Alignment and shields in the M2 primary proton beamline at J-PARC

Abstract

In the J-PARC project, the 3-GeV 333-μA proton beam will be transported from the 3-GeV ring to the neutron source located in the Materials and Life Science Facility. In the M2 tunnel, where the muon target is situated, the radiation level is expected to reach up to 20 MGy/y. Therefore, beamline components will need to be installed and aligned remotely from the maintenance area, which is located 4 m above the floor level. We have adopted alignment plates with pivots to position each component precisely in the beamline. Then, by using the surrounding iron shields as guides, a beamline component can be smoothly inserted and precisely aligned onto its alignment plate. In this paper, the alignment strategy used in the M2 tunnel is described.