Measurement of neutron induced fission of U-235, U-233 and Cm-245 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 U-235(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 U-235, U-233 and Cm-245 in the energy range from 0.050 eV to about 2 MeV.