Characteristics of a lead slowing-down spectrometer coupled to the LANSCE accelerator

摘要

A description is given of a lead slowing-down spectrometer (LSDS) installed at the 800-MeV proton accelerator of the Los Alamos Neutron Science Center (LANSCE). The LSDS is designed to study neutron-induced fission on actinides that can only be obtained or used in small quantities. The characteristics of this LSDS (energy-time relation, energy resolution, neutron flux) are presented through simulations with MCNPX and measurements with several different methods. Results on neutron-induced fission of ~(235)U and ~(239)Pu with tens of micrograms and tens of nanograms, respectively, are presented. Finally, additional MCNPX calculations have been performed to simulate the measurement of the cross-section for ~(235m)U(n, f) using different target quantities and different initial isomer-to-ground state compositions.