Estimation of the height of the first interaction in gamma-ray showers observed by Cherenkov telescopes

摘要

Very high energy gamma rays entering the atmosphere initiate Extensive air showers (EAS). The Cherenkov light induced by an EAS can be observed by ground-based telescopes to study the primary gamma rays. An important parameter of an EAS, determining its evolution, is the height of the first interaction of the primary particle. However, this variable cannot be directly measured by Cherenkov telescopes. We study two simple, independent methods for the estimation of the first interaction height. We test the methods using the Monte Carlo simulations for the 4 Large Size Telescopes (LST) that are part of the currently constructed Cherenkov Telescope Array (CTA) Observatory. We find that using such an estimated parameter in the gammaihadron separation can bring a mild improvement (similar to 10 - 20%) in the sensitivity in the energy range similar to 30 - 200 GeV. (C) 2018 Elsevier B.V. All rights reserved.