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GRS42 & 60: Spectral Gamma

The detector assembly comprises of a 25 x 50 mm (GRS42) or 50 x 150 mm (GRS60) cylindrical NaI crystal coupled to a thermally stabilised photomultiplier tube.

According to type the probe is capable of resolving 250 or 500 discrete gamma ray energy levels over the range 60 to 3 060 keV. Count rates from all of which are transmitted to the surface during logging.

Subsequently, discrete windows centred on the characteristic K, U and Th peak levels are used to derive the concentration of these radio-elements.

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Technical Specifications

Diameter GRS 42 : 42 mm

GRS 60 : 60 mm

Length : 1120 mm

Weight : 7 Kg

T° Max. : 70°C

Pressure Max : 200 bar

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Sensors Parameters

Detector GRS 42 : 25 x 50 mm

Detector GRS 60 : 50 x 150 mm

Spectral energy range : 60 to 3060 keV

Spectral resolution : GRS 42 : 250 channels, 12 keV per channel

Spectral resolution : GRS 60 : 500 channels, 6 keV per channel

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Borehole Conditions

Dry or fluidfilled

Open-hole or through steel or PVC casing 75mm minimum


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