First Observational Results of the ALPAQUITA Air Shower Array in Bolivia

ALPACA Collaboration

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Abstract

The ALPACA experiment, which consists of a large air shower (AS) array and water-Cherenkov-type muon detectors, is a new project to observe sub-PeV gamma rays in the southern hemisphere. The prototype AS array, named ALPAQUITA (1/4 scale of ALPACA), has been prior operated in the center of the ALPACA site at Chacaltaya plateau (4,740 m a.s.l.) in Bolivia. The ALPAQUITA AS array consists of 97 scintillation detectors each with an area of 1 m2, deployed with 15 m spacing. Using this AS array, we have successfully observed the cosmic-ray Moon shadow with a statistical significance −6.2σ for 73 live days. The angular resolution is estimated to be 0.9 based on the Moon shadow observation and the even-odd method. In this proceedings, we assess the performance of ALPAQUITA AS array, and outline the future prospects of the sub-PeV gamma-ray observation with the ALPAQUITA AS+MD array.

Original languageEnglish
Article number257
JournalProceedings of Science
Volume444
StatePublished - 27 Sep 2024
Event38th International Cosmic Ray Conference, ICRC 2023 - Nagoya, Japan
Duration: 26 Jul 20233 Aug 2023

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