Development of a tagged neutron facility at intermediate energies

A unique experimental facility has been developed to measure absolute neutron scattering cross-sections through the use of tagged intermediate-energy neutrons. The neutrons are produced via the reaction p + d --> n + 2p with an electron-cooled circulating proton beam of 200 MeV bombarding energy incident on a deuterium gas jet target. The "tagging" of the neutrons is accomplished by detection of the associated recoil protons in an array of silicon microstrip detectors located in vacuum. The detection of two protons in coincidence signals the production of a neutron, while energy and position measurements on the recoil protons allow for reconstruction of the four-momentum of the neutron, and its impact position on a secondary target, on an event-by-event basis. Performance characteristics of this facility are presented, and its future application to an absolute measurement of the up elastic scattering cross-section is described. (C) 2004 Elsevier B.V. All rights reserved.