Speaker
Description
Recently, the n_TOF Collaboration proposed a measurement of the neutron capture cross section of the radioisotope 94Nb, a physical quantity essential for both, nuclear astrophysics as well as for energy applications [1-2]. Current stellar models are unable to accurately reproduce 94Mo production in AGB stars via the s-process—a discrepancy further highlighted by isotopic anomalies found in pre-solar SiC grains. To resolve these modeling gaps, nuclear physics must provide Maxwellian-averaged cross sections (MACS) with significantly lower uncertainties than that provided by pure nuclear model calculations.
A first measurement of the capture cross section by the radioactive 94Nb has been successfully performed by time-of-flight at n_TOF [3]. This measurement provided the first experimental determination of the neutron capture cross section of 93Nb, in energies in which isolated neutron resonances are visible. In order to provide a MACS cross section, in the whole temperature range of interest for s-process nucleosynthesis, an activation measurement at the n_TOF NEAR Station, of the same sample used for the TOF experiment has been proposed and performed during the 2026 run at n_TOF.
The experimental techniques used for these experiments, preliminary results and implications will be presented in this contribution.
References:
[1] First measurement of the 94Nb(n,γ) cross-section
Javier Balibrea, César Domingo-Pardo et al. (The n_TOF Collaboration)
CERN-INTC-2020-062; INTC-P-577
[2] Neutron capture cross section on radioactive ⁹⁴Nb at the n_TOF NEAR Station
Rosa Vlastou, Sotirios Kopanos, Alberto Mengoni et al. (The n_TOF Collaboration)
INTC-P-577-ADD-1
[3] First 94Nb(n,g) Measurement: Constraining the Nucleosynthetic Origin of 94Mo in Presolar Grains
Javier Balibrea et al. (The n_TOF Collaboration),
Submitted for publication, https://doi.org/10.48550/arXiv.2603.17646 (March 2026)