoretical predictions at the high temperatures and densities of these environments require models capable of reproducing the relevant Gamow–Teller (GT) strength under terrestrial conditions. We report a measurement of the B (GT) distribution in the decay of 64Ge using the Total Absorption Gamma-ray Spectroscopy technique at CERN-ISOLDE. The experimentally determined B (GT) distribution is compared with large-scale shell-model calculations and with existing theoretical approaches. While shell-model-based calculations provide a good description of the data, QRPA results show significant discrepancies. Stellar weak-decay rates derived from our experimental B (GT) distribution provide the first experimentally constrained rates for 64Ge, and a stringent benchmark for nuclear-structure models employed in rp-process simulations.enBeta decayGamow–Teller strengthrp processStellar weak-decay ratesTotal absorption gamma-ray spectroscopyArticle