The electrofission cross section for ${}_{}{}^{234}{}_{}{}^{}\mathrm{U}$ from 5.5 to 25.4 MeV has been measured. From a combined analysis of it and the previously measured photofission cross section, using virtual-photon spectra calculated in the distorted-wave Born approximation, the $E2\mathrm{}$ photofission cross section has been determined. Parameters of the fission-decay branch of the giant quadrupole resonance for this nucleus have been obtained. A comparison of the $E2\mathrm{}$ and $E1\mathrm{}$ integrated photofission cross sections for the even uranium isotopes shows that the $E1\mathrm{}$ fission channel increases in strength more rapidly with fissility than does the $E2\mathrm{}$ channel.

NUCLEAR REACTIONS Measured $\sigma \mathrm{}(e,f)\mathrm{}$ for ${}_{}{}^{234}{}_{}{}^{}\mathrm{U}$; deduced ${\sigma }^{E2\mathrm{}}(\gamma ,f)$.

• Received 26 August 1980

DOI:https://doi.org/10.1103/PhysRevC.23.2595