Best-fit parameters δ and K₀/L and the corresponding χ²/d.f. as function of n₁ (solid lines) for models with re-acceleration in core-collapse SNRs (CC, left sub-panels) and with hadronic interactions in Type I/a SNRs (I/a, right sub-panels). The panel groups a), b) and c) show the fit results for data at E_min =  1, 10, 5, and 2 GeV nucleon^-1, respectively, for τ_snr =  20 kyr. Panel d) shows the results for τ_snr =  10, 20, 40, 60, and 80 kyr in the case of E_min =  2 GeV nucleon^-1. The horizontal dotted lines indicate the reference model parameters.