Resonance Fission Widths ofU235for Levels from 6 ev to 50 ev

The energy variation of the total and fission cross sections of ${\mathrm{U}}^{235}$ has been measured with the Nevis synchrocyclotron neutron velocity spectrometer. Fission widths for most of the levels up to 50 ev have been deduced from these measurements. The distribution of the 38 known fission widths shows that the number of channels available for the fission process is between one and four and is most probably two. If ${\overline{\Gamma }}_f$ is different for the two possible spin states of the compound nucleus, these cannot differ by more than an order of magnitude.