Helica owns and operates a spectrometer RSX-5 (by Radiation Solution Inc, Canada). It is a 5-crystal NaI(Tl) (sodium iodide doped with tallium) system with a 4-liter volume for each one.
The instrument is mounted on a specific support placed near the barycentric hook of the helicopter; this way it is possible to operate with the two geophysical sensors simultaneously. With its 1024 channels measurement, this spectrometer reaches the highest spectral resolution levels currently available on the market.
Each channel corresponds to an energy span of 3 keV in the entire gamma-ray radiation range between 30 and 3000 keV.
The system features five crystal detectors; one of them is partially screened and upward-looking, mainly aimed at the removal of atmospheric radon. This configuration is recommended in the Northern hemisphere, where the abundance of Cs-137 (Caesium 137) due to nuclear tests in the postwar period and to the Chernobyl incident interferes with the classical methods for the removal of atmospheric radon (IAEA, 1991).