EXTENSION OF THE FISSION PRODUCT REGION AND YIELDS OF HEAVY PRODUCTS IN THE NEUTRON FISSION OF Pu$sup 23$$sup 9$

Information on observatons of new fission product elements and on the more accurate definition of the Pu/sup 239/ fission yield curve in the heavy nass region is presented. Radiochemical studies, utilizing ion exchange chromatography, of the pile neutron fission of Pu/sup 239/ were made in the region beyong mass number 144. The fission product region was extended to include Dy/sup 166/ and Ho/sup 166/. Chain yiclds were measured relative to Mo/ sup 99/ for masses 147, 149, 153, 156, 159, 161, and 168. The mass distribution of the fission products of Pu/sup 239/ is wider than that of U/sup 233/ or U/sup 235/ since the heawy mass peak shifts toward higher mass numbers. It also exhabits a different shape on the high mass number side of the heavy peak. Fission yield values obtained in these studies expressed in % are: mass 147--2.2, mass 1491.2, mass 153--0.35. mass 156--0.11, mass 159--0.021, mass 161--0.0040 and mass 188--0.00007. The results obtained for masses 153 and 158 are in fair agreement with previously reported values of 0.39 and 0.12%~, respectively. (auth)