dot-dashed). Regions with no visible contours produced no antihelium in the $2\times 10^{10}$ annihilation events simulated while the ‘wavy’ lines are due to limited Monte Carlo statistics. We see that for most masses and final states that are potentially detectable (see discussion in Section \[sec:experiments\]) one should expect $10^{-3}-10^{-2}$ antihelium for each detected antideuteron. In the case of 10 GeV annihilation to b-quarks, the ratio is slightly lower as antihelium with a GAPS detectable kinetic energy requires a total energy of around 4.5 GeV. However, this quickly increases toward the higher mass results as the dark matter mass is increased away from this threshold. The effects induced by propagation of [$\overline{\text{D}}~$]{}relative to [$^3\overline{\text{He}}~$]{}are explored in the next section, but are sub-dominant compared with the nuclear physics uncertainties here. In Sec. \[sec:experiments\] we compute the actual flux and determine the detection prospects for future experiments.

Astrophysical Production and Propagation of Antihelium {#sec:propagation}
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The Dark Matter Source Term
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In order to create a Galactic model for dark matter annihilation throughout the galaxy which will allow us to map the [$^3\overline{\text{He}}~$]{}injection spectrum to the flux at Earth, we must assume a dark matter halo model, a WIMP annihilation cross-section and a 