Linearisation and control of amplification factor - for nuclear borehole test systems esp. gamma ray energy spectrums

摘要

The energy spectrum of gamma rays produced by constituents of the earth formation surrounding the bore hole is measured and in at least two predetermined energy zones of the gamma ray energy spectrum the number of counting operations on the gamma rays falling within these zones is measured. A signal proportional to the ratio of the counting operations within the two energy zones is produced and the ratio signal compared with at least one constant calibrating signal. An error signal proportional to the difference between the ratio signal and the calibrating signal is produced and is used to control the linearity of the bore hole test system.