STACEX: RPC-based detector for a multi-messenger observatory in the Southern Hemisphere

TL;DR

STACEX proposes a hybrid RPC and Water Cherenkov Detector array for enhanced low-energy gamma-ray detection in the Southern Hemisphere, aiming to improve sky surveys and transient detection between 100 GeV and 1 TeV.

Contribution

The paper introduces a novel hybrid detector design combining RPCs and WCDs to lower the energy threshold of EAS arrays to 100 GeV.

Findings

Potential for improved low-energy sensitivity in Southern Hemisphere surveys

Enhanced capability for transient detection in the 100 GeV to 1 TeV range

Complementary role alongside CTA for gamma-ray astronomy

Abstract

Extensice Air Shower (EAS) arrays are survey instruments able to monitor continuously all the overhead sky. Their wide field of view (about 2 sr) is ideal to complement directional detectors by performing unbiased sky surveys, by monitoring variable or flaring sources, such as AGNs, and to discover transients or explosive events (GRBs). With an energy threshold in the 100 GeV range EAS arrays are transient factories. All EAS arrays presently in operation or under installation are located in the Northern hemisphere. A new survey instrument located in the Southern Hemisphere should be a high priority to monitor the Inner Galaxy and the Galactic Center. STACEX is the proposal of a hybrid detector with ARGO-like RPCs coupled to Water Cherenkov Detectors (WCDs) mainly to lower the energy threshold at 100 GeV level. In this contribution we introduce the possibility of improving the low energy sensitivity of survey instruments by equipping RPCs, which were proved to be optimal detectors at 100 GeV energies by the ARGO-YBJ Collaboration, with WCDs. An EAS detector with high sensitivity between 100 GeV and 1 TeV would be a valuable complementary transient detector in the CTA era.