Nuclear charge and mass yields for $^{235}U(n_{th}, f)$

The fission product mass spectrometer 'Lohengrin' has been used to determine the mass and nuclear charge yields of light fission products as a function of their kinetic energy in the range 88.5 MeV<or=E<or =112.0 MeV. The proton pairing causes fine structures in the yields even at low kinetic energy. The large relative yields of nuclei with N>or=60 at high kinetic energy are tentatively explained by an oblate deformation of these nuclei at the scission point. (16 refs).