Prefission neutron multiplicities and the fission modes of ²²⁶ Th

Abstract

The neutron spectra associated to the two fission modes of 226Th have been measured in coincidence with the fragment yields of the 18O + 208Pb reaction at Elab = 78 MeV. The pre- and post-fission multiplicities and temperatures have been extracted. Surprisingly, the prefission neutron multiplicities associated with the asymmetric mode are larger than those associated with the symmetric mode.