MS-4000 product picture


The MS-4000 airborne gamma-ray sensor. A detector used by geophysical survey companies, geotechnical consultants, and research institutes to capture soil variation in large areas.


MS-4000 Medusa gamma-ray spectrometer

27 KG 
Weight optimized

4x4x16'' CsI crystal

500 hours
Internal storage


-20 / + 65 C
Arctic and desert mapping

Up to 90 km/h
Airborne mapping

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Airborne / Vehicle borne

The Medusa Radiometrics MS-4000 "Airborne" gamma-radiation detection system (AGRS) is our "classic" lightweight radiation sensor that was first introduced in 2006 and used for a large regional uranium survey in Madagascar. It is mostly used by geophysical survey companies, geotechnical consultants, and research institutes.

Leading in gamma-ray sensors

Leading in innovative gamma-ray solutions

Academic collaboration

Scientific collaboration with eminent research institutes and peer-reviewed publications of the analysis procedures. 


We have over 20 years of experience in developing gamma–ray spectrometers and applications. 

Youtube video
Gamma-ray spectrometer
Scintillation crystal 4000 ml CsI
Mapping speeds Up to 90 km/h
Recording frequency Up to 5hz
Online Radionuclide analysis 40K, 238U, 232Th and 137Cs
Type uBlox ZED-P9P
Signals GLONASS, BeiDou, Galileo
Accuracy 1.5 m CEP
RTK accuracy <1 cm
Streaming RS-232, ethernet and Wi-Fi
Sensors Spectrometer, GPS, PTH
Internal storage 16 GB
Dimension 174 (h) x 203 (w) 856 (l) mm
Weight 29 Kg
Operating T -20 to +65 °C
IP rating IP65
Input voltage 12-35V
Power consumption 3W (avg), 6W (max)
Battery n.a.
Wi-Fi 2.4 and 5 Ghz
Ethernet 100 Mbps
Port RS-232

mDOS & Gamman

medusa Detector Operating System (mDOS)

We offer a uniform interface across all our products. Whether conducting an airborne survey for mineral exploration, locating a lost source with a UAV, or utilizing our detector for a handheld survey to map the environment, you can rely on the same user-friendly interface. This software is specifically developed for in-the-field use, optimized for ease of use, and designed to automate your survey workflow.

GammAn post-processing software

For situations that require post-processing of data, a seamless connection with mDOS facilitates rapid reprocessing. The system is available with a graphical user interface and also as a set of command-line tools for both Windows and Linux, allowing you to integrate the analysis seamlessly into your existing workflow.

More about mDOS and GammAn

mDOS user interface