Nuclear charge distribution in fission: fractional cumulative yields of isotopes of krypton and xenon in 249Cf(nth,f) and 250Cf(sp.f)

The fractional cumulative yields (%) of the following rare gas isotopes were determined radiochemically in the thermal neutron induced fission of 249Cf and in the spontaneous fission of 250Cf and the following results were obtained for the two processes, respectively: 89Kr: 77.6 ± 1.5, —; [Formula: see text], [Formula: see text]; [Formula: see text];139Xe: 32.0 ± 3.5, 23.6 ± 6.0; 140Xe: 12.5 ± 2.0, 14.7 ± 7.0; 141Xe: 4.0 ± 0.3, [Formula: see text]; 142Xe: 0.9 ± 0.1, ≤ 3.61, and 143Xe: 0.22 ± 0.08, —. The results are discussed with respect to the systematies of nuclear charge distribution in fission.