Advancing Antideuteron Detection in Cosmic Rays: Innovations in Methods and Technologies

Low-energy antideuterons in cosmic rays (CRs) provide a unique probe of the matter–antimatter asymmetry and of dark matter annihilation in the Galactic halo. The PHeSCAMI project (Pressurized Helium Scintillating Calorimeter for AntiMatter Identification) demonstrated the use of delayed annihilation events in helium targets, but with limited scalability for balloon missions. We propose PLASTICAMI, a segmented plastic tracker optimized for the detection of the "two-step annihilation" signature of antideuterons. The detector consists of segmented plastic scintillator layers and an external Cherenkov veto for triggering and background rejection. Trigger logic, acceptance, and preliminary sensitivity have been evaluated with Geant4 simulations. Results indicate that PLASTICAMI could achieve competitive sensitivity to low-energy antideuteron flux in cosmic rays, allowing investigation of the predicted dark matter annihilation models.