Alpha decay via Gamow tunneling

What you are seeing: the alpha-decay process. An alpha wavefunction oscillates in the nuclear well, decays exponentially across the shaded classically forbidden Coulomb barrier (WKB suppression set by the Gamow exponent), and leaks a small transmitted wave. The nucleus emits alpha particles at a cadence mapped from the Geiger-Nuttall half-life, so a high-$Q$ nuclide streams alphas through a narrow barrier while a low-$Q$ one is nearly quiescent behind a wide one. The compact strip keeps the $\log_{10} T_{1/2}$ versus $Q^{-1/2}$ line with the live $(Z, Q)$ marker.