Determination of the probabilities of spontaneous fission in U233, U235, and Am243

The periods of spontaneous fission were determined for urnaium and americium by means of fission-fragment detectors in the form of glass plates; these were: (1.2±0.3)·1017 years for U233, (3.5±0.9)·1017 years for U235, (3.3±0.3)·1013 years for Am243. An attempt was made to systematize experimental data on the spontaneous-fission periods of odd-even and even-odd nuclei.