Measurement of Fission Product Yields from Neutron-Induced Fission of Americium-241

To determine the fission product yields from thermal and epithermal neutron-induced fissions of 241Am by the Cd-ratio technique, highly-purified 241Am targets and neutron flux monitors of Co/Al and Au/Al alloys were irradiated in an aluminum capsule by using Japan Material Testing Reactor. The neutron fluxes and their epithermal neutron fractions were determined by measuring γ-rays of 60Co and 198Au. The radioactivities of 95Zr, 99Mo, 103Ru, 106Ru, 127Sb, 129mTe, 131I, 132Te, 133Xe, 140Ba, 141Ce, 147Nd and 156Eu as fission products were measured by γ-ray spectrometry after irradiation. The fission-product yields from 241 Am were calculated from the radioactivities. In the calculation, the contribution from the fissions of 242mAm, 242gAm and 242Cm produced by the neutron capture reaction of 241Am was corrected for, assuming that the mass yield curves in thermal and epithermal neutron-induced fissions are identical among 241Am, 242mAm, 242gAm and 242Cm. The fluctuations of the yields by the neutron capture reactions of the fission products during irradiation were also considered for the determination of the precise fission yields.