Deployment and status of the Radar Echo Telescope

The Radar Echo Telescope for Cosmic Rays (RET-CR), a pathfinder experiment for a future ultrahigh energy neutrino detector, is a recently deployed experiment designed to detect the ionization trail from an in-ice cosmic ray shower via active radar sounding. In high-elevation ice sheets, a high-energy cosmic ray (E >10 PeV) at shallow zenith angle deposits more than 10 percent of its primary energy into the ice sheet producing a cascade with energy densities several orders of magnitude higher than in air. This dense in-ice cascade can then be interrogated with an in-ice radar system. RET-CR consists of a phased-array transmitter and an array of receiving antennas triggered by scintillator panels on the surface with a surface-based radio array to aid in cosmic ray reconstruction. RET-CR is a pathfinder experiment, which aims to test the radar echo method for the Radar Echo Telescope for Neutrinos (RET-N). RET-CR was deployed at Summit Station, Greenland, running from May to August 2024.