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The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a concept for a neutrino telescope designed to measure tau lepton air showers generated from tau neutrino interactions near the horizon. This detection mechanism provides a pure measurement of the tau flavor of cosmogenic neutrinos, which could be used to set limits on the observed flavor ratios for cosmogenic neutrinos in a manner complimentary to the all-flavor neutrino flux measurements made by other experiments. BEACON is expected to also be capable of detecting cosmic rays through RF-only triggers. BEACON aims to achieve this sensitivity by using mountaintop radio arrays of dual-polarized antennas operating in the 30-80 MHz band which utilize directional interferometric triggering. BEACON stations are designed to efficiently use a small amount of instrumentation, allowing for deployment in a variety of high-elevation sites. The interferometric trigger provides a natural tool for directional-based anthropogenic RFI rejection at the trigger level, broadening the list for potential station sites. The BEACON prototype has seen continuous design advancements towards improving the mechanical durability and scientific capabilities since its initial deployment at White Mountain Research Station in 2018. Here we present the current prototype's sensitivity to RF-triggered cosmic-ray background signals. We also present the next generation prototype, which includes scintillating cosmic ray detectors, improved antennas, and refined calibration techniques.

EUSO-SPB (Extreme Universe Space Observatory-Super Pressure Balloon) is the first pathfinder mission of the JEM-EUSO program aiming at the detection of the fluorescence light emitted by Extensive Air Shower (EAS) produced by cosmic ray particles in the atmosphere. EUSO-SPB has flown in Spring 2017 from the Wanaka base in New Zealand on board a NASA Super Pressure Balloon planning to reach up to a 100 days of flight, giving, therefore, the opportunity to observe for the first time a bunch of cosmic ray events with the fluorescence technique from the edge of space. By means of the ESAF (EUSO Simulation and Analysis Framework) package, which is one of the official simulation tools to study the performance of the different pathfinder missions of the JEM-EUSO program, prior to flight, extensive simulations have been carried out to determine the expected number of detectable events as a function of several parameters related to the detector performance itself (i.e. trigger logic, optics and electronics efficiency), to the different environmental conditions (i.e. night-glow level, presence of clouds at different heights with variable optical depth) as well as to the launch season and duration of the flight. The main results of these simulation studies are presented.

Many upcoming experiments seek to observe high energy cosmic events while observing from either sub-orbital or orbital altitudes, using the Earth atmosphere as an extremely large instrumental volume, thereby increasing the geometric acceptance of ground-based instruments in addition to supplying uniform exposure in both hemispheres. In particular, the planned Extreme Universe Space Observatory aboard a Super Pressure Balloon-2 (EUSO-SPB2) and future Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) experiments will both utilize UV sensitive optical cameras with nanosecond time resolution and observe near the Earth's limb to attempt to capture the Cherenkov emission produced by upwards going extensive air showers (EASs) sourced from high energy cosmic neutrino interactions in the Earth. In addition, these Cherenkov cameras also have coverage above the Earth limb, allowing access to the Cherenkov emission produced by cosmic rays skimming the Earth atmosphere at high altitudes. We show that sub-orbital and orbital based optical Cherenkov telescopes are quite sensitive to the above the limb cosmic ray signal, in particular the sub-orbital case being sensitive down to PeV scale energies, allowing for high event rates even for short observation periods. We argue that because the properties of the arriving Cherenkov photons are similar for neutrino induced EASs and those induced by above the limb cosmic rays, the latter provides an excellent benchmark for qualifying the technique for neutrino observation with a well understood and guaranteed signal.