Address decoder for use with multichannel analyzers

Abstract

The address scaler outputs of a multichannel analyzer are fed to two comparator circuits in an address decoder, one such address decoder being provided for each energy range of interest in the spectrum of detected gamma rays produced, or occurring, in earth formations surrounding a borehole. The address number from the multichannel analyzer is compared with two numbers preset by switches within the decoder, one group of switches and its associated comparator circuit being determinative of the lower boundary number, and a second group of switches and associated comparator circuit being determinative of the upper boundary number. The outputs from the comparators, one of which is inverted, are AND gated with a STORE pulse from the multichannel analyzer. If the address number from the multichannel analyzer falls within the lower and upper boundary numbers in coincidence with the STORE pulse, an output pulse is generated by the AND gate; otherwise, no output results. The AND gate output is coupled to a count rate meter and recorded. In addition, an intensity enable pulse is generated by a second AND gate having inputs from the two comparator circuits and is coupled back to the multichannel analyzer to allow intensification of the multichannel analyzer oscilloscope readout, thus providing a visual presentation of the region of interest selected by the decoder.