Beta Decay

Beta Decay

A beta ^- particle is an electron.
A beta ⁺ particle (which is the antiparticle of the electron) is a positron.

We will look closely at decays which produce each of these to learn more about the rules that apply in all interactions between particles.

First consider the decay of Carbon 14

So what's this antineutrino then?

Neutrinos are virtually undetectable. We know they are produced from looking at the energy of the beta particles produced. They do not seem to have all of the energy which you would expect to be released in this decay so another particle must be getting some kinetic energy, the antineutrino.

Now look at the decay of Oxygen 15

In both of these decays, as in ALL interactions, a number of quantities are conserved. Learn this list.

Mass / Energy	We will see how we can predict the energy released in a decay by looking at the difference in mass before and after then using E = mc²
Charge	If we lose a proton a positron is emitted, if we gain a proton an electron is emitted
Momentum	The daughter nucleus recoils, like a cannon that has just fired a ball
Lepton Number	the electron and neutrino have lepton number +1, the positron and antineutrino -1. Basically, if we create a particle we must also create an antiparticle.
Hadron Number	This is just the mass numbers (protons and neutrons) adding up.