Practical applicability of field gamma-ray scintillation spectrometry in geophysical surveys

We discuss the problems and calibration procedures for a portable gamma-ray scintillation spectrometer for determinations of potassium, uranium and th orium concentration in rocks. Particular emphasis was given to the evaluati on of the background radiation. The apparatus was tested in the field at tw o selected areas in NW Italy. We found appropriate sites which could be use d as reference targets to frequently check the gamma-ray equipment. An area formed by serpentinitic rocks showed such a low measured radioactivity tha t it could be used as a reference for the local background effect. An anoma lously high uranium amount against negligible potassium and thorium concent rations were found in outcrops of dolomitic rocks, which can be used to det ect possible changes in the instrument calibration constants. (C) 2000 Else vier Science Ltd. All rights reserved.