Potential for measuring the longitudinal and lateral profile of muons in TeV air showers with IACTs

Abstract

Muons are copiously produced within hadronic extensive air showers (EAS) occurring in the Earth's atmosphere, and are used by particle air shower detectors as a means of identifying the primary cosmic ray which initiated the EAS. Imaging Atmospheric Cherenkov Telescopes (IACTs), designed for the detection of γ-ray initiated EAS for the purposes of Very High Energy (VHE) γ-ray astronomy, are subject to a considerable background signal due to hadronic EAS. Although hadronic EAS are typically rejected for γ-ray analysis purposes, single muons produced within such showers generate clearly identifiable signals in IACTs and muon images are routinely retained and used for calibration purposes. For IACT arrays operating with a stereoscopic trigger, when a muon triggers one telescope, other telescopes in IACT arrays usually detect the associated hadronic EAS. We demonstrate for the first time the potential of IACT arrays for competitive measurements of the muon content of air showers, their lateral distribution and longitudinal profile of production slant heights in the TeV energy range. Such information can provide useful input to hadronic interaction models.

Systematic differences due to high energy hadronic interaction models in air shower simulations in the 100 GeV-100 TeV range

“…Such tests might be developed for air shower arrays such as HAWC or future facilities such as SGSO, however some assumptions of the cosmic ray composition would have to be made. Muon LDF and production height measurements should also be possible with the Cherenkov telescope array [27], however measurements in the 100 ĠeV to 1 TeV range may be challenging. Particularly the combination of ground particles and Cherenkov light measured by LHAASO may help to better distinguish between model predictions.…”

Muons as a tool for background rejection in imaging atmospheric Cherenkov telescope arrays

“…2. A thorough study of the different muon identification techniques and their performance is beyond the scope of this paper (see [12,21,22] for some recent efforts). Current background rejection methods implemented in IACTs rely on the properties of the time-integrated Cherenkov light images.…”

“…The ring-like images produced when ground-level muons pass through IACTs have long been used as a means of calibration [10], see [11] for a recent review. Recently, [12] suggested that the identification of a much higher fraction (2021) 81:1101 Large telescopes such as the central telescope of H.E.S.S. [13] and the Large-Sized Telescopes (LSTs) of CTA [14] enable the detection of individual muons out to large impact distance.…”

Muons as a tool for background rejection in Imaging Atmospheric Cherenkov Telescope arrays

“…Muon identification can be carried out via different techniques, which exploit the properties of the muon Cherenkov signal described in Section 2. A thorough study of the different muon identification techniques and their performance is beyond the scope of this paper (see [12,21,22] for some recent efforts). Current background rejection methods implemented in IACTs rely on the properties of the time-integrated Cherenkov light images.…”

“…The ring-like images produced when ground-level muons pass through IACTs have long been used as a means of calibration [10], see [11] for a recent review. Recently, [12] suggested that the identification of a much higher fraction of muons produced in extensive air showers is possible with IACTs.…”