What is the annihilation peak?

Pair production in the surrounding material of the detector gives rise to the ‘annihilation peak’ at 511 keV in the energy spectrum. This is due to the escape of one of the 511 keV gamma-rays to the detector. The annihilation peak can also be seen whenever a radioisotope emits positrons as part of its decay process.

What is annihilation of radiation explain with an example?

Definition of annihilation radiation : radiation produced by the mutually annihilating coalescence of a particle and its antiparticle from which two radiation quanta travel in opposite directions with a wavelength corresponding to that of very short gamma rays, being approximately 0.024 angstrom.

What is annihilation in gamma rays?

From Wikipedia, the free encyclopedia. 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.

What is the annihilation phenomenon?

Electron–positron annihilation occurs when an electron ( e − ) and a positron ( e + , the electron’s antiparticle) collide.

What is pair production and annihilation?

The conversion of a photon into an electron-positron pair on its interaction with the strong electric field surrounding a nucleus is called pair production. The converse of pair production in which an electron and positron combine to produce two photons is known as annihilation of matter.

Why does photo peak and annihilation peak appear on the spectrum?

This is know as coincidence summing. The pulse size reflects the sum of the energies deposited by the two photons. If both photons interact via the photoelectric effect, and this happens with sufficient frequency, a summation (sum) peak appears on the spectrum.

What is annihilation and pair production?

What is photo peak?

The photopeak refers to the region of the pulse height spectrum caused by the complete photoelectric absorption of gamma rays by the scintillator crystal of a gamma camera.

What causes the backscatter peak?

A Compton backscatter peak is found when γ-rays enter the material around the detector and are scattered back into the detector. Gamma photon can interact by Compton mechanism in shield or surrounding materials and is backscattered out of a material into sensitive volume.

What is the difference between annihilation peak and decay peak?

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.

What is the annihilation process?

Annihilation process happens on 2 particles which have exactly the opposite M&E characteristic, such as electron and positron. When both particles are attracted and combined together, the M&E field is restructured and released to become light or photon. The annihilation process is illustrated as follows,

What is the energy of annihilation radiation?

Annihilation radiation. 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.

How wide is the 511 keV line of the annihilation peak?

This is considerable compared to the total width of 2–3 keV of the annihilation peak meaning that the experimental lineshape is strongly influenced by the detector resolution. Therefore, various shape parameters are used to characterize the 511 keV line.