The GAPS experiment - a search for light cosmic ray antinuclei

Abstract

The General Anti Particle Spectrometer (GAPS) is a balloon-borne cosmic-ray experiment which is currently in its last phase of construction, undergoing system testing, and scheduled for a longduration balloon flight from McMurdo Station in the Antarctic in December 2024. Its primary scientific goal is the search for light antinuclei in cosmic rays at kinetic energies below 0.25 GeV/𝑛. This energy region is especially of interest for beyond-the-standard model dark matter searches and is still mostly uncharted. Searches for light antimatter nuclei with energies below 0.25 GeV/𝑛 are a novel approach to the search for dark matter because wide range of dark matter models proposes annihilation or decay into matter-antimatter pairs. GAPS will yield unprecedented sensitivity to low-energy antideuterons and will measure the low-energy antiproton spectrum with high statistics and precision. To reach the required sensitivity, the GAPS detector incorporates a new approach for antimatter detection, utilizing a tracker with custom, lithium-drifted silicon detectors, designed to measure the X-ray cascade expected from antimatter capture and charged particles from the subsequent annihilation. It also utilizes a fast time-of-flight system, allowing for a high-precision beta measurement. This proceeding highlights GAPS scientific goals.