A drone-borne gamma spectrometer with extremely high resolution 

The MS-700 gamma spectrometer used for drone-borne mapping.

Medusa’s gamma-ray spectrometers are commonly used for drone-borne mapping of soil properties and geology and our sensors have proven their application. But what if a client needs to map specific isotopes. That’s why we built our highest resolution gamma-spectrometer ever!

A gamma-ray sensor fitted to your needs 

Working on the optimisation of gamma-ray sensors is our everyday business and we aim to provide our clients with state of the art gammaspectrometer solutions. Each sensing project has unique needs, and we help our clients to get the best out of your set-up by finding the optimum radiation sensor for their project or platform. In practice this means we closely collaborate with our clients to find the sensor design optimised for their platform.

Medusa gamma-ray spectrometer under drone.


DUB-GEM project 

BGR, the German geological survey is coordinating the DUB-GEM project. 

DUB-GEM – Development of an Unmanned Aerial Vehicle (UAV) – based Gamma spectrometry for the Exploration and Monitoring of Uranium Mining Legacies  

The DUB-GEM project aims to develop exploration technology for rapid recording of the radioactive pollution situation in the vicinity of uranium mining sites in Kyrgyzstan, Tajikistan, Uzbekistan and Kazakhstan. Within the project a drone is developed that is used to carry gamma-ray spectrometers for mapping the sites and various gamma-ray spectrometers will be tested and compared. 


MS-700 with CeBr crystal

For the project, BGR acquired two MS-700 sensors for drone borne operations. One of these sensors contains our “standard” CsI crystal that is suited for mapping the concentrations of the natural occurring radionuclides. The other sensor contains a CeBr crystal. CeBr crystals are used for detailed spectroscopic measurements and come normally in small crystal sizes. However, these small crystals are not accurate enough to be used for drone-borne operations. That’s why we built a MS-700 with a CeBr crystal inside. This sensor gives extremely high spectral resolution and will give the opportunity to study out-of equilibrium conditions of the 238U decay series. This 700 ml CeBr crystal (delivered by Scionix) is the largest CeBr ever built and has a resolution at 667keV that is better than 3.9%. 

The measured spectra and the s0-called standard spectra of the natural occurring radionuclides clearly show the difference between the resolution of the CsI crystal and the CeBr crystal.

MS-700 CsI

Spectrum measured with an MS-700 CsI crystal.

MS-700 CeBr

Spectrum measured with an MS-700 CeBr crystal with unprecedented spectral resolution.


This MS-700 CeBr sensor is unique in its kind and will provide new opportunities for research of mine tailings.