Analysis of intermediate structure in the fission and capture cross sections of (235U+n)

Analysis of recent high resolution measurements of fission and capture cross sections of (235U+n) between 2 and 32 keV has been done to extract the energy dependence of the average s-wave fission width and neutron strength function. A correlation analysis of the data indicates that the large fluctuations in α, the capture-to-fission ratio, are due to intermediate structure in the average fission width. The structure can be simulated by using a double-humped barrier model that takes into account coupling of class I and class II states in exactly the same way that has been used successfully to describe structure in subthreshold fission. These results suggest that the presence of intermediate structure is a general phenomenon in suprathreshold fission as well, and that, to describe such structure in the unresolved resonance region, one must include the coupling between class I and class II states