INTRODUCTION

To start off, I'd like to look back at particles and antiparticles - mainly the way they interact. In Chapter 1 of your textbooks you should have come across annihilation and pair production of particles and antiparticles, as well as photons and their role.

Photons

We already know that light is a part of the electromagnetic spectrum of waves, where [λ=c/ f], and the speed of light is [3.00 x 10⁸ ms⁻¹]. 

Packets of electromagnetic waves - i.e. particles of light - are photons. 

The energy of a photon is equal to [h x f], where [f] is the frequency of the wave in Hz, and [h] is Planck's Constant: [6.63 x 10⁻³⁴ Js]. This equation will give us the energy of a photon in joules [J]. 

Matter and Antimatter

Antimatter is the 'mirror image' of normal, everyday matter. The table above shows how antimatter has the same mass as their correspondents, but an equal and opposite charge. 

When matter and antimatter meet, their mass is converted into pure energy in the form of photons - this is called annihilation. 

An absolute minimum of two photons are produced in annihilation, as a single photon being released would negate the Conservation of  Momentum, where charge and mass remain intact. 

The minimum energy of each photon produced can be calculated: [h x f min = E₀], where [E] is the rest mass of the electron (0.511MeV)

Likewise, pair production is the conversion of energy into mass, in the form of an antiparticle and a particle. The minimum energy of the photon needed can be calculated as such: [h x f min = 2E₀]

Recall [E = h x f], remembering that [Emin] equates to [hfmin], which in turn is equal to [2E₀].

[E₀ = mc²], which is the rest mass energy.

The Weak Nuclear Force

W-bosons are the exchange particle that causes a proton to change into a neutron, and vice versa in β decay. These exchange particles:

1) have a non-zero rest mass,

2) have a very short range of no more than 0.001 fm, and

3) are positively charged (the W+ boson) or negatively charged (W- boson)

Here are two instances of W-bosons acting as the exchange particles, and so showing the conservation of charge:

• A neutron interacting with a neutrino creates a β- particle (an electron)
• A neutron of no charge releases a proton of positive charge and a W- boson of negative charge
• The overall charge expelled is zero, which is the same amount going in - charge is conserved

• A proton interacting with an antineutrino creates a β+ particle (a positron) 
• A proton of positive charge releases a neutron of no charge and a W+ boson of positive charge
• The overall charge expelled is positive, which is the same amount going in - charge is conserved