An Alignment of J-PARC Linac

J-PARC linear accelerator components are now being installed in the accelerator tunnel, whose total length is more than 400 m including the beam transport line to 3GeV synchrotron. A precise alignment of accelerator components is essential for high quality beam acceleration. In this paper, planned alignment schemes for the installation of linac components and watching the long term motion of the building are described. Markings are placed on the floor, which act as a reference for the initial alignment at the installation. For a straight line alignment, the wire position sensor is placed on the offset position with respect to the beam center by a target holder. The hydrostatic levering system is used for watching the floor elevation over the long period.