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.
Lim designs, produces and commercializes measuring instruments and solutions dedicated to drilling.