Fundamental Concepts in Understanding Radiation
Understanding radiation in our world begins with understanding an atom’s structure. An
atom consists of positively charged protons and electrically neutral neutrons condensed in
a central nucleus, which negatively charged electrons orbit. The number of protons in a
nucleus is its Atomic Number, and the number of protons and neutrons is the mass number.
Atoms that contain an equal amount of protons and neutrons are electrically neutral and
therefore have no charge. Cations have more protons than electrons and are therefore
positively charged. Atoms with a difference in charge are chemically reactive and seek to
neutralize their charge by bonding with other ions. Atoms with differing numbers of
neutrons in their nucleus, or isotopes, can sometimes be radioactive. They seek to balance
the neutron to proton ratio by emitting radiation. Isotopes that undergo such radioactive
decay are called radioisotopes. Isotopes are variations in the element with different
numbers of neutrons, but always the same number of protons in the nucleus. Because of
this, all isotopes of an element act just like the element but have differing nuclear
properties.
Radiation is the energy emitted from radioactive sources that travels through a medium or
space. The energy radiates, traveling outward in straight lines in all directions from its
source. The energy intensity falls off with distance. The type of radiation to be focused on
is ionizing radiation (having sufficient energy to ionize an atom). Ionization is the
absorption of energy of the shortest wavelengths/highest energies into materials that ionize
their molecules. The energy is high enough to eject the electrons from the atoms, therefore
producing ions by breaking bonds. There are four types of ionizing radiation: alpha
radiation, beta radiation, photon radiation, and neutron radiation. Alpha Radiation is a form
of ionizing radiation that consists of 2 neutrons and 2 protons ejected from an atomic
nucleus, or the nucleus of a Helium atom. Alphas have a high charge, low velocity, and are
not very penetrating. One form of Beta Radiation is the Beta Minus Decay. This consists of
high energy, high speed electrons that are emitted by certain radioactive nuclei. Unstable
nucleus with excess neutrons undergo decay whereas a neutron is converted to a proton
that stays in the nucleus, and an electron and an antineutrino are emitted as a result. Photon
Radiation consists of X-Ray Radiation and Gamma Radiation. X-Rays are emitted by
electrons outside the nucleus while gamma rays are within the nucleus. Gamma rays are
