Completion of a new accelerator-driven compact neutron source prototype RANS-Ⅱ for on-site use

摘要

RIKEN accelerator driven compact neutron source Ⅱ (RANS-Ⅱ), a neutron source that is designed to serve as a prototype of a next-generation downsized accelerator-based compact system, has been constructed and has successfully generated neutrons. We aim to demonstrate the system's suitability for various applications, such as the on-site degradation diagnosis of concrete infrastructures, analysis of raw materials, and other uses. Based on the ~7Li(p,n)~7Be reaction for neutron production, the major components of RANS-Ⅱ include a newly developed ECR ion source, 2.5 MeV RFQ using copper plated steel as a proton accelerator along with a customized solid-state amplifier, and a thin lithium neutron production target deposited on a copper substrate deployed at the end of proton beamline. A movable collimator shielding assembly is placed to shield the neutron and gamma rays produced and extract the neutron beam for experimental purposes. Using this system, we succeeded in transporting a pulsed proton beam onto the Li target and observed neutron production at the target. RANS-Ⅱ was successfully installed in a dedicated space in the neutronics engineering facility at the RIKEN Wako campus. A preliminary test was conducted to analyze the neutron source characterization using conventional dosimetry for neutrons. Results confirm the validity of the proposed design parameters of the RANS-Ⅱ prototype.