Allen Bergeron

What are "The Roentgen, Rad, Rem, and Curie"?

Radioactivity has been an issue every since the development of the a-bomb. While radiation in this form catastrophic because of the dosage, we receive minute dosages every day. Radiation is even said to be good for humans when kept in a small dosage. There are three main types of radiation: alpha particles, beta particles, and gamma particles. The roentgen, rad, rem, and curie are forms of radiation measurement. The rad and rem are ways of distinguishing doses absorbed by objects, both organic and inorganic. The roentgen is a measurement of radiation in the air.

The roentgen is a unit used to measure a quantity called exposure. This can only be used to describe an amount of gamma and X-rays in the air. One roentgen is equal to depositing in dry air enough energy to cause 2.58E-4 coulombs per kg. It is a measurement of molecular ionization in one mass of air. The main advantage of this unit is that it is easy to measure directly, but it is limited because it is only measures deposits in air, and only for radiation in the form of gamma and x rays.

The rem (Roentgen Equivalent Man) is a unit used to derive a quantity called equivalent dose. This relates the absorbed dose in human tissue to the biological damage by the radiation. Rem is a measurement of potential damage done by radiation. Not all radiation has the same biological effect, even for the same amount of absorbed dose. Equivalent dose is often expressed in terms milli-rems. To determine equivalent dose (rem), you multiply absorbed dose (rad) by a quality factor (Q) that is unique to the type of incident radiation. Every year the average person is exposed to 360 milli-rem annually. This means we are exposed to about 1 milli-rem on a daily basis. At the website www.epa.gov/radiation/students/calculate.html there is a neat little survey you can fill out that gives your annual radiation expose and tells what factors its due to. High levels of rem cause radiation sickness.

The rad (Radiation Absorbed Dose) is a unit used to measure a quantity called absorbed dose. This relates to the amount of energy actually absorbed in some material, and is used for any type of radiation and any material. The difference between a rad and a rem is a rad is a measurement of radiation absorbed by the material not the potential affect of the radiation. One rad is defined as the absorption of 100 ergs per gram of material. The unit rad can be used for any type of radiation, but it does not describe the biological effects of the different radiations.

The curie is a unit used to measure radioactivity. One curie is the quantity of a radioactive material that will have 37,000,000,000 transformations in one second. The curie was originally a comparison of the activity of a sample of one gram of radium, which at the time was measured as 37 billion disintegrations per second. Each disintegration represents an atom of the sample releasing a radioactive particle. Often radioactivity is expressed in smaller units: thousandths (mCi), one millionths (uCi) or even billionths (nCi) of a curie. This measurement came about because scientists needed a something to measure mass disintegrations of a sample. Marie Curie is said to have coined the word "radiation". She won the Nobel Prize twice for her work with radiation and the unit curie is named after her.

 

While radiation can harm us, it plays an intergral part of our lives. Nuclear power plants light our homes. While this source of radiation is contained, there are sources present every day of our lives. Our tv's emit radiation while we watch them. Most smoke detectors contain small amounts of radioactive material. After the antrax letters were sent the U.S. Post Office needed a way to kill the antrax without harming the public or employees. They now bombard suspected mail with levels of radiation high enough to kill antrax. Even food consumed is a form of radiation. The potassium found in bananas, P 40, is a radioactive element. Meats and other consumables that may contain bacteria undergo forms of irradiation to kill the organisms in the meat. These are all approved forms of radiation the EPA (Environmental Protection Agency) allows and while most of it is harmless the long-term affects of these forms of man made radiation are not know. All the same we would be hard pressed to live at the quality of life we have achieved without these small, unknown risks.

 

 

 

Most information was acquired from the: U.S. Environmental Protection Agency

http://www.epa.gov/radiation

 

http://www.physics.isu.edu/radinf/terms.htm