Gamma-ray laser

A gamma-ray laser, or graser, is a device for stimulated emission of coherent gamma rays, similar to a laser which produces coherent electromagnetic radiation.

Conditions for one to be built:


 * broadening the gamma-ray spectral line, such as Doppler recoil broadening from thermal motion of molecules in the solid containing the excited isomer and recoil from gamma-ray emission, in which the emission spectrum is both shifted and broadened
 * excited states that would resonantly absorb the radiation
 * opaque impurities have to be removed
 * must not be loss in propagation through the crystal in which the active nuclei are embedded (overcome by matrix crystal alignment)


 * The time required to activate, separate, concentrate, and crystallize an appreciable number of excited nuclei must equal the excited state so that inversion persists

An antimatter-powered graser would produce light with wavelengths a thousandth the size of modern-day X-ray lasers, enabling it to probe incredibly tiny spaces and making it useful in medical imaging technology such as MRI. A matter-antimatter mixture called positronium would work as the gain medium. Energy is put into the positronium by a burst of infrared light to generate the beam.

The positronium has to be close to absolute zero to turn into a state of matter called a Bose-Einstein condensate, in which all the atoms enter the same quantum state, acting as a single supersized atom. Positrons are much lighter than protons, so positronium isn't stable, and within less than a billionth of a second, the electrons and positrons will collide and annihilate each other, releasing energy for the beam.