Spontaneous Fission

This paper summarizes part of the work on spontaneous nuclear fission performed at Los Alamos before 1945. The experimental technique used to detect spontaneous fission in the heavy alpha-active elements has been described, and the decay constants for spontaneous fission observed in a number of substances have been listed. The number of neutrons emitted per spontaneous fission of ${\mathrm{U}}^{238}$ has also been measured and found to be 2.2±0.3.