Accelerator-Driven Neutron Source for Cargo Screening

Advanced neutron interrogation systems for screening 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. The design of an accelerator-driven neutron source is described that utilizes the D(d,n)He reaction to produce a forward directed beam of up to 8.5 MeV neutrons. The key components of the neutron source are a high-current Radio Frequency Quadrupole (RFQ) accelerator and a neutron production gas target. The 5.1 m long, 200 MHz RFQ accelerates a 40 mA deuteron beam from a microwave-driven ion source coupled to an electrostatic Low Energy Beam Transport (LEBT) system to 6 MeV. At a 5% duty factor, the time-average D beam current on target is 1.5 mA. A thin entrance window has been designed for the deuterium gas target that can withstand the high beam power and the 2-3 atm gas pressure. The source will be capable of delivering a flux >1·10 n/(cm·s) at a distance of 2.5 m from the target and will allow full testing and demonstration of a cargo screening system based on neutron stimulated SNM signatures.