Abstract
Profile measurement using an inclinometer can evaluate straightness easily without highly accurate shape references.We consider adopting precise inclinometers for evaluating alignment of large linear particle accelerators (linacs).Here, we evaluated straightness of the 71-m-long part of the KEK linac, which corresponds to the single accelerator sector, with the standard deviations of less than 49 |im. The results agreed with those by an alignment telescope and our laser-based alignment system within sub mm range. Moreover, a pair of offset bars was adopted for avoiding obstacles in measurement and straightness for the 206-m-long part of the linac, which corresponds to the three consecutive accelerator sectors, was evaluated. Error estimation based on the error propagating rules agreed well with the measurements. It is expected that 500-m-long straightness for the full straight section of the KEK linac can be evaluated with the standard deviation of 0.3 mm.
