Symmetric and asymmetric fission of 226Ra induced by 5 to 15 MeV neutrons

Kinetic energy spectra of fragments in the 5–15 MeV neutron-induced fission of ²²⁶Ra are obtained. The fraction of fragments corresponding to the central peak of the mass yield curve is determined for each neutron energy used. It is shown that at low excitation energies of the ²²⁷Ra compound nucleus precluding second-chance fission the mass yield curve retains its triple-peaked nature. At still lower excitations, near the fission threshold, radium undergoes asymmetric fission, just as the heavier nuclei.