Neutron-induced fission fragment angular distribution and cross section of uranium targets at CERN-n TOF

Abstract

This thesis work focuses on the measurement of the fission fragment angular distribution (FFAD) and fission cross section of the reactions 234U(n,f) y 235U(n,f) using PPAC (Parallel Plate Avalanche Counter) detectors at the n_ TOF facility (CERN). This faci lity is characterised by a wide neutron spectrum from thermal to 1 GeV with a high energy resolution. This measurement has been performed using the tilted configuration of targets and detectors, which unlike the perpendicular configuration, allows to cover all the emission angles of the fission fragments. Results of the FFAD and the anisotropy parameter have been obtained up to 300 MeV for both reactions, providing for first time data of the 234U(n,f) above 15 MeV and completing the existing measurements of the 235U(n,f). The 235U(n,f) cross section has been obtained up to 100 keV using the neutron flux shape normalised to the IAEA secondary reference. The 234U(n,f) cross section has been calculated in two energy ranges up to 1 GeV using the 235U as reference. The obtained results of the FFAD and the fission cross section are discussed and compared with previous experimental data and with the evaluated libraries