ISO 9001:2008 certified ISO 14001:2004 certified ISO 18001:2007 certified

International Airborne Geophysics Safety Association

GPX Surveys is a member and supporter of IAGSA and operates in accordance with a stringent prescriptive safety management system.

Airborne GeophysicsRadiometrics

Airborne gamma-ray spectrometry (radiometrics) is an effective geological mapping tool in many different environments and has been applied to mineral, environmental, geothermal, hydrocarbon and water investigations.

Airborne gamma ray spectroscopy (radiometrics) measures the radioactive emissions from the soil surface which results from the natural decay of isotopes in the soil.

Airborne radiometric measurements have traditionally been obtained for four energy bands. These bands are indicative of total radiometric count and uranium, thorium and potassium concentrations. The data is usually obtained at an elevation of between 40 and 150m above ground level and a measurement is recorded every 50 - 60 metres along flight lines. Final data resolution is primarily determined by survey line spacing and elevation.

Emissions of gamma radiation from the land surface vary with many factors but essentially depend on the composition of radionuclides within the top 30cm of the soil surface. The composition depends on the parent material and the degree of breakdown, loss and/or accession, and therefore generally reflects the parent material and weathering.

Please click here for a flyer about airborne magnetic surveys.

APPLICATIONS

Mineral exploration
Gold, mineral sands, uranium and rare earth elements. Please click here for a flyer with information about our uranium exploration techniques.

Geothermal exploration
Potassic alteration.

Hydrocarbon exploration
Potassic/uranium alteration.

Geological mapping
Mineral, engineering and water exploration applications and paleodrainage systems.

Contamination mapping and detection
Military and industrial waste (eg. 137Cs and 60Co).

Emergency response
Fallout and nuclear contamination.

TECHNIQUE

Potassium, uranium and thorium emit gamma-rays with specific energies during their decay sequence. The gamma-ray spectrum is measured using crystals that scintillate during a gamma-ray interaction. Photomultipliers convert the scintillation to a voltage that is directly proportional to the energy of the gamma ray. Using calibration data and advanced processing techniques the raw gamma-ray data is converted to ground radioelement concentrations.

The peaks associated with potassium, uranium and thorium are shown in the following gamma-ray spectrum:

Raw Airborne Gamma-Ray Data

EQUIPMENT SPECIFICATIONS

Pico Envirotec GRS-10+ Spectrometer
Pico Envirotec GRS-10+ Radiometric Data Acquisition System is an advanced spectrometer utilising NaI detectors. It is a hardware-software design system, with advanced individual detector signal processing that reduced the potential hazards (or complex circuitry) of "zero base shift" and practically eliminates "dead time".
The GRS-10+ records real time calibrated summed 256 channel spectra. In addition, a raw 512-channel spectrum from each individual crystal is also recorded. This allows the data from individual crystals to be post-processed to achieve better energy calibration and as a result a high-resolution 512 channel summed spectra. 

Recorded Spectra: 256 or 512 channels
Data Sampling: 1 second sample rate
Energy Spectra: 50 keV (adjustable) to 3 MeV
Cosmic: Energies above 3MeV are detected as cosmic rays
Max. count rate: 1,000,000 per second (65,535 per channel)
Spectra Correction: Automatic gain control on individual detectors
Dead time: Negligible for normal detection rates
Configuration(s) 16.8 litres - 4 individual detectors in 1 pack
33.6 litres - 8 individual detectors in 2 packs

Exploranium GR-820

The Exploranium GR-820 is a modern spectrometer system that records 256 channels of summed data from either one or two crystal packs. The spectrometer employs automatic gain control to ensure stable peak positioning and therefore eliminate spectral drift.

The spectrometer system can be flown with either one or two crystal packs depending on the aircraft configuration.

Recorded Spectra: 256 channel summed spectra
Data Sampling: 1 second sample rate
Energy Spectra: 175 keV to 3 MeV
Cosmic: Energies above 3 MeV are detected as cosmic rays
Max. count rate: 1,000,000 per second
Spectra Correction: Automatic gain control on individual detectors
Dead time: Less than 5 microseconds
Configuration(s) 16.8 litres - 4 individual detectors in 1 pack
33.6 litres - 8 individual detectors in 2 packs
EnlargeCessna 210 aircraft configured with magnetic and radiometric survey equipment (Namibia)
EnlargeMagnetic and radiometric survey equipment
EnlargeRadiometric Ternary image of the South Kimberley region of Western Australia. Geophysical data courtesy of the Geological Survey of Western Australia, Department of Mines and Petroleum © State of Western Australia 2008