Examinando por Autor "Alvarez Castillo D.E."

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    Search for ultra-high energy photons through preshower effect with gamma-ray telescopes: Study of CTA-North efficiency
    (Elsevier B.V., 2020-12) Almeida Cheminant K.; Góra D.; Alvarez Castillo D.E.; Ćwikła A.; Dhital N.; Duffy A.R.; Homola P.; Kopański K.; Kasztelan M.; Kovacs P.; Marek M.; Mozgova A.; Nazari V.; Niedźwiecki M.; Ostrogórski D.; Smolek K.; Stasielak J.; Sushchov O.; Zamora-Saa J.
    As ultra-high energy photons (EeV and beyond) propagate from their sources of production to Earth, radiation-matter interactions can occur, leading to an effective screening of the incident flux. In this energy domain, photons can undergo e+/e− pair production when interacting with the surrounding geomagnetic field, which in turn can produce a cascade of electromagnetic particles called preshower. Such cascade can initiate air showers in the Earth's atmosphere that gamma-ray telescopes, such as the next-generation gamma-ray observatory Cherenkov Telescope Array, can detect through Cherenkov emission. In this paper, we study the feasibility of detecting such phenomenon using Monte-Carlo simulations of nearly horizontal air showers for the example of the La Palma site of the Cherenkov Telescope Array. We investigate the efficiency of multivariate analysis in correctly identifying preshower events initiated by 40 EeV photons and cosmic ray dominated background simulated in the energy range 10 TeV – 10 EeV. The effective areas for such kind of events are also investigated and event rate predictions related to different ultra-high energy photons production models are presented. While the expected number of preshowers from diffuse emission of UHE photons for 30 hours of observation is estimated around 3.3×10−5 based on the upper limits put by the Pierre Auger Observatory, this value is at the level of 2.7×10−4 (5.7×10−5) when considering the upper limits of the Pierre Auger Observatory (Telescope Array) on UHE photon point sources. However, UHE photon emission may undergo possible ”boosting” due to gamma-ray burst, increasing the expected number of preshower events up to 0.17 and yielding a minimum required flux of ~ 0.2 km−2yr−1 to obtain one preshower event, which is about a factor 10 higher than upper limits put by the Pierre Auger Observatory and Telescope Array (0.034 and 0.019 km−2yr−1, respectively). © 2020
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    Towards a global cosmic ray sensor network: Credo detector as the first open-source mobile application enabling detection of penetrating radiation
    (MDPI AG, 2020-11) Bibrzycki Ł.; Burakowski D.; Homola P.; Piekarczyk M.; Niedźwiecki M.; Rzecki K.; Stuglik S.; Tursunov A.; Hnatyk B.; Alvarez Castillo D.E.; Smelcerz K.; Stasielak J.; Duffy A.R.; Chevalier L.; Ali E.; Lakerink L.; Poole G.B.; Wibig T.; Zamora-Saa J.
    We present the purpose, long-term development vision, basic design, detection algorithm and preliminary results obtained with the Cosmic Ray Extremely Distributed Observatory (CREDO) Detector mobile application. The CREDO Detector app and related infrastructure are unique in terms of their scale, targeting many form-factors and open-access philosophy. This philosophy translates to the open-source code of the app, open-access in terms of both data inflow as well as data consumption and above all, the citizen science philosophy that means that the infrastructure is open to all who wish to participate in the project. The CREDO infrastructure and CREDO Detector app are designed for the large-scale study of various radiation forms that continuously reach the Earth from space, but with the sensitivity to local radioactivity as well. Such study has great significance both scientifically and educationally as cosmic radiation has an impact on diverse research areas from life on Earth to the functioning of modern electronic devices. The CREDO Detector app is now working worldwide across phones, tablets, laptops, PCs and cheap dedicated registration stations. These diverse measurements contribute to the broader search for large-scale cosmic ray correlations, as well as the CREDO-specific proposed extensive air showers and incoherent secondary cosmic rays. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.