A tunable gamma-ray source based on the single-quantum annihilation of positrons

A study of the single-quantum annihilation (SQA) of positrons has shown that a tunable gamma-ray source (TGRS) could be built based on the phenomenon, that could provide a photon beam of energy variable from 1 MeV upwards. The photon beam could have an excellent bandwidth, of around 1 keV, and a low background level for beam energies up to several MeV, and could be made polarized. The beam is highly self-collimated. The photon yield is much larger than the tunable gamma-ray sources envisaged by other means, which also employ particle beams. In simplicity as well as features, the SQA-based tunable gamma-ray source is potentially superior to other proposed sources.