Nitrogen doping/infusion of 650 MHz cavities for CEPC Cover Article Enhanced Publication

State Key Laboratory of Nuclear Physics and Technology & Institute of Heavy Ion Physics, Peking University,Beijing,China,100871;Institute of High Energy Physics, Chinese Academy of Sciences,Beijing,China,100049;Key Laboratory of Particle Acceleration Physics and Technology, Chinese Academy of Sciences,Beijing,China,100049;Center for Superconducting RF and Cryogenics, Institute of High Energy Physics, Chinese Academy of Sciences,Beijing,China,100049;University of Chinese Academy of Sciences,Beijing,China,100049