Radiation is classified into:
Higher energy electromagnetic waves (gamma) or heavy particles (beta and alpha).
High enough energy to pull electron from orbit.
Lower energy electromagnetic waves.
Not enough energy to pull electron from orbit, but can excite the electron.
ô It is a type of radiation that is able to disrupt atoms and molecules on which they pass through, giving rise to ions and free radicalsö.
A radiation is said to be ionizing when it has enough energy to eject one or more electrons from the atoms or molecules in the irradiated medium. This is the case of a and b radiations, as well as of electromagnetic radiations such as gamma radiations, X-rays and some ultra-violet rays. Visible or infrared light are not, nor are microwaves or radio waves.
Primary Types of Ionizing Radiation
Gamma rays (or photons)
X-Rays (or photons)
Alpha Particles: 2 neutrons and 2 protons
They travel short distances, have large mass
Only a hazard when inhaled Types and Characteristics of Ionizing Radiation Alpha Particles
Alpha Particles (or Alpha Radiation): Helium nucleus (2 neutrons and 2 protons); +2 charge; heavy (4 AMU). Typical Energy = 4-8 MeV; Limited range (<10cm in air; 60Ám in tissue); High LET (QF=20) causing heavy damage (4K-9K ion pairs/Ám in tissue). Easily shielded (e.g., paper, skin) so an internal radiation hazard. Eventually lose too much energy to ionize; become He.
Beta Particles: Electrons or positrons having small mass and variable energy. Electrons form when a neutron transforms into a proton and an electron or: