Particles and Anti-particles (Explanation)

Particles and anti-particles:

The electron and positron 

Electron:                      

Symbol:  e or e ⁻

                For beta decay  ß or  ß⁻ 

Mass =  9.11 ×  10⁻³¹ kg

Charge = -1.6 × 10⁻¹⁹ C

               = - 1 (relative units )

Electron is the member particles of lepton Family . The electron has a lepton number 1. This is the basic facts of the electron.

Positron:

This is the another elementary particles.

Symbol:  e⁺ or  ß⁺

Mass =  9.11 ×  10⁻³¹ kg

Charge = +1.6 × 10⁻¹⁹ C

              = +1 (relative units )

Positron is also the member particles of lepton Family. The positron has a lepton number -1. This is the basic facts of the positron.

So if we compare the electron and positron they have got a same mass and the other properties are reversed. The positron is called the anti-particle of electron but not because they have opposite properties. for further understanding lets discuss annihilation.

Annihilation:

let suppose that an electron is moving left to right and positron is moving left to right what will happen if they meet or collide each other

                                     
                                                                  ⇒  ⇐

                    Electron                      ⦽  ⦽                     Positron

They vanishes with giving radiation in the Form of gamma photon.

                      

                                         

                                     

Gamma photons

Gamma photons

                                       

                                   

we can say that the electron and positron 'annihilate'. And the process is called annihilation.

They destroy each other and their mass has turned into energy (two gamma photons). From this we knew that Particle and its corresponding anti-particle annihilate each other and produce energy:

   

                Particle + Anti-particle  ➨ Energy

In the form of equation we can express it as:

                   e ⁻   +    e⁺           =    2𝛄

  electron          positron        two gamma photon

It is very important process which helps to understand the nature of particles and anti-particles. And the opposite process of annihilation is pair production.

Pair production:

If a gamma photon passes through a nucleus it break downs into electron and positron.

This process so called pair production because it produces a pair particles and Anti-particles.
In this case energy has changed into Particles and anti-particles.

             

                          Energy ➨  Particle + Anti-particle

And the equation will be:


                           
          𝛄  =   e ⁻   +    e⁺      

A gamma photon turns into particle and anti-particle pair in this process. The photon must a minimum energy of  2 Mₑ C ² .
Where Mₑ is the mass of electron and positron and C is the velocity of light.
i.e
            
         Mₑ C ²       +        Mₑ C ²        =      2 Mₑ C ²     
   energy of electron              energy of positron                 energy of photon                                                                                                                                    required for pair production



Hope that this has helped a little bit for understanding about particle and anti-particle.