Measurement of neutron induced fission of 235-U, 233-U and 245-Cm with the FIC detector at the CERN n TOF facility

Abstract

A series of measurements of neutron induced fission cross section of various TRU isotopes have been performed at the CERN n TOF spallation neutron facility, in the energy range from thermal to nearly 250 MeV. The experimental apparatus consists in a fast ionization chamber (FIC), used as a fission fragment detector with a high efficiency. Good discrimination between alphas and fission fragments can be obtained with a simple amplitude threshold. In order to allow the monitoring of the neutron beam and to extract the n TOF neutron flux, the well known cross section of the 235U(n,f) reaction, considered as a fission standard, has been used. Preliminary results for the cross section are shown for some selected isotopes such as 235U, 233U and 245Cm in the energy range from 0.050 eV to about 2MeV.