IceAct, small Imaging Air Cherenkov Telescopes for IceCube

Abstract

IceAct is a proposed surface array of cost effective and compact Silicon Photomultipliers (SiPM) based small-size (50 cm) Imaging Air Cherenkov Telescopes above the IceCube in-ice detector. In coincidence with the in-ice and surface components of IceCube it forms a hybrid detector that enables new measurements combining the information from the Cherenkov light image, the surface particle footprint and the in-ice muon tracks of extensive air showers. During January 2019, two new versions of the IceAct telescope demonstrators featuring 61 SiPM pixels and improved optics were installed in the center of the IceTop surface detector at the geographic South Pole. Combining information from these two telescopes and IceCube, it is possible to test the performance in primary particle discrimination, detector calibration, and veto capabilities. We present the status of the project and the prospects of the upcoming data taking season during the Antarctic winter.

Design and performance of the first IceAct demonstrator at the South Pole

“…Direct measurements of the electromagnetic component of the air-shower with imaging air-Cherenkov telescopes can be compared to the high-energy muon component measured deep in the ice and the mixed component in IceTop. The independence of the telescopes from the ice and snow properties potentially provides a handle to reduce the influence of these systematic uncertainties [16][17][18]. The granularity of the camera of imaging air Cherenkov telescopes allows for precise measurements of cosmic ray-induced showers with very few telescopes.…”

“…• The ability to veto high-energy muon events detected with IceCube, when a surface detector detects a coincident air-shower signal. This will reduce the atmospheric background events of muons and neutrinos in IceCube for diffuse neutrino measurements and point source searches in the southern sky [10,[16][17][18]. The low energy threshold of imaging air Cherenkov telescopes might greatly increase the sensitivity of IceCube in the southern sky for astrophysical neutrino detection down to 30 TeV neutrino energy or lower with a dedicated array of IceAct telescopes [16,18].…”

“…This will reduce the atmospheric background events of muons and neutrinos in IceCube for diffuse neutrino measurements and point source searches in the southern sky [10,[16][17][18]. The low energy threshold of imaging air Cherenkov telescopes might greatly increase the sensitivity of IceCube in the southern sky for astrophysical neutrino detection down to 30 TeV neutrino energy or lower with a dedicated array of IceAct telescopes [16,18]. With a large enough sample of lower-energy astrophysical starting track events, it might also be possible to measure their inelasticity, and thus deduce the ν : ν ratio [20].…”