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,
Levitin effect Levitin effect The Levitin effect refers to the phenomenon, first documented by Dr. Daniel J. Levitin in 1994, that people – even those without musical training – tend to remember songs in the correct key. The finding stood in contrast to the large body of laboratory literature suggesting that such details of perceptual experience are lost during the process of memory encoding. In other words, laboratory experiments supported the idea that most people are incapable of any sort of absolute pitch, and thus would remember melodies with relative pitch. Despite its status as a classic result in cognitive psychology, the