Recently, Gan Zaiguo, a researcher in the Center of Nuclear Physics, Institute of Modern Physics, Chinese Academy of Sciences, and his collaborators synthesized a new nuclide actinium-204. This is the fourth nuclide outside the actinide proton drip line. Relevant achievements were published in Physical Communication B. Using the beam provided by the Lanzhou Heavy Ion Accelerator (HIRFL) and the China Superheavy Element Research Accelerator Facility (CAFE2), the researchers successfully synthesized a new nuclide actinium-204 and measured its α The decay energy and half-life are consistent with the theoretical predictions. The actinium-204 synthesized this time is the 35th new nuclide discovered in modern physics and the first new nuclide synthesized on the new gas filled recoil spectrometer (SHANS2). Because of the half-life of atomic nucleus and its released α The particle energy is related, usually the half-life is related to α The decay energy has synchronous odd even fluctuations when it changes with the neutron number of the isotope. Huang Minghui, a researcher of the research group, introduced that they found that this synchronous fluctuation did not occur in actinium-204 and other nuclides with neutron numbers less than 119. It is revealed that compared with actinium-205 with even number of neutrons, actinium-204 with odd number of neutrons is formed near the nuclear surface α The probability of clustering is lower, that is, the unpaired neutrons in the nucleus α The formation of clusters has a blocking effect. This study provides extreme distance β The mass and decay data of the stable line nuclides Actinidium-204 and Actinidium-205. This information is helpful for people to understand that single nucleon α The role played in the decay process. The work was completed by researchers from the Institute of Modern Physics of the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences, Dongjiang Laboratory of Guangdong Province, and researchers from Sun Yat sen University, Lanzhou University, Guangxi Normal University, the Institute of Theoretical Physics of the Chinese Academy of Sciences, Tongji University, and the Russian Joint Nuclear Research Institute. (Outlook New Times)