Gamma-Ray and AntiMatter Survey(GRAMS) experiment

TL;DR

GRAMS is a cutting-edge experiment employing a Liquid Argon TPC to measure MeV gamma rays and antiparticles, aiming to fill the MeV gap and enhance multi-messenger astronomy capabilities.

Contribution

It introduces a novel LArTPC-based approach for simultaneous gamma-ray and antiparticle detection, advancing sensitivity in the MeV range.

Findings

Progress towards prototype balloon flight in 2026.

Initial sensitivity calculations for antihelium-3.

Potential to improve MeV gamma-ray measurement accuracy.

Abstract

The Gamma-Ray and AntiMatter Survey (GRAMS) is a next-generation experiment using a Liquid Argon Time Projection Chamber (LArTPC) detector to measure MeV gamma rays and antiparticles. MeV gamma-ray observations are important for understanding multi-messenger and time-domain astronomy, enabling exploration of the universe's most potent events, such as supernovae and neutron star mergers. Despite the significance of MeV gamma-rays, GRAMS could also explore the so-called 'MeV gap' region to improve MeV gamma-ray measurement sensitivity that was restricted by the challenge of accurately reconstructing Compton events. Aside from gamma-ray detection, the GRAMS proposed method also serves as an antiparticle spectrometer, targeting the low-energy range of cosmic antinuclei measurements. This work will provide updates on the current status and progress towards the prototype balloon flight with a small-scale LArTPC (pGRAMS) scheduled for early 2026, as well as the recent progress on antihelium-3 sensitivity calculation.