Development of a Custom kV-amplitude, pressure-tolerant Radio-Frequency transmitter
Current experiments seeking first-ever observation of Ultra-High Energy Neutrinos (UHEN) typically utilize radio frequency (RF) receiver antennas deployed in cold, radio-transparent polar ice, to measure the coherent RF signals resulting from neutrino interactions with ice molecules. Accurate calibration of the receiver response, sampling the full range of possible neutrino geometries, is necessary to estimate the energy and incoming direction of the incident neutrino. Herein, we detail the design and performance of a custom radio-frequency calibration transmitter, consisting of a battery-powered, kiloVolt-scale signal generator (`IDL' pulser) driving an antenna (South Pole UNiversity of Kansas antenna, or `SPUNK') capable of operating at pressures of 200 atmospheres. Performance was validated by lowering the transmitter into a borehole at the South Pole to a depth of 1740 m, yielding high Signal-to-Noise ratio signals at a distance of 5 km from the source.