Browsing by Autor "C. Kato"

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A new high energy gamma-ray observatory in the southern hemisphere: The ALPACA experiment
(IOP Publishing, 2020) Carlos I. Calle; K. Hibino; N. Hotta; Y. Katayose; C. Kato; Shinsuke Kato; K. Kawata; W. Kihara; Y. J. Ko; Hironori Kojima
Abstract The ALPACA experiment is a new international project between Bolivia and Japan. It is going to consist of an 83,000 m 2 surface air-shower array and a 5,400 m 2 underground water Cherenkov muon detector array, and the experimental site is at Mt. Chacaltaya plateau at an altitude of 4,740 m. Its main target is to observe 100 TeV gamma rays and explore high-energy gamma-ray sources in the southern sky. This is because such high-energy gamma rays hold the key to identify the origin of cosmic rays at the knee region of the energy spectrum. So far many high-energy gamma-ray sources have been found in the southern sky. They are emitting gamma rays of several tens of TeV, so some of them could be PeVatrons which accelerate cosmic rays to PeV energy region in the Galaxy. By observing them in higher energy region, we will obtain new knowledge of cosmic-ray acceleration to the knee region, and discover new gamma-ray sources. As the prototype experiment of ALPACA, the ALPAQUITA experiment is now under construction. In a MC simulation, we found that ALPAQUITA has the ability of detecting bright gamma-ray sources in the southern hemisphere such as Vela X within 1 year.
ALPACA air shower array to explore 100TeV gamma-ray sky in Bolivia
(2019) T. Sako; Carlos I. Calle; K. Hibino; N. Hotta; Y. Katayose; C. Kato; Shin‐ichiro Kato; K. Kawata; W. Kihara; Y. Ko
Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA) is a new air shower array project as a collaboration between Bolivia and Japan to explore the 100 TeV gamma-ray sky in the southern hemisphere. In a plateau near the Chacaltaya mountain at 4,740 m altitude, a surface detector array covering 82,800 m$^{2}$ with underground water Cherenkov muon detectors of total 5,400 m$^{2}$ area will be constructed. Because of 2 m soil overburden, the muon detectors can detect muons of >1.2 GeV in air showers with a high purity. Using the conventional surface array to determine the primary energy and the arrival direction, the underground muon detectors improve the gamma/hadron separation and also mass identification of primary cosmic rays. For gamma-ray showers within zenith angle of 45 degrees, ALPACA has a full effective area above 20TeV. At 20 TeV and 100 TeV, 99% and 99.9% hadron showers are rejected, respectively, while keeping the gamma-ray detection efficiency above 90%. Many interesting galactic objects can be observed with 0.2 degree angular resolution at 100 TeV with >2,000 hours/year exposure. ALPACA enables us the first sensitive survey of the southern gamma-ray sky at 100 TeV energy range that is crucial to identify PeV accelerating objects. Preparation for infrastructure and con- struction of a pathfinder array ALPAQUITA are ongoing. Scientific targets, expected performance of ALPACA including the prospects for some CR observations and current status are described.
ALPACA experiment: A new air shower array to explore the sub-PeV gamma-ray sky in the southern hemisphere
(2022) T. Sako; M. Anzorena; A. Gomi; Y. Hayashi; K. Hibino; N. Hotta; A Jimenez-Meza; Y. Katayose; C. Kato; S. Kato
In the last few years, gamma-ray astronomy opens a new window in the sub-PeV to PeV range inaugurated by the Tibet AS𝛾 collaboration followed by the HAWC and LHAASO collaborations. The successful three experiments are located in the northern hemisphere and they are not able to study the southern sky where potential interesting objects are known to exist. Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA) is a project to cover the southern sub-PeV to PeV sky using a new air shower array at the plateau of the Chacaltaya mountain at the altitude of 4,740 m in Bolivia. The prime target of ALPACA is to reveal PeV cosmic-ray accelerators presumably existing in the galactic plane, including the galactic center. A prototype array ALPAQUITA consisting of 97 surface counters and 900 m$^2$ muon detectors is now under construction and planned to partly start data taking in 2022. The extension to the 401 counters and 3,700 m$^2$ muon detectors is scheduled in 2024. In this contribution, a general introduction to ALPACA, the current status of ALPAQUITA, and an extension plan after 2023 are presented.
ALPAQUITA Array in the ALPACA Project
(2017) K. Kawata; T. Asaba; K. Hibino; N. Hotta; M. Kataoka; Y. Katayose; C. Kato; Hironori Kojima; R. Mayta; P. Miranda
We are now proposing a new project which consists of a large air shower array (83,000 m^2) and a muon detector array (5,400 m^2) located at the altitude of 4,740 m near La Paz in Bolivia to observe 100 TeV gamma rays in the southern sky. The ALPAQUITA array is a prototype air shower array which will be constructed at the ALPACA site. This array consists of 45 scintillation counters of 1 m^2 in area each, and its effective area is approximately 8,000 m^2 (1/10 of ALPACA air shower array). In the present paper, we report on the current status and the performance of the ALPAQUITA array
The overview of the ALPACA Experiment
(2017) M. Ohnishi; T. Asaba; K. Hibino; N. Hotta; M. Kataoka; Y. Katayose; C. Kato; K. Kawata; H. Kojima; R. Mayta
The ALPACA experiment is a new project aimed at wide field-of-view high-sensitivity observations of high-energy cosmic rays and cosmic gamma rays, launched between Bolivia and Japan in 2016. It is composed of an 83,000 m$^2$ air shower array and a 5,400 m$^2$ underground muon detector array, on a highland at the altitude of 4,740 m, halfway up Mount Chacaltaya on the outskirts of La Paz, Bolivia.