6533b832fe1ef96bd129a128

RESEARCH PRODUCT

Investigations of Superheavy Quasiatoms via Spectroscopy of δ Rays and Positrons

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There exists a long-standing and very interesting problem in atomic physics, namely, the question: What is the binding energy of an electron if the strength of the Coulomb potential exceeds Zα = 1? According to the Dirac-Sommerfeld fine-structure formula for a point charge $$E = {m_e}{c^2}{[1 - {(Z\alpha )^2}]^{1/2}}$$ (1) the total energy of the lowest bound Is-state becomes imaginary for Zα > 1. But even as early as 1945 it was realized(59) that this property of Eq. (1) is caused by the singularity of the Coulomb potential at the origin. Assuming a realistic charge distribution of the nucleus there is no restriction suc as Zα < 1 for the binding energy. Recent calculations show (cf., e.g., Ref. 81) that the binding energy exceeds 2mec2 = 1.022 MeV at a critical charge Zcr ≃ 173.