Demand for alternate sources of energy has been increasing day by day. In addition to Titanium and Zirconium, the radiometric surveys do primarily concern with the search for Uranium, Thorium, and Potassium. There are about fifty naturally occurring radioactive isotopes. The instruments which are used to explore the radioactive minerals, do display the number of counts of emissions over a fixed period of time. The standard unit of gamma radiation is the Roentgen (R), which does correspond to the quantity of radiation which produces about 2X10 power 15 pairs of ions per cubic meter at standard temperature and pressure. The radiation anomalies would be expressed in terms of micro roentgen per hour. Geiger-Muller counter, Scintillometer, Gamma-ray spectrometer, radon – emanometer, etc are the major instruments being used to survey for the radioactive minerals.
When compared to other instruments, the Geiger-muller counter is cheaper and easier to use, but its use is limited to ground surveys only as it does respond only to beta ray emissions. The detecting chemical elements such as argon, water vapor, and alcohol or methane are kept in a sealed glass tube.
The scintillometer is most efficient and useful to measure the gamma radiation. The mechanism is that certain chemical substances such as thallium treated sodium iodide and lithium drifted germanium do convert gamma rays to light energy hence they scintillate.
Radon is the gaseous radioactive element. It does not form compounds with other elements and hence moves through several types of structural features such as faults, joints, and also through the pore spaces underground either as a single gaseous element or dissolved in the underground water bodies. Radon is a product of the radioactive disintegration or decay of Uranium hence it is a useful guide to detect deeper deposits of uranium. The radon – emanometer is also being used for mapping structural features such as faults which facilitate for the transportation of radon formed at great depths.
Most of the radiometric surveys are being done from the air. The radiometric data should be supplemented by the data collected from magnetic and electromagnetic surveys. Depending upon the size of the deposits the speed of the helicopters can be altered. The height of the flight is usually about a hundred meters. The collected data is generally interpreted in qualitative terms.
The radiometric surveys are also highly useful in geological mapping processes as different lithological differences can be identified based upon the variations in their radioactive signatures.
