Detector system based on PMT for Measuring Ultraweak Optical Emission from Biocultures
Nikita V. Dunin, Sergey A. Savinov, Timofei E. Demikhov, Sergey N. Mayburov, Eugeny. I. Demikhov, Lebedev Physical Institute, Russian Academy of Sciences, Moscow, Russia
Abstract
Ultraweak optical radiation is characterized by low intensity and time structure of narrow light pulses. When this radiation is detected using photomultiplier tubes (PMTs), there is a problem of separating a single-photoelectron useful signal (a pulse with a width of approximately 2−3 ns) from a single-electron dark current PMT signal.
When a PMT is used, the useful signal from weak optical emission is just the short and narrow pulse that is formed when a single-electron charge passes through the PMT. There is a problem of identifying the useful signal against the background of the PMT dark current and cosmic rays.
A small-sized block for detecting optical bioluminescence in the photon counting mode based on sensitive photomultiplier tubes (PMTs) with a differential discriminator circuit in each PMT channel has been created. A new four-channel detector system has been designed for detection and processing of electromagnetic oscillations generated by microorganisms in the active and resting phases. The characteristics of the optical emission from Saccharomyces boulardii have been investigated.
We designed detector system that selects single-photoelectron pulses. The presence of a built-in selection circuit based on differential discriminators makes it possible to separate single photoelectron pulses from large-amplitude pulses and provide an energy range for each of the four channels of the detector system. Each of the four PMTs can operate
in both the detection and anticoincidence mode. The system is characterized by low power consumption (less than 4 W), a wide aperture, and a 4000-mHz band width.
Speaker
Dunin Nikita
The Lebedev Physical Institute of the Russian Academy of Sciences
Russia
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