A new radiation surveying system using GPS (Global Positioning System) technology for geographical positioning has recently been launched by the Swedish manufacturer of radiation detec-tion equipment, Gammadata AB. The GDM 40 is said to be ideal for environmental analysis and large-scale mapping operations from a variety of platforms. The unit uses the GPS unit to determine exactly which section of land is being measured thereby giving an exact position of a potential radiation source.

The GDM 40 has been designed to carry out a variety of large-scale environmental analysis programs such as geographical surveys, radiation detection studies, as well as vehicle based and airborne radiation monitoring.
The system uses an advanced gamma-ray detector packed into a rugged, 3mm thick cylindrical tube to detect fluctuations in background radioactive emissions thereby giving a clear picture of the radiation status of a given area.
The unit’s 6-channel GPS sensor provides position accuracy to within a radius of approximately 100 metres using satellite triangulation. With the addition of an optional RDS (Radio Data System), definition can be improved to about 10 metres. In this way, source detection becomes extremely accurate providing an invaluable tool in localising radiation emissions, both on the ground and from the air.
The unit, which can be connected to any standard PC, uses software developed by the Swedish Radiation Protection Institute (SSI) to provide automated multi-dimensional display and data analysis.
The Gammamap software can be run either on or off line and comprises four separate programs which display data, check the instrument’s calibration, manipulate data files and present digital maps.
Information can be displayed as visual data on a colour PC screen in real time or stored for later analysis. Spectrum and two-dimensional maps can be displayed showing, overlaid, the geographic distribution of measured activity. The software is operated using pull-down menus and a standard RS232 or parallel communication is used for computer interface.
Power can either be supplied from the unit’s own internal battery (providing up to 8 hours operation), from any outlet or from a 13 - 18V car or aircraft battery.

For further information contact:
EG&G Instruments, Paul Davison,
Sorbus House, Mulberry Business Park,
Wokingham, Berkshire, RG11 2GY
Tel: 01734 773 003 Fax: 01734 773493
E-mail: Paul_Davison@Egginc.com

or

Gammadata AB, Stefan Isaksson
P.O. Box 15120, SE-750 15 Uppsala, Sweden
Tel: +46 18 56 58 00 Fax: +46 18 50 11 00
E-mail: stefan.isaksson@gammadata.se, info@gammadata.se
home page: http://www.gammadata.se


Technical details:
A 3” x 3” Nal gamma-ray detector with an EG&G ORTEC ScintiPack 296 photomultiplier base and EG&G ORTEC _ACE data acquisition board is used. Up to five different nuclei can be selected for individual analysis. The GDM 40 can be operated from a PC, in which case the data is stored on the PC’s disk. It can also be operated as a stand-alone instrument. In this case, the spectrum are stored in the instrument. With 256 channel spectra (at 2 bytes/channel), approximately 1,600 spectra can be stored. With an average 10 second sampling time, storage of more than 4 hours of data is, therefore, possible.

Captions:
1. A new radiation surveying system using GPS (Global Positioning System) technology for geographical positioning has recently been launched by Gamma

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