Annihilation radiation Annihilation radiation Annihilation radiation is a term used in Gamma spectroscopy for the gamma radiation produced when a particle and its antiparticle collide and annihilate. Most commonly, this refers to 511-keV gamma rays produced by a normal (negative) electron colliding with a positron. Annihilation radiation is not monoenergetic, unlike gamma rays produced by radioactive decay. The production mechanism of annihilation radiation introduces Doppler broadening. The annihilation peak produced in a gamma spectrum by annihilation radiation therefore has a higher full width at half maximum (FWHM) than other gamma rays in spectrum. The difference is more apparent with high resolution detectors,
Anti-greenhouse effect Anti-greenhouse effect The anti-greenhouse effect is a mechanism similar to the greenhouse effect, but with the opposite consequence of cooling the surface temperature of a planet. If gases in the atmosphere of a planet have a lesser transmittance for inbound radiation (for instance, solar rays in the Solar System) than for outbound radiation (typically thermal radiation of the planet's surface in the infrared domain), the surface temperature at which inbound and outbound heat fluxes are at equilibrium is lower. The haze containing organic molecules in Titan's upper atmosphere absorbs 90% of the solar radiation reaching Titan, but is inefficient at