Isomeric Transition in Samarium-143

Samarium oxide enriched in ${\mathrm{Sm}}^{144}$ has been bombarded by 14-MeV neutrons to produce the isomeric state of ${\mathrm{Sm}}^{143}$. The isomeric state was found to decay with a half-life of 65±3 sec by the emission of a 0.75±0.01-MeV gamma ray. Measured relative to a ${\mathrm{Cu}}^{63}\mathrm{}(n,2n)\mathrm{}{\mathrm{Cu}}^{62}$ cross section of 610 mb, a value of 1670±400 mb was found for the total ($n,2n$) cross section of ${\mathrm{Sm}}^{144}$. The ratio of the cross section for production of the isomeric state to the total ($n,2n$) cross section was determined to be approximately 0.5.