An $\alpha$-decay model is proposed based on the pick-up mechanism in which the $\alpha$ cluster formation is conceptualized as a process of the valence nucleons above the Fermi surface continuously picking up those below the Fermi surface and forming the specific quantum states. The probability of achieving a configuration with two neutrons and two protons is defined as the preformation probability of $\alpha$ cluster. The predicted $\alpha$ preformation probability accurately reproduces the nuclear shell structure without any adjustable parameters. The motion equation of the preformed $\alpha$ cluster is approximately described by a harmonic oscillator potential together with a Coulomb barrier, and an explicit expression of the barrier penetration probability is then derived, with the depth parameter $V_0$ of the potential well and the Bohr-Sommerfeld quantization condition. The measured $\alpha$ decay half-lives of 190 even-even nuclei can be well described with a root-mean-square deviation of 0.32. The $\alpha$ decay half-lives of the isotopic chains with $Z=118$ and $Z=120$ are predicted and systematically compared with the results from some other models.

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• Alpha decay
• Lifetimes & widths
• Models & methods for nuclear reactions
• Nuclear structure & decays