Speakers
Description
Low-energy antideuterons in cosmic rays offer a clean probe for dark matter annihilation and primordial antimatter in the Galaxy. The extremely low astrophysical background makes even a few detected events highly significant. Current limits from BESS Polar-II stand at $\Phi_{\bar{d}} < 6.7 \times 10^{-5}$ (m$^2$sr s GeV/n)$^{-1}$ for 163-1100 MeV/n, while experiments like AMS-02 and GAPS continue the search with improved sensitivity.
PLASTICAMI proposes a novel detection approach based on the two-step annihilation signature of antideuterons in hydrogen-rich targets. When an antideuteron annihilates, one antinucleon can annihilate promptly while the other survives with recoil energy, travels a finite distance, and subsequently annihilates. This produces spatially separated vertices, a distinctive topology exploitable in segmented plastic scintillators. The proposed detector consists of segmented plastic scintillator layers read out by SiPMs, surrounded by a Cherenkov veto (FB118, $\eta=1.5$) to reject fast particles ($\beta \gtrsim 0.8$) while maintaining high efficiency for low-velocity antideuteron candidates.
Recent developments include enhanced Geant4 simulations incorporating dead material and atmospheric effects, geometry optimization balancing detection efficiency with practical deployment constraints, and preliminary background studies evaluating signal-to-background ratios, proton-induced deadtime, and contamination effects. We are developing reconstruction algorithms, from classical tracking with vertexing to feedforward networks and CNNs, to classify events from hit maps. Prototype characterization with SiPMs built and tested in our laboratory is currently underway.
Preliminary simulations suggest competitive sensitivity to low-energy antideuteron flux for balloon-borne missions, complementing existing experimental approaches in probing dark matter scenarios.