Improved neutron capture cross section ofPu239

Abstract

The Pu($n,\ensuremath{\gamma}$) cross section has been measured over the energy range 10 eV to 1 keV using the Detector for Advanced Neutron Capture Experiments (DANCE) at the Los Alamos Neutron Science Center as part of a campaign to produce precision ($n,\ensuremath{\gamma}$) measurements on Pu. Fission coincidences were measured with a parallel-plate avalanche counter and used to measure the prompt fission $\ensuremath{\gamma}$-ray spectrum in this region to accurately characterize background. The resulting ($n,\ensuremath{\gamma}$) cross section is generally in agreement with current evaluations. The experimental method utilizes much more detailed information than past measurements on Pu and can be used to extend the measurement to higher incident neutron energies.