The Inelastic Scattering of Fast Neutrons in Lead and Bismuth

The energy spectrum of 14-Mev neutrons from the ($T-D$) reaction after transmission through 6 cm of lead, or bismuth, has been measured by the photographic emulsion method. Approximate agreement with the Weisskopf theory is found, the nuclear temperatures being 0.8 Mev for lead, 0.9 Mev for bismuth. In lead, there is some indication of a group with a discrete loss of energy of about 5 Mev.