Optimizing gamma-ray spectrometers for UAV-borne surveys with geophysical applications.

Heavy duty unmanned aerial vehicles (UAVs) have made it possible to fly with large gamma-ray spectrometers that weigh several kilograms. Moreover, they can be purchased at an affordable price. These large UAV-borne gamma-ray detection systems are used to map the naturally occurring radionuclides K, U, Th.

Footprint and height corrections for UAV-borne gamma-ray spectrometry studies.

Advancements in the development of gamma-ray spectrometers (GRS) have led to small and lightweight spectrometers that can be used under unmanned aerial vehicles (UAVs). Airborne GRS measurements are used to determine radionuclide concentrations in the ground, among which the natural occurring radionuclides K, U, and Th. For successful applications of these GRS sensors, it is important that absolute values of concentrations can be measured.

An inter-comparison of sediment classification methods based on multi-beam echo-sounder backscatter and sediment natural radioactivity data.

This contribution presents sediment classification results derived from different sources of data collected at the Dordtse Kil river, the Netherlands. The first source is a multi-beam echo-sounder (MBES). The second source is measurements taken with a gamma-ray scintillation detector, i.

Monte Carlo based calibration of scintillation detectors for laboratory and in situ gamma ray measurements.

The calibration of scintillation detectors for gamma radiation in a well characterized setup can be transferred to other geometries using Monte Carlo simulations to account for the differences between the calibration and the other geometry. In this study a calibration facility was used that is constructed from bricks of well-known activity concentrations of ⁴⁰K and of radionuclides from the ²³⁸U- and ²³²Th-series. Transfer of the calibration was attempted to a Marinelli beaker geometry with the detector inside a lead shield and to an in situ application with the detector positioned on a sand bed.

In situ radiometric mapping as a proxy of sediment contamination: assessment of the underlying geochemical and -physical principles.

Correlations between sediment contaminants like heavy metals or organic micro-compounds and natural or anthropogenic radionuclides ((40)K, (238)U, (232)Th, (137)Cs) facilitates in situ mapping of the contaminated sediment using gamma-ray detectors. These maps can be made quickly and economically using surveys with towed underwater gamma-ray detectors and based on the fundamental correlation of contaminants with radioactivity. This paper aims at an assessment of the geochemical and -physical principles underlying these correlations.