Annihilation radiation such as Germanium detectors, than with low resolution detectors such as Sodium iodide detectors. Because of their well-defined energy (511 keV) and characteristic, Doppler-broadened shape, annihilation radiation can often be useful in defining the energy calibration of a gamma ray spectrum. 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
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