Low-uncertainty measurement of the 239Pu (n, f) cross section at nTOF in a very broad energy range from 0. 02 eV up to 10 MeV

Key Points

The 239Pu(n,f) cross section was measured with uncertainties under 4% from 0.02 eV to 10 MeV of neutron energy at CERN's n_TOF facility.
A normalization standard of 1059(6) eV·b was established in the 9–20 eV energy range, confirming consistency with IAEA references.
Using a novel fission fragment detector, the integral ratio of I3/I1 was found to be 41.20(42), contributing key validation of measurements.
The approach provides significant improvements in uncertainty reduction for cross section measurements in neutron physics.

Abstract

The 239Pu (n, f) cross section was measured with uncertainties below 4 % from 20 meV up to 10 MeV of neutron energy at CERN’s nTOF facility using a novel fission fragment detector with a 185. 59 m flight path. Measured cross section was normalized to 1059 (6) eV · b in the 9–20 eV energy range, and is consistent within uncertainties with the standard thermal value and the IAEA reference 239Pu (n, f) cross section. Experimental key values include the integral ratio I3/I1=41. 20 (42) defined by Duran et al. 2024 and the spectrum averaged cross section in 252Cf (sf) reference neutron field of 1802 (40) mb.

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Low-uncertainty measurement of the 239Pu (n, f) cross section at nTOF in a very broad energy range from 0. 02 eV up to 10 MeV

Key Points

Abstract

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