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          Institute: MPI für Kernphysik     Collection: High-Energy Astrophysics     Display Documents

ID: 280939.0, MPI für Kernphysik / High-Energy Astrophysics
Cherenkov light in electron-induced air showers
Authors:Sahakian, V.; Aharonian, Felix; Akhperjanian, A.
Research Context:Cherenkov light; Imaging telescope; Gamma-rays; Cosmic ray electrons
Date of Publication (YYYY-MM-DD):2006-05
Title of Journal:Astroparticle Physics
Issue / Number:4
Start Page:233
End Page:241
Copyright:© 2006 Elsevier B.V
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:In this paper, we present the results of a comparative analysis of the Cherenkov light produced by electromagnetic air showers initiated by primary gamma-rays and electrons. It is shown that the lateral distribution functions of the Cherenkov light initiated by these showers are different. This fact is explained by the difference in the development of cascades from gamma-rays and electrons; electron-showers start to develop and produce light earlier than gamma-showers, but they attenuate rapidly. By propagating much farther into the atmosphere, the gamma-initiated shower carries a Cherenkov component much closer to the ground level than electron initiated showers do; this results in a more intense pool of light close to the shower axis. The difference in the altitudes of electron- and gamma-air showers maximums logarithmically decreases with the energy and is more significant for low energy showers with E ≤ 20 GeV. This can be important for low energy threshold Cherenkov telescopes (below 10 GeV), in which case the background events are due to diffuse cosmic ray electrons only. The minimum energy of primary electrons required for their reliable detection by an imaging atmospheric telescope will be higher than that for primary gamma-rays. For the reasonable value of the geomagnetic field strength of B ≥ 0.3 G and at the initial energies of E ≤ 20 GeV, the pulse width of the Cherenkov light generated by electron-showers is considerably larger than that from gamma-showers. At higher energies the shapes of Cherenkov pulse from showers induced by both primaries become almost similar.
Free Keywords:Cherenkov light; Imaging telescope; Gamma-rays; Cosmic ray electrons
External Publication Status:published
Document Type:Article
Affiliations:MPI für Kernphysik/Group of W. Hofmann/High Energy Astrophysics (F. Aharonian)
External Affiliations:Laboratory of Gamma Ray Astrophysics, Yerevan Physics Institute, Alikhanian Brothers, 2, Yerevan 375036, Armenia
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