Электронный каталог

Статья

Balibrea-Correa, J.
Frst *9*4Nb(n,*g) Measurement: Constraining the Nucleosynthetic Origin of *9*4Mo in Presolar Grains / J.Balibrea-Correa, V.Furman, Y.Kopatch, [a.o.]. – Text : electronic // Physical Review Letters. – 2026. – Vol. 137, No. 8. – P. 082701. – URL: https://doi.org/10.1103/538w-rhqb. – Bibliogr.: 61.

Isotopic measurements of presolar silicon carbide grains from dying stars have revealed a puzzling overabundance of *9*4 Mo that stellar nucleosynthesis models have failed to reproduce for two decades. This discrepancy challenged our understanding of the slow neutron-capture process (𝑠-process) that forges approximately half of the elements heavier than iron. The key uncertainty lies at *9*4 Nb , a radioactive branching point where competition between neutron capture and beta decay governs the *9*4 Mo production, yet the neutron-capture cross section had never been measured. Here, we report the first experimental determination of the *9*4 Nb ⁢(n,𝛾)⁢ *9*5 Nb cross section important for Mo isotopic abundances. The measurement was enabled by a coordinated effort involving high-purity target preparation at Institute of Solid State and Materials Research Dresden, radioactive sample production at the Institut Laue-Langevin Grenoble, radiochemical characterization at Paul Scherrer Institut Villigen, and the time-of-flight CERN n_TOF facility using for the first time segmented total-energy detectors. Incorporation of the resulting Maxwellian-averaged cross section into fully coupled nucleosynthesis models of low-mass asymptotic giant-branch stars brings them into agreement with the presolar grain data. These results remove a major nuclear-physics input uncertainty at the *9*4 Nb branching point and provide a firmer foundation for understanding the origin of *9*4 Mo in the Solar System.



ОИЯИ = ОИЯИ (JINR)2026