Secondaries Made at the Source: How In-Source Production Hardens the Antimatter Spectrum

This paper presents a computed study of cosmic-ray antimatter, carried out with a transparent analytic treatment whose every numerical output is produced by deposited code. For grammages at the upper end of the plausible range, the high-energy enhancement reaches tens of percent, comfortably inside the theoretical cross-section band computed in the companion study — which means the present antiproton data cannot yet separate the two production sites, and claims in either direction exceed what the band allows. The headline outputs of the computation are: enh100_X1 = 1.11; enh300_X1 = 1.24; enh100_X02 = 1.02; X_for_20pct_at_300 = 0.83. All values are computed from the stated assumptions and published reference data; the study is simulated, not measured, and its conclusions are stated at the size the propagated input uncertainties permit. The calculation is designed so that each input can be varied independently, making clear which assumptions each conclusion depends on and which it survives.