Li Zhihuan, Hua Hui’s research group and collaborators from the School of Physics observed the new nuclide 18Mg outside the proton drip line for the first time and found new evidence that the magic number of N=8 disappeared

Associate Professor Li Zhihuan and Professor Hua Hui of the Department of Technical Physics and the State Key Laboratory of Nuclear Physics and Nuclear Technology, Peking University School of Physics and their collaborators have observed the four-proton unstable nucleus ¹⁸ Mg (magnesium) for the first time in an experiment , which is more stable than nature The lightest isotope of magnesium has less than 6 neutrons, and it decays to the long-lived ¹⁴ O (oxygen) end state through a peculiar four-proton emission mode ; at the same time, the first possible 2 ⁺ state in ¹⁸ Mg was discovered , which is a proton.

Nucleus structure research far away from the stability line has discovered a large number of strange phenomena, such as the formation of nuclear halos, the generation of new magic numbers, and new decay modes

Recently, Associate Professor Li Zhihuan and Professor Hua Hui’s research group and collaborators carried out an experimental study on the multi-proton decay of magnesium isotopes outside the drip line at the National Superconducting Cyclotron Laboratory of Michigan State University in the United States: using a ²⁰ Mg radioactive beam in ⁹ Be (beryllium) The double neutron knockout reaction on the target successfully produced a new nuclide ¹⁸ Mg outside the proton drip line (Figure 1), and was charged with Si-CsI(Tl) (silicon detector, thallium-doped cesium iodide scintillation crystal) Particle telescopes, scintillation fiber detectors and S800 magnetic spectrometers have carried out efficient and high-resolution coincidence detections of five final particles (4p+ ¹⁴ O) produced by their instantaneous decay

Figure 1.

Figure 2.

The joint research team studied the energy correlation between the four protons in the final decay state and the remaining nucleus ¹⁴ O, and found that the ground state of ¹⁸ Mg decays through a cascade of two-step double proton emission at the same time

In this research work, Jin Yu, a 2017 PhD student in the School of Physics of Peking University, and Niu Chenyang, a postdoctoral fellow in the National Superconducting Cyclotron Laboratory of Michigan State University and a 2018 Ph.

The above-mentioned research work is supported by the National Key Research and Development Program and the National Natural Science Foundation of China

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