Question

What causes alpha and beta Decay? A lot of details please

Answer 1

Alpha Particle/Alpha Radiation:

These are 4 particles grouped together, 2 protons and 2 neutrons. They are basically the nucleus of a Helium atom. The Atomic number of the alpha particle is 2. And the Atomic mass of the alpha particle is 4. That's easy enough. The next thing to note is that Alpha particles are emitted usually from elements that contain far too many particles in the nucleus. The nucleus becomes very unstable due to the build up of electrostatic repulsion in the atom, basically the Strong force holds protons and neutrons together in the atom, however the strong force may be very powerful but it's range is very limited, the Strong nuclear force operates at about 1 to 2 femtometres(10^-15m) and acts as a joining force that overrides the electrostatic force of repulsion, this allows protons to stay close to one another in an atom, and what allows neutrons to also bind together with protons. At a distance of about 0.5fm or less, it acts as a repulsive force to keep protons and neutrons from combining into one another. However the more neutrons/Protons that exist in the nucleus the greater the build up of electrostatic repulsion, and due to the limited range of the Strong force, the electromagnetic force of repulsion eventually breaks some particles loose. These are usually emitted as Alpha particles. Like I mentioned only atoms of a very high number of protons and neutrons are affected by this.

Alpha particles are the heaviest of the 3 radiations, due to their mass they travel very slowly, and often a few cm of air would limit them greatly, also they can be stopped by a piece of paper...so indeed very weak on the outside. However contrary to what people assume, Alpha particles are the STRONGEST ionisers of the 3. If Alpha particles are ingested or inhaled into your body, it would cause far, far more damage than even Gamma rays, this is due to their mass. Estimated at about 100x more damage than similar mass of any other radiation.

Beta Radiation:

Beta particles are electrons that are emitted from Beta Negative decay, This is caused when a neutron changes into a proton in the nucleus. The frame work of this happening is when a down quark changes to an up quark in the neutron. Remember Proton is (up,up,down) and a Neutron is (up,down,down) quark combinations. This happens due to the Weak nuclear force. When the quark changes, a heavy W- Boson(The messenger particle of the Weak force) is emitted, this lasts a very short life span and then turns into an electron(-1) and an electron anti-neutrino(a massless neutral particle). The electron that is emitted is called a Beta particle.

By their very tiny masses, it should be obvious that they travel at very fast speeds...but Beta radiation would be stopped by a thin piece of aluminium. It is particularly dangerous when ingested. But not as dangerous as an Alpha particle.