Counting Antideuterons From a Balloon: Exposure, Background and the Three-Event Threshold

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 the reference exposure, the expected secondary count is a small fraction of an event, and an additional component must exceed the secondary band flux by a large multiple before three events accumulate. The headline outputs of the computation are: n_secondary = 0.47; n_10x = 4.7; n_50x = 24; multiple_for_3_events = 6. 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.