Key Laboratory of Particle Acceleration Physics and Technology;
Institute of High Energy Physics;
Chinese Academy of Sciences;
Beijing 100049;
China;
University of Chinese Academy of Sciences;
Beijing 100049;
China;
Shanghai Institute of Applied Physics;
Chinese Academy of Sciences;
Shanghai 201800;
China;
KB; mirror; Beam; size; measurement; Beam; diagnostic; Emittance; Synchrotron; radiation;