Other applications

Radioactive dating

Radioactive dating uses the principles of the radioactive disintegration, a procedure frequently used by geologists and archaeologists to determine the age of the materials.

The ratio between the radioactive atoms of C-14 and of C-12, their stable form in the atmosphere, remained constant for thousands of years. Although atoms of C-14 disintegrate, the isotope continues to build continuously, due to the fact that the neutrons coming from the cosmic radiation of the sun collide with the atoms of Nitrogen -14 from the atmosphere, keeping thus a constant ratio between C-14/C-12 in the atmosphere.

The carbon dioxide (CO₂) from the air molecules can contain any of the two isotopes of carbon. The plants in the growth process continually use this CO₂. Because the atmospheric ratio C-14/C-12 in CO₂ is constant, the plant assimilates a constant ratio between the two isotopes, as long as it is alive. When the plant dies, it won’t assimilate CO₂ anymore, and the ratio C-14/C-12 becomes descending over time. Similarly, because animals feed with plants, the proportion C-14/C-12 becomes descending after their death. By burning the sample of a fossil material, the reaction take place between the oxygen and the carbon contained by the sample; CO₂ will result, a gas that will include a radioactive component formed from isotope C-14, which is measurable. Knowing the relatively short half-life of the isotope C-14 (about 5730 years), the approximate age of the investigated object can be calculated. The sensitivity of detection of the current analytical equipment limits the usage of this method when the samples are older than 80000 years.

For the geological applications (rock age determination), isotopes with higher half-life are used.

Geology and the identification of the elements

The measurement of the radioactivity can be used at localizing and estimating the uranium or resources or other radioactive ores.

Within the mining industry, the identification of the constitutive elements from the rocks and minerals is based on the fluorescent effect that occurs when a primary radiation emitted by a source of radioactive material could lead to another sample material of X fluorescence radiations. By measuring the energy and the intensity of these fluorescence radiations, the qualitative and quantitative composition of the analysed material can be determined.

Smoke detectors

The smoke detectors are safety devices indispensable in many homes, firms, production and storage halls etc.

There are two types of smoke detectors. One type uses an optical sensor to detect changes in the light caused by the smoke, the other type uses, usually, americium-241 radioisotope, being much cheaper and more sensitive to a wide range of fire conditions.