Mass Yields from 235U(nth, f)-REACTION in the Symmetry Region

Mass yields and kinetic energy distributions of fission fragments from thermal neutron induced fission of ²³⁵U have been measured in the symmetry region with the mass separator Lohengrin of the Institute Laue-Langevin (Grenoble). The kinetic energy dip between asymmetric and symmetric fission amounts to 29 MeV, which agrees with previous data. A strong peak is observed in the widths of the kinetic energy distributions around the mass A = 112. A presence of the second peak in the rms distribution for the heavy mass group does not unequivocally follow from the data measured. A comparison of the data to the libraries and to previous experimental data has been done. A strong deviation in the yields from the predicted values is found for the masses from A = 113 to A = 127. The origin of this deviation (asymmetry in the mass distribution) is discussed.