Optics model determination for beam-based alignment of the J-PARC RCS

Beam-Based Alignment (BBA) of BPM is indispensable procedure to determine accurate offset of quadrupole magnet nearby. In the J-PARC RCS, its quadrupole magnets cannot be controlled their current individually. Because the precise optics model is already available, one can calculate absolute beam position inside the quadrupole magnet based on the model. Comparing the predicted value and measured position, one can determine the offset, namely performing BBA. Using all COD data, kicked by all steering magnets, one can emulate a local bump orbit at the quadrupole magnet. By changing focusing force of the quadrupole magnet, one can record the modification of the orbit and it is directly related to the original model. In this paper, we carry it out about one of seven quadrupole magnet families and report the comparison between the obtained results and the optics model. (author)