A study on 3-GeV proton beam transport line for JSNS

For the neutron science and the muon science, experimental facilities are to be built in the JAERI/KEK joint project on multi purpose high intensity proton accelerator. In the first phase of the project the proton beam power is l MW which will be up graded to 5 MW in the second phase. In the first phase both neutron and muon facilities utilize a common proton beam from the 3-GeV rapid cycling synchrotron. The muon science facility is located at upper stream of neutron facility. This configuration creates various technical problems. As in the first phase the intensity is high up to 333 μA, optimization of beam optics is stringently requires to provide adequate beam profile on the targets and minimize the beam loss. Beam optics, profile and spill of 3-GeV proton beam are thoughtfully studied. At the initial stage a 2-cm thick carbon target for the muon experiment will be placed in the beam line. This scheme, so called cascade targets, shares the beam efficiently. The beam optics and beam spill were calculated with the TRANSPORT and DECAY-TURTLE codes. A reference beam line was established, which had about 70 m in length. The profile and spill of the beam were calculated by taking into account of the coulomb and nuclear elastic scattering. The beam can be shaped at 13 and 5 cm in full width and height, respectively, on the neutron target, these dimensions satisfy the requirement from the neutron target. (author)