Nuclear and Particle Physics: Antiparticles

Antiparticles

Basic Concept of Antiparticles

Every fundamental particle has a corresponding antiparticle.
Antiparticles share the same mass as their corresponding particle, but possess the opposite charge and other quantum numbers.
For example, a positron (e+) is the antiparticle of an electron (e-). They have the same mass, but opposite charges.

Annihilation is the process where a particle and its antiparticle meet and destroy each other, producing energy in the form of photons.
During annihilation, a particle and its antiparticle destroy, mostly leading to the creation of two gamma photons (two photons of gamma radiation).
Pair production is the reverse process of annihilation. It involves producing a particle and its antiparticle from energy.
For pair production to happen, the energy available must be at least equivalent to the combined rest mass energy of the two particles being produced.

In quantum mechanics, antiparticles can be viewed as particles travelling backwards in time.

In any particle interaction, the total charge, total lepton number, total baryon number, and the total energy and linear momentum are conserved.
This allows for the prediction and explanation of the behaviour of particles and antiparticles during interactions.

This medical imaging technique uses annihilation to create detailed images of the body.
It involves injecting a patient with a substance that emits positrons, which then annihilate with electrons in the body, producing photons. Detectors then measure these photons to create 3D images of the inside of the body.