Measurement of the neutron capture cross section of the fissile isotope 235U with the CERN n_TOF Total Absorption Calorimeter and a fission tagging based on micromegas detectors

Abstract

Actual and future nuclear technologies require more accurate nuclear data on the (n,γ) cross sections and α-ratios of fissile isotopes. Their measurement presents several difficulties, mainly related to the strong fission γ-ray background competing with the weaker γ-ray cascades used as the experimental signature of the (n,γ) process. A specific setup has been used at the CERN n_TOF facility in 2012 for the measurement of the (n,γ) cross section and α-ratios of fissile isotopes and used for the case of the #^{235}U isotope. The setup consists in a set of micromegas fission detectors surrounding #^{235}U samples and placed inside the segmented BaF₂ Total Absorption Calorimeter.