Radiation resulting from particle-antiparticle collisions
Annihilation radiation is a term used in Gamma spectroscopy for the photon radiation produced when a particle and its antiparticle collide and annihilate. Most commonly, this refers to 511-keV photons produced by an electron interacting with a positron.[1] These photons are frequently referred to as gamma rays, despite having their origin outside the nucleus, due to unclear distinctions between types of photon radiation. Positively charged electrons (Positrons) are emitted from the nucleus as it undergoes β+ decay. The positron travels a short distance (a few millimeters), depositing any excess energy before it combines with a free electron. The mass of the e- and e+ is completely converted into two photons with an energy of 511 keV each. These annihilation photons are emitted in opposite directions, 180˚ apart. This is the basis for PET scanners in a process called coincidence counting.
A Germanium detector spectrum showing the annihilation radiation peak (under the arrow). Note the width of the peak compared to the gamma ray peaks from radioactive decay visible in the spectrum.
Annihilation radiation is not monoenergetic, unlike gamma rays produced by radioactive decay. The production mechanism of annihilation radiation introduces Doppler broadening.[2] The annihilation peak produced in a photon spectrum by annihilation radiation therefore has a higher full width at half maximum (FWHM) than decay-generated gamma rays in spectrum. The difference is more apparent with high resolution detectors, 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.
^Charlton M and Humberston JW. Positron Physics. Cambridge University Press, 2001, p. 6.
^Gilmore, G., and Hemmingway, J.: "Practical Gamma Ray Spectrometry", page 13. John Wiley & Sons Ltd., 1995
and 25 Related for: Annihilation radiation information
radiation introduces Doppler broadening. The annihilation peak produced in a photon spectrum by annihilationradiation therefore has a higher full width at half...
low-energy annihilation, photon production is favored, since these particles have no mass. High-energy particle colliders produce annihilations where a wide...
include electron-positron annihilation, neutral pion decay, bremsstrahlung, inverse Compton scattering, and synchrotron radiation. In October 2017, scientists...
Angular Correlation of Electron Positron AnnihilationRadiation (ACAR or ACPAR) is a technique of solid state physics to investigate the electronic structure...
particle radiation consists of particles of non-zero rest energy, such as alpha radiation (α), beta radiation (β), proton radiation and neutron radiation acoustic...
electron, annihilation occurs, resulting in their conversion into the energy of two or more gamma ray photons (see electron–positron annihilation). As positrons...
Since a positron in a solid will thermalize prior to annihilation, the annihilationradiation carries the information about the electron momentum. The...
development of PET technology and included the first demonstration of annihilationradiation for medical imaging. Their innovations, including the use of light...
as creation and annihilation operators, adding or subtracting fixed quanta of energy to the oscillator system. Creation/annihilation operators are different...
positrons annihilated each other, releasing gamma radiation that briefly reheated the universe. For reasons that remain uncertain, during the annihilation process...
Neutron radiation is a form of ionizing radiation that presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the...
keV, which usually indicates the annihilation of an electron-positron pair. This led to the nickname, "Great Annihilator." Early observations also showed...
positron/electron pair production.[citation needed] This work and that on annihilationradiation made him one of the first and leading experts on antimatter. That...
electromagnetic radiation. The word laser is an anacronym that originated as an acronym for light amplification by stimulated emission of radiation. The first...
beta+ radiation (positrons), the gamma radiation from the electron–positron annihilation reaction poses additional concern. Neutron radiation is not...
artifacts or human remains. The cosmic radiation at sea level usually manifests as 511 keV gamma rays from annihilation of positrons created by nuclear reactions...
A nuclear holocaust, also known as a nuclear apocalypse, nuclear annihilation, nuclear armageddon, or atomic holocaust, is a theoretical scenario where...
gamma rays (see antimatter as fuel). Positron annihilation has also been proposed for rocketry. Annihilation of positrons produces only gamma rays. Early...
period of sustained radiation. This accumulation is limited by defect recombination, by clustering of defects, and by the annihilation of defects at sinks...
requirements and the proximity of the 521 keV line to the 511 keV annihilationradiation related to the β+ decay. However, the auger electrons emitted during...
Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum...
total energy of annihilation emerges in the form of ionizing radiation. If surrounding matter is present, the energy content of this radiation will be absorbed...
evidence of a 130 GeV signal in the gamma radiation coming from the center of the Milky Way. WIMP annihilation was seen as the most probable explanation...
Global Information