Cosmic Ray Studies with IceAct: New Air-Cherenkov Telescopes at the South Pole

High-energy particles, known as cosmic rays, come from violent astrophysical events and are continuously shooting down through Earth’s atmosphere. They carry invaluable information about the universe, revealing insights into phenomena such as black holes, supernovae, and the conditions of the early universe. To find out more about the powerful processes that produce the particles, two IceAct telescopes have been deployed as a new sub-detector of the IceCube Neutrino Observatory (ICNO) at the geographic South Pole. The IceAct telescopes are small, inexpensive, and cold-hardy air-Cherenkov telescopes designed to detect the light produced by cosmic rays as they interact in the atmosphere. This Cherenkov light, in coincidence with the data from IceTop and IceCube (the surface array and in-ice array of the ICNO, respectively) allows us to reconstruct the primary cosmic ray’s energy and composition.

The IceAct telescopes are presently equipped with a Fresnel lens that focuses Cherenkov light from extensive air showers to the 61 pixel SiPM camera. The lens is protected by a glass plate and a heating coil system designed to prevent frost formation between the lens and the glass plate. The existing heating coil design covers about 13% of the window area and consumes considerable power reducing overall energy efficiency. In this work we present a modified design using thin flat Nichrome wires to reduce both the optical coverage and power consumption of the heating system. The goal is to maintain sufficient temperature for frost prevention while maximizing optical transmission and minimizing energy usage. Several wire types with different thicknesses and widths were tested to optimize grid spacing temperature uniformity and power requirements. The new design successfully reduces the power consumption and covers much less of the field of view.