Department of Physics Liaoning Normal University Dalian 116029 China;
Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and Physics Institute of Space Sciences Shandong University Weihai 264209 China;
State Key Laboratory of Nuclear Physics and Technology School of Physics Peking University Beijing 110871 China;
collective model; critical point symmetry; multiple chiral doublet bands;