Prompt neutron emission from the spontaneous fission ofMd260

We have made the first measurement of the number of neutrons emitted from the spontaneous fission of a nuclide in which very high fragment energies dominate the fission process. In bombardments of ${}_{}{}^{254}{}_{}{}^{}\mathrm{Es}$, we produced a large sample of 28-d ${}_{}{}^{260}{}_{}{}^{}\mathrm{Md}$, which was neutron counted in a 1-m-diameter spherical tank containing a Gd-doped scintillator solution. The average number of neutrons emitted per fission is only 2.58±0.11, substantially less than for other actinides. A linear dependence of neutron multiplicity on fragment-excitation energy is observed to the highest values of total kinetic energy.