Direct measurement of the astrophysical 93Nb(n,γ)94Nb reaction rate at the CSNS Back-n

The neutron capture cross section of 93Nb was measured by the time-of-flight method in the energy range of 10 eV to 1000 keV at the Back-n facility of the Chinese Spallation Neutron Source. In the resolved resonance region, the data reported multiple new resonance structures for the first time, including peaks at 966, 973, 1411, 2252, and 2284 eV, which are not present in existing evaluated libraries.

By utilizing a high-purity target and a Bayesian-based double-bunch unfolding algorithm, this work successfully clarified several historical discrepancies. Specifically, the spurious structures caused by 181Ta impurities and the pseudo-doublet artifacts observed in previous measurements were effectively identified and resolved. Maxwellian-averaged cross sections were calculated within the temperature range of the s-process nucleosynthesis model (kT=5-100 keV).