A Source-Based Test-Bed for Fast-Neutron Irradiation

Abstract: The "3He crisis" has resulted in a major effort worldwide to develop replacement neutron-detector technologies. Such technologies are in their infancy and need to be thoroughly tested before becoming mainstream. Neutron sources for controlled irradiation include accelerators, nuclear reactors and radioactive sources. Neutrons produced in nuclear reactors and at accelerators have a very high cost per neutron. In contrast, radioactive sources produce neutrons at a significantly lower cost per neu- tron and with a substantially lower cost of entry. A drawback associated with radioac- tive sources is the associated isotropic mixed neutron/gamma-ray field. This work in- troduces a cost-efficient test-bed for the production of 2-7 MeV neutrons based on an 241Am/9Be source, with the aim of lowering the barrier for precision neutron testing of detector technologies. Well-understood nuclear physics coincidence and time-of- flight measurement techniques are applied to unfold the mixed neutron/gamma-ray field and unambiguously identify the energies of the neutrons on an event-by-event basis.