Neutron Scattering at 2.2 Mev by Time of Flight

Abstract

A millimicrosecond time-of-flight technique has been applied to a study of the scattering of 2.2-Mev neutrons from targets of Fe, ${\mathrm{Pb}}^{206}$, and Y. The 3-Mev phase-focused proton beam from the BNL 18-inch cyclotron was used to produce high-intensity neutron pulses in the $\mathrm{T}(p, n){\mathrm{He}}^3$ reaction. The angular distributions of the elastically scattered neutrons have been measured for the above targets. The angular distributions of the inelastically scattered neutrons from the 0.845-Mev level in ${\mathrm{Fe}}^{56}$ and from the 0.803-Mev level in ${\mathrm{Pb}}^{206}$ have been carefully studied, and were found to be symmetric about ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=90\mathrm{}°$. The angular distributions of the inelastically scattered neutrons from levels at 1.34 and 1.43 Mev in ${\mathrm{Pb}}^{206}$ and from levels at 0.913 and 1.53 Mev in Y have been measured, and also appear to be symmetric about ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=90\mathrm{}°$. The inelastic scattering from ${\mathrm{Pb}}^{206}$ shows evidence for a new level at 1.15 Mev.