The background from single electromagnetic subcascades for a stereo system of air Cherenkov telescopes - Astrophysics > Instrumentation and Methods for AstrophysicsReport as inadecuate




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Abstract: The MAGIC experiment, a very large Imaging Air Cherenkov Telescope IACTwith sensitivity to low energy E < 100 GeV VHE gamma rays, has been operatedsince 2004. It has been found that the gamma-hadron separation in IACTs becomesmuch more difficult below 100 GeV Albert et al 2008 A system of two largetelescopes may eventually be triggered by hadronic events containing Cherenkovlight from only one electromagnetic subcascade or two gamma subcascades, whichare products of the single pi^0 decay. This is a possible reason for thedeterioration of the experiment-s sensitivity below 100 GeV. In this paper asystem of two MAGIC telescopes working in stereoscopic mode is studied usingMonte Carlo simulations. The detected images have similar shapes to that ofprimary gamma-rays and they have small sizes mainly below 400 photoelectronsp.e. which correspond to an energy of primary gamma-rays below 100 GeV. Thebackground from single or two electromagnetic subcascdes is concentrated atenergies below 200 GeV. Finally the number of background events is compared tothe number of VHE gamma-ray excess events from the Crab Nebula. Theinvestigated background survives simple cuts for sizes below 250 p.e. and thusthe experiment-s sensitivity deteriorates at lower energies.



Author: Dorota Sobczynska

Source: https://arxiv.org/



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