DEVELOPMENT OF A PULSE HEIGHT ANALYZER FOR A DOWNHOLE GEOPHYSICAL SPECTROMETRIC GAMMA-RAY LOGGING TOOL
R. Kabiev1, A. Malmakin1, S. Volkovskii1, A. Gribaev1, I. Sharkov1, A. Kulikov1, D. Kirgizov2, E. Asadullin2
1ITMO University, Saint-Petersburg, Russia
2Institute R&D TatNIPIneft, Bugulma, Russia
Keywords: Gamma spectrometer, pulse height analyzer, FPGA, digital signal processing, pulse pile-up, spectrometric gamma logging
Abstract
This paper presents the results of developing a pulse height analyzer for a downhole geophysical instrument intended for spectrometric gamma-ray logging. The module is implemented using a field-programmable gate array and enables real-time signal processing. An algorithm for converting biexponential responses of a scintillation detector into trapezoidal pulses is proposed. The efficiency of the implemented algorithm has been demonstrated in resolving pile-up pulses with a time delay of 300 ns. Using calibrated gamma-ray sources - Am241, Eu152, Cs137, Co60, and Th228 - the system’s energy coverage in the range of 50 to 3000 keV is confirmed. The pulse height analyzer features universal architecture and is compatible with various types of gamma-ray detectors.
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