The ALPACA experiment: The project of the first sub-PeV gamma-ray observation in the southern sky
Teruyoshi Kawashima for the ALPACA Collaboration
SciPost Phys. Proc. 13, 008 (2023) · published 28 September 2023
- doi: 10.21468/SciPostPhysProc.13.008
- Submissions/Reports
Proceedings event
21st International Symposium on Very High Energy Cosmic Ray Interactions
Abstract
The ALPACA experiment is a project aiming to observe sub-PeV gamma rays for the first time in the southern hemisphere. The main goal of ALPACA is to identify PeVatrons, the accelerators of Galactic PeV cosmic rays, by observing sub-PeV pion-decay gamma rays generated in interactions between PeV cosmic rays and the interstellar medium. This new air shower experiment is located at an altitude of 4,740 m above sea level in the middle of Mt. Chacaltaya in Bolivia. The air shower array consists of 401 scintillation counters covering an 83,000 m$^2$ surface area. In addition, a water-Cherenkov-type muon detector array with an area of 3,700 m$^2$ is installed to discriminate gamma rays from background cosmic rays. The prototype array ALPAQUITA will start data taking in 2022 and will extend to ALPACA in 2024. We report on a general introduction to ALPACA, the progress of the project, and the sensitivity to sub-PeV gamma rays.