Overview status of the ALPACA experiment

The ALPACA experiment, short for the Andes Large area Particle detector for Cosmic ray physics and Astronomy, is an international project initiated in 2016 by Bolivia and Japan. This collaboration is supported by a long-standing tradition of scientific collaboration between the two countries through their respective research institutions: IIF (Instituto de Investigaciones Físicas) in Bolivia and many Japanese institutes including ICRR (Institute for Cosmic Ray Research). In particular since 1961, the collaboration between IIF with ICRR has been ongoing and has recently been joined by the University of Guadalajara, Mexico. The ALPACA project aims to establish a gamma-ray observatory in La Paz, Bolivia, located near Mt. Chacaltaya at an altitude of 4740 meters above sea level (coordinates: 16^◦23⁰ S, 68^◦08⁰ W). The primary advantage of observing cosmic rays and gamma rays from the southern hemisphere is the broader field of view, which includes the center of our galaxy, an intriguing region for studying gamma-ray emission mechanisms. The focus of the cosmic-ray studies will be in the energy range around the "knee," spanning from 100 TeV to 100 PeV, while the gamma-ray observations will cover energy ranges from 5 TeV to 1 PeV. The full-scale ALPACA observatory is planned to consist of 401 scintillator detectors, spread over a large area of 83,000 m², with a separation of 15 meters between each detector. In addition, there will be underground muon detectors (MD) covering an area of 3,600 m². Despite the challenges posed by the COVID-19 pandemic, the first phase of the ALPACA observatory, known as "ALPAQUITA" (which means "small ALPACA" in Spanish), has begun. It currently features 97 plastic scintillator detectors deployed in an area of 18,450 m². Additionally, the construction of the muon detector, covering 900 m², is currently underway. In this paper, we will provide a comprehensive report on the current status of the ALPACA experiment.