We propose to investigate isotopic and isomeric yields from 241Pu thermal neutron induced reaction, in the heavy mass region (close to the symmetry): A=125 up to A=134. For that, fission products selected by Lohengrin will be implanted in a moving tape placed inside a vacuum chamber. Then, two ILL clover Ge detectors will be used to measure gamma-rays which follow beta-decays of fission products. In this way, the contributing nuclear charges can be identified. This method has already been applied successfully to measure isotopic yields of 239Pu(n_th,f) and 233U(n_th,f) reactions. This proposal is motivated for both nuclear energy applications and the expected improvement of our fission process understanding.