Speaker
Description
The ALPACA experiment, which consists of the large air shower array (83,000 m^2) and the water-Cherenkov-type muon detector (3,600 m^2), is a new project to observe cosmic rays and gamma rays in the energy range between TeV and PeV in the southern hemisphere. The prototype air shower array, named ALPAQUITA (18,000 m^2), has been fully operated at the Chacaltaya plateau (4,740 m a.s.l.) in Bolivia since April 2023. The ALPAQUITA array consists of 97 scintillation detectors with an area of 1 m^2, deployed with 15 m spacing.
The Moon and Sun block cosmic rays, and cast cosmic-ray shadows on Earth, so-called the Moon and Sun shadows. The geomagnetic and solar magnetic fields affect the trajectory of cosmic rays so that the position and depth of the shadow vary depending on cosmic-ray energy and time. These cosmic-ray shadows are utilized to evaluate the angular resolution, the pointing accuracy, and the absolute energy scale of the cosmic-ray instruments as well as the investigation of the time-dependent solar magnetic fields. In this work, we will evaluate the performance of the ALPAQUITA air shower array by the observed Moon shadow. We will also report on the Sun shadows observed around the solar maximum phase in solar cycle 25, compared with the Moon shadow.
| Collaboration(s) | The ALPACA Collaboration |
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