  Increasing interest in energetic particle effects on weather and climate has
motivated development of a miniature scintillator-based detector intended for
deployment on meteorological radiosondes or unmanned airborne vehicles. The
detector was calibrated with laboratory gamma sources up to 1.3 MeV, and known
gamma peaks from natural radioactivity of up to 2.6 MeV. The specifications of
our device in combination with the performance of similar devices suggest that
it will respond to up to 17 MeV gamma rays. Laboratory tests show the detector
can measure muons at the surface, and it is also expected to respond to other
ionizing radiation including, for example, protons, electrons (>100 keV) and
energetic helium nuclei from cosmic rays or during space weather events. Its
estimated counting error is about 10%. Recent tests, when the detector was
integrated with a meteorological radiosonde system, and carried on a balloon to
~25 km altitude, identified the transition region between energetic particles
near the surface, which are dominated by terrestrial gamma emissions, to
higher-energy particles in the free troposphere.
