Gamma-Ray Spectrometry

For more 33 years Aerogeophysica has been conducting airborne gamma-ray survey for different geological and ecological tasks:

• mapping of natural, K. U, Th, and artificial, ¹³⁷Cs, radioactive nuclides distribution, gamma-ray dose power, local component of “free’ ²²²Rn - with developed by Aerogeophysica original technology;
• geological structures mapping within near surface section;
• exploration for radioactive minerals;
• exploration for hydrothermal deposits and research into superimposed metamorphic processes;
• exploration for diamond, gold and rare metals deposits;
• exploration for oil&gas productive fields;
• remote ecological and engineering monitoring.

Estimation of radioactive contamination (¹³⁷Cs). Cherkassk region

Aerogeophysica made a real contribution to gamma-ray surveys for estimation of radioactive contamination caused by nuclear plants disaster. In last years has been completed government program regarding mapping of suffered after disasters at Chernobyl reactor and in the Chelyabinsk (Ural) region, after nuclear tests in the Semipalatinsk area and on the island of Novaya Zemlya. About 4 000.000 sq.km of data was obtained by Aerogeophysica under completed over these territories gamma-ray surveys.

The using by Aerogeophysica survey and data processing methods are certificated by IAEA.

Developed by Aerogeophysica data processing technologies allow:

To evaluate 137Cs concentration in soil layer;To evaluate “free’ 222Rn concentration in air without additional sensor;To select in total spectrum the most of gamma-ray radiation lines without a prior information and with resolution for 137Cs (662 МеV) up to 1.5 – 2%.

For airborne gamma-ray survey the thermo-stabilized 512 - channel spectral analyzer is used.

The gamma-ray detectors are sodium iodide (NaI) polyscin crystals with volumes of up to 48 liters (4,096 in3), with a resolution better than 9% for Cs-137 (0.662 MeV). The measurements range is 0.38 – 5.0 MeV. Measurements increment – 10 KeV. Measurement rate – 1 per second.

Stabilization of energy scale is carried out by detectors thermostating under temperature of 36°С

The spectrometer sensitivity is evaluated over test site by flights with altitude 150 m:

The various aircrafts makes it possible to carry out airborne gamma-ray spectrometry, as a rule together with another required geophysical systems, in different regions independently of local terrain features. As a survey platform can be chosen helicopters MI-8, KA-26, or airplanes AN-2, AN-26, AN-30.