Background from cosmic radiation

What background from cosmic radiation is expected for an unshielded 100 ml ion chamber which eidiibits an area of 100 cm perpendicular to the direction of the cosmic radiation ... 

Radiation impinges on us from the environment as background radiation, from radionuclides in the ground and water, and from cosmic radiation. Medical irradiation contributes a small but presumably significant fraction. By far the largest and most potent natural carcinogen is the ultraviolet component of sunlight. 

We are constantly exposed to background radiation from cosmic radiation (interaction of energy from the sun with the earth s atmosphere), terrestrial radiation from breakdown of uranium in the soil, and natural internal radiation in our bodies from carbon-14 that is present at birth. Man-made radiation sources include diagnostic X-rays, nuclear medicine (bone scans, thyroid scans, etc.), radiation therapy for cancer, nuclear power facilities, and nuclear weapons. 

Background Radiation. If the radiation from a radioactive source is measured, the spectmm also includes contributions from the radiations from the surrounding environment. This includes radiations from the radioactivity in the materials in and around the detector, including the stmcture of the building or nearby earth. There is also cosmic radiation that comes from space and interacts with the earth and atmosphere to produce radiations that may enter the detector, and thus is observed. 

Everyone receives small radiation doses every day Figure 8.3-5 illustrates some of the doses received from background and other types of radiation. Note that the scale is logarithmic , and that background and cosmic-ray doses vary over an order of magnitude just with location and elevation. In addition to these natural sources, most people receive some medical and dental doses each year. 

Background Radiation—The amount of radiation to which a member of the general population is exposed from natural sources, such as terrestrial radiation from naturally occurring radionuclides in the soil, cosmic radiation originating from outer space, and naturally occurring radionuclides deposited in the human body. 

In the United States, the average background dose of radiation from natural sources is about 100 mrem/year, but it can be approximately double that amount in some localities. It has been estimated that this background may contribute 4.5 to 45 cancers per million people per year. Minute amounts of radioactivity are found in all drinking waters. Some of this natural radioactivity (tritium) comes from cosmic ray bombardment. 

T. Villela, N. Figueiredo, and C. A. Wuensche, Photon Mass Inferred from Cosmic Microwave Background Radiation Maxwell s Equations in three-Dimensional Space, Instituto Nacional de Pesquisas Espaciais, Brazil, circa 1994, pp. 65-73. 

All matter is composed of both radioactive and nonradioactive isotopes. Small amounts of radioactive material in the air, water, soil, and so forth make up a part of the background levels. Cosmic rays from outer space continually bombard us with radiation, contributing to the total backgroimd. Owing to the inevitability of background radiation, there can be no such thing as "zero" radiation ... 

Background radiation, radiation from natural sources, is emitted by the sun as cosmic radiation, and from naturally radioactive isotopes found throughout our environment. 

The number of counts recorded in a radiochemical analysis includes a contribution from sources other than ihe sample. Background activity can be traced lo the presence of minute quantities of radon radionuclides in Ihe atmosphere, to ihe materials used in construction of the laboratory, to accidental contamination wiiliin the laboratory, lo cosmic radiation, and to the release of radioactive materials into ihe Earth s atmosphere. To obtain an accurate determination, then, it is necessary to correct the measured counting rate for background contributions. The counting period required to establish the background correction frequently differs from the counting period for the sample. As a result, it is mure convenient to employ counting rates as shown in Equation 32-15. 

The creation of our world occurred in intense radiation Helds and, consequently, we have inherited an Earth drenched in radiation from cosmic sources and the minerals in the groimd (Ch. S, 10 and 17). Though the intensity of these radiation sources is much smaller than produced by human techniques, no human can avoid these natural sources. Therefore, the effects of the natural radiation background has become an important health issue, particularly radon levels in houses. Closely related to this problem is the effects of man-made sources of similarly low levels, such as the storage of nuclear waste. Much research is presently devoted to the effects of low-level radiation. 

VOLCHOK Yes, the natural background that I showed in that chart, consisted of three parts which were about equal — the internal material in your body, the external material from the ground, and cosmic radiation from the sun. 

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