Distribution of the Number of Prompt Neutrons from the Spontaneous Fission ofPu240

A measurement of the distribution of the number of neutrons per fission of ${\mathrm{Pu}}^{240}$ yielded the following probabilities, $P_m$, for 0,1,2, etc. neutrons: $P_0=0.062\mathrm{}$, $P_1=0.198\mathrm{}$, $P_2=0.374\mathrm{}$, $P_3=0.228\mathrm{}$, $P_4=0.114\mathrm{}$, $P_5=0.027\mathrm{}$, $P_6=0.000\mathrm{}$. The measurement was made with a liquid scintillation counter.