Cosmic antihelium-3 nuclei sensitivity of the GAPS experiment

TL;DR

The GAPS experiment aims to detect low-energy antihelium-3 nuclei in cosmic rays, providing unprecedented sensitivity to these rare particles as potential dark matter signatures, with implications for understanding fundamental physics.

Contribution

This paper presents the first detailed sensitivity analysis of GAPS for antihelium-3 detection, based on comprehensive simulations and realistic atmospheric models.

Findings

GAPS can detect antihelium-3 fluxes as low as 1.3e-6 m^{-2} sr^{-1} s^{-1} in its energy range.

GAPS's detection technique offers higher identification power for low-energy antinuclei than previous experiments.

The experiment can set new upper limits or potentially detect antihelium-3 in cosmic rays.

Abstract

The General Antiparticle Spectrometer (GAPS) is an Antarctic balloon experiment designed for low-energy (0.1$-$0.3 GeV/$n$) cosmic antinuclei as signatures of dark matter annihilation or decay. GAPS is optimized to detect low-energy antideuterons, as well as to provide unprecedented sensitivity to low-energy antiprotons and antihelium nuclei. The novel GAPS antiparticle detection technique, based on the formation, decay, and annihilation of exotic atoms, provides greater identification power for these low-energy antinuclei than previous magnetic spectrometer experiments. This work reports the sensitivity of GAPS to detect antihelium-3 nuclei, based on full instrument simulation, event reconstruction, and realistic atmospheric influence simulations. The report of antihelium nuclei candidate events by AMS-02 has generated considerable interest in antihelium nuclei as probes of dark matter and other beyond the Standard Model theories. GAPS is in a unique position to detect or set upper limits on the cosmic antihelium nuclei flux in an energy range that is essentially free of astrophysical background. In three 35-day long-duration balloon flights, GAPS will be sensitive to an antihelium flux on the level of $1.3^{+4.5}_{-1.2}\cdot 10^{-6}\mathrm{m^{-2}sr^{-1}s^{-1}}(\mathrm{GeV}/n)^{-1}$ (95% confidence level) in the energy range of 0.11$-$0.3 GeV/$n$, opening a new window on rare cosmic physics.