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