<P> Charged particles (electrons, mesons, protons, alpha particles, heavier HZE ions, etc .) can be produced by particle accelerators . Ion irradiation is widely used in the semiconductor industry to introduce dopants into materials, a method known as ion implantation . </P> <P> Particle accelerators can also produce neutrino beams . Neutron beams are mostly produced by nuclear reactors . For the production of electromagnetic radiation, there are many methods, depending upon the wave length (see electromagnetic spectrum). </P> <P> In radiation protection, radiation is often separated into two categories, ionizing and non-ionizing, to denote the level of danger posed to humans . Ionization is the process of removing electrons from atoms, leaving two electrically charged particles (an electron and a positively charged ion) behind . The negatively charged electrons and positively charged ions created by ionizing radiation may cause damage in living tissue . Basically, a particle is ionizing if its energy is higher than the ionization energy of a typical substance, i.e., a few eV, and interacts with electrons significantly . </P> <P> According to the International Commission on Non-Ionizing Radiation Protection, electromagnetic radiations from ultraviolet to infrared, to radiofrequency (including microwave) radiation, static and time - varying electric and magnetic fields, and ultrasound belong to the non-ionizing radiations . </P>

What names are given to the two main types of particle radiation found on earth