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Radiation Radiation is energy travelling as waves or particles. Radioactive materials are composed of atoms that are unstable. An unstable atom gives off excess energy until it becomes stable. The energy the atom emits is radiation. The process by which an atom changes from an unstable state to a more stable state by emitting radiation is called radioactivity.
Radiationcan be classified as either non-ionizing (low energy) or ionizing (high energy) radiation. Types of non-ionizing radiation are ultraviolet light, visible light, infrared radiation, radio frequency radiation and microwaves. Ionizing radiation is given off by the sun (cosmic rays), radioactive materials, and high energy electronic devices (X-ray machines)..
Ionizing radiationhas enough energy to change the chemical composition of matter. Non-ionizing radiationhas less energy but can still excite moleculesand atomscausing then to vibrate faster.
What is Ionizing Radiation? Ionizing radiation is radiation that has sufficient energy to remove electrons from atoms.
Types of Ionizing Radiation The four most common forms of ionizing radiation are alpha, beta, gamma, and neutron radiation. They have the following characteristics: Alpha Particles are positively charged particles made up of two neutrons and two protons. They are relatively heavy and slower moving than other radioactive emissions. Alpha particles can be stopped by a piece of paper or the dead outer layer of our skin.
Beta Particles are negatively charged particles made up of an electron. A beta particle is lighter and faster than an alpha particle and can be stopped by a thin piece of aluminium or a short span of air.
Gamma Rays are short wavelength electromagnetic radiation emitted in the radioactive decay of an unstable atom. Gamma radiation is highly penetrating and is stopped by lead.
The Penetrating Powers of Alpha and Beta Particles and Gamma Rays
X-rays are similar to gamma rays, but are generally lower in energy and less penetrating. X-rays are emitted from processes outside the nucleus, while gamma rays originate inside the nucleus. A few millimeters of lead can stop medical x-rays.
Radiation Dose and Measurement Units: Rem: The rem is a measure of the dose of any ionizing radiation to the body tissue in terms of its estimated biological effect relative to a dose of one Roentgen. For low doses we use the term millirem. 1/1000 of a rem is equal to one millirem
Rad The Rad is a measure of the dose of ionizing radiation to the body in terms of energy absorbed per unit mass of the tissue.
Curie A measure of the activity of the radioactive material. (One Curie is equivalent of 3.7 x 10 -10 disintegrations per second).
Roentgen A special unit used for measuring exposure to radiation. (2.58 x 10-4 coulomb per kilogram of air)
Radiation Sources We receive approximately 360 millirem/year from natural background radiation and manufactured sources of radiation Exposure to background radiation results in a dose of 300 millirem/year and comes primarily from:
What are some natural sources of ionizing radiation? Ionizing radiation is the energy produced from natural and artificial radioactive materials. It is present in the environment because of naturally occurring radioactive minerals remaining from the very early formation of the planet. This leads to exposure to gamma rays and radioactive radon gas from certain rocks and from radioactive material in our food and drink. We are also exposed to natural ionizing radiation that comes from outer space and passes through the atmosphere of the planet – so-called cosmic radiation.
What are some artificial sources of ionizing radiation? There are three main sources of artificial ionizing radiation. They are: · medical uses including diagnosis of many diseases and treatment of cancer; · industrial uses, mainly in measurement and scientific research; and · fallout from nuclear weapons testing and accidents around the world.
Is artificial radiation more dangerous than natural radiation? The damaging effects of ionizing radiation come from the packages of high energy that are released from radioactive material. Although different types of ionizing radiation have different patterns of energy release and penetrating power (see ionizing radiation topics) there is no general property that makes artificial ionizing radiation different and more damaging than the ionizing radiation that comes from natural radioactive material. This means that we can make direct comparisons between doses from artificial sources of ionizing radiation and those from natural sources.
Non-ionizing Radiation Non-ionizing radiation is electromagnetic radiation that does not have sufficient energy to remove electrons from the outer shells of atoms. Types of non-ionizing radiation are: ultraviolet (UV), visible light, infrared (IR), microwave, radio (and television), and extremely low frequency). Non-ionizing radiation is produced by a wide variety of products in the home and in the workplace, from lasers to power lines, tanning beds to household appliances, cellular phones to ham radios.
What are some examples of non-ionizing radiation? Solar radiation consists of several different forms of non-ionizing radiation and many modern technologies such as, power-lines, electrical equipment and mobile phone systems, also produce forms of non-ionizing radiations.(See Committee on Electromagnetic Energy Public Health Issues (CEMEPHI) EME Series Factsheets for more detail)
We cannot eliminate radiation from our environment but by having a good understanding of radiation and controlling our exposure, we can reduce our risk.
References Www.gaec.gr/.../president/_info_radiation_ion www.stoller-eser.com/ionizing_radiation.htm info.lu.farmingdale.edu/depts/met/ind310/ioni... jolisfukyu.tokai-sc.jaea.go.jp/.../2007/6_5.html www.ndhealth.gov/AQ/RAD/ionize.htm
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