Types of radiation
There are many types of radiation.
This site descusses alpha rays, beta rays, gamma rays and
neutron rays.
neutron rays.
Alpha rays
Alpha rays are the flow of high speed alpha particles.Alpha particles contain two protons and two neutrons.
Alpha particles have two protons so alpha rays take a positive charge.
As a result, alpha rays pull another element's electrons so it changes for negative ion.
That is why alpha rays have a strange ionizotion action.
Alpha rays burst out when an atom undergoes an alpha collapse.
（examine in detail →『Mechanism of the radiation』）
Alpha rays's penetrating power is so low that it can be stopper by paper.
An alpha particle is big (two protons and two neutrons),
so it can't pass between another substance's atoms.
Therefore, if you are exposed to this radiation, your body is protected by your skin.
However, alpha rays have a strong ionization action.
If you ingest something including alpha rays,
your body is greatly influenced by it.
For example,
uranium and plutonium except for plutonium 241 emit alpha rays.
Beta rays
Beta rays are the flow of high speed electrons.When particles anderso a change to an unstable atomic nucleus, high speed electrons burst out from there.
（examine in detail →『Mechanism of the radiation』）
Beta rays are the flow of electrons so they have a negative charge,
however beta rays have a smaller mass than alpha rays,
beta rays penetrating power is between alpha rays and gamma rays.
Beta rays are stopped by a metallic plate or a plastic board centimeter thick so they can influence us.
For example,
strontium 90 or cesium 137 emit beta rays.
Incidentally,beta rays that are artificially made to pick up high-speed electrons are called electron rays.
Gamma rays and X rays
Gamma rays are very short electromagnetic waves.Their atomic nucleus is usually stable, however when it has extra energy, it becomes unstable.
The energy wave that bursts out just then is gamma rays.
Gamma rays'penetrating power is very high so gamma rays are only stopped by concrete and sheets of lead.
Therefore, if you are exposed gamma rays, gamma rays penetrate deep into your body.
X rays are heard of in hospitals.
It is a very short electromagnetic wave and it's energy is very high.
That is why gamma rays and X rays have almost the same electromagnetic wave.
Neutron rays
Neutrons are the flow of high speed neutrons.
Neutrons are emitted when uranium fuel is broken down through nuclear fission.
Moreover, neutrons primarily occur from artificial substances.
Neutron rays don't influence electric energy because neutrons don't have electricity.
So, neutron ray's penetrating power is very strong and stopping it is difficult.
When it run against into the substance what a mass about the same as a neutron, the neutron's energy is absorbed,
namely neutron ray are stopped by light atomic nuclei.
Hydrogen is the lightest at the atomic nuclei because it contains only at single proton.
Therefore, a substance that has hydrogen and hydrogen ions is effective to stop neutrons.
For example, water, concrete and so on.