The Medusa Radiometrics MS-50 is a small, CeBr-based spectrometer intended for survey work requiring very high peak resolution. The crystal material used has a resolution better than 4% on 137Cs, making it very suitable for detecting (cocktails of) man-made nuclides. With a weight of less than 1kg, the system is intended for use under smaller, low-payload UAVs. Like all our low-power, lightweight and robust gamma-ray sensors, it was developed with unmanned aerial vehicle (UAV) applications in mind. Our systems are fully self-contained as they integrate data acquisition, processing and storage into a single embedded system. 

The MS-50 can also easily be used as a handheld system, operated from a smartphone or tablet PC.


The system comprises a 1.5x1.5 inch (50 ml) CeBr3-based scintillation detector connected to a tailor-made spectrum processing unit. This unit comprises a single PCB containing a 4096-channel MCA, a GPS board and a data processing/storage board. The board communicates via cable and WiFi.

The unit runs mDOS - our award-winning detector operating system that provides access to the multiple functions of the device, i.e.

  • Set-up of the system;

  • Status view to inspect data and functioning of the system;

  • Single and continuous measurement modes;

  • Download view to allow retrieval of recorded data.

mDOS can be accessed via any standard web browser.

The data is stored in records containing energy-stabilised gamma-ray spectra, together with count rate and activities of 40K, 238U, 232Th and 137Cs. Other radionuclides can be added on request. The data is geo-referenced using the built-in GPS.

System Operation

The system is designed for minimum operator interaction. It provides various views on the data streams while being acquired, allowing for online system checks. The system has a maximum capacity of 32GB of embedded data storage, yielding space for thousands of hours of continuous logging. The system can be user-configured to output gamma-ray spectra continuously, connecting the sensor to multiple data acquisition systems.



  • Ultrahigh sensitivity

  • Lightweight and rugged carbon housing

  • 1.5x1.5 inch CeBr scintillator for high-resolution spectra

  • Full spectrum recording

  • Automatic gain stabilisation

  • Online nuclide-specific count rates

Radiation Sensor

  • CeBr crystal, other crystal types on request

  • Dedicated Spectrum Processing Unit comprising

    • 4096 channel MCA (16384 channel version on request)

    • Spectrum stabilisation

    • Nuclide-specific data

  • Up to 4GB on-board data storage

  • Wireless connection via WIFI and Bluetooth

  • Battery-powered


  • On-board data logging

  • Set up, control and viewing of data via a built-in web server - mDOS

System Data

  • Housing: Carbon fibre; end caps: Anodized aluminium

  • Connectors: one 8-pin LEMO M-series

  • Environmental: 
    -40 0C to +85 0C; 
    IP68 protected

  • Power: 12V, (1W nominally, 3W max)

  • Data acquisition rate: single shot – 1Hz

  • Data storage capacity: 32GB internal

  • Connectivity: user-configurable output streams over IP or serial link

  • Built-in WIFI

  • Built-in Pressure/Temp/Humidity sensors

Size, weight

  • Size: 80mm ⌀ x 220mm (L)

  • Weight: 990 grams (CeBr version)