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
Greenhouse effect surface; anti-greenhouse effect is about atmosphere NOT letting radiation in, while letting thermal radiation out, which lowers the equilibrium surface temperature. Such an effect has been cited about Titan A runaway greenhouse effect occurs if positive feedbacks lead to the evaporation of all greenhouse gases into the atmosphere. A runaway greenhouse effect involving carbon dioxide and water vapor has long ago been hypothesized to have occurred on Venus, . The greenhouse effect on Venus is particularly large because its dense atmosphere consists mainly of carbon dioxide. "Venus experienced a runaway greenhouse in the past, and we expect that Earth will