Neutron-induced fission cross section of ^natPb and ²⁰⁹Bi from threshold to 1 GeV: An improved parametrization

Neutron-induced fission cross sections for ^natPb and ²⁰⁹Bi were measured with a white-spectrum neutron source at the CERN Neutron Time-of-Flight (n TOF) facility. The experiment, using neutrons from threshold up to 1 GeV, provides the first results for these nuclei above 200 MeV. The cross sections were measured relative to ²³⁵U and ²³⁸U in a dedicated fission chamber with parallel plate avalanche counter detectors. Results are compared with previous experimental data. Upgraded parametrizations of the cross sections are presented, from threshold energy up to 1 GeV. The proposed new sets of fitting parameters improve former results along the whole energy range.