| dbo:abstract
|
- 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. 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. 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 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. (en)
- 湮滅輻射是指粒子和反粒子互相湮滅所產生的輻射。根據質能轉換公式，其輻射的能量等於粒子的質量(一般湮滅後會產生兩個光子，每個光子都等於粒子的質量。)。在自然界中，最常見的湮滅輻射就是成對產生而造成的輻射，能量是511keV，成對產生是電磁波脈衝穿過原子時在原子核附近形成的形成正電子和電子，而電子-正電子對很快就會湮滅并释放511 keV 伽马射线。 (zh)
|
| dbo:thumbnail
| |
| dbo:wikiPageID
| |
| dbo:wikiPageLength
|
- 2428 (xsd:nonNegativeInteger)
|
| dbo:wikiPageRevisionID
| |
| dbo:wikiPageWikiLink
| |
| dbp:wikiPageUsesTemplate
| |
| dcterms:subject
| |
| gold:hypernym
| |
| rdfs:comment
|
- 湮滅輻射是指粒子和反粒子互相湮滅所產生的輻射。根據質能轉換公式，其輻射的能量等於粒子的質量(一般湮滅後會產生兩個光子，每個光子都等於粒子的質量。)。在自然界中，最常見的湮滅輻射就是成對產生而造成的輻射，能量是511keV，成對產生是電磁波脈衝穿過原子時在原子核附近形成的形成正電子和電子，而電子-正電子對很快就會湮滅并释放511 keV 伽马射线。 (zh)
- 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. 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 dir (en)
|
| rdfs:label
|
- Annihilation radiation (en)
- 湮滅輻射 (zh)
|
| owl:sameAs
| |
| prov:wasDerivedFrom
| |
| foaf:depiction
| |
| foaf:isPrimaryTopicOf
| |
| is dbo:wikiPageWikiLink
of | |
| is foaf:primaryTopic
of | |
