Search for an Energy Dependence in235U 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.