Accelerator-Driven Neutron Source for Cargo Screening

Advanced neutron interrogation systems for the screening of sea-land cargo containers for shielded special nuclear materials (SNM) require a high-yield neutron source to achieve the desired detection probability, false alarm rate, and throughput. An accelerator-driven neutron source is described that produces a forward directed beam of high-energy (up to 8.5 MeV) neutrons utilizing the D(d,n)3He reaction at deuteron beam energies of up to 6 MeV. The key components of the neutron source are a high-current RFQ accelerator and an innovative neutron production target. A microwave-driven deuteron source is coupled to an electrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1 meter-long, 200 MHz RFQ. The RFQ is based on an unusual beam dynamics design and is capable of operating at a duty factor that produces more than 1.2 mA timeaverage beam current. The beam is transported to a 2-atmosphere deuterium gas target with a specially-designed, thin entrance window. A high-frequency dipole magnet is used to spread the beam over the long dimension of the 4 by 35 cm target window. The source will be capable of delivering a neutron flux of ~;2 x 107 n/(cm2 x s) to the center of a sea-land cargo container and is expected t o satisfy the requirements for full testing and demonstration of advanced neutron interrogation techniques based on stimulated SNM signatures.