Inelastic Scattering of Neutrons byCd111

Abstract

Neutrons with an energy spread of ±40 kev bombarded a disk of natural cadmium; among the products of bombardment was metastable ${\mathrm{Cd}}^{111m}$ produced by inelastic scattering. The yield of ${\mathrm{Cd}}^{111m}$ was measured from its threshold at 396 kev up to 1300 kev. Abrupt changes in the slope of the yield curve are interpreted as showing the onset of ($n, n^{\prime }$) excitation of higher levels. Such levels occur at 720 and 1150 kev. Below 720 kev, the ${\mathrm{Cd}}^{111m}$ was excited only by direct transition from the ground state. We have measured at 720 kev the cross section for this ($n, n^{\prime }$) event, which involves known changes of energy, spin, and parity. The cross section is about 10 millibarns.