Abstract: A method for determining X-ray, or gamma ray photon energy by, irradiating a high resistance n-type or p-type cadmium telluride alloy crystal with X-ray or gamma ray photons respectively providing first and second electrical contacts which are in electrical communication with the crystal, which are respectively negatively and positively biased and which provide free flow of electrons from the negatively biased contact to the crystal, and wherein holes, generated by absorption of photons in the crystal, recombine with the electrons, and determining the photon energy by measuring the amount of charge generated per photon absorbed be the crystal.

Abstract: Laser detection apparatus comprising a laser defining an active region and providing a double beam of coherent radiation, a sample to be tested located in a first part of the double beam of coherent radiation, a radiation detector arranged to receive radiation passing through the sample to be tested for providing an output indication of absorbance, a reference sample disposed in a second part of the double beam, apparatus for sensing absorption of the coherent radiation at the reference sample, apparatus for providing selectable heating of the active region of the laser, and apparatus for providing a control signal to the selectable heating apparatus in accordance with the sensed absorption of the coherent radiation at the reference sample.