Advanced design of high-intensity beam transport line in J-PARC

A 3-GeV proton beam transport (3NBT) line provides high-intensity proton beam for an experimental facility of Japan Proton Accelerator Research Complex (J-PARC). Its beam optics and components were intensively designed to transport the proton beam of large emittance with extremely low loss rate. The 3NBT accommodates an intermediate target that causes large beam loss. The scheme of the cascade target system was carefully devised to overcome difficulties due to high radiation.