Extended Data Fig. 2: Typical γ-ray spectra and corresponding level scheme.

Left, Typical γ-ray spectra taken with a 4π BGO array at JUNA during proton bombardment of an implanted ¹⁹F target, at proton energies of (a) 356 keV and (b) 250 keV. The heavy γ-ray background from the competing ¹⁹F(p, αγ)¹⁶O channel and their summing signals are indicated. The summing γ-ray peak for the target ¹⁹F(p, γ)²⁰Ne channel is indicated by red arrows. The inset shows the coincident γ-ray spectrum gated on the summing peak located in the shaded region. Right, The corresponding level scheme, where the summing γ-ray and the gated γ-ray transitions are illustrated by the coloured arrows.