Results of a Low-Background Measurement of the Fission Neutron Spectrum from ²⁵²Cf in the 9- to 29-MeV Energy Range

By means of a time-of-flight experiment, the high-energy part of the ²⁵²Cf fission neutron spectrum is investigated with excellent shielding against cosmic radiation. Data analysis was performed with four different bias settings and results in the 9- to 29-MeV energy range were obtained. Small deviations from the Maxwellian shape (T = 1.42 MeV) were found; however, no indication of any neutron excess above 20 MeV was found.