Why does electron positron annihilation produce two photons?

These photons are emitted in opposite directions and each have an energy of 0.511 MeV. (The reason TWO photons are produced may seem a bit complicated, but two are needed to conserve both momentum and energy. Briefly, since the electron and the positron were at rest, the total system had no momentum.

Why does annihilation produce two photons?

Annihilation occurs when a particle and a corresponding antiparticle meet and their mass is converted into radiation energy. Two photons are produced in the process (as a single photon only would take away momentum which isn’t allowed, as no outside forces act).

Why is it not possible that only one photon is produced by this annihilation?

Low-energy case Conservation of energy and linear momentum forbid the creation of only one photon. The probability for such process is on the order of 10000 times less likely than the annihilation into photons.

Why do antiparticles annihilate?

Of course there are many other changes. But this difference of charges creates the attraction of the particles. Because difference charges attract. Thats why matter and antimatter annihilate each other when they meet.

What does electron positron pair mean?

pair production, in physics, formation or materialization of two electrons, one negative and the other positive (positron), from a pulse of electromagnetic energy traveling through matter, usually in the vicinity of an atomic nucleus. Pair production is a direct conversion of radiant energy to matter.

What is the wavelength of the photons produced in electron positron pair annihilation?

1.2132 picometer
The photon must have higher energy than the sum of the rest mass energies of an electron and positron (2 ⋅ 511 keV = 1.022 MeV, resulting in a photon-wavelength of 1.2132 picometer) for the production to occur.

What’s the difference between electron-positron annihilation and photon production?

But in electron-positron annihilation with photon production (talking about low energies only) there’s electromagnetic interaction (is it?) which means a photon being a virtual particle. So there’s an exchange of a photon between electron and positron which results into production of two photons?

What is the spin of the photons produced from 3 electrons?

In this case, 3 photons (or more) are produced. The electrons (and positrons) have 1/2 spin, thus they can annihillate in +1/2, -1/2 or in +1/2, +1/2 configuration. Thus, their summed spin is either 0 or 1. The spin of the photons is 1, also they can have opposite or equal sign, thus their total spin want to sum up to 0 or 2.

Is it possible to annihillate 3 photons at once?

It is impossible. If their spins are into the same direction, even the 2-photon annihillation is not possible on a different conservation law, the spin conservation. In this case, 3 photons (or more) are produced. The electrons (and positrons) have 1/2 spin, thus they can annihillate in +1/2, -1/2 or in +1/2, +1/2 configuration.

What is a virtual electron-positron?

The virtual electron-positron can be off shell, which means different frames might even disagree about whether it is a virtual electron or a virtual positron . But it is not really an electron or a positron.