An Efficient Detector for Tau Neutrinos at the Highest Energies: The Beamforming Elevated Array for COsmic Neutrinos (BEACON)*

When ultrahigh energy tau neutrinos skim the Earth, they can generate tau leptons that then decay in the atmosphere, forming upgoing extensive air showers. The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a novel detector concept that utilizes a mountaintop radio interferometer to search for the radio emission due to these extensive air showers. The prototype, located at the White Mountain Research Station in California, consists of 4 custom crossed-dipole antennas operating in the 30-80 MHz range and uses a directional interferometric trigger to achieve reduced thresholds and background rejection.  The prototype will first be used to detect extensive air showers from down-going cosmic rays to validate the detector model. In this talk, we detail the ongoing cosmic ray search which utilizes both analysis of data collected by the prototype, and simulation. We also discuss recent upgrades made to the BEACON prototype design, as well as the calibration of the antenna array.