electron-positron annihilation

Electron-positron annihilation is the process in which a positron collides with an electron resulting in the annihilation of both particles.  Electrons (or β- particles) and positrons (or β+ particles) are of equal mass but opposite charge. Positrons are the antimatter equivalent of an electron, produced from B+ decay

According to the law of conservation of energy, their masses are converted to 2 annihilation gamma photons with an energy of around 511 keV and moving in 2 opposite directions.

e− + e+ ------>  γ + γ

Where e− is the electron, e+ is the positron and γ are gamma rays emitted.

511 keV is the approximate amount of energy created when an electron or positron (which each have a mass of 9.11x10 kg) are converted to energy according to Einstein's famous equation:

E = mc

Where E = energy , m = particle mass and c = velocity of light.

i.e. E= 9.11x10 kg x (3x10 m s).

Therefore E= 8.20x10J = 511 keV.

This process is of particular importance as it is the basis of positron emission tomography.

Siehe auch: