This is often referred to as Pair Production.

This pair production occurs when a high energy photon collides with a heavy atom that absorbs the energy. There is far too much energy in the super high frequency wave. Ewave=hf for it to be transferred to the atom, and so it produces particles from the energy. But like the conservation of Energy/Mass and that of momentum we also must consider the conservation of charge,

The conservation of charge is the principle that the total charge in a system does not change.

Particle Accelerators

In high powered particle accelerators we can get particles to travel with extremely high energies. When they collide their energies turn to mass, these masses are of a number of new particles.

P+ + P+ + Q → P+ + P+ + nx

LC Question

In a circular accelerator, two protons, each with a kinetic energy of 1 GeV, travelling in opposite directions, collide. After the collision two protons and three pions are emitted.

What is the net charge of the three pions? Justify your answer. (9)


(i) the combined kinetic energy of the particles after the collision;

(ii) the maximum number of pions that could have been created during the collision.

A pion has a mass of 1.115 × 10–27 kg


Write a nuclear equation to represent the disintegration of a lithium nucleus when bombarded with a proton. (9)

Calculate the energy released in this disintegration. (12)