GAMMA-RAY DEVICES
This new field of astronomy has burgeoned in the last decade or so from modest beginnings, employing balloons and rockets, to satellites (European and Ameri· can) carrying highly sensitive gamma-ray detectors. Like that of X rays, the great penetrating power of gamma·ray photons makes observation and detection different from those for visible photons. Gamma·ray photons carry the highest energy of any photon. The primary gamma·ray detector used for space astronomy is a crystalline material that absorbs the gammaray photon, converting its energy to a flash of visible light. The visible photons can then be detected by a photoelectric device.
In 1978 came the first evidence of several gammaray spectral lines. The search for additional discrete lines will be greatly extended with the launch of the Gamma Ray Observatory in 1985.
