Experimental Gamow-Teller strength in the <i>β</i> decay of the rp-process waiting-point nucleus 64Ge and its impact on stellar weak-decay rates

Nacher, E.; Parra, S.; Briz, J.; Poves, A.; Gelletly, W.; Rubio, B.; Agramunt, J.; Algora, A.; Aguilera, P.; Berry, T.; Borge, M.; Carmona-Gallardo, M.; Fraile, L.; Illana, A.; Ganioglu, ELA; Guadilla, V.; Lica, R.; Marroquin, I.; Molina, F.; Morales, A.; Singh, B.; Orce, J.; Orrigo, S.; Perea, A.; Romero-barrientos, J.; Sotty, C.; Tengblad, O.; Tain, J.; Tolosa, A.; Vaquero, V.; Vedia, V.; Wang, L.

doi:10.1016/j.physletb.2026.140800

Experimental Gamow-Teller strength in the <i>β</i> decay of the rp-process waiting-point nucleus 64Ge and its impact on stellar weak-decay rates

Nacher E., Parra S., Briz J. A., Poves A., Gelletly W., Rubio B., ...More

PHYSICS LETTERS B, vol.880, 2026 (SCI-Expanded, Scopus)

Publication Type: Article / Article
Volume: 880
Publication Date: 2026
Doi Number: 10.1016/j.physletb.2026.140800
Journal Name: PHYSICS LETTERS B
Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, INSPEC, MathSciNet, zbMATH, Directory of Open Access Journals, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
Istanbul University Affiliated: Yes

Abstract

The beta 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.