Methods of measurement for the beam-based alignment system in HLS

The beam-based alignment system is given in HLS (Hefei light source), in which a switchable shunt resistor was installed on quadrupole to bypass a small percentage of the magnet current. The system can be used to position the beam in the magnetic center of quadrupoles. In measurement, some methods (linear fitting with single corrector, parabola fitting with single corrector, linear fitting with local bump, and parabola fitting with local bump) are used. These measurement results are given, and compared among above methods.