Energy channel selection for Runs 1, 2, and 3 (left to right). Panels A: particle flux energy spectra vs. energy; the chosen energy channels of interest are labeled 1–6. Panels B: spectral index α(E) = dlog₁₀f(E)∕dlog₁₀E (blue line) and its derivative in β(E) = dα(E)∕dlog₁₀E. The locations of the six most prominent extrema of the second derivative β are indicated in panels B in electronvolts, and the prominence of the peak is color-coded: blue at the lowest and dark red at the highest values of prominence.