Cross-section measurements of ^191mIr production using a rapid irradiated target transfer system

A high precision data set of the ¹⁹¹Ir(n,n'γ)^191mIr reaction cross section has not previously measured directly measured due to its short 4.9 s half-life. Iridium was used as a neutron fluence monitor during weapons tests and recent neutron dosimetry applications in the stockpile stewardship field have called for improved cross-section measurements on iridium. A natural iridium target was activated using monoenergetic neutrons from the TUNL tandem accelerator. Following irradiation, the rapid belt-driven irradiated target transfer system (RABITTS) would transfer the Ir foils to a counting station where two HPGe detectors would measure the gamma rays emitted by the decay of the isomeric state ^191mIr. The irradiation and counting cycles were repeated for hours to accumulate data and the resulting photopeak yield is used to calculate the isomer production cross section. The measured cross sections have an average uncertainty of 4.5% and compare well to previous measurements done at Los Alamos National Laboratory, which relied on nuclear models to assess the feeding of the 11/2^- isomeric state.