Search for an Energy Dependence in ²³⁵U Delayed Neutron Spectra

A sensitive search for a dependence of composite (aggregate) delayed neutron spectra on the energy of neutrons inducing fission of ²³⁵U was performed for eight nearly contiguous delay time intervals between 0.17 to 85.5 s. The experimental arrangement combined a helium jet and tape transfer system with a beta-neutron time-of-flight spectrometer. Thermal and fast neutron measurements were performed successively. Results are compared with spectra derived from individual precursor data complemented by theoretical estimates of missing spectra.