# Why pair production which particle is having energy loss?

## Why pair production which particle is having energy loss?

Pair production occurs only for gamma-rays of high energy. Because an electron has a rest mass equivalent to 0.511 MeV of energy, a minimum gamma-energy of 1.02 MeV is required for this pair production.

## What happens to excess energy in pair production?

Pair production is a direct conversion of radiant energy to matter. It is one of the principal ways in which high-energy gamma rays are absorbed in matter. Photon energy in excess of this amount, when pair production occurs, is converted into motion of the electron-positron pair.

How is energy conserved in pair production?

Pair production often refers specifically to a photon creating an electron–positron pair near a nucleus. As energy must be conserved, for pair production to occur, the incoming energy of the photon must be above a threshold of at least the total rest mass energy of the two particles created.

Why is pair production not possible in empty space?

Reason: The pair production can not take place in a vacuum or space. The pair production can happen only in the presence of an external object like an atomic nucleus which can experience some recoil during the collision process to conserve the energy and the momentum at the same time.

### What happens to excess energy when the photon energy is greater than the minimum energy?

The “extra” energy goes into the kinetic energy of the pair and (a little bit) into the recoil energy of the heavy “spectator” (required to balance momentum). Each particle will receive a kick, in a manner that conserves the total energy and momentum of the initial photon.

### Which is not conserved in pair production?

In this process, termed pair production, a photon can simply vanish and in its place a matter-antimatter pair of particles can appear. This phenomenon is a wonderful illustration of the fact that mass is not conserved, since the mass of the electron and positron can be created from the energy of the massless photon.

Can pair production occurs in vacuum?

Originally Answered: why does pair production cannot occur in vacuum? Nothing spacial, pair production in vacuum is not possible because you have to take care of both energy and momentum conservation laws.

What is the threshold energy for pair production?

For photon energies below 2m0c^2, the process cannot occur; in other words, 1.02 MeV is the threshold energy for pair production.

## How energy and momentum is conserved in pair production?

In the pair-production process a third body is required for momentum conservation. When that body is a heavy nucleus, it takes very little recoil energy, and therefore the threshold is just twice the rest energy of the electron; i.e., twice its mass, m, times the square of the velocity of light, c2, or 2mc2.

## Can charge be created and destroyed?

Charges can be created, like the charges of an electron and a positron in pair production, but their total value must always be zero (i.e., total charge can’t be created). Charge s can be created and destroyed. Total charge cannot. Whenever you create an electron, charge − 1, you must also create a positron, charge + 1.

Can an electron be created or destroyed?

An electron can never be created on its own. Or it takes its charge from other particles, or a positron is created at the same time. Likewise, an electron can’t be destroyed without another equally, but oppositely, charged particle being created. When the electron is isolated, it can never be destroyed.

What is the inverse of pair production?

There exists an inverse process to pair production called pair annihilation, in which a particle and its antiparticle collide and annihilate each other, the total energy of the two particles appearing as electromagnetic radiation. In the case of an electron and positron, the energy balance can be represented as:

### How do electrons destroy each other without violating charge conservation?

So the mechanisms which generate and destroy electrons happen to be such that they never violate charge conservation. Let’s take pair annihilation for example, an electron and a positron meet and they become two photons. Before, the total charge is zero: the positron has positive charge and the electron has the exact opposite negative charge.