The Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescope in La Palma, Spain, detects flashes of light produced when gamma rays hit the upper atmosphere. Now a group led by Daniel Ferenc at the University of California, Davis, has developed detectors based on light-sensitive semiconducting materials. When photons hit the semiconductors, they emit electrons, which can be measured.
The energy spectrum of photons emitted from isotopes of uranium or plutonium in the 40-1000 keV energy range give unique signatures that, if accurately measured, give inspectors important information about the age and enrichment of the material and therefore its intended purpose.
As has been pointed out in the previous article, if the US can search for and find nuclear bombs and material from a distance (like 9000 meters) and the detector can go in a plane. This capability would let them target and destroy the nuclear weapons and weapons program of Iran and North Korea.