Gamma ray
spectroscopy
Gamma ray
radiometry is a geological tool use to estimate the concentration of radioactive
element in the earth (given place). Radiometry measures the level of
radioactive element in any sample given; the property take into consideration
is the amount of gamma ray emission.
Gamma rays are
originated from the natural decay of rocks and soils. The most penetrative of all type of ray, move
at the speed of light and can move several hundredths of meters in air. By using a low-flying aircraft, the
radioactivity of the earth can be measured. Gamma ray spectroscopy is great geological
mapping tool, it can detect all mineral deposits underground in any given
earth. With airborne Gamma ray radiometry a low-flying aircraft with elevation of
50-150 meter above can and measure the data after each 50-60m along flight line.
(1)
All rocks
and soil types have unique concentration of natural radioelement like
potassium, uranium and thorium, changes in soil or rock type result to change
in concentrations of these radioelement. Gamma ray emitted from each of
potassium, uranium or thorium has its characteristic energy, therefore easy to
identify what radionuclide(either potassium, thorium or uranium) the ray originate. By knowing the nature of
the ray and its concentration, the rock or soil type can be detected.
The reading
s are taken when gamma ray makes contact with a crystal that emits
scintillation when in interaction with the gamma ray. A photomultiplier convert the scintillation to a voltage that
is directly proportional to energy of the gamma and finally datas are converted
to ground radioelement ray concentrations.(2)
Gamma ray
spectroscopy is mostly used for uranium, hydrocarbon, groundwater, geothermal and
mineral investigations. It is a good
mapping tool for environmental mapping
and mineral explorations.
in a sample
of rocks with concentration of both radioactive and stable in a given ratio, how can we calculate the age of the rock, assuming the rock was formed when time =0,
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