Neutrons from the Breakup of He

The energy spectrum of the neutrons from the disintegration of lithium by 0.8-Mev deuterons has been measured by the method of recoil particles in a high pressure cloud chamber at different stopping powers. A sharp drop in the number-energy curve at 3.8 Mev is interpreted as indicating the maximum energy of the neutrons from the two-stage reaction $\{{\mathrm{Li}}^7+{\mathrm{D}}^2\to {\mathrm{He}}^4+{\mathrm{He}}^5+14.3\mathrm{} \mathrm{Mev},\}\{{\mathrm{He}}^5\to {\mathrm{He}}^4+n^1+0.8\mathrm{} \mathrm{Mev}.\}$ By measuring the alpha-particle spectrum with an ionization chamber-linear amplifier-counter, the relative number of alpha-particles from (1) gave the relative probability of reaction (1) and hence (1.0) in good agreement with the observed relative number of neutrons.